Background: Cardiac resynchronization therapy (CRT) is beneficial for patients with medically refractory heart failure due to severe left ventricular (LV) systolic dysfunction and interventricular conduction delay. A hemodynamically optimzied atrioventricular (AVD) and interventricular delay (VVD) during CRT is important to maximize the response to this treatment and lower the rate of non-responders. While long atrioventricular delays (AVDs) reduce the left ventricular filling time resulting in an incomplete mitral valve closure and diastolic mitral regurgitation, a premature closure of the mitral valve during short AVDs may limit the atrial contribution to LV filling. Thus a dilatation of the left atrium can result possibly favouring the incidence of atrial fibrillation. A low biventricular stimulation proportion during atrial fibrillation often worsens heart failure. Aim of this study was to retrospectively evaluate the impact of short AVDs and long VVDs on the occurrence of atrial fibrillation in CRT patients.
Methods: In a total of 150 patients, we reviewed the programming of the AVD and VVD as well as the long-term Holter with regard to the occurrence of atrial fibrillation (episodes longer than 5 seconds). In 70 patients an automatic hemodynamic optimization was performed with the QuickOpt algorithm upon implantation with iterative optimizations during follow-up visits.
Results: In 42 % of all patients episodes of atrial fibrillation were documented. Mean AVD in the atrial fibrillation group was 161 ms paced and 120 ms sensed, mean VVD was 31 ms (range 0 to -65 ms). While VVDs in patients without documentation of atrial fibrillation were significantly shorter (mean VVD 23 ms, range 0 to -70 ms, p<0.01), also only sensed AVDs were shorter in the non-atrial fibrillation group (mean 115 ms, p<0.01).
Conclusions: Atrial fibrillation is a frequent arrhythmia in heart failure patient. During CRT, the programmation of long VVDs seems to favour the occurrence of atrial fibrillation in this group of patients. Thus, a hemodynamic optimization is crucial for heart failure patients with biventricular pacing.