Usefulness of atrioventricular delay optimization using Doppler assessment of mitral inflow in patients undergoing cardiac resynchronization therapy.

This study evaluated the utility of atrioventricular (AV) optimization using Doppler echocardiography in patients who undergo cardiac resynchronization therapy (CRT). AV optimization in patients who undergo CRT is performed inconsistently, with few data supporting its utility. Data were collected from 215 patients in New York Heart Association class III or IV heart failure (66% ischemic) who underwent AV optimization <30 days after implantation from 1999 to 2003. All patients arrived with AV delay programmed at the time of their CRT procedures (100 to 120 ms). AV delay was optimized using Doppler mitral inflow data to target stage I diastolic filling. Baseline clinical characteristics, AV delay, and diastolic functional stage were recorded. The mean follow-up period was 23 months. Five hundred patients underwent CRT, 215 of whom underwent AV optimization <30 days after implantation. Baseline mean age was 66 +/- 12 years, left ventricular (LV) ejection fraction 19 +/- 8%, LV end-diastolic dimension 6.5 +/- 1 cm, LV end-systolic dimension 5.5 +/- 1 cm, QRS duration 166 +/- 27 ms, and time to AV optimization 2.5 +/- 4 days. Baseline and final AV delay means were 120 +/- 25 and 135 +/- 40 ms, respectively (p = 0.0001). In 40% of patients (86 of 215), final AV delay settings were >140 ms. Left atrial diameter and AV block predicted patients in whom AV delay settings >140 ms were optimal. There was no difference in mortality in patients with final AV delays of >140 ms. In conclusion, AV optimization in patients who underwent CRT resulted in final AV delay settings of >140 ms in 40% of patients. AV delay optimization based on Doppler echocardiographic determination of optimal diastolic filling is useful and safe in patients who undergo CRT.