Do higher-risk patients benefit from off-pump coronary artery bypass grafting? Evidence from an ecologic analysis of randomized trials.

Abstract

It is commonly believed that especially higher-risk patients benefit from off-pump coronary artery bypass grafting. However, analyses from several registries give different results. A common shortcoming of all those analyses is the fact that they concentrate on evidence from nonrandomized trials. In an ecologic analysis, we included all randomized trials comparing the on- and off-pump techniques until January 2011. By logistic regression, we investigated whether the effect of off-pump surgery on mortality, myocardial infarction, stroke, and atrial fibrillation is modified across the range of the 3 risk factors: age, proportion of women, and ejection fraction. Eighty-six studies with a total population of 9906 patients reported on at least 1 risk factor and 1 outcome. We found a superiority of the off-pump technique in patients with lower ejection fraction values for the outcomes mortality and atrial fibrillation. No effect modification was seen for the risk factors age and proportion of women. Our ecologic analysis of nearly 10,000 patients from 86 randomized trials found a superiority of the off-pump technique in patients with lower ejection fraction values, especially for the most valid outcome of mortality. As every ecologic analysis is prone to ecologic bias, a definite answer on the benefit of the off-pump technique in higher-risk patients can only be given by meta-analyses using individual patient data.