Discussion
MICS CABG has been proven to be a reliable and reproducible alternative to conventional CABG 6. Convincing data show that MICS CABG provides the benefits of a low transfusion rate, short length of hospital stay, and rapid recovery to normal activity7,12. Graft patency and CR are predictive of the short- and long-term outcomes of patients who undergo coronary revascularization. Most previous studies used 64- or 256-slice CT angiography as a noninvasive approach, which showed reliable and convincing results 12,15. In our preliminary study using CT evaluation (data not shown), the trunk of the graft was well constructed while the distal anastomosis was less precise for assessment than transcatheter angiography, especially when the FitzGibbon grade was B (impaired anastomosis but patent graft). Despite its high invasiveness, selective coronary and graft angiography via insertion of a catheter into the orifice of the target vessel was a precise approach for assessment of the coronary artery or graft.
Invasive postoperative angiography has proven the effectiveness and superior long-term outcome of CABG versus PCI, which is attributed to the high CR rate and good graft patency. Some studies did not involve invasive angiography, mostly because the patients were reluctant to undergo an invasive intervention. Patients who were not evaluated were usually asymptomatic; thus, the graft patency rate might have been underestimated. Furthermore, early postoperative silent occlusion of the graft makes the real graft patency rate more unpredictable16.
In our institution, postoperative invasive angiography is routinely performed for every patient who undergoes surgical revascularization without a contraindication for quality control. Complementary PCI is performed to revise either a problematic graft or native coronary vessel.
Notably, although interventionists are trained to be skillful in native coronary angiography, not all of them are familiar with LITA and SV/RA graft angiography. It is sometimes necessary to switch to a femoral approach for selective angiography of the proximal anastomosis in the anterior wall of the A.o. The exact location of the proximal anastomosis might be anywhere in the anterior wall of the A.o. An excessive exposure time and contrast use makes this challenging. The most likely location of the proximal anastomosis performed with a side-biter during MICS CABG is the anterior wall of the A.o just at the level of the tracheal carina, which can be easily identified by X-ray fluoroscopy in the catheter laboratory. Selective angiography of the LITA can be performed via the left RA or femoral artery. The patients in the present study underwent successful coronary and graft inspection with the above-described method.
ICR induces postoperative angina, may jeopardize the late outcome, and usually necessitates repeat revascularization. The technical difficulty of off-pump heart manipulation and the limited exposure for target vessel anastomosis in MICS CABG add to the difficulty of accomplishing CR. The clinical volume of surgical coronary revascularization was 500 to 600 cases (half OPCAB and half sternum-sparing cases) per year in our center. Before we adopted MICS CABG in our clinical practice, we had performed more than 800 minimally invasive direct CABG procedures for treatment of isolated LAD lesions or in combination with PCI procedures for treatment of multivessel disease. We adopted the “Nambiar technique” 10 when starting MICS CABG with the bilateral internal thoracic arteries and performed this procedure in about 50 cases. Once we had become comfortable with handsewn proximal anastomosis using a side clamp, we routinely performed the “proximal first” sequential graft 17 after LITA-to-LAD anastomosis. This strategy provides the greatest possible blood supply to the myocardium during manipulation of the heart, minimizing the possibility of intraoperative hemodynamic instability.
Total arterial revascularization provides good short- and long-term graft patency and is superior to venous grafting. We have widely performed MICS CABG with deployment of the bilateral internal thoracic arteries and RA, and we plan to provide our data in the near future.
The causes of ICR include an invisible target vessel, hemodynamic instability precluding positioning of the heart, and underestimation of the target vessel caliber. One patient underwent complementary PCI for CR of the myocardium. The CR rate in this group of patients undergoing MICS CABG was not inferior to that of patients undergoing OPCAB or on-pump CABG in other studies 18,19. This finding proves that MICS CABG can attain a good CR rate similiar to that attained by conventional procedures.