Cardiac output-based versus empirically programmed AV interval - how different are they?

Aims: To compare empirically programmed and cardiac output-based programmin g of atrioventricular (AV) interval in patients with dual chamber pacemaker s. Methods and Results: In 19 patients with implanted dual chamber pacemakers due to AV block but otherwise normal hearts, cardiac output was assessed us ing an impedance cardiography device. In all patients, the AV interval had been previously programmed empirically by an experienced cardiologist. Card iac output was estimated at AV intervals from 50 to 250 ms during VDD pacin g. AV intervals adjusted by serial cardiac output estimations caused a rise in cardiac output in 84% of patients. The maximal achievable cardiac outpu t was greater by 12% +/- 8% (range 0-32%), P<0.001, than was observed with empirically programmed AV intervals. Conclusions: In patients with dual chamber pacemakers due to AV block and o therwise normal hearts, empirically selected AV intervals may lead to compr omise of cardiac haemodynamics. Optimal AV intervals may be selected by ser ial cardiac output measurements.