Introduction: The optimal left ventricular (LV) pacing site for cardiac resynchronization therapy (CRT) is unclear. The current study aims to explore the clinical significance of LV lead concordance to delayed contraction segment in CRT.
Methods and results: Concordant LV lead position was defined as the lead tip located by fluoroscopy at or immediately adjacent to the LV segment with latest contraction determined by tissue Doppler imaging. Echocardiographic and clinical outcomes among 101 consecutive patients with or without concordant LV lead positions were compared. There was no significant difference in changes in LV volumes and clinical parameters between patients with concordant (n = 46) or nonconcordant (n = 55) LV lead positions at 3 and 6 months. In multivariate analysis, the baseline asynchrony index (beta= 1.092, 95% CI: 1.050-1.114; P < 0.001), but not LV lead concordance, was the only independent predictor of LV reverse remodeling. By Cox regression analysis, ischemic etiology, and LV reverse remodeling, but not LV lead concordance, were independent predictors of mortality (beta= 2.475, 95% CI: 1.183-5.178; P = 0.016, and beta= 0.272, 95% CI: 0.130-0.567; P < 0.001, respectively), cardiovascular hospitalization (beta= 1.551, 95% CI: 1.032-2.333; P = 0.035, and beta= 0.460, 95% CI: 0.298-0.708; P < 0.001, respectively), and heart failure hospitalization (beta= 0.486, 95% CI: 0.320-0.738; P = 0.001 for LV reverse remodeling).
Conclusion: LV lead concordance to the delayed contraction segment may not be a major determining factor for favorable echocardiographic and clinical outcomes after CRT.