Predictive factors and clinical effect of optimized cardiac resynchronization therapy

The aim of this study was to assess the effectiveness of cardiac resynchronization therapy (CRT) by intracardiac delay optimization using echocardiography. Sixty-five patients were implanted with a CRT device randomly assigned to receive simultaneous biventricular pacing or echo-optimized sequential CRT. Forty-two patients were defined as responders and 23 patients were classified as non-responders. During a 12-month follow-up period, the positive response rate, QRS duration, New York Heart Association class, mitral insufficiency grade, left ventricular end-systolic volume and LV end-diastolic volume were similar in the optimized and non-optimized groups (P>0.05), whereas 6-minute walking distance, quality-of-life score, left ventricular (LV) ejection fraction and aortic velocity time integral were significantly improved in the optimized group (P<0.05). The baseline QRS durations of the responders and non-responders were similar (P>0.05), whereas heart failure aetiology, clinical and echocardiographic measurements showed significant differences (P<0.05). The mean decrease in QRS duration after 12 months of CRT used for separating responders and non-responders was significantly different (P<0.05), and significant differences were observed in the mean decrease of QRS duration between responders and non-responders (P<0.05). Echocardiographic optimization may further improve the effectiveness of CRT. Moreover, severe mitral regurgitation and greater LV volume are likely to indicate a poor response to CRT.