Cardiac resynchronisation therapy for heart failure with reduced ejection fraction (HFrEF)

Patients with left ventricular dysfunction and heart failure frequently have impaired electromechanical coupling that further reduces ventricular systolic function. Prolongation of the QRS interval, particularly with left bundle branch block, is associated with poor coordination of ventricular contraction (dyssynchrony). This can be improved by cardiac resynchronisation therapy (CRT) by biventricular pacing (ie pacing of both ventricles). The left ventricle is paced via a lead placed in a branch of the coronary sinus or on the epicardium via a small thoracotomy. The pacemaker is also connected to the atrium to provide optimal atrioventricular synchronisation.

CRT may be delivered by a pacemaker (CRT-P) or by a device that is also an implantable cardioverter defibrillator (CRT-D).

CRT improves heart failure symptoms and cardiac function, and decreases mortality. Not all patients respond to CRT. Optimal patient selection, pacemaker lead placement and device programming, and ongoing heart failure management are essential. CRT implantation should be performed by an experienced operator at a centre with a low complication rate.

CRT is recommended for patients in sinus rhythm who have symptomatic heart failure (despite optimal medical therapy) with left ventricular ejection fraction 35% or less and QRS duration of 0.13 seconds or moreMoss, 2009Tang, 2010. CRT may also be beneficial in similar patients with chronic atrial fibrillation (provided there is predominant biventricular capture) or in patients with heart failure with reduced ejection fraction (HFrEF) with an indication for ventricular pacing to treat bradyarrhythmias.