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.