Does off-pump coronary artery bypass surgery have a beneficial effect on mortality in patients with left ventricular dysfunction?

A best evidence topic was written according to a structured protocol. The question addressed was whether off-pump coronary artery bypass surgery (OPCAB) offered any beneficial effect on mortality when compared with on-pump coronary artery bypass surgery (ONCAB) in patients with left ventricular dysfunction (LVD). A total of 491 papers were found using the reported searches of which 17 represented the best evidence. The authors, date, journal, study type, outcome measures and results are tabulated. The 17 studies (only containing patients with LVD) comprised of one prospective randomized trial, one meta-analysis and 15 retrospective studies. The prospective trial associated the OPCAB technique with significantly lower in-hospital mortality. By comprising of seven studies and 1512 patients, the meta-analysis showed no significant difference in terms of operative mortality. Of the retrospective studies, all 15 compared short-term mortality (<30-day) of which four showed significantly lower mortality in the OPCAB group. Nine of the studies compared mid-term mortality (30 days to 5 years) with no significant difference detected and three of the studies compared long-term mortality (>5 years) with no significant difference detected. We conclude that there is limited evidence to associate the OPCAB technique with improved short-term mortality. The majority of the studies suffered from significant limitations such as containing data from operations carried out prior to the year 2000, a period when off-pump surgery was in its infancy. They frequently contained major differences in baseline characteristics with no specific inclusion/exclusion criteria, description of handling of patients converted from off-pump to bypass or reporting of myocardial viability and concomitant mitral regurgitation. Nine studies reported completeness of revascularization of which eight associated the OPCAB group with a poorer degree of revascularization making comparisons less valid. The lack of high-quality data indicates that prospective randomized trials are needed. The CRISP Trial ('Coronary artery grafting in high-risk patients randomized to off-pump or on-pump surgery') has recently been halted due to recruitment difficulties. The CORONARY ('Coronary artery bypass surgery off- or on-pump revascularization study') trial is a large international multicentre randomized study that is recruiting well and is likely to provide valuable information in the near future.