Cardiac resynchronization therapy in heart failure patients: An update

Abstract

Heart failure continues to be a major public health problem with high morbidity and mortality rates, despite the advances in medical treatment. Advanced heart failure patients have severe persistent symptoms and a poor quality of life. Cardiac resynchronization therapy (CRT), an invasive therapy which involves synchronized pacing of both right and left ventricles, improves ventricular conduction delay and left ventricular performance. Several clinical trials of CRT in medically refractory heart failure patients with wide QRS (> 120 ms), left ventricular ejection fraction £ 35% and New York Heart Association (NYHA) class III and IV have shown improved quality of life, NYHA class, left ventricular ejection fraction and reduced mortality. About 30% of heart failure patients who receive CRT do not respond to treatment. Mechanical dyssynchrony may play a role in identifying patients who may respond better to CRT treatment. However, recent large scale clinical trials PROSPECT and RethinQ have challenged this concept. The role of CRT in heart failure patients with narrow QRS (< 120 ms), NYHA class I and II, atrioventricular nodal ablation in patients with atrial fibrillation and triple site pacing are evolving. Our review discusses the current evidence, indications, upcoming trials and future directions.