ALternate Site Cardiac ResYNChronization (ALSYNC): a prospective and multicentre study of left ventricular endocardial pacing for cardiac resynchronization therapy

Aims The ALternate Site Cardiac ResYNChronization (ALSYNC) study evaluated the feasibility and safety of left ventricular endocardial pacing (LVEP) using a market-released pacing lead implanted via a single pectoral access by a novel atrial transseptal lead delivery system. Methods and results ALSYNC was a prospective clinical investigation with a minimum of 12-month follow-up in 18 centres of cardiac resynchronization therapy (CRT)-indicated patients, who had failed or were unsuitable for conventional CRT. The ALSYNC system comprises the investigational lead delivery system and LVEP lead. Patients required warfarin therapy post-implant. The primary study objective was safety at 6-month follow-up, whichwas defined as freedom from complications related to the lead delivery system, implant procedure, or the lead >= 70%. The ALSYNC study enrolled 138 patients. The LVEP lead implant success rate was 89.4%. Freedom from complications meeting the definition of primary endpoint was 82.2% at 6 months (95% CI 75.6-88.8%). In the study, 14 transient ischaemic attacks (9 patients, 6.8%), 5 non-disabling strokes (5 patients, 3.8%), and 23 deaths (17.4%) were observed. No death was from a primary endpoint complication. At 6 months, the New York Heart Association class improved in 59% of patients, and 55% had LV end-systolic volume reduction of 15% or greater. Those patients enrolled after CRT non-response showed similar improvement with LVEP. Conclusions The ALSYNC study demonstrates clinical feasibility, and provides an early indication of possible benefit and risk of LVEP.