[Efficacy of biventricular pacing on preventing heart failure in patients with high degree atrioventricular block (BIVPACE-AVB Trial)]

To investigate the long-term effect of biventricular (BIV) and right ventricular apical (RVA) pacing on cardiac function in patients with high-degree atrioventricular block (AVB) and left ventricular ejection fraction(LVEF)over 35%.A total of 118 consecutive patients with high-degree AVB in six hospitals from East China between May 2009 and December 2012 were enrolled in this randomized, double-blind and parallel controlled study. Patients were randomly assigned to BIV and RVA pacing with or without LV lead on after one-week cardiac resynchronization therapy (CRT). Cardiac function including New York Heart Association(NYHA), 6 minute walking distance (6MWD), Minnesota living with heart failure (MLHF) score, LVEF, left ventricular end-diastolic volumes/diameters (LVEDV/LVEDD) and other echocardiography parameters, as well as N-terminal pro-B-type natriuretic peptide (NT-proBNP)were assessed at 6 months and 12 months.A total of 114 patients were successfully implanted with CRT. Cardiac function was significantly improved after one-week BIV pacing (n=57) compared with pre-CRT: rate of patients with NYHA Ⅲ (25.44%(29/114) vs. 9.65%(11/114)), MLHF score (17.1±13.6 vs. 26.9±21.6), 6MWD ((315.4±121.8)m vs. (291.8±102.9)m) and NT-proBNP (157.0(70.0, 639.0) ng/L vs. 444.7(144.0, 1 546.0)ng/L, all P0.05). In BIV group, 6MWD extended from (314.8±142.7)m to (332.7±117.5)m at 6 months (P0.05), LVEF increased from (60.7±7.9)% at 1 week to (56.6±10.7)% at 6 months(P0.05), both LVEDV and LVEDD decreased at 12 months compared with at 1 week ((116.2±39.5)ml vs. (131.4±49.6)ml and (50.2±5.6)mm vs. (52.5±6.8)mm, P0.05). In RVA group (n=57), 6MWD increased at 6 months compared that at 1week ((342.4±109.9)m vs. (310.2±105.1)m, P0.05), NT-proBNP was higher at 12 months than that at 1 week (349.5(191.8, 884.3)ng/L vs. 127.0(70.3, 336.7)ng/L, P0.05). Compared with RVA group, BIV group had a bigger shrink in LVEDV decrease at 12 months was more significant in BIV group ((-16.68±24.30)ml vs. (9.09±29.30)ml, P0.05).Cardiac pacing could acutely improve the cardiac function in patients with high-degree AVB and LVEF over 35%. Improvements on cardiac function and remodeling are more significant after 12-month BIV pacing than that of RVA pacing. Clinical Trail Registry: Chinese Clinical Trial Registry, ChiCTR-TRC-10000832.