bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nationwide study of sudden cardiac death among children and young adults in Iceland
Authors: Jonsdottir V , Tryggvason T , Einarsson G O , Bjornsson J , Gunnarsson G 
Published: October 2021

Abstract

Introduction
Sudden cardiac death (SCD) in children and young adults is a devastating event.
Ischemic heart disease is the predominant cause of sudden cardiac death in older persons. Whereas among persons 1–35 years of age, SCD is more often caused by structural heart disease or purely arrhythmogenic causes.
In studies on SCD in the young up to 40% of all autopsies show no cardiac abnormalities. Which raises suspicion of underlying arrhythmogenic causes. Many of these arrhythmogenic causes of SCD have an underlying genetic basis and are inherited.

Purpose
In Iceland, the true impact of SCD in children and young adults is unknown. The aim of this investigation is to study the incidence and causes of SCD in persons aged 1–35 years in nationwide settings.

Methods
This is a nationwide retrospective population-based study in Iceland. All deaths in persons aged 12–35 years in 1974–2015 and all deaths in persons aged 1–12 years 2005–2015 were included. Death certificates, autopsy reports and medical records were reviewed to confirm SCD. Medical records were also reviewed for medical history and circumstances of death.
Individuals that were resuscitated after cardiac arrest but died later in hospitals were included. Individuals that fulfilled the criteria of SUDEP (sudden unexpected death in epilepsy) were excluded from the study.

Results
We found 73 (68% male) cases of SCD, of which 64 (88%) were autopsied. The most common find in autopsy was structurally normal heart (16%), myocarditis (16%), hypertrophic cardiomyopathy (16%) and ischemic heart disease (16%). Death occurred during daily activities in 36% of cases, sleep in 27% cases and physical activities in 19% of cases. Incidence rate was 1.4 per 100.000 in 1–35 years old in the years 2005–2015 and 1.6 per 100.000 for 12–35 years old in the years 1974–2015.

Conclusion
Incidence of SCD in the young in Iceland is similar as for other nations. Post-mortem diagnoses are often difficult to establish. Because of the possibility of unrecognized underlying inherited cardiac disorder it is important to consider genetic analysis as a part of the post-mortem examination.
Majority of SCD in the young occurred related to normal daily activities or during sleep or at rest. This raises many questions about the connections between any underlying cause of SCD and behaviour.
It is important to discuss and study further the connection between sudden unexplained death in epilepsy (SUDEP) and SCD. SUDEP is most often unwitnessed events with cases found deceased in bed. SUDEP is characterized by an absence of any identifiable cause of death post-mortem, which can suggest underlying arrhythmogenic cause.

Funding Acknowledgement
Type of funding sources: None. Figure 1Figure 2
An electrocardiographic diagnostic model for differentiating right from left ventricular outflow tract arrythmias origin
Authors: Luna R , Gonzalez-Torrecilla E , Arenal A , Atienza F , Datino T , Avila P , Soto N , Peinado R , Fernandez-Aviles F 
Published: October 2021

Abstract

Background/Introduction
Several ECG signs have been proposed to discern the focal origin of ventricular outflow tract arrhythmias with a transition ≥V3. Their independent predictive value is unclear.

Purpose
The aim of the study is to establish a predictive model of independent ECG parameters to obtain an acute success in right-sided catheter ablation of isolated premature ventricular contractions (PVCs) or ventricular tachycardia (VT) from the ventricular outflow tract with a transition ≥V3.

Methods
We included 122 patients (62 women, mean age 54±16 years) with documented PVCs or VT showing a lower axis and predominantly negative QRS complexes in V1 and V2 who underwent ablation between January 2014 and June 2020. The achievement of acute ablation success from right endocardial positions was assessed. We performed a predictive model by multivariate logistic regression analysis including the following ECG variables associated with a right origin of the ventricular focus in previous studies: Transitional Zone (TZ) index, V2 transition ratio, V2S / V3R index, R-wave duration index, R/S-wave amplitude index in V2, variable coupling interval, and the presence of QS morphology in lead I.

Results
Two independent predictive ECG variables were identified: the V2S / V3R index (odds ratio 1.223; 95% CI, 1.024–1.460; p=0.026) and a coupling interval variability &gt;60 ms (odds ratio 0.307; 95% CI, 0.129 - 0.731; p=0.008). The area under the curve of this model was 0.733 (Picture 1). Arrhythmias with transition in V3 present a greater electroanatomic overlap and, therefore, a higher probability of right failure (59.3% vs 73.5% in arrhythmias with transitions after V3). In these, the V2 transition ratio is useful to predict the origin of the ectopy.

Conclusion
Two easily identifiable ECG variables (the V2S / V3R index and coupling interval variability &gt;60 ms) predict the acute success of a right-sided approach in the ablation of focal ventricular arrhythmias with predominantly negative QRS complexes in V1 and V2.

Funding Acknowledgement
Type of funding sources: None. Predictive accuracy of the ECG model
Correlation of signal averaged electrocardiography findings with fibrosis on cardiac magnetic resonance imaging
Authors: Saad S , Ahmed J , Drutel R , Clark D , Danrad R , Lelorier P 
Published: October 2021

Abstract

Background
Signal averaged electrocardiogram (SAECG) is a non invasive test to record delayed depolarization of myocardium with slow conduction that can potentially be the substrate for monomorphic ventricular tachycardia in high risk patients. Cardiac magnetic resonance imaging (cMRI) techniques for fibrosis imaging using late gadolinium enhancement (LGE) and T1 mapping remain the gold standard for characterization of myocardial tissue and triaging patients for risk of ventricular arrhythmias. However, cMRI remains unavailable in some areas, is time consuming, expensive and impossible for some patients to obtain due to claustrophobia, renal impairment or implanted hardware. To date, data is lacking with regards to correlation of findings between these two modalities.

Purpose
To investigate whether late potentials identified by SAECG correlate with the presence of fibrosis seen with cMRI. If correlation is established, SAECG could potentially be used as a non-invasive, cheaper, more convenient and readily available tool for risk stratification in patients at high risk for ventricular arrhythmias.

Methods
SAECGs were obtained in 25 consecutive patients undergoing cMRI. Patients with wide QRS (&gt;120 ms) on ECG were excluded. Positive SAECG was defined as at least 1/3 abnormal criteria. Standard criteria were used. Results of the 2 modalities were compared. Sensitivity and specificity of SAECG for diagnosing fibrosis on cMRI were calculated.

Results
The mean age of the patients was 50.3±5.8 years and the mean ejection fraction was 48.9±5.8% as determined by cMRI. Forty-eight percent of the patients had fibrosis on cMRI by either LGE, T1 mapping or both. The sensitivity and specificity of SAECG were 75% and 100%, respectively. Seven patients had history of ventricular tachycardia and 6 patients had dilated cardiomyopathy.

Conclusion
SAECG is extremely specific in identifying patients with myocardial fibrosis on cMRI. A positive test may confer a lesser indication to pursue cMRI solely for purposes of risk stratification, and may correlate with risk of ventricular arrhythmia.

Funding Acknowledgement
Type of funding sources: None.
Clinical impact of continuous electrical monitoring in patients with arrhythmic myocarditis: a prospective cohort study
Authors: Peretto G , Mazzone P , Della Bella P , Sala S 
Published: October 2021

Abstract

Background
Although potentially life-threatening, arrhythmias in myocarditis are under-reported.

Purpose
To assess diagnostic yield and clinical impact of continuous arrhythmia monitoring (CAM) in patients with arrhythmic myocarditis.

Methods
We enrolled consecutive adult patients (n=104; 71% males, age 47±11y, mean LVEF 50±13%) with biopsy-proven active myocarditis and de novo ventricular arrhythmias (VA). All patients underwent prospective monitoring by both sequential 24-hour Holter ECGs (4/y in the first year; 2/y in years 2–5; 1/y later) and CAM, including either ICD (n=62; 60%) or loop recorder (n=42; 40%).

Results
By 3.7±1.6 y follow-up, 45 patients (43%) had VT, 67 (64%) NSVT, and 102 (98%) premature ventricular complexes (PVC). As compared to Holter ECG (average 9.5 exams per patient), CAM identified more patients with VA (VT: 45 vs. 4; NSVT: 64 vs. 45; both p&lt;0.001), more VA episodes (VT: 100 vs. 4%; NSVT: 91 vs. 12%), and earlier NSVT timing (median 6 vs. 24 months, p&lt;0.001). Conversely, Holter ECG allowed VA morphology characterization and daily PVC quantification. The time to first treatment modification was 12±9 months by CAM vs. 33±16 months by Holter ECG (p&lt;0.001), and drug withdrawal was always CAM-dependent. Guided by CAM findings, 8 patients (8%) started anticoagulants for newly-diagnosed atrial arrhythmias. Differently from ICDs, loop recorders did not interfere with the interpretation of cardiac magnetic resonance.

Conclusion
In patients with arrhythmic myocarditis, CAM allowed accurate arrhythmia detection and showed a considerable clinical impact. As a complementary exam, VA characterization and PVC burden were better assed by repeated Holter ECGs.

Funding Acknowledgement
Type of funding sources: None.
A novel machine learning algorithm has the potential to reduce by 1/3 the quantity of ILR episodes needing review
Authors: Rosier A , Crespin E , Lazarus A , Laurent G , Menet A , Gozlan A , Varma N 
Published: October 2021

Abstract

Background
Implantable Loop Recorders (ILRs) are increasingly used and generate a high workload for timely adjudication of ECG recordings. In particular, the excessive false positive rate leads to a significant review burden.

Purpose
A novel machine learning algorithm was developed to reclassify ILR episodes in order to decrease by 80% the False Positive rate while maintaining 99% sensitivity.
This study aims to evaluate the impact of this algorithm to reduce the number of abnormal episodes reported in Medtronic ILRs.

Methods
Among 20 European centers, all Medtronic ILR patients were enrolled during the 2nd semester of 2020. Using a remote monitoring platform, every ILR transmitted episode was collected and anonymised.
For every ILR detected episode with a transmitted ECG, the new algorithm reclassified it applying the same labels as the ILR (asystole, brady, AT/AF, VT, artifact, normal). We measured the number of episodes identified as false positive and reclassified as normal by the algorithm, and their proportion among all episodes.

Results
In 370 patients, ILRs recorded 3755 episodes including 305 patient-triggered and 629 with no ECG transmitted. 2821 episodes were analyzed by the novel algorithm, which reclassified 1227 episodes as normal rhythm. These reclassified episodes accounted for 43% of analyzed episodes and 32.6% of all episodes recorded.

Conclusion
A novel machine learning algorithm significantly reduces the quantity of episodes flagged as abnormal and typically reviewed by healthcare professionals.

Funding Acknowledgement
Type of funding sources: None. Figure 1. ILR episodes analysis
Features of changes in left ventricular mechanics in patients with epicardial obesity
Authors: Gritsenko O , Chumakova G 
Published: October 2021

Abstract

Currently, there is no single non-invasive marker that can directly assess left ventricular (LV) diastolic function. Untwist of LV contributes to diastolic suction and early filling. Speckle-tracking imaging can be used to diagnose diastolic dysfunction at the preclinical stage.

Objective
To study the features of changes in the parameters of LV mechanics and their relationship with the levels of serum markers of myocardial fibrosis in patients with epicardial obesity (EO).

Materials and methods
The study included 125 men with general obesity. All patients underwent transthoracic echocardiography (ECG) to assess the thickness of epicardial adipose tissue (tEAT) as equivalent to visceral obesity, as well as to diagnose diastolic dysfunction (DD) of left ventricle (LV). According to the results of ECG, the patients were divided into 2 groups: EO(+) with epicardial fat thickness (tEAT) ≥7 mm (n=78); EO(−) with (tEAT) &lt;7 mm (n=40). DD LV was detected in 7 patients, who were subsequently excluded from the analysis.
Profibrotic markers in blood serum (MMP-3, collagen I, collagen III, TGF-β, VEGFA, PICP) were determined in all patients using enzyme immunoassay. Using speckle-tracking ECG, the mechanics of LV were studied (twist LV, peak twist ratio LV, time to peak twist of LV, peak untwist ratio LV, time to peak untwist of LV). The exclusion criteria were the presence of coronary pathology, arterial hypertension, and type 2 diabetes mellitus.

Results
In the group of patients with EO(+) statistically significant increase the level of all studied profibrotic markers was revealed. According to the results of speckle-tracking ECG in the EO(+) group an increase peak untwist ratio LV to −125.56 (−141.0; −117.0)deg/s (p=0.003) and an increase time to peak untwist of LV of 469.44 (509.0; 401.0) msec was determined in comparison with the EO(−) group (p=0.03). A weak statistically significant effect of tEAT on the peak untwist ratio LV in EO(+) group was revealed (r=0.28; p=0.03). In addition, there was a significant relationship between peak untwist ratio LV and markers of myocardial fibrosis MMP-3 (r=0.23; p=0.03) and collagen type III (r=0.25; p=0.04).

Conclusion
Thus, LV unwinding may be a new non-invasive marker of LV DD at the preclinical stage, since this parameter reflects the mechanical aspect of global diastolic function, especially the early phase of diastole.

Funding Acknowledgement
Type of funding sources: None.
Patients with reflex syncope have a higher prevalence of atrial fibrillation than general population which is predicted by the type of the tilt table test response
Authors: Farinha J M , Parreira L , Esteves A F , Fonseca M , Pinheiro A , Ferreira J , Coelho R , Mesquita D , Marinheiro R , Amador P , Caria R 
Published: October 2021

Abstract

Introduction
Reflex syncope is the result of an imbalance between the sympathetic and parasympathetic nervous system. The autonomic nervous system has been associated to some forms of atrial fibrillation (AF).

Objective
The aim of this study was to assess the prevalence of AF in patients with reflex syncope and a positive tilt table test and to identify the type of tilt test response in patients with AF in comparison to patients without AF.

Methods
We retrospectively studied consecutive patients that underwent a tilt table test at our institution between 2016 and 2019. We selected those patients with a positive test. Patients with an implanted pacemaker at the time of the tilt test and patients followed in a different institution were excluded. Previous diagnoses of AF episodes were assessed. We analysed the clinical characteristics and the tilt table test results according to previous history of AF.

Results
We studied 49 patients with a positive tilt test. Seven (14.3%) patients had previously diagnosed paroxysmal AF at the time of the tilt table test. Patients with AF were older, had more frequently hypertension, and the tilt test response was more frequently a vasodepressor than mixed or cardioinhibitory response (71.4% vs. 28.6%) (Table). In univariate analysis, age and hypertension were associated with AF, respectively, OR 1.08 (95% CI 1.01–1.17), p=0.034 and OR 10.80 (95% CI 1.19–98.36), p=0.035. A vasodepressor response was also associated with AF (OR 6.25, 95% CI 1.06–36.74, p=0.043).

Conclusions
Patients with reflex syncope and a positive tilt table test had a higher prevalence of AF than the general population. A vasodepressor response was associated with AF as were age and hypertension, demonstrating the possible impact of the autonomic nervous system and the multifactorial nature of AF.

Funding Acknowledgement
Type of funding sources: None.
Nine year experience of the Northern Ireland Inherited Cardiac Conditions Service (NI ICC of slow vs. rapid ajmaline infusion protocols for the diagnosis of Brugada syndrome (BrS)
Authors: Msulaiman H , Connolly H , McOsker J , Jardine T , McCall D , McKeown P , Muir A 
Published: October 2021

Abstract

Background
BrS is diagnosed in patients with ST-segment elevation with type1 morphology ≥2mm in one or more leads among the right precordial leads V1 and/or V2 positioned in the second, third or fourth intercostal space, occurring either spontaneously or after provocative drug test with intravenous administration of sodium channel blockers (ie. ajmaline, flecainide, procainamide or pilsicainide). The specific protocol for Ajmaline provocation testing for diagnosis of BrS has been debated between ICC services worldwide. Concerns regarding safety and false positive rates are perceived to be associated with a more rapid infusion protocol. This retrospective observational cohort study describes the safety and positivity rates for patients undergoing ajmaline provocation challenge by both protocols over nine years.

Method
Consecutive adults undergoing ajmaline challenge test from Mach 2011 to Feb 2020 were retrospectively collected. Data on patient demographics, indication for testing, genetic information, adverse events and positivity rates were compared by test protocol used. Slow protocol was defined as total dose of 1mg/kg ajmaline capped at 100mg given at rate of 10mg/min over 10 minutes. Rapid protocol was defined as 1mg/kg ajmaline capped at 100mg given over 5 minutes.

Results
A total of 350 ajmaline challenges were included (275 (73%) slow vs. 75 (27%) rapid protocol) [Mean age 40±15 years; 53% male]. Indication for conducting the test was a) Family history of Brugada syndrome 164 (43%) b) Family history of SADS/SUD 103 (28%), c) OOHCA 22 (6%) d) abnormal ECG 39 (11%) and e) syncope 22 (6%). Among the positive test group, average time for test positivity is 5.92 minutes and average dose was 55mgs (p&lt;0.05). There were no differences between positivity rate between the two protocols, group A vs. group B, p=0.45, ns. Comparison between all patients with positive vs. negative results regardless of the protocol, showed no statistical differences. Predominantly male in both groups (p=0.71, ns) and mean age of patients in their 40's (p=0.93, ns). There is a trend that positive patients likely to have family history of BrS p=0.08, ns). 2 patients had experience jaundice at later stage which resolved.

Conclusion
In NI ICC service to date, we have performed 350 Ajmaline test over the last nine years. Our positivity rate was 21% (75/350). We did not identify any significant evidence of ventricular dysrhythmia (0) or QRS broadening (2) that resulting in early termination of the protocol. Abnormal ECG with absence of symptoms yields low. Therefore we will continue fast protocol in our service for efficiency in our unit.

Funding Acknowledgement
Type of funding sources: Public hospital(s). Main funding source(s): Belfast Health and Social Care TrustCormac Felowship
Prognostic implication of left atrial strain in patients undergoing totally thoracoscopic ablation of atrial fibrillation
Authors: Kim J K 
Published: October 2021

Abstract

Background
Atrial fibrillation (AF) is a common form of arrhythmia and associated with poor quality of life. Totally thoracoscopic ablation (TTA) is a novel minimally invasive strategy for symptomatic atrial fibrillation (AF) refractory to other therapy. However, some of patients undergoing TTA are still exposed to a risk of AF recurrence.

Purpose
The aim of this study is to investigate prognostic factors related with AF recurrence after TTA, and to determine the prognostic implication of left atrial (LA) strain in this population.

Methods
This was a prospective observational study. Between February 2012 and March 2015, left atrial appendage (LAA) was harvested from patients who underwent TTA in our Medical Center. Degree of LAA fibrosis was expressed as the percentage of area of positive collagen staining in the total area of the image of specimen. All echocardiographic parameters were measured in preoperative echocardiography. The primary outcome was any recurrence of AF detected in 12- lead electrocardiogram or holter monitoring during 5 years of follow-up.

Results
Out of 150 patients who underwent TTA during the study period, 129 were eligible for analysis with appropriate surgery, LAA specimen, and echocardiographic images. A mean age was 54.4±8.8 years, and 123 patients (95.3%) were male. Twenty four patients (18.6%) had paroxysmal AF and a mean CHA2DS2 VASc score was 1.1±1.2. A median value of peak longitudinal LA strain (reservoir strain) was 15.2% (IQR 12.1–19.2), and the median value of LAA fibrosis was 38.5% (IQR 33.0–44.7). Among clinical and echocardiographic variables, peak longitudinal LA strain (p&lt;0.001) and left ventricular ejection fraction (p=0.044) were significantly associated with degree of LAA fibrosis (Figure). Of 129 patients, 47 (36.4%) experienced recurrent AF during the median 3.9 years of follow-up. In a multivariable Cox regression analysis using clinical, echocardiographic and operative parameters, peak longitudinal LA stain was the only predictor of recurrent AF (adjusted HR 0.89, 95% CI 0.81–0.98, p=0.024; Table).

Conclusions
Peak longitudinal LA strain was associated with LAA fibrosis, and was a significant predictor of recurrent AF after TTA

Funding Acknowledgement
Type of funding sources: None.