SyncAV Post-Market Trial

SyncAV PMT

Patient / Population Intervention / Exposure Comparison Outcome

In 1,288 CRT recipients with left bundle branch block, dynamic AV-delay optimisation did not reduce the reduction in LV end-systolic volume at 12 months compared with a fixed AV delay.

N

1,288patients

Design

Prospective, international multicentre, randomised (1:1), open-label post-market trial sponsored by Abbott; patients receiving a new Abbott quadripolar CRT system randomised 2–6 weeks after successful implant to SyncAV dynamic atrioventricular-delay optimisation programmed ON (offset selected by QRS narrowing) versus a fixed nominal AV delay; follow-up at 3, 6 and 12 months; started October 2019, primary completion estimated mid-2026.

Endpoint

Change in left ventricular end-systolic volume from baseline to 12 months (continuous), compared between arms

Relevance

2Important — one of several pillars.

ResultLeft ventricular end-systolic volume at 12 months did not differ (P = 0.054), nor did the proportion of responders with a fall of at least 15% (P = 0.16). Paced QRS was shorter with the algorithm (123 vs 138 ms; P < 0.0001) and atrial fibrillation lasting more than 10 days was less frequent (2.0% vs 4.4%; P = 0.03). Mortality 2.1% vs 2.4%. In the exploratory half with a PR interval of 185 ms or more, the clinical composite ran 10.3% vs 21.5% (P = 0.006).

Varma N, Mont L, Zareba W, et al. Presented at ESC Congress 2026, Hot Line 10, 31 August.

Discussion & critique

An algorithm that keeps fusion pacing as the PR interval wanders produced the narrower paced QRS it was designed for and no better remodelling at a year — the electrical target moved, the ventricle did not. The primary endpoint at P = 0.054 will be quoted as a near miss; it is a miss, and the responder analysis agrees. What may survive is the subgroup with a PR interval of 185 ms or longer, where fixed programming loses fusion and the clinical composite halved — half the cohort, entirely exploratory, and the trial's own hypothesis for the next one.