Incidence and predictors of super-response to cardiac resynchronization therapy

Objectives: Cardiac resynchronization therapy (CRT) has significantly improved management of patients with heart failure with reduced ejection fraction (HFrEF). A significant number of patients have a dramatic response and have been termed "super-responders". The characteristics of this subset of patients in Indian and Asian population have not been well studied. In this study, we sought to assess the prevalence and clinical characteristics of this cohort of patients.

Methods: This was a retrospective study involving patients undergoing CRT. Changes in ejection fraction and LVESV at the end of one year of follow-up following device implantation were assessed, and patients were stratified into non-responders, responders, and super-responders. Responders had a 15-29% decrease in LVESV while super-responders had a >30% decrease in LVESV.

Results: Of the 74 patients who had undergone CRT-P/CRT-D implantation, 16 patients did not have echocardiograms at the end of one year of follow-up and were excluded from the analysis. Thus, 58 patients were enrolled for analysis. We identified 16 patients (27.6%) to be super-responders, 26 patients (44.8%) to be responders, and 16 patients (27.6%) to be non-responders. Factors associated with a super-response were a diagnosis of dilated cardiomyopathy as against ischemic cardiomyopathy (93.7% vs 6.3%; p - 0.01), prior right ventricular (RV) apical pacing (25% vs 2.4%; p - 0.02) and absence of a prior history of myocardial infarction (MI) (0% vs 33.3%; p - 0.02).

Conclusion: In our study, 27.6% of patients were super-responders, and a diagnosis of dilated cardiomyopathy, absence of a prior history of MI and prior RV apical pacing predicted a super-response to CRT.