Left ventricular pacing site in cardiac resynchronization therapy: clinical follow-up and predictors of failed lateral implant.

The effects of the left ventricular (LV) pacing site on the clinical results of resynchronization therapy (CRT) are not well characterized. The aim of this study was to define the effect of LV lead location on clinical response and LV remodelling, and to identify predictors of failure to implant the LV lead in a lateral location. One hundred and seventy two consecutive patients were evaluated at baseline and 6 months after CRT. In 128 patients, the LV lead was implanted in the lateral region (Group 1), while 44 received an anterior implant due to anatomical or electrical factors (Group 2). Group 1 was associated with a significantly better functional outcome assessed both by NYHA class (p<0.001) and by the six-minute-walk test (p=0.01) compared with group 2. LV ejection fraction and volumes, and inter- and intraventricular dyssynchrony only improved significantly (p<0.01) in group 1. The only independent predictor of a failed lateral implant was the presence of ischaemic cardiomyopathy (OR 3.29, 95% CI 2.2-13.7; p=0.02). In conclusion, a lateral lead location results in a better functional outcome and greater reverse LV remodelling compared with anterior locations. The presence of ischaemic cardiomyopathy is a risk factor for a failed lateral LV implant.