Change in indication for cardiac resynchronization therapy?

Cardiac resynchronization therapy (CRT) has rapidly evolved as a standard therapy for heart failure (HF) patients with ventricular conduction delay. Although in early trials, only patients with sinus rhythm and advanced stages of HF have been candidates for CRT, more recent data have expanded the indications to patients with mild-to-moderate HF and atrial fibrillation and patients in need of antibradycardia pacing with reduced left ventricular function. On the other hand, it is now well recognized that patients with a wide QRS (>150 ms) and left bundle branch block morphology benefit most from CRT, whereas in patients with a more narrow QRS complex (<130 ms) CRT may actually be harmful despite the evidence of ventricular dyssynchrony by echocardiography. There is no prospective randomized study showing mortality benefit from a combined CRT defibrillating device over a CRT pacer alone. This is especially important because recent data indicate that older patients with non-ischaemic cardiomyopathy may not benefit from the implantable cardioverter-defibrillator as much as previously thought. Thus, the decision for a CRT pacer versus CRT defibrillating should be tailored to the therapeutic goal (improvement in prognosis versus symptomatic relief), patient age, underlying cardiac disease and comorbidities. This article gives an overview over the current indications for CRT according to published literature and the European guidelines for pacing and HF.