Prognostic significance of QRS duration and morphology

QRS duration and morphology, evaluated via a standard 12-lead electrocardiogram (ECG), represent an opportunity to derive useful prognostic information regarding the risk of subsequent cardiac events or therapeutic outcomes. Prolonged QRS duration, and the presence of intraventricular conduction abnormalities, usually indicate the presence of changes in the myocardium due to underlying heart disease. Prolonged QRS duration is often associated with depressed ejection fraction or enlarged left ventricular volumes, but several studies have demonstrated that this simple ECG measure provides independent prognostic value, after adjusting for relevant clinical covariates. Post-infarction patients with prolonged QRS duration have a significantly increased risk of mortality, although data associating QRS prolongation specifically with sudden death is less supportive. In non-ischemic cardiomyopathy, there is no evidence that QRS duration has prognostic significance in predicting mortality or sudden death. Prolonged QRS duration, and especially presence of left bundle branch block, seems to predict a benefit from cardiac resynchronization therapy in both ischemic and non-ischemic cardiomyopathy patients. Therefore, QRS duration and morphology should not only be considered a predictor of death or sudden death in patients after myocardial infarction, and in those suspected of coronary artery disease, but also as a predictor of benefit from cardiac resynchronization therapy in patients with heart failure, whether of an ischemic or non-ischemic origin. (Cardiol J 2011; 18, 1: 8-17

The Downside of Right Ventricular Apical Pacing

The right ventricular (RV) apex has been the standard pacing site since the development of implantable pacemaker technology. Although RV pacing was initially only utilized for the treatment of severe bradyarrhythmias usually due to complete heart block, today the indications for and implantation of RV pacing devices is dramatically larger. Recently, the adverse effects of chronic RV apical pacing have been described including an increased risk of heart failure and death. This review details the detrimental effects of RV apical pacing and their shared hemodynamic pathophysiology. In particular, the role of RV apical pacing induced ventricular dyssynchrony is highlighted with a specific focus on differential outcome based upon QRS morphology at implant

Atrioventricular delay programming and the benefit of cardiac resynchronization therapy in MADIT-CRT.

The optimal atrioventricular pacing delay (AVD) in cardiac resynchronization therapy (CRT) remains to be determined

Predictors of spontaneous reverse remodeling in mild heart failure patients with left ventricular dysfunction.

There are limited data regarding factors associated with spontaneous left ventricular reverse remodeling (S-LVRR) among mildly symptomatic heart failure (HF) patients and its prognostic implications on clinical outcomes