To assess short-, mid-and long-term clinical effect of dynamical VV delay optimization on cardiac function and neuroendocrine factors during cardiac resynchronization therapy(CRT)in patients with congestive heart failure.

Thirty-eight patients with congestive heart failure were treated with CRT.All patients were regularly performed AV and VV delay optimization at 3^th days, 15^th days, 1^th, 3^th, 6^th and 12^th months after implantation of CRT.First of all, all patients were programmed for optimal AV delay.Randomized and crossover trial with default VV delay or individualized optimal VV delay was used at 1^th month after implantation of CRT.Then, all patients were accepted optimal AV and VV delay pacing.During the follow-up, indexes of ventricular synchronization, cardiac functional parameters and neuroendocrine factors were measured.

Compared with the default VV delay group at one month after implantation of CRT, left ventricular ejection fraction(LVEF), standard deviation of time-to-peak systolic velocity of 12 LV segments(Ts-SD)and interventricular mechanical delay(IVMD)improved significantly in optimal VV delay group(P<0.05)and neuroendocrine factors, such as plasma angiotensin Ⅱ(Ang Ⅱ)and N terminal pro-brain natriuretic peptide(NT-proBNP)also improved significantly(P<0.05). Compared with pre-operation and 1^th month post-operation without optimization, Ts-SD and IVMD continued to improve significantly at 3^th months post-operation with optimization(P<0.05 or P<0.01). Meanwhile, the left ventricular end-diastolic diameter(LVEDD), the left ventricular end-systolic diameter(LVESD), LVEF and mitral regurgitation area(MR)also improved significantly(P<0.05 or P<0.01). Compared with pre-operation and 1^th month post-operation without optimization, LVEDD, LVESD, LVEF, aortic valve forward flow velocity time integral(VTI), MR, Ts-SD and IVMD improved significantly at 6^th months and 12^th months post-operation with optimization(P<0.05 or P<0.01). Compared with pre-operation and 1^th month post-operation without optimization, over time, neuroendocrine factors declined gradually at 3^th, 6^th and 12^th months post-operation with optimization(P<0.05 or P<0.01).

Early optimization AV and VV delay can improve patient′s cardiac synchronization, which is crucial to improve heart function.Heart function improves gradually with the extension of optimizing CRT therapy.Therefore, it is very important to strengthen the mid-and long-term follow-up and optimize AV and VV delay in patients implanted CRT with congestive heart failure treated.

Cardiac resynchronization therapy; Echocardiography; AV and VV delay optimization; Cardiac function; Neuroendocrine factors