Anaortic Off-pump Coronary Artery Bypass Graft Approaches
As discussed above, RCTs and meta-analyses do not consistently support the hypothesis that routine implementation of off-pump CABG might reduce the risk of stroke compared with on-pump CABG. However, the specific technique used to perform off-pump CABG in those RCTs has not been reported in detail.7 Off-pump CABG in fact encompasses a variety of surgical techniques that entails different levels of aortic manipulation, including partial or side clamping of the aorta, use of the HEARTSTRING® Proximal Seal System (MAQUET, San Jose, CA, US)32 and total arterial revascularisation without cross-clamping.
Partial clamping entails surgical manipulation, and does not eliminate the clamp-related risk of stroke. In sharp contrast, anaortic approaches avoids any clamping of the aorta during off-pump procedure by performing in situ grafting using both mammary arteries and/or T- or Y-grafting. Several studies have suggested that anaortic approaches may minimise the risk of stroke in patients undergoing CABG. In a meta-analysis including 12 observational studies, the anaortic approach was associated with a significant reduction in the risk of stroke compared with both conventional CABG and off-pump CABG with partial clamping.33 In addition, Halbersma et al. showed very low rates of stroke in a cohort of 400 consecutive patients undergoing off-pump CABG with anaortic approaches.34 When the results were analysed in the perspective of the surgical arm of the Synergy between percutaneous coronary intervention with Taxus and Cardiac Surgery (SYNTAX) trial,35 a clear trend was apparent, suggesting a reduction of the risk of stroke in patients treated with anaortic approaches compared with patients treated with conventional CABG (0.8 % in the study by Halbersma et al. versus 2.2 % in the surgical arm of the SYNTAX trial). Moreover, the 0.8 % risk of stroke associated with anaortic approaches34 closely matched the 0.6 % risk of stroke associated with stenting in the SYNTAX trial.35
Another device that can be used to minimise aortic manipulation is the HEARTSTRING seal. The HEARTSTRING seal is delivered at the site of circular aortotomy to avoid uncontrolled spurting of blood while the graft is sutured.32 After completion of the anastomosis and before tightening of the suture, the device is removed. In a propensity score matched analysis including 4,314 patients, Emmert at al. showed that the occurrence of stroke was significantly lower in patients treated with anaortic approaches using the HEARTSTRING device compared with patients treated with off-pump CABG using partial clamping.36 Moreover, the HEARTSTRING device had similar rates of stroke as total in situ arterial revascularisation, which avoids any touch of the aorta and therefore is considered the gold standard technique to minimise the risk of stroke.