Identification and characterization of super-responders after cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) has been shown to induce a spectacular effect on left ventricular (LV) function in certain patients. Our aim was to analyze and characterize the super-responders (SRs) to CRT using echocardiography in 186 patients with a conventional indication according to the European Society Cardiology guidelines. The investigation took place before and 6 months after implantation. CRT-SRs were defined by an improvement of the New York Heart Association functional class and LV ejection fraction to > or = 50% in absolute values associated with a relative LV end-systolic volume reduction of > or = 15%. Of the 186 patients, 18 (9.7%) were identified as CRT-SRs and had a significantly lower prevalence of ischemic etiology (11%), lower LV dimensions, lower left atrial volume, and greater global longitudinal strain at baseline. Receiver operating characteristics curves identified global longitudinal strain as the strongest parameter for predicting CRT-SRs, with a cutoff value of -12% (area under the curve 0.87, sensitivity 71%, and specificity 85%, p <0.01). In conclusion, in the present retrospective study, only a left atrial volume <55 ml and global longitudinal strain < or = -12% were independent predictors of CRT-SRs.