Impact of Synchronized Left Ventricular Pacing in Cardiac Resynchronization Therapy

BackgroundThe adaptive cardiac resynchronization therapy (aCRT) algorithm enables synchronized left ventricular pacing (sLVP) to produce fusion with intrinsic right ventricular activation in normal atrioventricular (AV) conduction. Although sLVP presents benefits over biventricular pacing (BVP), the adequate sLVP rate for better clinical outcomes remains unclear. This study aimed to assess the association between sLVP rates and clinical outcomes. MethodsAmong our cohort of 271 consecutive patients who underwent CRT implantation between April 2016 and August 2021, we evaluated 63 patients who underwent CRT without considerably prolonged AV conduction and applied the aCRT algorithm (48 men, mean age: 64 {+/-} 14 years; median follow-up period: 316 days [interquartile range: 212-809 days]). ResultsAt 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 (ROC) curve analysis revealed that the optimal cut-off value during the sLVP rate was 59.4% for 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 [&ge;]59.4%, n = 43) had better prognosis (cardiac death and heart failure hospitalization) than the lower sLVP group (sLVP <59.4%, n = 20) (log-rank p<0.001), and multivariate Cox hazard analysis revealed that a higher sLVP rate was associated with good prognosis (p<0.001). ConclusionsLVP was associated with CRT response, and higher sLVP rate ([&ge;]59.4%) is important for good prognosis in patients with aCRT. CLINICAL PERSPECTIVEO_ST_ABSWhat Is New?C_ST_ABSO_LISynchronized left ventricular pacing(sLVP) >59.4% was a significant predictor of cardiac resynchronization therapy(CRT) responders and better clinical outcomes, evidenced by the results of the multivariate analysis. C_LIO_LIIn this study, which included patients with moderately prolonged PR intervals, high sLVP rates were associated with better clinical outcomes. C_LI What Are the Clinical Implications?O_LIsLVP rate was associated with the improvement of cardiac function after CRT implantation. C_LIO_LIA higher sLVP rate was associated with a lower risk of cardiac death and heart failure hospitalization. C_LI