Abstract 11672: Improved Clinical Outcomes with Synchronized Left-Ventricular Only Pacing by an Automated Cardiac Resynchronization Therapy Algorithm: Analysis of the Adaptive CRT Trial
Introduction: Previous studies have suggested that in CRT patients with preserved atrio-ventricular (AV) conduction, left-ventricular (LV) only pacing, synchronized to produce optimal fusion with intrinsic activation results in superior ventricular function compared to biventricular (BiV) pacing. The adaptive CRT algorithm (aCRT) periodically measures intrinsic conduction and provides LV only pacing synchronized to the intrinsic right-ventricular activation when the intrinsic AV interval is normal (≤200 ms) and the heart rate does not exceed 100 bpm, and BiV pacing otherwise. The randomized double-blind Adaptive CRT trial demonstrated safety and efficacy of aCRT compared to echocardiography-optimized BiV pacing. This sub-analysis tested whether synchronized LV pacing resulted in better clinical outcomes.
Methods: The clinical outcomes [defined as the improvement in Packer’s Clinical Composite Score (CCS) and time to death or first heart failure (HF) hospitalization] were compared between the aCRT (n=150) and Control (n=91) patients with normal intrinsic AV interval at randomization. In the aCRT patients (n=318), a multivariate Cox proportional hazards model was used to assess the relationship between LV pacing [measured by percent of total ventricular pacing (% LV pacing)] and clinical outcome.
Results: In the subgroup with normal AV, a greater proportion of aCRT patients were improved in CCS at 6 months (81% vs. 69%, p=0.04) than Controls. There was also a trend towards lower death and HF hospitalization (HR=0.59, 95% CI: 0.31-1.12, log-rank p=0.10) with aCRT compared to Control in this subgroup. In the aCRT arm, % LV pacing ≥50% was associated with decreased risk of death or HF hospitalization (HR=0.49, 95% CI: 0.28-0.85, p=0.012). As expected, aCRT patients with a normal AV interval (n=150) received higher % LV pacing (73±25% vs. 18±28%, p<0.001) through 6 months than those with a prolonged AV interval (n=168).
Conclusions: In patients with normal AV conduction, the aCRT algorithm provided mostly synchronized LV pacing and resulted in better clinical response compared to BiV pacing with echocardiographic optimization. Higher % LV pacing with the aCRT algorithm was associated with decreased risk of death and HF hospitalization.
- © 2012 by American Heart Association, Inc.