Effect of cardiac resynchronization therapy on left atrial reverse remodeling: role of echocardiographic AV delay optimization

Background/objectives: Cardiac resynchronization therapy (CRT) improves left ventricular (LV) function in patients with advanced heart failure (HF) and there are some evidences about beneficial effects also on left atrial (LA) dimension and function. The contribution of atrioventricular delay (AVD) optimization on LA changes has not been evaluated. The purpose of the present study was to further investigate the effect of CRT on LA reverse remodelling and to evaluate the contribution of AVD optimization.

Methods and results: From the Cardiology Department of Piacenza Hospital and Modena University Hospital fifty one patients with refractory systolic HF and left bundle branch block were prospectively enrolled before CRT implantation. Patients were 1:1 randomized to either an optimized AVD (AV Opt group) determined by continuous wave Doppler aortic velocity-time integral (VTI) or an empiric AVD of 110 ms (AV Fixed group). Optimal AVD was defined as the AVD that yielded the largest aortic VTI at one of eight tested AV intervals (between 60 and 200 ms). LA volumes and emptying fractions were assessed by two-dimensional echocardiography at baseline and 6 months after CRT. At 6-month follow-up, CRT induced LA reverse remodeling in the whole population (maximal LA volume: 55.8 ± 16.4 ml/m² vs 50.3 ± 18.9 ml/m², p=0.006; pre-systolic LA volume: 47.0 ± 15.2 ml/m² vs 41.4 ± 17.4 ml/m², p=0.003; post-systolic LA volume: 36.4 ± 15.0 ml/m² vs 30.3 ± 18.0 ml/m(2), p=0.001); nevertheless, no substantial difference was observed about LA structural and functional remodeling between both AV Opt group and AV Fixed group.

Conclusion: CRT induces LA reverse remodeling that appears independent from AVD optimization.