Influence of QRS duration on outcome of death or appropriate defibrillator therapy by strategy of left ventricular lead placement in cardiac resynchronization therapy recipients.

Purpose: Echocardiography-guided (EG) lead placement at the site of latest left ventricular (LV) mechanical activation improves outcome in patients receiving a cardiac resynchronization therapy (CRT) defibrillator (D). The purpose of this study is to examine whether a strategy of EG LV lead placement equally improves outcome in CRT recipients with wide (≥150 ms) versus intermediate (120-149 ms) QRS duration.

Methods: Patients treated with a CRT-D in the Speckle Tracking Assisted Resynchronization Therapy for Electrode Region (STARTER) prospective, randomized trial (108 EG strategy and 75 routine strategy) were followed to the endpoint of death or first appropriate CRT-D therapy. Of the patients enrolled in STARTER, 115 had QRS ≥ 150 ms and 68 had 120 < QRS ≤ 149 ms.

Results: Over a mean follow-up period of 3.7 ± 2.1 years, 62 (33 %) patients died and 40 (22 %) received appropriate CRT-D therapy. Compared to patients with QRS ≥ 150 ms, patients with intermediate QRS had meaningfully worse survival free from ICD therapy (HR = 1.48, p = 0.056). CRT-D therapy-free survival was significantly worse in patients with intermediate QRS duration randomized to the routine LV lead placement strategy, compared to patients with intermediate QRS duration randomized to the EG LV lead placement strategy or patients with wide QRS duration regardless of LV implantation strategy (HR = 2.08, 95 % confidence interval = 1.21-3.56, P = 0.008). This finding was independent in type of cardiomyopathy.

Conclusion: A strategy of EG LV lead placement improves survival free from defibrillator therapy in patients with QRS between 120-149 ms to levels comparable to those of patients with QRS ≥ 150 ms.