title: The role of repeating optimization of atrioventricular interval during interim and long-term follow-up after cardiac resynchronization therapy.
abstract: 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.
authors: 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.
authors: Qing
authors: Q
authors: Zhang
authors: Jeffrey Wing-Hong
authors: JW
authors: Fung
authors: Yat-Sun
authors: YS
authors: Chan
authors: Hamish Chi-Kin
authors: HC
authors: Chan
authors: Hong
authors: H
authors: Lin
authors: Skiva
authors: S
authors: Chan
authors: Cheuk-Man
authors: CM
authors: Yu
mesh_terms: 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