Introduction
The prevalence of coronary artery disease is rapidly increasing [1]. In China, the prevalence is estimated at 4.6 per thousand residences of all ages, effecting 5 million adults [2]. Coronary artery disease is the most major cause of left ventricular dysfunction, commonly defined in terms of reduced left ventricular ejection fraction (<50%) [2-4]. Coronary artery bypass graft (CABG) is the common type of cardiac surgery worldwide. Paradoxically, there is strong evidence from recent studies that left ventricular dysfunction is a predictor of early mortality and a leading cause of high healthcare cost after conventional coronary artery bypass grafting (cCABG), posing a great burden on both patients and society [5, 6].
Despite advances in surgical techniques, the management of patients with decreased left ventricular ejection fraction is still challenging. Off pump coronary artery bypass surgery (OPCAB) is an attractive alternative in patients with impaired left ventricular function, comparing with cCABG. The benefits of OPCAB theoretically were centered around the avoidance of cardiopulmonary bypass and aortic manipulation, which were endorsed by observations of avoiding the negative effects of cardiopulmonary bypass on markers of inflammation, coagulation, micro-embolization, thermoregulation, acid based balance, and regional perfusion [7-9]. Substantially, positive short- and middle- term outcomes of reducing morbidity and mortality were observed in study [10, 11]. In light of these advantages, OPCAB now accounts for more than 50% of all CABG operations in China and other developing countries [12].
However, lifting and rotating the heart during OPACB potentially alter such hemodynamics as left ventricular end-diastolic pressure, right atrial pressure and cardiac outputs, as a result of the worsened preservation of interventricular septal movement, the activation of inflammatory mediators and the non-physiologic ventricular geometry of the empty heart impeding collateral flow to ischemic areas [13]. The decrease in short-term mortality seen with OPCAB may be negated by reduced long-term graft patency, increased needs for repeat revascularization procedures and inferior long-term survival compared with CCAB in left ventricular dysfunction patients [14]. The clinical evidence base surrounding OPCAB in this population remains equivocal, ridden with biased observational studies, and relatively small randomized trials [15]. Given these concerns, it may seem still challenging for surgeons to take OPCAB procedure in patients with left ventricular dysfunction.
To address some of the evidence gaps regarding prevailing practices in management of patient with left ventricular dysfunction, we conducted present study to compare the short and long-term outcomes in patients with different ejection fractions undertaken OPCAB by the same surgeons team, using the real-life registry database with an analysis of a propensity score matching.