Cardiac Resynchronization Therapy For Patients With Asymptonmatic And Symptomatic Heart Failure Due To Left Ventricular Systoloic Dysfuction And Cardiac Dyssynchrony: A Systematic Review

Objective systematic assess the effectiveness of cardiac resynchronization therapy in asymptomatic and symptomatic heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony.Method public domain electronic databases were systematically searched up to December 2009 irrespective of language. Randomized controlled trials that evaluated the effects of CRT in patients with asymptomatic and symptomatic heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony were selected for this analysis. Studies selection and quality assessment, data extraction and analysis were undertaken by two independent reviewers according to the Cochrane Handbook for Systematic Reviews of Interventions. Meta-analysis were also performed by using the Review manager 5.0.0.Results 10 studies including 6107 patients were identified and analyzed. Our meta-analysis demonstrated that CRT, as compared with therapy without CRT, significantly reduced all-cause mortality by 20%[RR=0.80, 95%CI(0.69,0.92), P<0.001] and hospitalization for worsening heart failure by 42% [RR=0.58, 95%CI(0.51,0.67)], P<0.001]. In addition CRT improved LVEF [MD=2.3%, 95%CI(2.17%-2.43%)], P<0.001]. In the NYHAⅢ～Ⅳsubgroup, the reduction of all-cause mortality and hospitalization for the worsening heart failure were also observed ([RR=0.77, 95%CI(0.66,0.91), P<0.001]; [RR=0.53, 95%CI(0.42,0.67), P<0.001], respectively). In the NYHAⅠ～Ⅱsubgroup, CRT also reduced hospitalization for worsening heart failure ([RR=0.58, 95%CI(0.48,0.70), P<0.001]) but failed to demonstrate further improvement of survival and 6MWD.Conclusion CRT reduced all-cause mortality and hospitalization for worsening heart failure and further improved LVEF in asymptomatic and symptomatic heart failure patients due to left ventricular systolic dysfunction and cardiac dyssynchrony. For the NYHA classⅢ～Ⅳpatients, CRT even showed improvement of functional capacity measured by 6MWD, however, for the NYHA classⅠ～Ⅱpatients, evidence from this analysis were insufficient to show the superiority of CRT in the aspects of improvement in survival and 6MWD.