Optimal Pacing Mode in Dual Chamber Pacing with Long AV-Intervals:A Pressure Volume Loop Study

Abstract

Objectives: This study aimed to assess if dual chamber pacemaker patients with prolonged atrioventricular (AV-) intervals at rest and maintained LV function will benefit from spontaneous AV-conduction compared to AV synchronous pacing at optimized AV-intervals (DDD-OPT). Background: AV-hysteresis and mode change algorithms allow very long AV-intervals to avoid right ventricular pacing, however, the optimal long AV interval remains undefined. Methods: LV pressure volume loops were obtained via a conductance catheter in 19 dual chamber pacemakers patients with resting AV-intervals >250 ms. Hemodynamic data were recorded during atrial pacing at 70/min (AAI) and DDD-OPT. The optimal AV-interval was defined by the largest consequent stroke work. Results: Mean AV-interval during atrial pacing was 302{±}32 ms. Systolic parameters were not different between pacing modes with the exception of +dp/dt max (AAI: 1398{±}393 mmHg/s; DDD-OPT 1319{±}377 mmHg/s; p=0.006). Stroke work was higher in 9/19 patients with AAI and in 10/19 with DDD-OPT. The diastolic parameters tau (DDD-OPT: 38{±}8 ms; AAI: 35{±}8 ms; p=0.002) and peak filling rate (DDD-OPT: 832{±}450 ml/s; AAI: 627{±}231 ml/s; p=0.001) showed superior results for DDD-OPT. Differential values between the two modes for stroke work and +dp/dtmax correlated significantly with the resting AV-interval ( 320 ms favored DDD-OPT whereas AV-intervals <280ms favored AAI. Conclusion: In dual chamber pacemaker patients with long resting AV-intervals there is a trade-off between pacing-induced LV systolic dysfunction and impaired diastolic filling. Maintaining spontaneous AV-conduction at all cost might not be the preferred option in this patient group.