The Clinical Challenge of Predicting and Preventing Sudden Cardiac Death Immediately after Myocardial Infarction

Despite many advances in treatment of myocardial infarction (MI) with percutaneous coronary intervention (PCI) and pharmacologic therapies, mortality immediately after MI remains high in patients with impaired left ventricular function. One of the greatest challenges facing the contemporary cardiologist is predicting and preventing sudden cardiac death (SCD) immediately after MI. Unfortunately, the trials assessing the role of the implantable cardioverter defibrillator (ICD) in patients at high risk for SCD immediately post MI have failed to show survival benefit. Current clinical guidelines restrict ICD implants to patients at least 40 days after MI with continued left ventricular dysfunction while on optimal medical therapy. It is evident that additional research is needed to identify strategies to prevent SCD and improve survival immediately after MI. In the meantime, clinicians should optimize and individualize therapy in the immediate post MI patient while carefully considering the risk of SCD and the competing risk of mortality from other causes

Cardiac Resynchronization Therapy in Mild Heart Failure/ REVERSE, MADIT-CRT & RAFT studies & Meta-analyses / Expanding CRT-D Indications to Lower Risk Patients

Cardiac resynchronization therapy (CRT), effected via biventricular pacing, has been shown to improve symptoms and left ventricular (LV) systolic function and to reduce mortality and hospitalizations among patients with moderate to severe heart failure symptoms (class III and IV), reduced LV ejection fraction (EF), and a wide QRS complex on electrocardiogram, usually in the form of left bundle branch block. Recent evidence from randomized clinical trials and meta-analyses demonstrate that the beneficial effects of CRT on LV remodeling, heart failure symptoms, hospitalizations, and mortality also extend to patients with milder heart failure symptoms (class II). These data support the expansion of indications for CRT to less symptomatic patients with heart failure who have LVEF <0.35 and wide QRS duration in sinus rhythm. Accordingly the guidelines for CRT therapy by the European Society of Cardiology (ESC) and the American heart Association (AHA) have been updated to expand CRT indications to patients with milder heart failure symptoms

Primary Prevention of Sudden Cardiac Death: Implications of Recent Trials

Based on the results of randomized multicenter studies, such as the MADIT I, MADIT II, DINAMIT, and SCD-HeFT and DEFINITE trials, patients can be identified who are at high risk for sudden cardiac death (SCD) who demonstrate a reduction in arrhythmic mortality and total mortality with the implantation of an implantable cardioverter defibrillator (ICD). These are patients with coronary artery disease, impaired left ventricular function, spontaneous nonsustained ventricular tachycardia and inducible ventricular tachycardia not suppressed by procainamide. Also patients with coronary artery disease and left ventricular ejection fraction < 30% benefit from ICD placement.  Based on the SCD-HeFT results, patients with ischemic or nonischemic cardiomyopathy and class II or III congestive heart failure also benefit from the ICD.  At the same time, based on the results of the DINAMIT study, it has become apparent that the ICD does not play a role in patients within 45 days of myocardial infarction. The implications of these trials are further analyzed in this overview

Sudden Death in the Athlete

Arrhythmias in the athlete can range from benign and asymptomatic to highly symptomatic and life-threatening.  There is risk of not diagnosing an important cardiovascular condition which may predispose to a serious or life threatening arrhythmia.  At the same time there is the risk of unnecessarily restricting the athlete with a more benign condition. Sudden cardiac death in the athlete, although relatively uncommon, remains a challenge as the screening techniques for identification of individuals at risk are insensitive. Many of the underlying cardiovascular diseases responsible for sudden death with exercise can be identified. These include hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, Wolff-Parkinson-White syndrome, anomalous origin of the coronary artery, and the inherited long QT syndromes. To prevent fatalities and unnecessary restriction on athletic participation, the best available information has recently been updated with consensus recommendations and guidelines regarding eligibility. In this manuscript the cardiovascular conditions and cardiac arrhythmias that predispose to sudden cardiac death in the athlete are discussed

Ventricular pacing or dual-chamber pacing for sinus-node dysfunction

BACKGROUND Dual-chamber (atrioventricular) and single-chamber (ventricular) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinically significant bradycardia. However, it is unknown which type of pacing results in the better outcome. METHODS We randomly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing (1014 patients) or ventricular pacing (996 patients) and followed them for a median of 33.1 months. The primary end point was death from any cause or nonfatal stroke. Secondary end points included the composite of death, stroke, or hospitalization for heart failure; atrial fibrillation; heart-failure score; the pacemaker syndrome; and the quality of life. RESULTS The incidence of the primary end point did not differ significantly between the dual-chamber group (21.5 percent) and the ventricular-paced group (23.0 percent, P=0.48). In patients assigned to dual-chamber pacing, the risk of atrial fibrillation was lower (hazard ratio, 0.79; 95 percent confidence interval, 0.66 to 0.94; P=0.008), and heart-failure scores were better (P CONCLUSIONS In sinus-node dysfunction, dual-chamber pacing does not improve stroke-free survival, as compared with ventricular pacing. However, dual-chamber pacing reduces the risk of atrial fibrillation, reduces signs and symptoms of heart failure, and slightly improves the quality of life. Overall, dual-chamber pacing offers significant improvement as compared with ventricular pacing

ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Writing Committee to revise the ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemakers and antiarrhythmia devices)

This revision of the “ACC/AHA/NASPE Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices” updates the previous versions published in 1984, 1991, 1998, and 2002. Revision of the statement was deemed necessary for multiple reasons: 1) Major studies have been reported that have advanced our knowledge of the natural history of bradyarrhythmias and tachyarrhythmias, which may be treated optimally with device therapy; 2) there have been tremendous changes in the management of heart failure that involve both drug and device therapy; and 3) major advances in the technology of devices to treat, delay, and even prevent morbidity and mortality from bradyarrhythmias, tachyarrhythmias, and heart failure have occurred