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OBJECTIVE: Minimally invasive coronary artery bypass grafting (MICS CABG) via a small left thoracotomy is a novel technique for coronary revascularization that is increasingly utilized around the world. However, multivessel MICS CABG is difficult, and concerns about repeat revascularization have been raised. This study describes the rates of repeat revascularization among patients who have undergone MICS CABG, and identifies targets for improvement.
METHODS: A prospective observational study was performed on the 306 MICS CABG patients operated on by a single surgeon from 2005 to 2015. MICS CABG was performed through a small thoracotomy, using the in situ left internal mammary artery, ± a radial artery and 1 to 3 saphenous veins anastomosed proximally to the aorta. Patients were followed annually. We examined the difference between the first and second half of the series to ascertain the effects of a learning curve.
RESULTS: Eighty percent of the procedures were done off-pump. The median number of grafts done were 2, and the LAD, diagonals, OMs, and PDA were the distal targets in 94%, 12%, 44% and 26%, respectively. The graftability index (grafts/ acceptable distal territory targets of 1.5mm or more) was 0.93. Revascularization of targets smaller than 1.5 mm decreased from 69% to 50% (p=0.002) between the series’ first and second halves. Overall, repeat revascularization was needed in 21 patients (6.9%), and was performed at a mean of 629±600 days postoperatively. The culprit lesion was attributed to the index surgical procedure (“graft-associated”) in 52%, to a stent stenosis or progression of native disease in 43%, and was unidentified in 5%. Patients with graft-associated repeat revascularization had a lower graftability index at operation (0.73 vs 0.94), and more frequent involvement of the circumflex system (0.8 vs 0.3) (P<0.05). The overall rate of repeat revascularization at 3 years decreased from 11% in the first half, to 2.6% in the second half (P=0.001).
CONCLUSIONS: The need for repeat revascularization is part of the learning curve with MICS CABG, involves a graft in half of the cases, is more common in patients who had a lower graftability index at operation, and markedly improves with experience.