Michael L. Bernard

The State of the Art: Atrial Fibrillation Epidemiology, Prevention, and Treatment

As the most common sustained arrhythmia in adults, atrial fibrillation (AF) is an established and growing epidemic. To provide optimal patient care, it is important for clinicians to be aware of AFs epidemiological trends, methods of risk reduction, and the various available treatment modalities. Our understanding of AFs pathophysiology has advanced, and with this new understanding has come advancements in prevention strategies as well as pharmacological and nonpharmacological treatment options. Following PubMed and MEDLINE searches for AF risk factors, epidemiology, and therapies, we reviewed relevant articles (and bibliographies of those articles) published from 2000 to 2016. This state-of-the-art review provides a comprehensive update on the understanding of AF in the world today, contemporary therapeutic options, and directions of ongoing and future study.

T-peak to T-end interval for prediction of ventricular tachyarrhythmia and mortality in a primary prevention population with systolic cardiomyopathy

BACKGROUNDnThe electrocardiographic T-wave peak to T-wave end interval (Tpe) correlates with dispersion of ventricular repolarization (DVR). Increased DVR increases propensity toward electrical reentry that can cause ventricular tachyarrhythmia. The baseline rate-corrected Tpe (Tpec) has been shown to predict ventricular tachyarrhythmia and death in multiple patient populations but not among cardiomyopathic patients undergoing insertion of an implantable cardioverter-defibrillator (ICD) for primary prevention.nnnOBJECTIVEnThe purpose of this study was to assess the risk stratification ability of the Tpec in patients with systolic cardiomyopathy without prior ventricular tachyarrhythmia (ie, the primary prevention population).nnnMETHODSnWe performed prospective follow-up of 305 patients (73% men; left ventricular ejection fraction [LVEF] 23 ± 7%) with LVEF ≤35% and an ICD implanted for primary prevention. Baseline ECGs were analyzed with automated algorithms. Endpoints were ventricular tachycardia (VT)/ventricular fibrillation (VF), death, and a combined endpoint of VT/VF or death, assessed by device follow-up and Social Security Death Index query.nnnRESULTSnThe average Tpec was 107 ± 22 ms. During device clinic follow-up of 31 ± 23 months, 82 patients (27%) had appropriate ICD therapy for VT/VF, and during mortality follow-up of 49 ± 21 months, 91 patients (30%) died. On univariable analysis, Tpec predicted VT/VF, death, and the combined endpoint of VT/VF or death (P < .05 for each endpoint). Multivariable analysis included univariable predictors among demographics, clinical data, laboratory data, medications used, and electrocardiography parameters. After correction, Tpec remained predictive of VT/VF (hazard ratio [HR] per 10-ms increase 1.16, P = .009), all-cause mortality (HR per 10 ms 1.13, P = .05), and the combined endpoint (HR per 10 ms 1.17, P = .001).nnnCONCLUSIONnTpec independently predicts both VT/VF and overall mortality in patients with systolic dysfunction and ICDs implanted for primary prevention.

Optimal method of measuring the T-peak to T-end interval for risk stratification in primary prevention

AimsnSeveral published investigations demonstrated that a longer T-peak to T-end interval (Tpe) implies increased risk for ventricular tachyarrhythmia (VT/VF) and mortality. Tpe has been measured using diverse methods. We aimed to determine the optimal Tpe measurement method for screening purposes.nnnMethods and resultsnWe evaluated 305 patients with LVEF ≤ 35% and an implantable cardioverter-defibrillator implanted for primary prevention. Tpe was measured using seven different methods described in the literature, including six manual methods and the automated algorithm 12SL, and was corrected for heart rate. Endpoints were VT/VF and death. To account for differences in the magnitude of Tpe measurements, results are expressed in standard deviation (SD) increments. We evaluated the clinical utility of each measurement method based on predictive ability, fraction of immeasurable tracings, and intra- and interobserver correlation. >Over 31 ± 23 months, 82 (27%) patients had VT/VF, and over 49 ± 21 months, 91 (30%) died. Several rate-corrected Tpe measurement methods predicted VT/VF (HR per SD 1.20-1.34; all P < 0.05), and nearly all methods (both corrected and uncorrected) predicted death (HR per SD 1.19-1.35; all P < 0.05). Optimal predictive ability, readability, and correlation were found in the automated 12SL method and the manual tangent method in lead V2.nnnConclusionnFor the prediction of VT/VF, the utility of Tpe depends upon the measurement method, but for the prediction of mortality, most published Tpe measurement methods are similarly predictive. Heart rate correction improves predictive ability. The automated 12SL method performs as well as any manual measurement, and among manual methods, lead V2 is most useful.

Current Evidence-Based Understanding of the Epidemiology, Prevention, and Treatment of Atrial Fibrillation*

Atrial fibrillation (AF) is the most common atrial arrhythmia in adults worldwide. As medical advancements continue to contribute to an ever-increasing aging population, the burden of atrial fibrillation on the modern health care system continues to increase. Therapies are also evolving, for treatment of the arrhythmia itself, and stroke risk mitigation. Internists and cardiologists alike are, in most instances, the frontline contact for AF patients, and would benefit from remaining facile in their understanding of care options. To continue to deliver high-quality care to this expanding patient group, an updated, concise review for the clinician is prudent. This article provides a comprehensive summary of the current epidemiology and pathophysiology of AF, as well as contemporary procedural therapeutic options.

Cardiac Defibrillators and Heart Failure

Congestive heart failure affects over five million people in the United States with over 500,000 new cases reported annually. Roughly half of patients die from heart failure related causes within the first 5 years of diagnosis. Conventional medical therapy including beta blockers, renin-angiotensin antagonists and aldosterone antagonists has improved morbidity and mortality in this population. However Sudden Cardiac Death (SCD) remains the leading cause of death in this group of patients. Implantable Cardioverter-Defibrillators (ICDs) were initially used to prevent future arrhythmic deaths in patients who survived SCD. Utilization of ICDs was greatly expanded when landmark clinical trials demonstrated that ICDs reduce mortality, particularly due to arrhythmic events, in heart failure patients. In addition to conventional medical therapy, ICD implantation has become the standard of care in patients with reduced ejection fraction, no matter the etiology of their heart failure.

CORRELATION BETWEEN POSITRON EMISSION TOMOGRAPHY STRESS MYOCARDIAL BLOOD FLOW AND VENTRICULAR TACHYARRHYTHMIA OR DEATH IN PATIENTS WITH CARDIOMYOPATHY

In patients with cardiomyopathy (CM) and an implantable cardioverter-defibrillator (ICD), the relationship between positron emission tomography (PET) stress myocardial blood flow (sMBF) and adverse cardiac events including ventricular arrhythmia (VT/VF) is unknown.nnPatients with CM with an ICD in