Sites of Left and Right Ventricular Lead Implantation and Response to Cardiac Resynchronization Therapy Observations From the REVERSE Trial
Does right ventricular (RV) and/or left ventricular (LV) lead placement impact response to cardiac resynchronization therapy (CRT)?
This was a secondary analysis from the REVERSE trial, which was a double-blind, randomized trial of CRT versus device implant without CRT enabled in patients with New York Heart Association class I-II heart failure (HF), an LV ejection fraction (EF) ≤40%, and a QRS ≥120 ms. This substudy was restricted to the patients in the active CRT arm who had available data. Anteroposterior and lateral chest X-rays were evaluated after device implant to assess LV and RV lead position. Echocardiograms and electrocardiograms were obtained prior to implant and after 12 months of CRT to assess LV systolic volume index (LVSVi) and QRS duration, respectively. The endpoints of interest were evaluated based on CRT lead position and included: 1) the proportion of patients who had “worse” clinical outcome based on HF clinical composite response, 2) the proportion of patients who had a decrease in LVSVi by ≥15%, 3) change from baseline in QRS duration after CRT, 4) time to first HF hospitalization, 5) time to all-cause death, and 6) time to first HF hospitalization or death.
Of the 419 patients in the active CRT arm, 285 (68%) and 345 (82%) had X-rays to allow for precise assessment of LV and RV lead placement, respectively. The LV lead was placed laterally or posterior laterally in 80% (n = 229) and anterior or anterior laterally in 20%. The LV lead was nonapical in 86% (n = 246). The RV lead was placed apically in 69% (n = 237). After 12 months of follow-up, patients who received nonapical LV pacing were more likely to experience a decrease in LVSVi than those with apical LV pacing (58% vs. 35%, p = 0.016). Patients with an LV lateral lead or an LV nonapical lead had more narrow QRS intervals than those with nonlateral or apical LV leads. The location of RV pacing did not influence any outcome and LV lead laterality had no impact on the clinical composite response. Patients with LV lateral lead positions (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.19-0.99; compared with nonlateral) and those with nonapical LV leads (HR, 0.27; 95% CI, 0.11-0.63 compared with apical) had a lower risk of the composite death/HF hospitalization endpoint, but there was no difference in mortality alone.
The authors concluded that CRT outcomes are more favorable in those receiving lateral and nonapical pacing.
In this secondary analysis, LV lead position (and therefore location of LV pacing) appeared to have a favorable impact on QRS duration and HF outcomes. Outcomes were mainly driven by a reduction in HF rehospitalization, and this reduction was most evident at 2 years following device implant. An important limitation of this analysis is that RV lead analyses were not exclusive to those patients who also had LV lead data and the ‘n’ at risk after 12 months of follow-up (when differences were greatest) was low. Should patients have a coronary sinus venogram prior to CRT implant to provide patients better education on likelihood of having a response? Does one forego biventricular upgrade in stable patients with class I/II symptoms if anatomy is not favorable lateral lead placement? Many questions remain.
Keywords: X-Rays, Coronary Sinus, Electrocardiography, New York, Systole, Cardiac Resynchronization Therapy, Heart Failure, Confidence Intervals, Hospitalization, Ventricular Dysfunction, Left, Heart Ventricles, Echocardiography
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