The importance of myocardial contractile reserve in predicting response to cardiac resynchronization therapy

Aim: To perform a meta-analysis and systematic review of published data to assess the relationship between contractile reserve and response to cardiac resynchronization therapy (CRT) in patients with heart failure.

Methods and results: We searched MEDLINE/PubMed and Cochrane for all papers published up to 26 April 2016, supplemented by manual searches of reference lists from retrieved articles. The search strategy yielded nine observational studies that met our eligibility criteria with a total of 767 patients of which 757 provided data for this analysis. Contractile reserve after dobutamine infusion was present in 496 patients (66%). During follow-up 474 patients (63%) qualified as CRT responders. The presence of contractile reserve was associated with a higher chance of CRT response (odds ratio 4.42, 95% confidence interval 2.15-9.07, P < 0.001) using a random-effects model. There was evidence of publication bias. Imputation of missing studies attenuated the association to some extent, but the positive association between contractile reserve and CRT response remained with an odds ratio of 2.42 (95% confidence interval 1.17-5.05, P = 0.018).

Conclusion: The presence of global contractile reserve at baseline, as assessed by dobutamine stress echocardiography, is associated with a higher chance of CRT response in patients with heart failure.