The role of repeating optimization of atrioventricular interval during interim and long-term follow-up after cardiac resynchronization therapy.
BACKGROUND
Cardiac resynchronization therapy (CRT) is an effective therapy for heart failure patients with electromechanical delay. Optimization of atrioventricular interval (AVI) is a cardinal component for the benefits. However, it is unknown if the AVI needs to be re-optimized during long-term follow-up.


METHODS
Thirty-one patients (66+/-11 years, 20 males) with sinus rhythm who received CRT underwent serial optimization of AVI at day 1, 3-month and during long-term follow-up by pulse Doppler echocardiography (PDE). At long-term follow-up, the optimal AVI and cardiac output (CO) estimated by non-invasive impedance cardiography (ICG) were compared with those by PDE.


RESULTS
The follow-up was 16+/-11 months. There was no significant difference in the mean optimal AVI when compared between any 2 time points among day 1 (99+/-30 ms), 3-month (97+/-28 ms) and long-term follow-up (94+/-28 ms). However, in individual patient, the optimal AVI remained unchanged only in 14 patients (44%), and was shortened in 12 (38%) and lengthened in 6 patients (18%). During long-term follow-up, although the mean optimal AVIs obtained by PDE or ICG (94+/-28 vs. 92+/-29 ms) were not different, a discrepancy was found in 14 patients (45%). For the same AVI, the CO measured by ICG was systematically higher than that by PDE (3.5+/-0.8 Vs. 2.7+/-0.6 L/min, p<0.001).


CONCLUSIONS
Optimization of AVI after CRT appears necessary during follow-up as it was readjusted in 55% of patients. Although AVI optimization by ICG was feasible, further studies are needed to confirm its role in optimizing AVI after CRT.
Zhang
Qing
Q
Division of Cardiology, S.H. Ho Cardiovascular and Stroke Centre, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
Fung
Jeffrey Wing-Hong
JW
Chan
Yat-Sun
YS
Chan
Hamish Chi-Kin
HC
Lin
Hong
H
Chan
Skiva
S
Yu
Cheuk-Man
CM
D000368:Aged; D000704:Analysis of Variance; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002307:Cardiography, Impedance / Q000379:methods; D018619:Echocardiography, Doppler, Pulsed; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011336:Probability; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome