No benefit from cardiac resynchronisation therapy in patients with a narrow QRS complex

Cardiac-resynchronisation therapy (CRT) has known benefits in patients with severe left ventricular systolic dysfunction and prolonged QRS duration (>120 ms). However, up to half of patients with systolic dysfunction appear to have left ventricular dyssynchrony by echocardiographic measures, despite a QRS duration of less than 120 ms. As a result, CRT is often used for patients with echocardiographic evidence of dyssynchrony and a narrow QRS complex, despite a lack of clear benefit to this approach. The Echocardiography Guided Cardiac Resynchronisation Therapy (EchoCRT) study sought to determine the effect of CRT on patient outcomes in the setting of symptomatic heart failure, echocardiographic findings of dyssynchrony, and QRS duration <120 ms.

In this multicenter double blind trial, patients with severe symptomatic left ventricular failure (EF<35% and NYHA class III or IV) with a QRS duration of <130 ms (mean 105 ms) and evidence of dyssynchrony either on tissue Doppler or speckle tracking echo parameters, were all implanted with CRT devices with ICDs and then randomised so that half of study participants had the CRT function turned off. The primary outcome was a composite of all cause death or hospitalisation for heart failure. Following a pre-planned interim analysis, the study was terminated prematurely after recruitment of 809 out of a planned 1132 patients due to futility. By study close, 116 patients in the CRT group had met the primary …