Future New Indications for CRT: Which Patients Might Benefit?

Abstract

Cardiac resynchronisation therapy (CRT) is a non-pharmacological treatment for patients with severe congestive heart failure (CHF) due to systolic dysfunction who also present an intraventricular conduction abnormality and a QRS duration greater than 120 ms [1]. CRT has been shown to improve functional status, quality of life, and exercise tolerance and to decrease hospitalisation frequency in these patients: recent results of the MUSTIC [2] and MIRACLE [3] trials are consistent in showing an improvement in NYHA class, quality of life scores, and distance covered during a 6-min walking test. A decrease in dynamic mitral regurgitation, increase in left ventricular ejection fraction, and reverse remodelling effect on the left ventricle has also been noted. The COMPANION study has recently demonstrated that CRT provides significantly better results regarding a combined endpoint of mortality and heart failure hospitalisation [4].

Consequently, CRT has been included in the current American Heart Association/American College of Cardiology/North American Society of Pacing and Electrophysiology guidelines for the implantation of permanent pacemakers as a therapeutic option for patients with systolic heart failure, NYHA class ≥ 3, QRS duration ≥ 130 ms, left ventricular end-diastolic diameter ≥ 55 mm and ejection fraction < 35% [5]. According to these criteria, between 13% and 35% of patients with heart failure would be eligible for CRT [6, 7]. However, a growing body of evidence seems to suggest that a larger proportion of heart failure patients could benefit of CRT. Some of the ‘new’ indications for CRT are discussed in this paper.