Electrical Delay In Apically Positioned Left Ventricular Leads And Clinical Outcome After Cardiac Resynchronization Therapy

Electrical Delay in Apically Positioned LV Leads.Introduction: In recent studies, an anatomical apical left ventricular (LV) lead pacing location has been associated with deleterious outcome after cardiac resynchronization therapy (CRT). The differential impact of the LV lead electrical location in these patients remains unknown. Methods and Results: Thirty-one consecutive CRT patients (mean age 71.7 +/- 12.7 years, 55% left bundle-branch block [LBBB] morphology) with an apical LV lead and LV lead electrical delay (LVLED) were studied. Anatomical LV lead location was determined via review of coronary venography and chest radiographs. Electrical location was assessed through intraprocedural LVLED measurement. Patients were dichotomized into either long LVLED (LVLED 50% of QRS) or short LVLED groups (LVLED < 50%). Patients in the long LVLED group demonstrated significantly greater freedom from a primary composite endpoint of all-cause death, heart failure hospitalization, and cardiac transplantation at 2 years (81% vs 30%, P = 0.007 vs short LVLED patients). Longer LVLED was also associated with more favorable LV remodeling (LV end-systolic volume 41.9 +/- 10.3 mL vs 4.3 +/- 17.2 mL; P = 0.05), and greater improvement in LV ejection fraction (+9.4 +/- 2.9% vs +2.3 +/- 7.5%; P = 0.04). Even after multivariate adjustment, LVLED remained an independent predictor of the primary composite endpoint (HR 0.47, P = 0.031). Conclusions: Electrical lead localization, as estimated by LVLED 50%, is associated with improved long-term clinical outcome and measures of LV remodeling in patients with apical LV leads. Intraprocedural LVLED assessment may provide incremental utility in targeting lead placement even in conventionally unfavorable anatomical segments.(J Cardiovasc Electrophysiol, Vol. 24, pp. 182-187, February 2013)