AV interval optimization using pressure volume loops in dual chamber pacemaker patients with maintained systolic left ventricular function.

BACKGROUND: Atrioventricular (AV) interval optimization is often deemed too time-consuming in dual-chamber pacemaker patients with maintained LV function. Thus the majority of patients are left at their default AV interval.
OBJECTIVE: To quantify the magnitude of hemodynamic improvement following AV interval optimization in chronically paced dual chamber pacemaker patients. PATIENTS AND METHODS: A pressure volume catheter was placed in the left ventricle of 19 patients with chronic dual chamber pacing and an ejection fraction >45 % undergoing elective coronary angiography. AV interval was varied in 10 ms steps from 80 to 300 ms, and pressure volume loops were recorded during breath hold.
RESULTS: The average optimal AV interval was 152 ± 39 ms compared to 155 ± 8 ms for the average default AV interval (range 100-240 ms). The average improvement in stroke work following AV interval optimization was 935 ± 760 mmHg/ml (range 0-2,908; p < 0.001), which translates into an average improvement of 14 ± 9 % (range 0-28). A 10 ms variation of the AV interval changes the average stroke work by 207 ± 162 mmHg/ml. AV interval optimization also leads to improved systolic dyssynchrony indices (17.7 ± 7.0 vs. 19.4 ± 7.1 %; p = 0.01).
CONCLUSION: The overall hemodynamic effect of AV interval optimization in patients with maintained LV function is in the same range as for patients undergoing cardiac resynchronization therapy for several parameters. The positive effect of AV interval optimization also applies to patients who have been chronically paced for years.