Is cardiac resynchronization therapy an option in heart failure patients with preserved ejection fraction? Justification for the ongoing KaRen project.

The relevance of electrical and mechanical dyssynchrony has been demonstrated in heart failure with reduced ejection fraction. Preserved ejection fraction is present in as many as 50% of patients with chronic heart failure. Recent small studies suggest that both electrical and mechanical left ventricular dyssynchrony are sometimes present in patients with heart failure and preserved ejection fraction (HFPEF). These data remain controversial and a robust validation of this hypothesis has to be achieved. In the present paper, we review in detail the concepts and try to justify the ongoing KaRen registry. This is a prospective, multicentre, international, observational study to characterize the prevalence of electrical or mechanical dyssynchrony in HFPEF and the resultant effect on prognosis. Patients are enrolled currently at the time of an acute congestive episode. The diagnosis of HFPEF is made according to clinical data, natriuretic peptides and echocardiography for the measurement of ejection fraction. Once stabilized, patients return for a hospital check-up. They undergo clinical and biological evaluation, electrocardiography and Doppler echocardiography. Thereafter, patients are followed every six months, for at least 18 months for mortality, and heart failure-related and non-cardiovascular hospitalizations. KaRen aims to characterize electrical and mechanical dyssynchrony and to assess its prognostic impact in HFPEF. The results may improve our understanding of HFPEF and generate answers to the question of whether or not dyssynchrony could be a target for cardiac resynchronization therapy in HFPEF.