The role of repeating optimization of atrioventricular interval during interim and long-term follow-up after cardiac resynchronization therapy

Background: Cardiac resynchronization therapy (CRT) is an effective therapy for heart failure patients with electromechanical delay. Optimization of atrioventricular interval (AVI) is a cardinal component for the benefits. However, it is unknown if the AVI needs to be re-optimized during long-term follow-up. Methods: Thirty-one patients (66 ± 11 years, 20 males) with sinus rhythm who received CRT underwent serial optimization of AVI at day 1, 3-month and during long-term follow-up by pulse Doppler echocardiography (PDE). At long-term follow-up, the optimal AVI and cardiac output (CO) estimated by non-invasive impedance cardiography (ICG) were compared with those by PDE. Results: The follow-up was 16 ± 11 months. There was no significant difference in the mean optimal AVI when compared between any 2 time points among day 1 (99 ± 30 ms), 3-month (97 ± 28 ms) and long-term follow-up (94 ± 28 ms). However, in individual patient, the optimal AVI remained unchanged only in 14 patients (44%), and was shortened in 12 (38%) and lengthened in 6 patients (18%). During long-term follow-up, although the mean optimal AVIs obtained by PDE or ICG (94 ± 28 vs. 92 ± 29 ms) were not different, a discrepancy was found in 14 patients (45%). For the same AVI, the CO measured by ICG was systematically higher than that by PDE (3.5 ± 0.8 Vs. 2.7 ± 0.6 L/min, p < 0.001). Conclusion: Optimization of AVI after CRT appears necessary during follow-up as it was readjusted in 55% of patients. Although AVI optimization by ICG was feasible, further studies are needed to confirm its role in optimizing AVI after CRT.