In a previous study we demonstrated that the institution of biventricular pacing in chronic heart failure (CHF) acutely facilitates the arterial baroreflex. The arterial baroreflex has important prognostic value in CHF. We hypothesized that the acute response in baroreflex sensitivity (BRS) after the institution of cardiac resynchronization therapy (CRT) has predictive value for midterm response. One day after implantation of a CRT device in 33 CHF patients (27 male/6 female; age, 66.5 ± 9.5 yr; left ventricular ejection fraction, 28 ± 7%) we measured noninvasive BRS and heart rate variability (HRV) in two conditions: CRT device switched on and switched off (on/off order randomized). Echocardiography was performed before implantation (baseline) and 6 mo after implantation (follow-up). CRT responders were defined as patients in whom left ventricular end-systolic volume at follow-up had decreased by ≥15%. Responders (69.7%) and nonresponders (30.3%) had similar baseline characteristics. In responders, CRT increased BRS by 30% ( P = 0.03); this differed significantly ( P = 0.02) from the average BRS change (−2%) in the nonresponders. CRT also increased HRV by 30% in responders ( P = 0.02), but there was no significant difference found compared with the increase in HRV (8%) in the nonresponders. Receiver-operating characteristic curve analysis revealed that the percent BRS increase had predictive value for the discrimination of responders and nonresponders (area under the curve, 0.69; 95% confidence interval, 0.51–0.87; maximal accuracy, 0.70). Our study demonstrates that a CRT-induced acute BRS increase has predictive value for the echocardiographic response to CRT. This finding suggests that the autonomic nervous system is actively involved in CRT-related reverse remodeling.
Myocardial substrate after cardiac resynchronization therapy and the risk of ventricular arrhythmias
