Long-term outcome of cardiac resynchronization therapy in patients with drug-refractory heart failure

Objective To study the long-term outcome of cardiac resynchronization therapy (CRT) in drug refractory heart failure patients through retrospective analysis and to ivestigate the underline reasons of unsuccessful cases in the study. Methods The study comprised a total of 48 patients (mean age 70±18.5 years; 83% male) with New York Heart Association class Ⅲ (86%) or class Ⅳ (14%) heart failure and LVEF≤35%. All patients fulfilled the standard CRT indications with the QRS duration ≥130 and LVEDd≥60 mm. Only one of the 48 patients was implanted with a combination of automatic implantable cardioverter-defibrillator and CRT device. The outcome of CRT was evaluated in terms of QRS duration, LVEF through echocardiography, 6 minute hall walk and tissue doppler echocardiography. Results Within a mean clinical follow-up of 29.0±7.5 month, the QRS duration was significantly shortened by biventricular pacing compared with right ventricular or left ventricular pacing. [(169±26) ms vs (188±40) ms and (222±34) ms vs (212±42) ms, respectively]. The NYHA functional class was improved from class Ⅲ-Ⅳ before the operation to class Ⅰ-Ⅱ at 1 week and 1 month during the follow up period. LVEF increased gradually from (28.30±3.94)% to (37.80±3.98)% after one week and increased to (42.99±7.87)% at the end of the follow-up. There was significant difference in LVEF before and 1 week after the operation (P0.05). However, there was no difference in LVEF between 1 week and the end of the follow up. Six-minute hall walk improved from (398±168) m to (478±126) m after one week and reached (506±134) m at the end of the follow-up. Significant improvement was observed in 6 minute walk at each time point thoughout the follow up period (P0.05). Six patients died and one patient underwent cardiac transplantation. Among the 6 deceased patients, 3 of them died of sudden cardiac death. One patient died of the acute myocardial infarction of multiple ressels leisons 1 year from the operation. One patient died of progressive heart failure due to elevation in the lead threshold value and battery exhaustion. One patient did not show benefit after the operation and died at the end of the study. Conclusion Cardiac resynchronization therapy improves symptoms,the quality of life,heart function and ability of exercise in patients with progressive heart failure by improving synchrony. These bvenefits may obtain through a long term follow up.