bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 16816: Plasma Vitamin D Metabolites and Vitamin D Receptor Polymorphisms Are Associated with Risk of Hypertension in Men
Authors: Wang Lu , Ma Jing , Manson JoAnn E , Buring Julie E , Gaziano J. M , Sesso Howard D
Published: April 2024

Introduction:
Laboratory and clinical studies have suggested that inadequate vitamin D may be involved in development of hypertension. However, evidence from epidemiologic studies that support a relation between vitamin D metabolism and signaling pathways and risk of hypertension remains limited.

Hypothesis:
We assessed the hypothesis that plasma vitamin D metabolites, vitamin D receptor (VDR) gene polymorphisms, and their possible interaction are prospectively associated with risk of hypertension in adult men.

Methods:
We conducted analyses among 1207 men in the Physicians' Health Study who were free of hypertension at baseline and had baseline measurements of major vitamin D metabolites (including plasma 25hydroxy-vitamin D (25(OH)D) and 1,25dihydroxy-vitamin D (1,25(OH)
2
D)) and VDR gene polymorphisms (including
Bsm
I and
Fok
I). During 15.3 years of follow-up, 697 out of the 1207 men developed incident hypertension.

Results:
After adjusting for age, race, exercise, smoking status, alcohol use, body mass index, and history of diabetes and hypercholesterolemia, the multivariable hazard ratios (HR) and 95% confidence intervals (CI) of hypertension were 1.00 (reference), 0.96 (0.71-1.31), 0.71 (0.51-0.98), and 0.86 (0.62-1.18) across season-specific quartiles of 25(OH)D (p, trend: 0.53), and 1.00 (reference), 0.88 (0.63-1.21), 1.09 (0.80-1.50), and 1.17 (0.85-1.60) across quartiles of 1,25(OH)
2
D (p, trend: 0.15). Compared with the VDR
Bsm
I bb carriers, the HR of hypertension were 1.27 (1.04-1.55) for the bB carriers and 1.19 (0.90-1.56) for the BB carriers. The risk associated with the VDR
Bsm
I B allele carrier status was particularly strong among men who had 25(OH)D below the median levels (HR: 1.58, 0.98-2.55) but was weaker and not significant among men who had 25(OH)D above the median levels (HR: 1.21, 0.78-1.87)
.
There was no relation of the VDR
Fok
I polymorphism or its interaction with vitamin D metabolites with risk of hypertension.

Conclusions:
In a prospective cohort of US men, plasma concentrations of 25(OH)D but not 1,25(OH)
2
D were inversely associated with risk of hypertension. Men carrying the B allele of VDR
Bsm
I polymorphism had an increased risk of hypertension, particularly among those with low plasma 25(OH)D level.
Abstract 16917: Enodcardial Scar Size Predicts Adverse Outcomes Following Radiofrequency Catheter Ablation in Patients with Recurrent Ventricular Tachycardia
Authors: Peters Matthew , Abutaleb Ameer , Tian Jing , Ahmad Ghada , Jimenez Alejandro , Saliaris Anastasio , See Vincent , Shorofsky Stephen , Dickfeld Timm
Published: April 2024

Introduction:
Sustained Ventricular Tachycardia (VT) often occurs in the setting of structural heart disease and myocardial scar. Little is known about the prognostic value of endocardial scar or border zone after VT ablation.

Methods
48 consecutive ICD patients with structural heart disease and documented VT underwent detailed endocardial voltage mapping (> 200 LV points). Endocardial scar and border zone were defined as < 0.5mV and 0.5-1.5 mV, respectively. Scar burden was defined as the ratio between endocardial scar and total left ventricular (LV) endocardial area, scar + border zone burden as the ratio between scar plus border area divided by LV area. Follow-up was included if ICD clinic notes or interrogations could be obtained at < 6 month intervals. VT recurrence (VTR) was defined as any VT >30s or causing appropriate ICD shocks. Mortality was determined using the Social Security Database.

Results:
All patients (46 male, age 62+12.18; 81% CAD; EF 26.39+12.47) underwent clinically indicated VT ablation with a mean follow-up of 31.5±8.7 months. A scar burden of >10% was associated with a higher rate of first VT recurrence (VTR) with 1.9, 1.5,and 1.2 fold increases seen at 12, 24 and 36 moths, respectively. Similarly, a scar+border zone burden of >25% resulted in 2.0, 1.6 and 1.2 fold increases of VTR at 12, 24 and 36 months, respectively. A scar burden of >10%was also associated with a 4.0, 3.7 and 3.9 fold increase in mortality at 12, 24 and 36 months, respectively. Similarly, a scar+border zone burden of >25% was associated with a 6.0, 3.8 and 3.8 fold increase in mortality at 12, 24 and 36 months, respectively.

Conclusions:
Large myocardial scar/border zone substrate correlates with earlier recurrence of VT and higher long-term mortality after VT ablation. This finding may allow for more refined risk stratification and guide an individualized pharmacologic/ablation-based approach to VT.
Abstract 16936: Vitamin D Supplementation Lowers Blood Pressure and Improves Control Rates in a Predominantly African American Hypertensive Cohort
Authors: Ference Brian A , Nasser Samar A , Levy Phillip D , Zhang Shiling , Singh Manmeet , Hedquist Lowell A , Flack John M
Published: April 2024

Background:
Vitamin D deficiency, highly prevalent in African Americans, has been associated with elevated blood pressure (BP) and hypertension in epidemiological studies. However, vitamin D supplementation has not been shown to consistently lower BP.

Methods:
Six hundred forty eight hypertensive patients with vitamin D blood levels and BP above JNC goal levels, with at least one follow-up visit, were followed a median of 10.6 months (5 clinic visits). At baseline, mean age was 56.5 years, mean BP 156/92 mm Hg, (mean of 22.3/8.8 mm Hg above JNC BP goal), mean vitamin D level 17.6 ng/ml; 67.2% were women and 87.7% were African American. Mixed effects general linear models were used to estimate longitudinal BP changes. Cox proportional hazards models were used to estimate the impact of vitamin D supplementation on first attainment of JNC goal BP. Repeated event proportional hazards analysis was utilized to determine the incremental (per 1 category higher of vitamin D supplementation) likelihood of attainment of JNC goal BP during follow-up. Models were adjusted for age, sex, initial BP level, baseline vitamin D level (< 15, > 15 ng/ml), antihypertensive drug therapeutic intensity, and vitamin D supplementation (0 = no vitamin D, 1 = < 2000 IU/d, 2 = > 2000 IU/d); the latter two variables were entered into the models as time-varying covariates.

Results:
Relative to no vitamin D supplementation, longitudinal SBP change was - 3.9 (p = 0.0089) and - 10.7 mm Hg (p = 0.0003) greater at incrementally higher vitamin D supplementation; DBP change was -2.5 (p = 0.0042) and - 7.0 mm Hg (p < 0.0001) greater. Per 1 category higher vitamin D supplementation, there was no effect on first attainment of goal SBP HR = 1.15, 95% CI 0.94 - 1.39. However, first time DBP control was favorably impacted - HR = 1.28, 95% CI 1.09 - 1.50. Repeated events proportional hazards analysis showed greater BP control per 1 category higher vitamin D supplementation (SBP goal HR = 1.32, 95% CI 1.21 - 1.44; DBP goal HR =1.30, 95% CI 1.20 - 1.41).

Conclusion:
Vitamin D supplementation appears to lower BP and improve BP control rates independent of the intensity of antihypertensive treatment in a dose-dependent manner. The BP lowering effect is, however, most pronounced at > 2000 IU/d.
Abstract 16937: Age at Genetic Testing is Negatively Correlated with the Number of Mutations Found in Five Cardiac Channelopathies and Cardiomyopathies
Authors: Salisbury Benjamin A , Callis Thomas E , Carr Janet L , Susswein Lisa , Pollevick Guido D
Published: April 2024

INTRODUCTION:
Although dominantly inherited diseases are defined as being caused by a single mutant gene copy, other factors can affect disease expression. Here we examined the relationship between mutation count and age at genetic testing across five autosomal dominant cardiac diseases.

METHODS:
We examined data for 2596 probands referred for genetic testing for arrhythmogenic right ventricular cardiomyopathy (ARVC), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), hypertrophic cardiomyopathy (HCM), or long QT syndrome (LQTS). Age at testing was used as a clinical correlate of age of onset. Mutations were categorized as either class I (definite or probable pathogenic) or class II (variant of uncertain significance).

RESULTS:
Among mutation-positive patients, 12% had two mutations and 1% had three; these two percentages were similar across all diseases, although the overall positive rate varied considerably. In all five diseases, age at testing was lower for positive than negative probands, and even lower for those with two mutations. In three out of the four diseases where at least one patient had three mutations, those patients were even younger. While differing by disease, the average age drop from 0 mutations to 1 was 3.5 years (p=0.00013) and from 1 mutation to 2 was 5.2 years (p=0.012). The patterns held when restricting to either class I or II mutations.

CONCLUSIONS:
This study found a remarkable 12% multiple-hit rate across five so-called autosomal dominant diseases and identified a correlation between mutation count and age at testing. This correlation may have multiple explanations: First, each mutation may contribute to disease severity or onset. Second, “more mutations” may reflect a higher probability that at least one is deleterious and that the patient indeed has the disease. Overall, the results point to a complexity that must continue to be explored as science and medicine grapple with the genetics of disease.
Abstract 16941: The Role of the PERK-Mediated Unfolded Protein Response Pathway in the Regulation of Cardiac Sodium Channel During Human Heart Failure
Authors: Gao Ge , Xie An , Jeong Euy-Myoung , Gu Lianzhi , Dudley Samuel C
Published: April 2024

Background:
The unfolded protein response (UPR) is a series of interrelated signaling pathways that occur when the endoplasmic reticulum (ER) experiences excess secretory load, accumulates misfolded proteins, or is subject to other pathological conditions. UPR acts to attenuating general protein synthesis, induces the expression of ER chaperone proteins, and enhances the degradation of misfolded proteins. In published work, we have shown that heart failure (HF) increases alternative splicing of the SCN5A gene (encoding cardiac Na
+
channel), generating mRNA variants E28C and E28D encoding truncated, nonfunctional Na
+
channel. The presence of these variants causes a dominant negative downregulation of the wild-type SCN5A mRNA and Na
+
current to a sufficient extent to be arrhythmogenic. We tested whether PERK-mediated UPR contributed to the dominant negative effect on Na
+
current when truncated Na
+
channel mRNA variants are present in HF.

Methods:
The correlation of expression changes among PERK, major chaperon proteins (calnexin, CHOP) and SCN5A were analyzed by both qPCR and Western Blot in human HF tissue samples and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). Hypoxia and Ang II were used as inducers of abnormal splicing since they have been shown to mediate some of the pathological consequences of HF. hESC-CMs were divided into six experimental groups: normoxic, 1% O
2
hypoxia-treated, 100 nmol/L Ang II-treated, E28C overexpressed, E28D overexpressed, and empty vector control. E28C and E28D constructs were transduced to overexpress the truncated proteins.

Results:
The expressions of major UPR components (PERK, calnexin, CHOP) were increased in HF tissues, and cardiac Na
+
channels were downregulated. In hESC-CMs, induction of SCN5A variants E28C and E28D with Ang II or hypoxia as well as expression of exogenous variants could induce major UPR components (PERK, calnexin, CHOP). Finally, downregulation of PERK prevented the loss of full-length SCN5A mRNA abundance with these stimuli.

Conclusions:
SCN5A variants could induce the expression of major UPR components and could induce PERK-mediated Na
+
channel downregulation. The results indicate that the UPR contributes to Na
+
channel regulation during human HF.
Abstract 16945: Role of Thromboxane A
2
-Activated Nonselective Cation Channels in Hypoxic Pulmonary Vasoconstriction of Rat
Authors: Yoo Hae Young , Park Su Jung , Zeifman Amy , Earm Yung E , Yuan Jason X , Kim Sung Joon
Published: April 2024

Hypoxia-induced pulmonary vasoconstriction (HPV) is a physiological mechanism responsible for controlling the ventilation-perfusion ratio in the lungs. Maintenance of the ventilation-perfusion ratio at 0.8-1 is critical for the optimization and maximization of gas exchange in the lung. Inhibition of K
+
channels has been shown to be a mechanism for hypoxia-induced membrane depolarization in pulmonary arterial smooth muscle cells (PASMCs). Pharmacological inhibition of K
+
channels, however, does not induce significant contraction in isolated rat pulmonary arteries, but significantly enhances HPV. These results suggest that, in addition to K
+
channel inhibition, other mechanisms are involved in hypoxia-induced membrane depolarization. We recently found that a partial contraction by thromboxane A
2
(TXA
2
) is required to induce HPV. Therefore we hypothesize that TXA
2
receptor (TP) stimulation is involved in eliciting membrane polarization by activating nonselective cation (NSC) channels. Consistently, we found that 5-10 nM U46619, a stable agonist of TP, was essential for the contraction of isolated rat pulmonary arteries by 4-aminopyridine, a blocker of voltage-gated K
+
channel (Kv). Whole-cell voltage clamp experiments with rat PASMCs revealed that U46619 induced a weakly outward-rectifying NSC current (I
NSC,TXA2
), which was blocked by ruthenium red (RR), an antagonist of the transient receptor potential vanilloid (TRPV) subfamily. In addition, 2-aminoethoxydiphenyl borate, an agonist for TRPV1-3, activated NSC channels. In contrast, agonists for TRPV1 (capsaicin), TRPV3 (camphor), or TRPV4 (4α-PDD) rarely increased the membrane conductance. RT-PCR analysis showed the expression of transcripts for TRPV2 and TRPV4 in rat PASMCs. Finally, it was confirmed that the pretreatment with RR and tranilast (a TRPV2 inhibitor) both significantly inhibited HPV in the presence of U46619. Taken together, these data suggest that the concerted effects of I
NSC,TXA2
increase and Kv inhibition during under hypoxia are required to induce membrane depolarization sufficient for eliciting HPV. Our results also imply that TXA
2
-activated NSC might be formed by TRPV2 in rat PASMCs and contribute to the hypoxia-induced membrane depolarization in PASMCs.
Abstract 16964: SCN5A Splice Variant Potentiates Dysfunction of a Novel LQT3 Mutation Associated with Life-threatening Arrhythmia in a 19 Week Fetus
Authors: Murphy Lisa , Moon-Grady Anita , Cuneo Bettina , Wakai Ronald , Yu Suhong , Kunic Jennifer , Benson D W , George Alfred L
Published: April 2024

BACKGROUND:
Inherited arrhythmia susceptibility such as the congenital long-QT syndrome (LQTS) can contribute to infant mortality, but the biological basis for LQTS presenting in utero is poorly understood. The purpose of this study was to elucidate the molecular genetic and pathophysiologic basis for LQTS and torsade de pointes in a fetus presenting at 19-weeks gestation, the earliest known presentation of this disease.

METHODS:
Molecular genetic studies of an affected fetus demonstrated a de novo SCN5A mutation. To elucidate the functional consequences of the mutation, in vitro electrophysiological studies were conducted on wild type (WT) and mutant human cardiac sodium channels in the canonical channel and in an alternatively spliced form expressed in fetal heart.

RESULTS:
A fetus presented at 19-6/7 weeks with episodes of ventricular ectopy that progressed to incessant ventricular tachycardia and hydrops fetalis. Family history did not suggest inherited arrhythmia susceptibility, but fetal magnetocardiography demonstrated torsade de pointes and a prolonged rate-corrected QT interval (604 ms). Genetic analysis following pregnancy termination disclosed a novel, de novo heterozygous SCN5A mutation (L409P) and homozygosity for the common SCN5A variant H558R. In vitro studies demonstrated that the mutation in combination with R558 causes significant depolarized shifts in voltage-dependence of steady-state inactivation and activation, accelerated recovery from inactivation and a 7-fold increase in persistent current (1.4% of peak current vs 0.2% for WT). However, when the mutation was expressed in the background of a fetal-expressed SCN5A transcript, channel dysfunction was potentiated with a marked increase in persistent current (11% of peak current) and greater shifts in voltage-dependence. Also, R558 alone in the fetal splice variant evoked a large increased persistent current (3.7% of peak current), hence both alleles were dysfunctional.

CONCLUSION:
Fetal LQTS may present as early as 19 weeks gestation. The functional effects of certain SCN5A mutations and variants may be magnified by alternative splicing events during fetal development helping to explain the unusual clinical severity of LQT3 in this setting.
Abstract 16998: Ventricular Systolic and Diastolic Dyssynchrony and Their Relationship with Ventricular Function in Patients with Single Ventricular Circulation
Authors: Seki Mitsuru , Saiki Hirofumi , Masutani Satoshi , Senzaki Hideaki
Published: April 2024

BACKGROUND:
Recent studies highlighted importance of ventricular diastolic dyssynchrony as well as systolic dyssynchrony in the pathophysiology of adult heart failure. However, little is known about interaction between diastolic and systolic dyssynchrony and their impacts on ventricular function in pediatric patients with single ventricular circulation.

METHODS:
We studied 24 pediatric patients (mean age; 2.1±1.3 years) with single ventricular circulation and 12 age-matched control subjects. Transthoracic two-demensional speckle tracking echocardiography (Vivid 7, GE) was performed to assess ventricular dyssynchrony (EchoPac workstation, GE). Systolic and diastolic dyssynchrony was measured as a maximal time delay in peak systolic and early diastolic velocities of longitudinal strain at four segments. Comprehensive ventricular systolic and diastolic function was assessed by employing pressure-area relationships during preload varied by transient inferior vena caval balloon obstruction.

RESULTS:
Systolic and diastolic time delay were 31.8±14.5 ms and 29.2±14.6 ms respectively in single ventricular patients, and were significantly larger than in the controls (16.2±11.9 ms for systolic and 15.8±11.2 ms for diastolic, both p<0.01). There was no significant correlation between systolic and diastolic dyssynchrony in the patient group. Systolic dyssynchrony was negatively correlated with ventricular contractility indexes of end-systolic elastance (r=0.34, p<0.05) and maximum rate of pressure rise (r=0.585, p<0.05). Diastolic dyssynchrony was positively correlated with end-diastolic pressure (r=0.719, p<0.05), but not with time constant of ventricular relaxation.

CONCLUSIONS:
Not only systolic but also diastolic dyssynchrony has important impacts on ventricular function in patients with single ventricular circulation. These data suggest important notion that diastolic as well as systolic dyssynchrony is an important therapeutic target when considering cardiac resynchronization therapy for patients with single ventricular circulation.
Abstract 170: Theoretical Model for Weighting Chest Compression Fraction During Cardiopulmonary Resuscitation
Authors: Salcido David , Menegazzi James J
Published: April 2024

Background:
The quality of cardiopulmonary resuscitation (CPR) is often measured by the metric of chest compression fraction, which has been associated with survival to hospital discharge. However, this metric may not provide the optimum information when analyzing the relationship between CPR quality and its effectiveness.

Objective:
We sought to demonstrate that a simple mathematical model that weights chest compression fraction by the chest compression rate would provide more textured and detailed information about CPR quality, with results that are disparate from unweighted measures.

Methods:
Using a hypothetical bout of CPR, we weighted the chest compression fraction by the chest compression rate (in beats/minute), incorporating periods of no CPR during which a patient might be moved or undergoing airway management. Different chest compression rates could represent different rescuers, or rescuer fatigue. These data can be captured with current defibrillator/monitor technologies.

Results:
Hypothetical Example: Consider a 16-minute period of resuscitation. Minutes 1-2: No chest compressions (2 min) Minutes 3-6: chest compressions (4 min) @ 100/min (Weight = 1) Minutes 7-8: No chest compressions (2 min) Minutes 9-11: chest compressions (3 min) @ 50 / min (Weight = 0.5) Minutes 12-13: No chest compressions (2 min) Minutes 14-16: chest compressions (3 min) @ 75 / min (Weight = 0.75) Chest compression Fraction = (4+3+3) / (2 + 4 + 2 + 3 + 2 + 3) = 0.63 Weighted Chest Compression Fraction = (4*1 + 3*0.5 + 3*0.75) / (2 + 4 + 2 + 3 + 2 + 3) = 0.48

Conclusion:
In this theoretical example, the simple chest compression fraction (0.63) may overestimate the true quality of the CPR performed. The weighted measure value (0.48) may be a better indicator of the true quality of the CPR and may be useful in further differentiating CPR metrics.
Abstract 17022: Non-High Density Lipoprotein Cholesterol in Incident and Progression of Coronary Artery Calcium
Authors: Veeranna Vikas , Zalawadiya Sandip , Niraj Ashutosh , Ramesh Krithi , Panaich Sidakpal , Kommuri Naga , Afonso Luis
Published: April 2024

Background
Non-High density lipoprotein cholesterol (non-HDLc) is an independent predictor of cardiovascular (CVD) risk, with elevated levels signifying an increased risk beyond low density lipoprotein (LDL) . We sought to evaluate the association between non-HDL c and development (incident) and progression of coronary artery calcium (CAC) in multi-ethnic asymptomatic individuals.

Methods
The study cohort was derived from the limited access dataset of the Multi Ethnic Study of Atherosclerosis obtained from the National Heart Lung and Blood Institute. The cohorts for incident CAC as well as CAC progression included 2778 subjects with a median follow-up of 2.4 ± 0.8 years. Multivariable regression analysis was performed to derive the association between non-HDL c and incident CAC and non-HDLc and progression of CAC.

Results
In population without CAC at baseline, non-HDL c, especially > 200mg/dl, was an independent predictor of incident CAC in the overall population and in both the genders beyond the traditional risk factors including for age, sex, race, systolic blood pressure, anti-hypertension medications use, smoking status, diabetes, lipid lowering therapy use, follow-up duration and waist-hip ratio. (Table 1) Similarly, in those with CAC at baseline, non-HDLc levels >200mg/dl was associated with significant CAC progression in overall population and in both the genders upon similar adjustments.(Table 2)

Conclusion
Non-HDLc, especially >200mg/dl, is associated with increased risk of incident CAC as well as progression of CAC in a multi-ethnic cohort of individuals without any CVD. Non-HDLc provides a second measure of atherogenic risk ad progression beyond LDL.
Abstract 17038: Long-Acting Phosphodiesterase-5 Inhibitor Tadalafil Attenuates Oxidative Stress and Protects Against Myocardial Ischemia/Reperfusion Injury in Type 2 Diabetic Mice
Authors: Koka Saisudha , Das Anindita , Salloum Fadi N , Kukreja Rakesh C
Published: April 2024

Background:
Diabetic patients exhibit increased risk for the development of cardiovascular diseases. Recent findings from our laboratory suggest that phosphodiesterase-5 (PDE-5) inhibitor, sildenafil, restores NO signaling and protects against ischemia/reperfusion injury. In this study, we determined the effect of long-acting PDE-5 inhibitor, tadalafil (TAD), on type 2 diabetes associated complications in db/db mice.

Methods and Results:
Adult male db/db mice (n=24/group) were randomized to receive: DMSO (10%, 0.2 ml, i.p.) or TAD (1 mg/kg, i.p) for 28 days. The mice were sacrificed and blood was collected for assessment of biochemical parameters. Cardiomyocytes were isolated from the hearts and subjected to 40 min simulated ischemia followed by 1 h of reoxygenation. Dichlorodihydrofluorescein diacetate and JC-1 staining were used to measure ROS generation and mitochondrial membrane potential (Δψm), respectively. A second subset of mice hearts were subjected to 30 min global ischemia followed by 60 min reperfusion in Langendorff mode. Infarct size was measured using computer morphometry of tetrazolium stained sections. A third subset of mice hearts were used for the estimation of lipid peroxidation, GSSH/GSH and the expression of myocardial pAKT and pAMPK by Western blot. TAD treatment reduced the body weight (48.5±1.5 g vs 51.9±1.3 g), fasting plasma glucose levels (466.1±41.4 mg/dl vs 567.7±29.7 mg/dl), insulin (2.97±0.67 ng/ml vs 14.42±3.15 ng/ml; p<0.02) and triglycerides (91.2±12.3 mg/dl vs 190.5±38.5 mg/dl; p<0.05) as compared to control db/db mice. TAD-treated mice also showed reduced infarct size compared to the control db/db mice (21.2±1.8% vs 45.8±2.8%; p<0.01). Control db/db mice demonstrated enhanced oxidative stress as indicated by significantly increased ROS production, lipid peroxidation and GSSH/GSH ratio which were attenuated in TAD-treated mice. Furthermore, TAD treatment preserved the loss of Δψm and enhanced the expression of myocardial pAKT and pAMPK compared to the control (n=4/group; p<0.05).

Conclusion:
Chronic treatment with TAD attenuates oxidative stress and improves mitochondrial integrity while providing powerful cardioprotective effects through Akt-AMPK signaling in type 2 diabetes.
Abstract 17075: Preferential Targeting of Bnip3 Isoforms to Mitochondria or Endoplasmic Reticulum During Metabolic Stress Promotes Autophagy or Cell Survival of Post-Natal Ventricular Myocytes
Authors: Gordon Joseph W , Wang Yan , Hai Yan , Dhingra Rimpy , Gang Hongying , Kirshenbaum Lorrie A
Published: April 2024

Autophagy is an evolutionary conserved process that allows cells to recycle or discard macromolecular constituents or damaged organelles during times of metabolic crisis. Alternative mRNA splicing is a versatile mechanism by which cells generate proteins with different or even antagonistic properties. Herein, we show that inclusion or skipping of exon3 of Bnip3 mRNA generates proteins with distinct and opposing actions on autophagy and cell survival. Metabolic stress imposed by hypoxia or nutrient deprivation resulted in the synthesis of two Bnip3 mRNA isoforms in post-natal ventricular myocytes in vitro and in vivo. Notably, one Bnip3 mRNA comprised of exons 1 through 6 encoded a protein of 26kDa, while a second mRNA generated by the fusion of exon2 and exon4 encoded a truncated Bnip3 protein of 8.2kDa. Sequence analysis revealed the truncated isoform encodes a conserved C-terminus domain that exclusively targets Bnip3 to the endoplasmic reticulum (ER) and not mitochondrion. While the 26kDa Bnip3 induced mitochondrial perturbations and autophagy, the spliced isoform suppressed Bnip3 induced mitochondrial defects and autophagy. Interestingly switching from glucose to fatty metabolism by supplementing nutrient deprived ventricular myocytes with carnitine but not pyruvate preferentially accumulated the spliced isoform of Bnip3 and the association of Bcl-2/Beclin-1 complexes at the ER, while suppressing autophagy. Furthermore, C-terminal domain mutations of the spliced variant defective for ER targeting sensitized cardiac myocytes to mitochondrial perturbations and apoptosis. To our knowledge our data provide the first direct evidence for a novel survival mechanism whereby the metabolic status of the cell programs autophagy or apoptosis by preferentially targeting Bnip3 isoforms to mitochondria or ER during metabolic stress.
Abstract 17081: Risk Factors for Developing Takotsubo Cardiomyopathy
Authors: Deshmukh Abhishek , Kumar Gagan , Dibu George , Raina Sameer , Gobal Freij , Rihal Chiranjit , Mehta Jawahar L
Published: April 2024

Background:
Takotsubo cardiomyopathy (TTC) has emerged as a new clinical entity which has not been fully understood. Numerous case reports exist regarding association of TTC with high adrenergic state conditions like Pheochromocytoma. Our aim was to explore the association of common medical conditions with TTC.

Methods:
This was a cross sectional study using the National Inpatient Sample (NIS) 2007 database.TTC or Broken heart syndrome or Reversible left ventricular dysfunction following sudden emotional stress or Stress induced cardiomyopathy or Transient left ventricular apical ballooning syndrome was defined as patients discharged with any ICD code of 429.83 (
http://www.cdc.gov/nchs/data/icd9/agendasept05.pdf
). The common medical conditions were identified by appropriate ICD 9 codes

Results:
We indentified total 6229 discharges with any discharge diagnosis of TTC. The likelihood of common medical conditions with TTC is shown in Table 1.

Conclusions:
This is the first study to explore the association of common medical conditions associated with TTC on a nationwide basis. We conclude that the patient with hyperlipidemia, smoking, pulmonary hypertension, sub arachnoid hemorrhage, migraine, hyperthyroidism, collagen vascular diseases, anxiety state, and stress have higher odds of developing TTC. Further research needs to be done for better understanding the causes and pathophysiology of TTC which in turn will help risk stratification and define optimal therapy.
Abstract 17082: Hematocrit Significantly Affects the Results of the Verifynow Assay in Patients Receiving Dual Antiplatelet Therapy
Authors: Kakouros Nikolaos , Kickler Thomas S , Laws Katherine , Rade Jeffrey J
Published: April 2024

Background:
A number of assays have evolved to assess platelet reactivity and identify patients on dual antiplatelet therapy who remain at risk of thrombotic events. The goal of this study was to assess how a number of these assays are affected by clinical and hematological factors.

Methods:
We prospectively recruited patients with known vascular disease or risk factors presenting for coronary catheterization and assessed platelet reactivity at baseline and after clopidogrel loading using the VerifyNow P2Y12 assay, Platelet Function Analyzer (PFA-100):Collagen/Epinephrine(Col/Epi), PFA-100:Collagen/ADP(Col/ADP), and platelet aggregometry with 5μ M, 10μ M and 20μ M ADP agonists. Univariate and multivariate regression models were developed to identify clinical and laboratory factors affecting the assays.

Results:
Of 198 patients who entered the study 79 patients were excluded due to intraprocedural use of GPIIb/IIIa antagonists or lack of repeat blood sample. Fifty-five patients underwent coronary intervention. Plasma vonWillebrand factor antigen (vWFAg) levels were a significant univariate predictor of PFA-100:Col/Epi (p=0.002) but not Col/ADP closure times. VerifyNow base and platelet reactivity results (PRU) both prior to and after clopidogrel load had a strong negative correlation with hematocrit (p<0.0001, p=0.0004) as did impedance and light aggregometry. Hematocrit remained the only strong predictor of post-Clopidogrel VerifyNow result in multivariate analysis modeling (p=0.001).

Conclusions:
Plasma vWFAg levels significantly affect the PFA-100:Col/Epi assay. In contrast to prior small validation studies, performed in normal individuals, we found hematocrit level to have a strong negative correlation with VerifyNow results in this cohort of patients. It is unclear whether the observed correlation is due to truly increased in vivo platelet reactivity in anemic patients or an in vitro phenomenon inherent to the VerifyNow system.
Abstract 17083: Progress and Paradox in the Real World Penetration of Percutaneous Coronary Intervention for Treatment of ST-Elevation Myocardial Infarction
Authors: Pathak Elizabeth B , Forsyth Colin J , Strom Joel A
Published: April 2024

Background:
Much of the surveillance data on the use of percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI) comes from patient registries with voluntary hospital participation or from Medicare data. Non-PCI capable hospitals are significantly underrepresented in registry data, and large hospitals are over-represented; consequently registry data is likely to signficantly overestimate the use of PCI in STEMI on a true population basis. Medicare data are more comprehensive, but include only the elderly population. In this study, we used an unselected population-based hospital surveillance system to investigate temporal trends in the use of PCI for STEMI in Florida from 2001-2009. Florida is the 4th largest state with over 18 million persons.

Methods:
We used statewide hospital discharge data, including detailed diagnosis and procedure codes to identify STEMI patients who did vs. did not receive same-day PCI. We created county maps for 2001, 2003, 2005, 2007, and 2009 to observe geographic disparities in the use of primary PCI. Data for over 100,000 STEMI patients were analyzed.

Results:
Statewide, same-day PCI for STEMI increased from 23.4% in 2001 to 63.5% in 2009. County-level maps revealed marked and persistent geographic disparities. In 2009, some major metropolitan areas fell below the state average, while some small rural counties had >80% of STEMI patients receiving PCI. Small urban counties with one non-PCI providing hospital had lower rates than many rural counties with no hospital. Counties with only one high-volume PCI center had the highest rates of primary PCI.

Conclusions:
Few studies have reported population-based rates of primary PCI usage. We found significant progress in the use of same-day PCI from 2001 to 2009 in Florida, but also paradox with some major metropolitan areas lagging behind smaller urban and rural areas. Rural counties adjacent to major metro areas with high-volume PCI centers had high rates of PCI usage. In contrast, major metro areas with many hospitals had average or below average usage rates. Our results suggest that excessive hospital competition creates barriers for STEMI patients to receive primary PCI.
Abstract 17111: Temporal Trends in the Incidence of Heart Failure and its Risk Factors
Authors: Velagaleti Raghava , McLaughlin-Gavin Cara , Gaziano John M , Djousse Luc
Published: April 2024

Background:
It has been proposed that the rising population burden of cardiovascular risk factors is driving an epidemic of heart failure (HF). However, few studies have simultaneously examined the secular trends in heart failure and its risk factors.

Methods:
In 22067 male participants (mean age 55 years) of the Physician's Health Study I, we examined secular trends for diabetes, hypertension, hyperlipidemia, myocardial infarction (MI) and HF between years 1984 and 2004. We used Cox proportional hazards models to estimate the risk for occurrence of each condition in time periods 1989-1993, 1994-1998 and 1999-2004 using 1984-1988 as the referent period.

Results:
Over the 4 time periods, we observed an increase in the incidence of diabetes, hypertension, and hyperlipidemia (
Table
). After adjustment for age and covariates, there was a graded increase in the risk for diabetes, hypertension and hyperlipidemia in the latter time-periods compared to the referent period (
Table
). In contrast, we noted a statistically significant decreased risk for MI occurrence in the later time-periods, compared to the referent period. However, the incidence of HF increased over the 4 time-periods we evaluated, an effect that was largely accounted for by age and changing prevalence of other factors (
Table
).

Conclusion:
Although there has been a significant decrease in MI risk over the past three decades, the incidence of HF has increased in parallel to increase in diabetes, hypertension and hyperlipidemia incidence, suggesting that these conditions may be driving the HF epidemic.

Footnotes for Table:
PY = person years; HR = Hazards ratio; CI = confidence interval Cox model adjusted for * age, hypertension, smoking, body-mass index (BMI) and treatment arm (ASA) † age, diabetes, smoking, BMI and ASA ‡ age, diabetes, smoking, BMI, alcohol use and ASA § age, diabetes, hypertension, smoking, BMI, ASA and HF ¥ age, diabetes, hypertension, smoking, BMI, ASA and prevalent and incident MI.
Abstract 17126: Tackling Cardiovascular Disease Risk in Primary Care: Does Sex Matter?
Authors: Cox Jafna L , Szpilfogel Claudine C , Andreou Pantelis , Vallis Terrance M , Carr Brendan S , O'Neill Blair J
Published: April 2024

Purpose:
To ascertain whether men and women respond differently to an intervention intended to decrease cardiovascular disease (CVD) risk in primary care (PC) through individualized systematic risk factor screening, risk-weighted behavioral counseling and pharmacological treatment.

Methods:
We studied two geographically diverse PC practices in Nova Scotia, Canada, with differing reimbursement models vs a comparison group. Patients completed a health risk assessment (HRA) and readiness to change assessment that triggered an intervention individualized around both parameters with 1-year follow-up and a final HRA. The primary endpoint was the proportion of subjects with moderate and high baseline 10-year Framingham Risk Scores reducing risk by 10% and 25%, respectively. Sex-differences in response to the intervention were explored.

Results:
1509 intervention patients enrolled; 72% completed the study. Results are presented for 561 subjects with moderate or high baseline Framingham risk but no diabetes or established CVD. Mean age was 55.4 years; 57.8% were female. 43% vs 31% controls achieved the primary endpoint (p=0.06, ARR = 12%, RRR = 38%, NNT=9). Females (ARR=15%, RRR=46%, NNT= 7) did better than males (ARR=5.2%, RRR=17.2%, NNT=20). When comparing sexes, there was significantly greater reduction in systolic blood pressure (p< 0.001) and a higher increase in HDL cholesterol (p=0.04) for females. Significantly more (p < 0.0001) females changed their metabolic syndrome status (prevalence 93.5% vs 58.6% pre and post intervention, respectively) vs. males (59.5% vs. 46.8% pre and post intervention, respectively). The specific metabolic syndrome risk factors that drove the difference included waist circumference (p <0.0001), HDL cholesterol (p=0.03) and blood pressure (p=0.04). These results were obtained largely through lifestyle modification; drug use did not change significantly.

Conclusion:
In an intervention to improve CVD risk in primary care, women did better than men. Differences were seen especially around improved metabolic risk, predominantly as a result of lifestyle change. These findings suggest that prevention programs may need to modify their approaches according to patient sex.
Abstract 17196: An Improved Equation for Estimation of LDL Cholesterol in European and African American Adults
Authors: Wang Harrison , Becker Diane M , Vaidya Dhananjay , Moy Taryn F , Yanek Lisa R , Kral Brian G
Published: April 2024

Introduction:
The Friedewald equation (FE) has been the US standard for estimating LDL-cholesterol (LDL-C) levels when direct measures are not available, but loses accuracy at triglyceride (TG) levels ≥400 mg/dL. A new formula (Chen et al) has been shown to more accurately estimate LDL-C across the range of TG, including values ≥400 mg/dL in a Chinese population. We tested the new Chen formula (CF) and the FE against LDL-C measured by NMR spectroscopy in European (EA) and African American (AA) adults.

Methods and Results:
The sample consisted of 937 apparently healthy subjects ages 31 to 75 years (51.3 ± 8.1 years; 58.3% female; 47.2 EA, 52.8 % AA). Blood was obtained in fasting subjects and total cholesterol (TC), HDL cholesterol (HDL-C), and TG were measured using standard enzymatic methods; LDL-C was estimated using both the FE, [(LDL-C)=(TC)-(HDL-C)-(TG/5)], and the CF [(LDL-C)=0.9[(TC)-(HDL-C)] - 0.1(TG)]. LDL-C was also measured directly using proton NMR spectroscopy (NMR) as the reference standard. Overall mean LDL-C was 130.2 ± 40.mg/dL 1 for FE and 128.6 ± 36.5 mg/dL for CF, p=<0.0001 for correlation (r2= 0.95). The % error for each the FE and CF against NMR LDL-C is plotted against TG levels (log) in the Figure. The FE underestimates NMR LDL-C as TG increases, (beta -1.6% error per 10% higher TG), whereas the CF only slightly overestimates NMR LDL-C at higher values of TG (beta 0.5% error per 10% higher TG) and remains accurate at levels ≥400 mg/dL.

Conclusion:
The CF more accurately estimates LDL-C compared with the FF across all TG values and remains accurate for levels ≥400 mg/dL in both races. Thus, the Chen formula may offer improved LDL-C estimation utility in African American and European American adults, particularly for TG levels ≥400 mg/dL, when direct measurement of LDL-C is not accessible or cost prohibitive. Figure: Friedewald Equation and Chen Formula Estimates of LDL-C Across TG Levels
Abstract 17278: The Cardiac Channel Molecular Autopsy for Structurally Normal Heart Sudden Unexplained Death
Authors: Tester David J , Medeiros-Domingo Argelia , Will Melissa L , Ackerman Michael J
Published: April 2024

Background:
Potentially lethal syndromes such as long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) may account for a significant number of autopsy-negative sudden unexplained deaths (SUD). Here, the spectrum and prevalence of putative LQTS-/CPVT-causative mutations in autopsy- negative SUD was determined following a cardiac channel molecular autopsy.

Methods:
From September 1998 to October 2010, 173 cases of SUD (106 males, 18 ± 13 years, 89% white) were referred by Medical Examiners/Coroners for a cardiac channel molecular autopsy. Using PCR, DHPLC, and DNA sequencing, a comprehensive mutational analysis of the LQTS-susceptibility genes (
KCNQ1
,
KCNH2
,
SCN5A, KCNE1,
and
KCNE2
) and a targeted analysis of the CPVT1-associated gene (
RYR2
) was conducted.

Results:
Overall, 45 putative pathogenic mutations (20
RYR2
, 11
KCNQ1
, 6
KCNH2
, 6
SCN5A
, and 2
KCNE2
, absent in 400 - 700 controls, were identified in 45 (26%) autopsy negative SUD cases. The yield was greatest for those with an exercise-induced death (16/46, 35%) or a positive personal/family history of a syncope (13/25, 52%), or sudden death (9/20, 45%). Females had a higher yield (26/67, 39%) than males (19/106, 18%, p < 0.005) especially if the SUD was during adolescence (12/25, 48% females vs. 9/50, 18% males). Females were more likely to have LQTS-associated mutations (65%) while males were more likely to have CPVT1-associated mutations (58%). Among SUD victims with exercise-induced death, the yield was much higher among the 1 - 10 year olds compared to the 11 -20 year olds (females, 71% vs 14%, p<0.05; males, 60% vs 15%, p = 0.07). However for those with death during a period of sleep, the 11 - 20 year olds had a much higher yield than the 1-10 year old group (females, 75% vs 0%, p<0.01; males 18% vs 6%).

Conclusions:
Over one-fourth of autopsy-negative SUD may stem from LQTS and CPVT. A cardiac channel molecular autopsy should be considered as a standard part of the evaluation of autopsy-negative SUD especially among children with exercise-induced SUD, adolescent females, and those with a positive personal/family history of cardiac events. A two-tiered approach starting with the LQTS-susceptibility genes in females and the CPVT-susceptibility genes in males may be prudent.
Abstract 17292: Long QT Syndrome Variant 3 Patient Derived Induced Pluripotent Stem Cells: Novel and Critical Platform for Drug Screening
Authors: Terrenoire Cecile , Wang George K , Keller Gordon , Kotton Darrell N , Kass Robert S
Published: April 2024

Congenital LQTS is a heritable family of arrhythmias caused by mutations in 12 genes coding for ion channels or ion channel associated proteins. Variant 3 (LQT-3) is caused by mutations in SCN5A, the gene coding for the α subunit of the primary cardiac Na+ channel. Based primarily on studies in heterologous expression systems, a mutation-specific pharmacology has proven useful in which drugs such as Mexiletine that preferentially inhibit mutation-induced late Na+ channel current (INaL), have been shown to be effective as therapeutic agents in the treatment of LQT-3. Here we isolated cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) produced by lentiviral reprograming of skin fibroblasts from three individuals in a LQT-3 family: a proband carrying a de novo SCN5A mutation (INa_F1473C) and the proband's parents who carried wild type (WT) Na+ channels. Whole-cell patch clamp recordings were used to characterize INa properties in the three subjects: INa_F1473C channels failed to completely inactivate during 100ms-depolarizing pulses (INaL) in the action potential plateau voltage range, and were characterized by steady state inactivation that was significantly shifted in the depolarizing direction compared with WT channels. These properties agree well with those determined previously of the same mutation in HEK293 cells and are consistent with mutation-induced QT interval prolongation in the proband. Based on HEK cell experiments, we previously reported that mutation-induced Na+ channel dysfunction was corrected by 50 µM Mexiletine, a result confirmed for the mutant channels expressed in hiPSC-CMs. However, we find that the same Mexiletine concentration significantly inhibits two off target channel currents ICaL and IKr, results that could not be obtained from heterologous expression studies. These results, establish the critical importance of hiPSC-CMs not only as mechanistic models of channelopathies such as LQTS, but as important and unique platforms for screening drugs, for both effectiveness in correcting mutation-induced dysfunction and also for target specificity.
Abstract 17305: Overexpression of Sodium Channel beta 4 Subunit is Responsible for Increase in Late Sodium Current in Mice with Mecp2 Deficiency
Authors: Yoo Shin , McCauley Mark , Herrera Jose , Wang Tiannan , Arvide Melissa , Neul Jeffrey L , Wehrens Xander H
Published: April 2024

Introduction:
The methyl-CpG-binding protein (MeCP2) is an epigenetic modifier of genetic expression and repression, and its dysfunction has been shown to cause Rett Syndrome, a progressive neurological disorder associated with sudden cardiac death. MeCP2 dysfunction has also been shown to be associated with QT interval in human patients, however the underlying mechanisms are unclear. We evaluated mice deficient in MeCP2 (KO) to determine whether there were differences in expression of genes commonly associated with long QT syndrome (LQTS).

Hypothesis:
MeCP2 dysfunction alters expression of plasma membrane ion channels or its interacting proteins, which are necessary for normal cardiomyocyte action potential.

Methods and Results:
qPCR was performed on wild type mice (WT) and KO heart lysates. Among 11 LQTS genes, SCN4B, one of beta subunits of the cardiac voltage gated sodium channel, was elevated 2.5 fold (n = 3,
P
= 0.04), while other 10 LQTS genes were not significantly altered. Western blot analysis on heart lysates showed increase of SCN4B protein in KO, consistent with immunostaining on isolated ventricular myocytes, which showed a qualitative increase of plasma membrane enhancement of SCN4B. Sodium current was recorded from a holding potential of -120 mV and activated to -20 mV. There was no change in peak sodium current, however, late sodium current was significantly increased in KO compared to WT (WT, -170.4 ± 29.2 pA, n = 5 vs. Rett, -590.0 ± 145.7 pA, n = 5; WT vs. Rett, p < 0.01). and Phenytoin, a late sodium current blocking agent, reduced late sodium current near normal levels (Rett + Phenytoin, -183.8 ± 40.6 pA, n = 5; Rett vs. Rett + Phenytoin, p < 0.05).

Conclusion:
Mice deficient in MeCP
2
have an increase in SCN4B expression, which may be associated with prolongation of QT interval. Phenytoin inhibits the late sodium current and may be an effective treatment for prevention of arrhythmias in patients with MeCP2 dysfunction.