Does a minimally invasive approach result in better pulmonary function postoperatively when compared with median sternotomy for coronary artery bypass graft?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Does a minimally invasive approach result in better pulmonary function postoperatively when compared with median sternotomy for coronary artery bypass graft?'. Procedures such as limited sternotomy and minimally invasive direct coronary artery bypass (MIDCAB) though a minithoracotomy were regarded as minimally invasive. Overall, 681 papers were found, of which eight represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, evidence level, relevant outcomes and results of these papers were tabulated. Three randomized, controlled trials (RCT) were included: One study suggested that ministernotomy dividing the corpus sterni (n = 50) offers no advantage over standard sternotomy (n = 50) during the first 10 postoperative days. Two further studies reported on minithoracotomy: one trial presented data suggesting that minithoracotomy (n = 21) is as safe as standard sternotomy with (n = 18) or without (n = 19) cardiopulmonary bypass, but without the benefit ascribed to the minimally invasive incision. A two-centre report investigated pulmonary function as a secondary outcome and claimed that minithoracotomy worsens FEV1 and FVC. The study was not powered to detect these differences as pulmonary function data were available only for one of the centres. Five non-randomized reports were also included in this analysis: These investigated outcomes after minithoracotomy or limited sternotomy compared with standard sternotomy. Patient groups were small, involving < 20 subjects per group. Non-randomized studies suggested a benefit to postoperative lung function in using thoracotomy. One of these reports included only patients with severe chronic obstructive pulmonary disease (COPD) (FEV1 < 70% of predicted) and detected benefits in selected patients undergoing MIDCAB. A further study was in agreement with the above statement in patients without COPD. MIDCAB may be more painful initially, but results in quicker recovery of lung function. Demonstrating the benefits of ministernotomy compared with the standard sternal incision was less clear. One paper demonstrates better outcomes when compared with standard sternotomy, while another reports no difference. We conclude that non-randomized studies support the hypothesis that minimally invasive coronary artery bypass benefits postoperative lung function in patients with known respiratory problems.