bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk factors related to the occurrence of silent myocardial ischemia in mexicans
Authors: Unzueta‐Montoya Alberto , Rubio Arturo Torres‐Y Gutiérrez , Unzueta Alberto , Ordonez‐Toquero Guillermo , Hernández Héctor Hernández‐Y , De La Peña Jorge Escobedo , Pérez‐Reyes Patricia
Published: February 2009

Background: Silent myocardial ischemia is a growing world health problem. It has been related to factors that promote an increase in myocardial oxygen demand or affect coronary vasomotor tone. Coronary artery disease has shown an increasing trend in Mexico in this century.

Hypothesis: The aim of the study was to estimate the strength of the association between some risk factors and the occurrence of silent myocardial ischemia.

Methods: A cross‐sectional study was conducted and 249 individuals were screened by 24‐h Holter electrocardiogram. Silent myocardial ischemia was diagnosed in patients with painless transient ST‐segment depression. All subjects were interviewed for coronary risk factors and total serum cholesterol was measured.

Results: Silent ischemia was diagnosed in 115 patients (46%), who were older (59±9 vs. 57±11 years; p=0.01). In a logistic regression analysis, a lower risk for silent ischemia was found in patients with thrombolysis [odds ratio (OR) 0.28; 95% confidence interval (CI 95%) 0.14–0.53], or those who followed their medical treatment (OR 0.16; CI 95% 0.04–0.68). The major risk factors were hypercholesterolemia (OR 1.6; CI 95% 0.9–2.9) and more severe coronary artery disease (OR 2.5; CI 95% 1.1–5.7).

Conclusions: Some coronary risk factors are related to silent ischemia. It is still important to diagnose this entity, but modification of its related risk factors should be kept in mind to diminish its occurrence and its severe consequences.
Long‐term prognosis of patients with angina treated with enhanced external counterpulsation: fiVe‐ year follow‐up study
Authors: Lawson William E. , Hui John C. K. , Cohn Peter F.
Published: February 2009

Background: Enhanced external counterpulsation (EECP) is a noninvasive treatment for coronary artery disease (CAD) that has been used successfully in patients not responding to medical and/or surgical therapy.

Hypothesis: The study was undertaken to evaluate the effect of EECP on long‐term prognosis in such patients.

Methods: Major adverse cardiovascular events (MACE) were tracked in 33 patients with CAD treated with EECP. Patients were subgrouped based on whether or not they demonstrated an early improvement in radionuclide stress perfusion imaging (Responders vs. Nonresponders) and followed for MACE over a mean follow‐up of 5 years. Patient population characteristics included 73% with multivessel disease; 45% with prior myocardial infarction(s); and 61% who had undergone either coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA), or both.

Results: There were 26 of 33 (79%) Responders, and 7 of 33 (21%) Nonresponders. Subsequent MACE over the 5‐year follow‐up included four deaths and eight patients with cardiovascular events [acute myocardial infarct (4), new CABG or PTCA (6), valve replacement (1), unstable angina (1)]. Nonresponders had significantly (p <0.01) more MACE (6/7 or 86%) than Responders (6/26 or 23%). Overall, 21 of the 33 (64%) patients remained alive and without MACE and the need for revascularization 5 years post EECP treatment

Conclusion: This study suggests that, particularly for the majority of patients demonstrating improvement in radionuclide stress perfusion post treatment, EECP may be an effective long‐term therapy.
Plasma big‐endothelin levels, cardiac autonomic neuropathy, and cardiac functions in patients with insulin‐dependent diabetes mellitus
Authors: Erbas Tomris , Gedik Olcay , Koray Zehra , Erbas Belkis , Kabakci Giray , Aksöyek Serdar
Published: February 2009

Background: The alteration of endothelin (ET) levels in diabetic patients with cardiac autonomic neuropathy (CAN) has not been studied extensively and its correlation with cardiac function parameters has not been discussed.

Hypothesis: The aim of the present study was to discuss the correlation between the degree of cardiac autonomic neuropathy, plasma big‐ET levels, and cardiac functions in diabetic patients who were clinically free of cardiovascular disease.

Methods: Twenty subjects (32.1 ± 7.8 years, 11 men, 9 women) with insulin‐dependent diabetes mellitus (IDDM) were studied to evaluate the relationship between circulating big‐endothelin (big‐ET1) levels, CAN, and cardiac functions. The severity of CAN was scored according to Ewing's criteria. Cardiac functions were assessed using Doppler echocardiography.

Results: Left ventricular systolic function in the patient group was within normal limits and comparable with the values of the control group (n = 10). The mean E/A values of diabetics with CAN (1.15 ± 0.33, p = 0.004) and without CAN (1.34 ± 0.17) were significantly lower than those of controls (1.57 ± 0.27). Diabetics with CAN had significantly higher big‐ET1 values (81.1 ± 94 pg/ml) compared with others (12.4 ± 5.9 and 21.1 ± 17.7 pg/ml, p = 0.04). Circulating big‐ET1 levels showed a significant correlation with E/A values in the control group (p = 0.01, r = ‐ 0.7) and with peak A values (p = 0.003, r = 0.64) in diabetics. The CAN score correlated negatively with E/A values (p = 0.01, r = 0.54).

Conclusions: High big‐ET levels might have an important role in the pathogenesis or consequences of diastolic dysfunction in diabetics with CAN. Their role in cardiac autonomic neuropathy and diastolic dysfunction should be investigated further.
Potential reduction of costs and hospital emergency department visits resulting from prehospital transtelephonic triage—the shahal experience in israel
Authors: Roth Arie , Laniado Shlomo , Malov Naomi , Carthy Ziv , Golovner Michal , Naveh Rachel , Alroy Iki , Kaplinsky Elieser
Published: February 2009

Background: The rising cost of services provided by hospital emergency departments is of major concern. Attempts to reduce the costs of emergency cardiac care have thus far focused primarily on medical and administrative management in the hospital. The role of the patient in appropriate prehospital decision‐making has been generally ignored.

Hypothesis: Membership in “Shahal” (an integrative telemedicine system) may have beneficial effects on patient decision‐making and national health costs.

Methods: During a 6‐month period, a random group of subscribers who had called for medical assistance during the previous 24 h were asked what action they would have taken had they not been Shahal subscribers. All study patients were followed for at least 7 days.

Results: In all, 1,608 subscribers (age 71 ± 13 years) were included. Of these, 514 replied that they “would have waited,” 363 “would have contacted their physicians,” and 731 “would have sought emergency department care.” Of the presenting medical problems, 86% were resolved without utilizing hospital facilities. A mobile intensive care unit was dispatched in 412 (26%) cases. A cost estimate of abuse indicated that the service resulted in a savings to the national economy of approximately $830,000 per 10,000 members per year.

Conclusions: This study demonstrated that Shahal membership can reduce costs of medical care and the number of hospital emergency department visits.
Enhanced detection of ischemic but viable myocardium by qt interval dispersion on treadmill exercise electrocardiograms of patients with healed anterior wall myocardial infarcts
Authors: Koide Yasushl , Yotsukura Masayuki , Tajino Kazuhiro , Yoshino Hideaki , Ishikawa Kyozo
Published: February 2009

Background: The presence of ischemic but viable myocardium in infarcted areas is an important indication for coronary revascularization, but is often difficult to detect with the use of treadmill exercise electrocardiography (ECG).

Hypothesis: QT interval dispersion (QTd) is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarcted areas.

Methods: Forty‐five patients with Q‐wave anterior wall myocardial infarctions who underwent treadmill exercise ECG, exercise reinjection thallium‐201 (201T1) scintigraphy, radionuclide angiocardiography, and coronary angiography 1 month after infarction were enrolled in this study. The presence of viable myocardium in the infarct area was determined by exercise reinjection 201T1 scintigraphy. Patients who had no redistribution in the infarct area after reinjection were included in Group 1, and those with redistribution were included in Group 2.

Results: QTd immediately after exercise, and the difference between QTd before and immediately after exercise, were significantly greater in Group 2 than in Group 1. The sensitivity, specificity, and accuracy of conventional ST‐segment depression criteria for detecting viable myocardium in the infarct area were 48,64, and 56%, respectively. The measurement of QTd immediately after exercise (abnormal: ≥ 70 ms; normal: < 70 ms) improved the sensitivity, specificity, and accuracy to 78,82, and 80%, respectively.

Conclusions: This novel diagnostic method using QTd‐based criteria significantly improves the clinical usefulness of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarct areas in patients with healed Q‐wave anterior wall myocardial infarctions.
Tricuspid valve group b streptococcal endocarditis after an elective termination of pregnancy
Authors: Kangavari Simon , Collins Jennifer , Cercek Bojan , Atar Shaul , Siegel Robert
Published: February 2009

A patient developed fever, chills, and shortness of breath after an elective first trimester dilation and curettage. Blood cultures grew Group B streptococcus, and a transesophageal echocardiogram revealed a 2 × 2 cm vegetation on the tricuspid valve and global left ventricular hypokinesis. A 6‐week course of parenteral antibiotics and vasodilator therapy resulted in resolution of the valvular vegetation as well as of the left ventricular dysfunction.
Should interventional cardiac catheterization procedures take place at the time of diagnostic procedures?
Authors: Panchamukhi Varadendra B. , Flaker Greg C.
Published: February 2009

Background: In many cardiac catheterization laboratories interventional procedures are performed at a date later than the diagnostic study, causing increased hospital days and costs. Few data exist which compare procedural success, complications, and costs between procedures performed at the time of diagnostic study and those performed later.

Hypothesis: The purpose of this study was to evaluate the safety and success of same‐day interventional procedures and to quantitate hospital cost savings with this strategy.

Method: In all, 357 consecutive patients who underwent an elective interventional procedure of a native coronary artery either at the time of diagnostic study (same day, n = 244) or later (delayed, n = 113) were reviewed. Procedural success [< 30% residual lesion post‐percutaneous transluminal coronary angioplasty (PTCA) or 0% residual lesion post‐stent], major complications [death, emergent coronary artery bypass grafting (CABG), myocardial infarction, and ventricular fibrillation], hospital days, and costs were analyzed. Procedural expense, including the diagnostic and interventional procedure in the cardiac catheterization laboratory, and hospital expense were analyzed.

Results: Both groups were similar in terms of age, gender, coronary risk factors, indications (myocardial infarction, unstable angina, abnormal stress test), the culprit coronary artery, type of intervention (PTCA, stent), and lesion complexity (type A, B, C). The average hospital stay for the two groups was 4.37 ± 2 and 6.55 ± 2.4 days, respectively (p < 0.0001). The procedural charges were $ 8,207.99 and 10,581.87, respectively (p<0.0001).

Conclusion: Catheter intervention performed at the same time as the diagnostic cardiac catheterization procedure is as successful and as safe as that performed at a later date. Hospital stay and costs, as well as procedural expenses are significantly reduced by this practice.
The use of angiotensin‐converting enzyme inhibitors in patients with acute myocardial infarction in community hospitals
Authors: Dwamena Francesca C. , El‐Tamimi Hassan , Watson Ralph E. , Kroll Jill , Mclane Annette , Holmes‐Rovner Margaret , Mcintosh Barbara , Kupersmith Joel , Stein Aryeh D.
Published: February 2009

Background: Previous studies documenting underutilization of angiotensin‐converting enzyme inhibitors (ACEIs) in acute myocardial infarction (AMI) have been limited to Medicare populations.

Hypothesis: This study examines ACEI prescription rates and predictors in a community sample of hospitalized patients with AMI.

Methods: The charts of 1163 community patients with AMI, prospectively identified at admission between January 1, 1994, and April 30, 1995, were reviewed.

Results: Only 64 of 158 (40%) patients considered ideal candidates for ACEI prescription were discharged with a prescription for an ACEI. In a multivariate logistic regression model, prior ACEI utilization [adjusted odds ration (OR) = 3.26; 95% confidence interval (CI) = 2.05–5.20], presence of congestive heart failure (OR = 2.33; CI = 1.50–3.61) and black race (OR = 2.20; CI = 1.34–3.64) were identified as positive predictors of ACEI prescription. Conversely, lack of left ventricular ejection fraction (LVEF) measurement (OR = 0.46; CI = 0.28–0.75), LVEF > 40 (OR = 0.27; CI = 0.18–0.40), and acute renal failure (OR = 0.08; CI = 0.01–0.44) were negative predictors. Women were also less likely to be discharged with an ACEI prescription (OR = 0.71; CI = 0.48–1.05). Furthermore, women were significantly less likely to have LVEF measured prior to discharge than were males (77 vs. 85%, p = 0.001).

Conclusion: This study underscores the need for improvement in the utilization of ACEI in eligible patients with AMI. It also identifies opportunities for improvement in prescription rates, especially in women.
Exercise‐induced QTc‐interval changes for predicting improvement in regional blood flow in ischemic myocardium and cardiac output after coronary angioplasty in patients with right bundle‐branch block
Authors: Watanabe Takuya , Katagiri Takashi , Yamanaka Hideyuki , Akutsu Yasushi , Michihata Tetsuo , Okazaki Osamu , Harumi Kenichi
Published: February 2009

Background: We have previously shown that QT‐interval changes are more useful than ST‐T changes in evaluating the severity of exercise‐induced myocardial ischemia in patients with right bundle‐branch block (RBBB).

Hypothesis: The purpose of this study was to evaluate whether the improvement in regional myocardial blood flow (RMBF) in ischemic areas and cardiac output after percutaneous transluminal coronary angioplasty (PTCA) can be predicted by exercise‐induced QT‐interval changes prior to PTCA.

Methods: The RMBF and cardiac output were quantified with nitrogen‐13 ammonia positron emission tomography at rest and during exercise in 20 patients with RBBB and ischemic heart disease before and 6 months after PTCA, and in 9 healthy volunteers.

Results: Before PTCA, exercise‐induced prolongation by <20 ms or shortening of the Bazett‐corrected QT (QTc) interval (454 ± 38 to 451 ± 41 ms, p = NS) was observed in 13 patients (Group 1) and prolongation by ≥20 ms (429 ± 44 to 466 ± 50 ms, p < 0.002) was observed in 7 (Group 2). The number of regions of exercise‐induced ischemia was significantly greater in Group 2 than in Group 1 (4.0 ± 1.2 vs. 2.1 ± 1.2, p < 0.01). The RMBF in regions of exercise‐induced ischemia and cardiac output at rest was not significantly different between Groups 1 and 2, whereas during exercise both the parameters were significantly lower in Group 2 than in Group 1 (both p < 0.05). After successful PTCA, RMBF both at rest and during exercise improved significantly in Group 1 (0.67 ± 0.04 to 0.71 ± 0.06 ml/min/g, 0.74 ± 0.05 to 0.84 ± 0.08 ml/min/g; both p < 0.0001), but did not improve significantly in Group 2 (0.63 ± 0.05 to 0.65 ± 0.07 ml/min/g, 0.65 ± 0.04 to 0.69 ± 0.11 ml/min/g; both p = NS). Cardiac output during exercise improved significantly in Group 1 (6.4 ± 0.7 to 7.4 ± 0.9 l/min; p<0.002) but not in Group 2 (5.7 ± 0.6 to 5.9 ± 0.6 l/min; p = NS).

Conclusions: Our results suggest that the marked prolongation of the QTc interval induced by pre‐PTCA exercise may predict a lack of improvement in RMBF in ischemic areas and cardiac output after PTCA in patients with RBBB and ischemic heart disease.
Cardiac sympathetic activity in the asymmetrically hypertrophied septum in patients with hypertension or hypertrophic cardiomyopathy
Authors: Shimizu Masami , Ino Hidekazu , Okeie Kazuyasu , Emoto Yorito , Yamaguchi Masato , Yasuda Toshihiko , Fujino Noboru , Fujii Hiroyuki , Fujita Shinichiro , Mabuchi Hiroshi , Nakajima Kenichi , Taki Junichi
Published: February 2009

Background: In patients with essential hypertension (HT), proportional (symmetric) left ventricular hypertrophy (LVH) is common. In contrast, hypertrophic cardiomyopathy (HCM) is characterized by disproportional LVH and, in particular, asymmetric septal hypertrophy (ASH); however, some hypertensive patients also develop ASH. It has not been determined whether such cases represent a distinct type of hypertensive LVH or HCM combined with hypertension.

Hypothesis: The study was undertaken to evaluate sympathetic activity in the interventricular septum in patients with HT and ASH or in patients with HCM.

Methods: The patients were evaluated by I–123 metaiodobenzylguanidine (MIBG) and thallium‐201 (201Tl) single‐photon emission computed tomography (SPECT), respectively. They were divided into three groups: patients with essential HT and symmetric septal hypertrophy (Group A), patients with HT and ASH (Group B), and patients with HCM and ASH (Group C).

Results: Compared with the lateral wall, early uptake of MIBG in the septum was significantly higher in Group B than in Group A, but not significantly different between Groups A and C. Compared with the lateral wall, early uptake of 201Tl in the septum did not differ among the three groups. No significant difference in the MIBG clearance in the lateral wall was seen among the three groups. By contrast, MIBG clearances in the septum and apex were significantly greater in Group C than in Groups A and B. There was an inverse correlation between systolic thickening and MIBG clearance in the septum.

Conclusion: These findings suggest that sympathetic activity in the septum differs between patients with HT and ASH and patients with HCM.
Influence of autonomic neuropathy upon left ventricular dysfunction in insulin‐dependent diabetic patients
Authors: Monteagudo Patricia T. , Zanella M. Teresa , Moisés Valdir A. , Lima Valter C. , Kohlmann Osvaldo , Ribeiro Artur B.
Published: February 2009

Background: Diabetic cardiomyopathy is a well‐defined complication of diabetes that occurs in the absence of ischemic, vascular, and hypertensive disease.

Hypothesis: The study was undertaken to test the relationship among autonomic neuropathy (AN), 24‐h blood pressure (BP) profile, and left ventricular function.

Methods: Nineteen type‐1 diabetic patients underwent autonomic tests and echocardiographic examination. Patients were divided according to the presence (AN+) or absence (AN‐) of AN.

Results: In the AN+ group (n = 8), the E/A ratio at echo was lower than in the AN– group (n = 11) (1.1 ± 0.3 vs. 1.6 ± 0.3; p < 0.005). Systolic and diastolic BP reductions during sleep were smaller in the AN+ than in the AN– group (6.6 ± 6.6 vs. 13.0 ± 4.3%; p < 0.03 for systolic and 12.8 ± 6.8 vs. 20.0 ± 4.0% for diastolic BP reduction; p < 0.03, respectively). Considering all patients, the E/A ratio correlated inversely with awake diastolic BP (r – 0.63; p = 0.005); sleep systolic BP (r – 0.48; p = 0.04), and sleep diastolic BP (r – 0.67; p = 0.002). The AN correlated with diastolic interventricular septum thickness (r 0.57; p = 0.01), sleep systolic BP (r 0.45; p = 0.05), sleep diastolic BP (r 0.54; p = 0.02), and correlated inversely with systolic and diastolic sleep BP reduction (r – 0.49; p = 0.03 and r – 0.67; p = 0.002, respectively). Finally, E/A ratio and AN score correlated between themselves (r – 0.6; p = 0.005).

Conclusion: Our results suggest that left ventricular diastolic dysfunction may be detected very early in type‐1 diabetic patients with AN. Parasympathetic lesion and nocturnal elevations in BP could be the link between AN and diastolic ventricular dysfunction.
Effects of intravenous dofetilide in patients with frequent premature ventricular contractions: A clinical trial
Authors: Pool Peter E. , Singh Steven N. , Friedrich Tilman
Published: February 2009

Background: Although suppression of premature ventricular contractions (PVCs) is not a predictor of mortality over the long term, the extent of PVC suppression is an important characteristic of any antiarrhythmic drug.

Hypothesis: This study was undertaken to determine whether intravenous (IV) dofetilide has the ability to suppress PVCs in patients who have frequent occurrences.

Methods: Subjects were men and women, aged 18 to 75 years, with > 30 PVCs/h on two consecutive 24‐h Holter recordings while drug free, and > 50 PVCs/h during a 2‐hour telemetric electrocardiogram. The study was randomized, double‐blind, and placebo controlled. Subjects received a single‐blind, IV infusion of placebo and were randomized (3:1) to receive a double‐blind second infusion of placebo or an infusion of dofetilide (a 15‐min loading infusion of 4 g/kg followed by a 60‐min maintenance infusion of 3.5 g/kg, for a total dose of 7.5 g/kg).

Results: Dofetilide produced an 82.6% and placebo a 2.9% median reduction in PVCs. Drug responder rate, defined as 80% reduction in PVCs, was 50% in the dofetilide group and 0% in the placebo group.

Conclusion: Intravenous dofetilide significantly reduced PVCs in patients who had > 30 PVCs/h at baseline, and it produced ≥ 80% reduction in PVCs in 50% of all subjects.
Comparison of echocardiography and electron beam tomography in differentiating the etiology of heart failure
Authors: Le Thuy , Ko John Y. , Tina Kim H. , Akinwale Pamela , Budoff Matthew J.
Published: February 2009

Background: The clinical manifestations in patients with ischemic cardiomyopathy are often indistinguishable from those in patients with primary dilated cardiomyopathy (DCM). Clinicians often base work‐up of patients with heart failure on echocardiographic wall motion abnormalities; however misclassification can lead to unnecessary coronary angiography.

Hypothesis: The study was undertaken to evaluate the diagnostic ability of echocardiography and electron beam tomography (EBT) to differentiate between ischemic and nonischemic cardiomyopathy.

Methods: The accuracy of EBT and echocardiography was compared in 111 patients undergoing coronary angiography for the evaluation of heart failure. The presence of coronary calcification (CC) by EBT or segmental wall motion abnormalities by echocardiography was used as evidence of coronary‐induced cardiomyopathy.

Results: Of 63 patients, 61 (97%) with obstructive coronary artery disease had CC by EBT. This sensitivity was significantly higher compared with 43 of 63 patients (68%) with segmental wall motion abnormalities by echocardiography (p < 0.001). Of 48 patients without obstructive coronary artery disease by angiography, 39 (81%) had no CC by EBT and 35 (73%) had no segmental wall motion (global hypokinesis) by echocardiography (p = 0.33). The overall accuracy of EBT to differentiate ischemic from nonischemic cardiomyopathy was 90%, significantly higher than echocardiography (70%, p < 0.001).

Conclusion: This double‐blind study demonstrates that the presence of CC by EBT is superior to that of segmental wall motion abnormalities by echocardiography to distinguish ischemic from nonischemic cardiomyopathy. This modality may prove to be an important diagnostic tool when the etiology of the cardiomyopathy is not clinically evident.
Is ventricular repolarization heterogeneity a cause of serious ventricular tachyarrhythmias in aortic valve stenosis?
Authors: Batur M. K. , Açil T. , Önalan O. , Yildirir A. , Övünç K. , Kabakci G. , Oto A. , Özkutlu H. , Nazli N. , Gürsel G. , Kes S.
Published: February 2009

Background: It is well known that there is a close relation between sudden cardiac death and serious ventricular tachyarrhythmias in patients with aortic valve stenosis (AS). QT dispersion (QTd) reflects the ventricular repolarization heterogeneity and has been proposed as an indicator for ventricular arrhythmias.

Hypothesis: This study investigated the QTd and its relevance to the clinical and echocardiographic variables.

Methods: In all, 51 patients (33 men, 18 women, mean age 56±12) with isolated AS and 51 age‐ and gender‐matched healthy controls comprised the study group. Left ventricular mass index (LVMI) was calculated by the Devereux formula, and we used continuous‐wave Doppler (n = 15) and cardiac catheterization (n = 36) for the determination of the maximum aortic valve pressure gradient (PG).

Results: Corrected QTd (QTcd) (89±39 vs. 49±15 ms, p<0.001) and LVMI (176±69 g/m2 vs. 101±28 g/m2, p<0.001) in patients with AS were significantly different from those in the control group. The group of 21 patients had a significantly greater number of 24‐h mean ventricular premature beats (VPB) and mean number of couplet VT episodes than did the control group (p<0.05). QTcd also correlated significantly well with LVMI (r=0.58, p<0.001), PG (r=0.41, p=0.003), and number of 24‐h VPB (r=0.56, p=0.008). With respect to symptoms (e.g., angina, syncope, and dyspnea) patients without symptoms (n=19) displayed less QTcd (71±31 vs. 100±39 ms, p=0.007) and less LVMI (144±80 g/m2 vs. 195±57 g/m2, p=0.01) than patients with symptoms. Statistical analysis was similar for all variables with uncorrected QTd values.

Conclusion: We found that ventricular repolarization heterogeneity was greater in patients with AS than in controls. Our findings also showed that QTd in the patient group correlates well with LVMI, severity of AS, and PG. The present results suggest that serious ventricular arrhythmias in patients with AS may be due to spatial ventricular repolarization abnormality.
The prediction of coronary atherosclerosis employing artificial neural networks
Authors: George Jacob , Levy Yair , Gilburd Boris , Shoenfeld Yehuda , Ahmed Alaa , Patnaik Madhumita , Terrybery Jeff , Shen Guo Qui , Peter James , Adler Yehuda , Sagie Alex , Herz Itzhak , Harats Dror , Snow Peter , Brandt Jeff
Published: February 2009

Background: Atherosclerosis is a complex histopathologic process that is analogous to chronic inflammatory conditions. Several factors have been shown to correlate with the extent of atherosclerosis. Whereas hypertension, obesity, hyperlipidemia, diabetes, smoking, and family history are all well documented, recent literature points to additional associated factors. Thus, antibodies to oxidized low‐density lipoprotein (oxLDL), cytomegalovirus (CMV), Chlamydia pneumonia, Helicobacter pylori, as well as homocysteine and C‐reactive protein (CRP) levels have all been implicated as independent markers of accelerated atherosclerosis.

Hypothesis: In the current study we attempted to formulate a system by which to predict the extent of coronary atherosclerosis as assessed by angiographic vessel occlusion.

Methods: The 81 patients were categorized as having single‐, double‐, triple‐, or no vessel involvement. The clinical data concerning the “classic” risk factors were obtained from clinical records, and sera were drawn from the patients for determination of the various parameters that are thought to be associated with atherosclerosis.

Results: Using four artificial neural networks, we have found the most effective parameters predictive of coronary vessel involvement were (in decreasing order of importance) antibodies to oxLDL, to cardiolipin, to CMV, to Chlamydia pneumonia, and to β2‐glycoprotein I (β2GPI). Although important in the prediction of vessel occlusion, hyperlipidemia, hypertension, CRP levels, and diabetes were less accurate.

Conclusion: The results of the current study, if reproduced in a larger population, may establish an integrated system based on the creation of artificial neural networks by which to predict the extent of atherosclerosis in a given subject fairly and noninvasively.
The effect of transient balloon occlusion of the mitral valve on left atrial appendage blood flow velocity and spontaneous echo contrast
Authors: Wang Jianan , Choo Daniel Chung Ann , Zhang Xianglan , Yang Qian , Xian Tangchao , Lu Duan , Jiang Shan
Published: February 2009

Background: Spontaneous echo contrast (SEC) is a phenomenon that is commonly seen in areas of blood stasis. It is a slowly moving, cloud‐like swirling pattern of “smoke” or increased echogenicity recorded on echocardiography. SEC is commonly seen in the left atrium of patients with mitral stenosis or atrial fibrillation. The prescence of SEC has been shown to be a marker of increased thromboembolic risk.

Hypothesis: By using transesophageal echocardiography during percutaneous balloon mitral valvotomy (PBMV), the study investigated the relationship between SEC and varying left atrial appendage (LAA) blood flow velocity in the human heart.

Methods: Thirty—five patients with rheumatic mitral stenosis underwent percutaneous balloon mitral valvotomy with intraoperative transesophageal echocardiography monitoring. We alternatively measured LAA velocities and observed the left atrium for various grades of SEC (0 = none to 4 = severe) before and after each balloon inflation.

Results: Left atrial appendage maximal ejection velocity was reduced from 35 ± 14 to 6 ± 2 mm/s at peak balloon inflation and increased to 40 ± 16 mm/s after balloon deflation. In comparison with the values before balloon inflation and after balloon deflation, LAA velocities were significantly lower (p < 0.001). New or increased SEC grade was observed during 54 of 61 (88%) inflations and unchanged in 7 (12%) inflations at peak balloon inflation. Spontaneous echo contrast became lower in grade after 55 balloon deflations (90%), completely disappeared after 18 deflations (30%), and remained unchanged after 6 deflations (10%). The mean time to achieve maximal SEC grade (2.5 ± 1.2 s) coincided with the mean time to trough LAA velocities (2.3 ±1.1 s) after balloon inflation. Upon deflation, the mean time to lowest SEC grade (2.9 ± 1.8 s) coincided with mean time to achieve maximal LAA velocities (2.7 ± 1.6s).

Conclusion: During balloon inflation, the severity of SEC was enhanced with corresponding reduction in LAA flow velocity. Upon balloon deflation, SEC lightens or disappears with increase in LAA flow velocity.
Relation of transesophageal echocardiographic findings to subtypes of cerebral infarction in patients with atrial fibrillation
Authors: Shinokawa Noriko , Hirai Tadakazu , Takashima Shutaro , Kameyama Tomoki , Obata Yoshiko , Nakagawa Keiko , Asanoi Hidetsugu , Inoue Hiroshi
Published: February 2009

Background: Transesophageal echocardiography (TEE) has been used to identify the potential risk for cardiogenic embolism in patients with atrial fibrillation (AF). However, ischemic stroke in patients with AF is not always attributable to embolism. Identification of the risk of embolic versus athero‐thrombotic stroke should lead to the optimal individualized management of patients with AF.

Hypothesis: The goal of the study was to determine the relation between cortical infarction and perforating infarction and TEE findings in patients with AF.

Methods: We investigated the clinical usefulness of TEE in the risk stratification of clinical subtyping of the cerebral infarctions which were divided into two territories of the cortical branch (cortical infarction due to embolism) and deep perforators (perforating infarction due to atherothrombosis). Left atrial spontaneous echo contrast, peak flow velocity in the left atrial appendage, and generalized atherosclerosis as estimated by the intima‐media wall thickness of the thoracic aorta were assessed by TEE in 118 consecutive patients with either paroxysmal (n = 44) or chronic (n = 74) AF. All patients underwent either brain computed tomography or magnetic resonance imaging.

Results: Cortical and perforating infarction was found in 39 and 18% of patients, respectively. The grade of spontaneous echo contrast was higher in patients with than in those without cortical infarction (p<0.05). In contrast, patients with perforating infarction showed significant increase in the aortic wall thickness when compared with patients without perforating infarction (p <0.05). In addition, multivariate logistic analysis revealed that spontaneous echo contrast was an independent predictor of cortical infarction, while intima‐media wall thickness of the aorta, hypertension, and age were useful in predicting the risk of perforating infarction.

Conclusions: Transesophageal echocardiography has a potential role in the risk stratification for cortical and perforating infarction in patients with AF.
Failure of magnesium to protect isolated cardiomyocytes from effects of hypoxia or metabolic poisoning
Authors: Gallagher Mark M. , Allshire Ashley P.
Published: February 2009

Background: MgSO 4 appears to reduce infarct size in animal models of myocardial infarction‐reperfusion, but only if given before reperfusion. The mechanisms underlying this effect have not been established, nor has the discrepancy between these results and the lack of efficacy in the Fourth International Study of Infarct Survival (ISIS‐4) been explained.

Hypothesis: The study was undertaken to examine the hypothesis that Mg 2+ protects myocardium threatened by ischemia.

Methods: We studied the effects of extracellular magnesium [Mg2+ ] e at 0.6 and 1.8 mmol/l on isolated myocytes exposed to 2.5 mmol/l NaCN + 5 mmol/l 2‐deoxyglucose or to profound hypoxia.Results: Nonpaced cells shortened at a mean of 8.8 min after onset of metabolic inhibition in [Mg 2+] e =1.8 mmol/l, 9.6 min in [Mg 2+]s e = 0.6 mmol/l (not significant). Paced cells shortened after 9.5 min in [Mg 2+] e = 1.8 mmol/l, 10.2 min at [Mg 2+ ] e = 0.6 mmol/l. On washout of inhibitors, 93% of cells underwent hypercontracture at [Mg 2+ ] e = 1.8 mmol/l, 94.8% at [Mg 2+ ] e = 0.6 mmol/l. During hypoxia, nonpaced cells in [Mg 2+ ] e = 1.8 mmol/l shortened after 67 ± 11 min compared with 62.5 ± 28 min at [Mg 2+ ] e = 0.6 mmol/l. Paced cells shortened after 25.8 ± 12.9 min at [Mg 2+] e = 1.8 mmol/l and after 28.7 ± 13.6 min at [Mg 2+ ] e = 0.6 mmol/l. Although there was a trend toward longer survival at higher [Mg 2+ ] e, the difference was small and not significant (p > 0.05, Student's paired t‐test).

Conclusion: We find no evidence to support the hypothesis that [Mg 2+ ] protects myocardium threatened by ischemia.This is consistent with clinical data but contradicts data from animal experiments.
Cox‐maze procedure for treatment of atrial flutter associated with an atrial septal defect
Authors: Dakik Habib A. , Arnaout Samir , Khoury Maurice , Obeid Mounir
Published: February 2009

A 52‐year‐old man presented with atrial flutter and was found to have an atrial septal defect (ASD). The paper describes an effective surgical approach for the treatment of this atrial arrhythmia utilizing a right sided Cox‐maze EI procedure concomitant with ASD closure. Review of the literature and clinical implications are discussed.
Prognostic role of plasminogen—activator—inhibitor—1 levels in treatment with streptokinase of patients with acute myocardial infarction
Authors: Sinkovič Andreta
Published: February 2009

Background: The antifibrinolytic effect of plasminogen—ac—tivator—inhibitor type 1 (PAI—1) may be responsible for delays in reperfusion and/or reinfarctions after streptokinase (STK) therapy in patients with acute myocardial infarction (AMI).

Hypothesis: This study aimed to demonstrate the prognostic role of pretreatment PAI—1 levels for the outcome of STK therapy in patients with AMI, depending on reperfusion and/or reinfarction.

Methods: The mean pretreatment PAI—1 level of 104 patients with AMI, treated with STK, determined by chro—mogenic method, was 5.8 ± 8.6 U/ml, range 0.3—66.2 U/ml. Streptokinase therapy was successful when reperfusion was achieved, as assessed noninvasively, without subsequent rein—farction; it failed when reperfusion was delayed and/or rein—farction developed.

Results: Fibrinolysis with STK failed significantly in patients with elevated pretreatment PAI—1 levels (p < 0.05), especially with levels >4.0 U/ml (p<0.01). The mean pretreatment PAI—1 level was significantiy higher in unsuccessfully treated patients. Multivariate statistical testing demonstrated that among pretreatment variables, elevated PAI—1 activity was the most significant independent risk factor of failed fibrinolysis with STK.

Conclusions: Among pretreatment variables, elevated pretreatment PAI‐1 activity in patients with AMI was the most significant independent risk factor of failed fibrinolysis with STK, especially at levels > 4.0 U/ml.
Medical management of significant coronary angiographic stenoses: Outcome of 60 patients observed for 433 patient years
Authors: Baird Charles L. , Crater Scott E.
Published: February 2009

Background: Percutaneous transluminal coronary angioplasty (PTCA) has become routine in the management of patients with stable angina pectoris and significant coronary stenoses, while medical management of such patients has declined.

Hypothesis: The purpose of the present study was to evaluate the outcome of 60 patients at the Virginia Heart Institute with stable angina pectoris, observed between 1976 and 1997, who had documented evidence of severe angiographic disease but were elected to be monitored and managed in an outpatient pharmacologic rehabilitation program.

Methods: Sixty patients with significant stenoses by coronary angiography (21 with single‐vessel, 26 with double‐vessel, and 13 with triple‐vessel) without impaired ventricular function, exercise‐induced ischemia or hypotension, limited exercise performance, malignant arrhythmias, or drug intolerance were enrolled in a program of pharmacologic rehabilitation and observed for an average of 7.2 years.

Results: Among the 60 patients, there were 6 deaths at a mean interval of 8.3 years. Two deaths were in patients ineligible for revascularization. Another patient who died had refused revascularization after new‐onset left ventricular dysfunction, and another died intraoperatively during abdominal aortic aneurysm repair. Two patients died while exercising. Thirteen patients underwent follow‐up catheterization for worsening angina; 11 of 13 showed progression, predominantly from new lesions. Four of 11 were referred for revascularization; 7 of 11 continued medical treatment; 49 patients were stable on medical therapy throughout the period of observation.

Conclusion: Medical management of selected patients with significant coronary stenoses is safe and effective.
Left ventricular myocardial remodeling and contractile state in chronic aortic regurgitation
Authors: Taniguchi Kazuhiro , Kawamaoto Tomohide , Kuki Satoru , Masai Takahumi , Mitsuno Masataka , Nakano Susumu , Kawashima Yasunaru , Matsuda Hikaru
Published: February 2009

Background: In chronic aortic regurgitation, eccentric hypertrophy, with combined concentric hypertrophy of the left ventricle, is an important adaptive response to volume overload, which in itself is a compensatory mechanism for permitting the ventricle to normalize its afterload and to maintain normal ejection performance (physiologic hypertrophy). However, progressive dilatation of the left ventricle leads to depressed left ventricular (LV) contractility and myocardial structural changes, including cellular hypertrophy and interstitial fibrosis (pathological hypertrophy).

Hypothesis: The study was undertaken to determine the relationship between left ventricular myocardial structure and contractile function in 14 patients with chronic aortic regurgitation by cardiac catheterization and endomyocardial biopsies.

Methods: Myocardial cell diameter and percent interstitial fibrosis were obtained from biopsy samples. Contractile function was evaluated from the ratio of end‐systolic wall stress to end‐systolic volume index (ESS/ESVI) and the ejection fraction‐end‐systolic stress (EF‐ESS) relationship, which was obtained from 30 normal control subjects.

Results: Myocardial cell diameter correlated significantly with the ESVI (r = 0.72, p< 0.005), ejection fraction (r = −0.58, p<0.05), and ESS/ESVI (r = −0.58, p<0.05). The percent interstitial fibrosis also correlated inversely with ESS/ESVI (r = −0.71, p< 0.005). Compared with very few patients with an ESVI <70 ml/m2, the majority of patients with ESVI ≥ 70 ml/m2 had a cell diameter of ≥30 m̈m and a percent interstitial fibrosis of ≥l0%. The nine patients who had depressed contractile function, as assessed from the EF‐ESS relationship, had a higher percent interstitial fibrosis (p <0.05) than five patients showing a normal EF‐ESS relationship, despite the fact that there was no significant difference in myocardial cell diameter between them. Thus, advanced cellular hypertrophy and excessive interstitial fibrosis were significantly and independently associated with myocardial contractile dysfunction and appeared to be responsible for ventricular remodeling.

Conclusion: Our findings suggest that in many patients with aortic regurgitation, eccentric hypertrophy changes its nature from physiologic to nonphysiologic during the earlier stages in the course of the disease rather than during the stage described previously.
Exercise conditioning and heart rate variability: Evidence of a threshold effect
Authors: Pardo Yosef , Noel Merz C. Bairey , Velasquez Ivan , Paul‐Labrador Maura , Agarwala Aalok , Peter C. Thomas
Published: February 2009

Background: A protective effect of exercise in preventing sudden cardiac death is supported by studies in healthy populations as well as in patients with cardiac disease. The mechanisms involved in this protective effect are unknown.

Hypothesis: We hypothesized that exercise conditioning would beneficially alter autonomic nervous system tone, measured by heart rate variability.

Methods: We prospectively studied 20 cardiac patients enrolled in a Phase 2 12‐week cardiac rehabilitation program following a recent cardiac event. The patients underwent 24 h Holter monitoring at program entry and 12 weeks later. Heart rate variability analysis was assessed for both time domain and spectral analysis.

Results: The group demonstrated a modest mean conditioning effect, indicated by an average reduction in resting heart rate from 81 ± 16 to 75 ± 12 beats/min (p = 0.03), and an increase in training METS from 2.1 ± 0.4 to 3.3 ± 1.1 (p< 0.0001). Overall, 15 of 20 (75%) patients demonstrated increased total and high‐frequency power, and mean high‐frequency power was significantly increased (3.9 ± 1.4 vs. 4.4 ± 1.0 In, p = 0.05). When stratified according to the magnitude of exercise conditioning, patients achieving an increase of > 1.5 training METS demonstrated significant increases in SDNN, SDANN index, SDNN index, pNN50, total power, and high‐frequency power (all p < 0.05) (see text for explanation of abbreviations).

Conclusions: Exercise conditioning improves heart rate variability in cardiac patients, particularly in patients who achieve a threshold of > 1.5 training METS increase over a 12‐week period. These study results are supportive of the concept that exercise training lowers the risk of sudden cardiac death via increased vagal tone, which likely beneficially alters ventricular fibrillatory and ischemic thresholds.
True‐Positive exercise electrocardiogram/false‐negative thallium‐201 scintigram: A proposal of a mechanism for the paradox
Authors: Madias John E. , Knez Predrag , Win Moe Thu
Published: February 2009

A 72‐year‐old man with exertional angina had a strongly positive exercise electrocardiogram (EECG) with a negative thallium‐201 myocardial perfusion scintigram (Tl). Arteriography revealed triple‐vessel coronary artery disease, for which he underwent aortocoronary bypass grafting. Repeat EECG was negative, and it was again associated with a negative Tl. The false‐negative Tl on the first test was felt to be due to a rare phenomenon of homogeneously distributed reversible exercise‐induced myocardial ischemia, leading to a uniform radiotracer count density. The even distribution of ischemia would also be expected to render a false‐negative EECG, due to electrocardiographic cancellation, and this is frequently the case. However, in the patient presented herein, we propose that the ischemic cardiac apex rendered the EECG strongly positive because its position was not opposed by an ischemic muscular region, and thus an uncancelled ischemic ST‐segment vector was generated. This hypothesis is supported by our recent work showing the unique role of the ischemic apex (among all the other myocardial territories) in rendering the EECG positive.
Worsening of left ventricular diastolic dysfunction during exercise causes decreased exercise tolerance in hypertension
Authors: Khan Ijaz A. , Nair Vinod M. , Tekin Uygur N. , Rahmatullah Syed I. , Arora Pratheep , Mahankali Bhavani D. , Sacchi Terrence J. , Vasavada Balendu C.
Published: February 2009

Background: Exercise tolerance is reduced in hypertension. Hypertension affects left ventricular (LV) diastolic filling by causing abnormal relaxation and decreasing compliance.

Hypothesis: This study was designed to determine whether worsening of LV diastolic dysfunction during exercise causes decreased exercise tolerance in hypertension.

Methods: Left ventricular diastolic filling parameters were examined at mitral valve by Doppler echocardiography at rest and at peak exercise in hypertensive patients and were compared with those of age‐ and gender‐matched normotensive individuals. Treadmill exercise stress test was performed according to the Bruce protocol and the exercise time was recorded.

Results: Exercise time was significantly shorter in the hypertensive group than that in the normotensive group (320 ± 29 vs. 446 ± 38 s, p 0.03). The hypertensive group demonstrated abnormal relaxation pattern of diastolic mitral inflow at rest, which became pseudonormal at peak exercise (E/A velocity ratio, rest 0.86 ± 0.06 vs. exercise 1.19 ± 0.09, p<0.001). The diastolic mitral inflow pattern remained normal at peak exercise in the normotensive group. The deceleration time and the pressure half time of early mitral inflow at peak exercise were significantly shorter in the hypertensive group than those in the normotensive group (deceleration time, 182 ± 20 vs. 238 ± 22 ms, p 0.02: pressure half time, 54 ± 5 vs. 70 ± 12 ms, p 0.01).

Conclusions: This study demonstrates that reduced exercise tolerance in hypertension is associated with worsening of diastolic dysfunction during exercise consistent with an increase in left atrial pressure.