Evaluation of synchronized left ventricular pacing rate over biventricular pacing in cardiac resynchronization therapy

Background The adaptive cardiac resynchronization therapy (aCRT) algorithm enables synchronized left ventricular pacing (sLVP) to achieve fusion with intrinsic right ventricular activation. Although sLVP presents benefits over biventricular pacing, the adequate sLVP rate for better clinical outcomes remains unclear. We aimed to assess the association between sLVP rates and clinical outcomes. Methods Our study cohort included 271 consecutive patients, who underwent CRT implantation between April 2016 and August 2021. Results We evaluated 63 patients on whom we applied the aCRT algorithm [48 men, mean age: 64 ± 14 years; median follow-up period: 316 days (interquartile range: 212–809 days)]. At the 6-month follow-up after CRT implantation, the frequency of CRT responders was 71 % (n = 45). The sLVP rate was significantly higher in responders than in non-responders (75 ± 30 % vs. 47 ± 40 %, p = 0.003). Receiver operating characteristics curve analysis revealed that the optimal cut-off value during the sLVP rate was 59.4 % for the prediction of CRT responders (area under the curve, 0.70; sensitivity, 80 %; specificity, 61 %; positive predictive value, 84 %; and negative predictive value, 55 %). Kaplan–Meier analysis demonstrated that the higher-sLVP group (sLVP ≧59.4 %, n = 43) had a better prognosis (cardiac death and heart failure hospitalization) than the lower-sLVP group (sLVP <59.4 %, n = 20) (log-rank p < 0.001). Multivariate Cox hazard analysis revealed that a higher sLVP rate was associated with a good prognosis (p < 0.001). Conclusions sLVP was associated with CRT response, and a higher sLVP rate (≧59.4 %) was important for good prognosis in patients with aCRT.