Temporal variation in optimal atrioventricular and interventricular delay during cardiac resynchronization therapy

Background: Tailored atrioventricular delay (AVd) and interventricular delay (VVd) combination improves hemodynamics in patients treated with cardiac resynchronization therapy (CRT). Whether tailored AVd-VVd combination changes over time is not known. Methods and Results: Twenty-two patients (18 M, aged 69.9 +/- 12.5 years, New York Heart Association class III, QRS >= 130 ms, ejection fraction 29.6 +/- 8.8%) were implanted with a biventricular device with programmable VVd. Myocardial performance index (MPI) was evaluated during pacing at different VVds and AVds at baseline and after 6 and 12 months. The optimal AVd-VVd combination was identified by the minimum MPI. After optimization, the appropriate AVd-VVd combination was programmed in each patient. MPI at 6-month follow-up after optimization was significantly higher compared with baseline (.79 +/- .21 vs..59 +/- .15, P <.05). Re-optimization of AVd-VVd combination was required after 6 months in 21 of 22 (95%) patients. Re-optimization significantly reduced MPI compared with the value prior to re-optimization (.56 +/-.15 vs..79 +/-.21, P <.05). The MPI remained unchanged at 12-month compared with 6-month follow-up (.59 +/-.19 vs..56 +/-.15, P = NS). Clinical symptoms and reverse left ventricular remodeling were sustained at 6-month and 12-month follow-up. Conclusion: Optimal AVd and VVd combination changes over time in patients with heart failure. Sustained improvement in clinical symptoms and reverse left ventricular remodeling after CRT are not temporally associated with improvement in MPI.