Usefulness of Echocardiographically Guided Left Ventricular Lead Placement for Cardiac Resynchronization Therapy in Patients With Intermediate QRS Width and Non–Left Bundle Branch Block Morphology

The current guidelines most strongly support cardiac resynchronization therapy (CRT) for patients with heart failure with a QRS width of ≥150 ms and left bundle branch block (LBBB). Our objective was to assess the potential benefit of echocardiographically guided left ventricular (LV) lead positioning for patients with a QRS width <150 ms or non-LBBB as a substudy of the Speckle Tracking Assisted Resynchronization Therapy for Electrode Region (STARTER) prospective, randomized controlled trial. The STARTER trial randomized 187 patients with heart failure, a QRS of ≥120 ms, and ejection fraction of ≤35% to LV lead guided to the site of latest mechanical activation by speckle tracking radial strain versus routine implantation. The predefined primary end point was heart failure hospitalization or death within 2 years. This substudy included 151 CRT patients with matching echocardiographic and LV lead position data and complete follow-up data. Patients with a QRS width of 120 to 149 ms or non-LBBB and LV lead concordant or adjacent to the site of latest mechanical activation had favorable outcomes after CRT similar to those with LBBB or a QRS width of ≥150 ms. In contrast, patients with a QRS of 120 to 149 ms or non-LBBB and remote LV leads had unfavorable outcomes (hazard ratio 5.45, 95% confidence interval 2.36 to 12.6, p <0.001, and hazard ratio 4.92, 95% confidence interval 2.12 to 11.39, p <0.001, respectively, with significant interaction after adjusting for baseline variables, p = 0.038 and p = 0.008). In conclusion, LV lead positioning with respect to the echocardiographic site of latest activation was significantly associated with more favorable clinical outcomes in patients with a QRS duration <150 ms and/or non-LBBB. Additional prospective study is warranted.