Left ventricular electrical delay predicts volumetric response to leadless cardiac resynchronization therapy

Background: Leadless left ventricular (LV) endocardial pacing is an emerging cardiac resynchronization therapy (CRT) technology. Predictors of response to leadless CRT are poorly understood. Implanting the LV endocardial pacing electrode in sites with increased electrical latency (Q-LV) may improve response rates.

Objective: The purpose of this study was to examine the association between Q-LV and echocardiographic remodeling response to leadless CRT delivered with the WiSE-CRT system.

Methods: A post hoc analysis (n = 122) of the SOLVE-CRT trial examined the relationship between LV pacing site Q-LV with rate of left ventricular end-systolic volume (LVESV) reduction >15% at 6 months. Multivariable regression analysis, adjusting for age, sex, previous CRT nonresponse, cardiomyopathy etiology, QRS morphology, and QRS duration was performed, followed by receiver operating characteristic analysis and analysis of variance by Q-LV quartile. A subgroup analysis of the ischemic cardiomyopathy cohort was undertaken.

Results: Complete Q-LV data were available for 122 of 153 patients (80%) in the active arms SOLVE-CRT. Overall, the 6-month LVESV response rate was 46%. Logistic regression identified Q-LV as an independent response predictor with borderline significance (adjusted odds ratio 1.015; P = .05). Analysis by Q-LV quartile demonstrated a significant improvement in response rate in quartile 4 (longest Q-LV 64%) compared to quartile 1 (shortest Q-LV 28%) (P <.01). This association was primarily driven by strong Q-LV-response correlation in patients with ischemic cardiomyopathy, demonstrated by subgroup logistic regression (adjusted odds ratio 1.034; P = .004).

Conclusion: Increased Q-LV was associated with improved reverse remodeling following leadless CRT. Targeting LV endocardial sites of high Q-LV may deliver additional benefit compared to empirical LV electrode implantation.