Comment
Optimal treatment strategy for MB is still controversial. As a treatment option, medication therapy, transcatheter stenting, CABG, and unroofing were reported. Lee, et al. reported that the rate of major adverse cardiac events was significantly higher in the MB group compared to the non-MB group (18.1% vs. 9.8%, p = 0.024) in 551 patients who underwent percutaneous coronary intervention by drug eluting stents [4]. New atherosclerotic lesion proximal to MB generated by endothelium-mediated vasodilators and in-stent restenosis caused by fractures of stent were major causes [5]. On the other hand, Ji, et al. compared the outcomes between unroofing and CABG [3]. For the treatment of MB in LAD without concomitant proximal coronary stenosis, unroofing had a significantly lower incidence of adverse angiographic results than bypass grafting (3.7% vs. 75.0%, p = 0.001). Acute obstruction of the internal thoracic artery graft was thought to be related to the presence of a competitive flow of the native coronary arteries. Therefore, CABG was recommended in a case with concomitant proximal stenosis in symptomatic MB patients. In results, patients without atherosclerotic lesions are good candidate for unroofing.
Unroofing is commonly performed by using cardio-pulmonary bypass and cardioplegic arrest. However, cardiac arrest increases a risk of incomplete unroofing due to inadequate intraoperative evaluation. Mitsuharu, et al. reported successful off-pump unroofing of MB and intraoperative CAG was useful to evaluate remaining MB [6]. Avoidance of full heparinization can reduce surgical bleeding. Three-dimensional reconstruction of cardiac CT was useful to determine the appropriate incision site and products for MICS-CABG were helpful for good exposure [7]. As a less invasive surgery, Mirzai, et al. reported totally endoscopic robotic assisted off-pump approach for symptomatic MB of LAD [8].
Minimally invasive off-pump unroofing for MB was beneficial for patients requiring early rehabilitation and intraoperative evaluation under heart beating was a different advantage to reduce residual lesions.