Cardiac surgery performed with CCPB may lead to serious complications in up to 20% of low-risk patients [
19]. More than two decades ago, Kirklin et al. [
1] reported complement activation following CCPB which triggers a whole body defense reaction which may lead to significant alterations of cerebral function and multiple other harmful effects. After introduction of the minimally invasive direct coronary artery bypass (MIDCAB) procedure for treatment of single vessel (LAD) disease [
20], the evolution of that promising off-pump approach approach let to the interdisciplinary multivessel "hybrid procedure" with MIDCAB-grafting of the LAD culprit lesion followed by interventional stenting of remaining coronary lesions [
21]. However, long-term outcome of hybrid procedures might be limited by the known restenosis rates of stented areas [
22]. The complete surgical multivessel revascularization on the beating heart (OPCAB) was introduced in the mid-1990's [
2] and is a safe and well-established technique. Patients who undergo coronary surgery with this strategy were initially shown to have a lower incidence of postoperative complications and remarkable advantages in terms of hospital stay [
23]. However, although there was a significantly lower deterioration in psychometric tests in OPCAB patients in the early postoperative course as compared to CCPB patients [
24], this advantage of the OPCAB technique has resolved with respect to the 5-year cognitive and cardiac outcomes [
25]. Furthermore, complete coronary revascularization may not be achievable in all patients by off-pump techniques owing to the complex anatomy of coronary lesions and the possibility of hemodynamic instability while the beating heart is manipulated [
4]. Interestingly, recent studies show inferior long-term patency rates and incompleteness of revascularization with regard to OBCAB-techniques [
26,
27]. In the recently published ROOBY trial [
28], especially the lower patency rate of saphenous vein grafts in the OPCAB group accounted for the observed differences in graft function. However, with special attention to the prognostically important left internal thoracic artery grafts to the LAD culprit lesions, it could be shown that - with classification of those grafts according to the established FitzGibbon grade [
29] - there were significantly fewer grade A grafts in the OPCAB group than in the cardiopulmonary bypass group indicating lower quality of graft anastomoses. As a consequence, multiple efforts were taken to achieve the same advantages with modified cardiopulmonary bypass systems as can be achieved with OPCAB approaches. The solution was miniaturization of CBP-systems thus resulting in reduction of foreign surfaces, avoidance of blood-air contact and significant reduction of priming volume. The advantages of such minimized systems have been shown in several clinical studies so far [
30,
31]. Overall experience indicates an inferior biocompatibility of CCPB compared to Mini-HLM [
32] which is considered to be caused by contact activation of blood cells with artificial surfaces and air, the ischemia and reperfusion injury and hemodilution. Furthermore, the endoxemia caused by intestinal hypoperfusion represents a predominant trigger of complement activation and profound endothelial damage [
33]. In this context, a modern approach for assessing endothelial integrity includes the determination of circulating endothelial cells (CEC) in the peripheral blood. CEC are defined as mature endothelial cells in the peripheral blood, detached from vessel walls as a result of injury via mechanical strain or disease or inflammation via paracrine or endocrine factors. The correlation of CEC and cardiovascular disease and its implications have recently been reviewed extensively [
34]. Under physiologic conditions, CEC occur in humans in the range of 5-10 cells per ml blood, whereas elevated numbers are found in patients with different vascular disorders and type 2 diabetes mellitus [
35,
36]. The detachment of endothelial cells into the blood stream represents a serious injury of the endothelium as one of multiple severe adverse effects of CCPB [
1,
11], and overall CEC values are significantly lower in OPCAB patients when compared to standard cardiopulmonary bypass procedures [
37]. CEC do not only unveil endothelial damage but also correlate with activity and degree of endothelial injury [
12]. Therefore, CEC are considered to represent a novel marker of the intrinsic endothelial damage caused by CCPB, and use of modern Mini-HLM systems were found to be associated with significantly reduced CEC release as compared to CCPB [
11].
The main results of this present study indicate that a Mini-HLM approach by means of the ROCSafe™ system can achieve overall clinical results that are completely comparable to those of OPCAB revascularisation. Although non-elective patients and patients with insulin-dependent diabetes mellitus had to be excluded from the study as unstable angina and/or acute myocardial infarction as well as diabetes per se significantly increase CEC numbers [
17], no further restrictions were imposed with regard to enrollment, and the study patients therefore represent an institution-based cohort of routine coronary surgical practice. As the development of modern and risk-adjusted concepts for complete and safe revascularization in coronary patients is one of the main goals in coronary surgery, use of Mini-HLM and thus minimizing the side effects of CCPB is a desirable modern approach. In today's economically affected health care systems, this conclusion is especially important as OPCAB procedures are associated with longer hospital stays and greater overall hospitalization costs in significant dimensions [
38]. Increasingly, the referring cardiologists or the patients themselves insist on an OPCAB procedure. The medical decision to apply the OPCAB technique in these patients is a delicate balance between handling the pressure to compete for more CABG cases and providing sound surgical care [
38]. Therefore, performing OPCAB in every single patient who seems to be a candidate for surgical myocardial revascularisation for the sole purpose of attracting more patients or due to other political and economic pressures may not be appropriate and economically hazardous [
38]. With regard to the increasing overall excellent experience with Mini-HLM worldwide [
39,
40], OPCAB should be restricted to carefully selected special cases, i.e. patients presenting with severely calcified aorta etc..
The described results should be considered provisional and worthy of further investigation in larger studies, because the relatively small sample size might represent a limitation to our conclusions. However, the major finding of the present investigation is the fact that CEC release and, thus, endothelial damage, is completely comparable between Mini-HLM procedures and the OPCAB technique.