OPCAB was initially used in selected groups of patients, but it is now being used in more and more difficult situation, and many groups have reported good results in high-risk patients, including patients with poor LV function. Off-pump coronary artery bypass, however, is not yet considered the gold standard by many coronary surgeons. Furthermore, especially in high-risk patients, most surgeons are reluctant to use beating heart operations. Therefore, patients with unstable hemodynamics and low left ventricular ejection fraction are frequently cited as contraindications to beating heart interventions. The major reasons given are the difficulties for optimal coronary artery exposure in cases of low ejection fraction associated with enlarged ventricles and hemodynamic instability or severe rhythm disturbances during displacement of the heart.

Severe left ventricular dysfunction has been reported as an independent predictor of operative mortality in patients undergoing coronary artery bypass grafting [1–4]. However, the long-term benefits of coronary artery bypass grafting operation compared with medical therapy are more pronounced in patients with reduced left ventricular function [5]. In an ischemic heart or critically impaired left ventricle, any hemodynamic instability may lead to increased complication or death. Hausmann and coworkers [6] reported an operative mortality of 7.1 % in a series of 514 patients with EF ranging from 10 to 30 %. Bouchart and colleagues [7] reported an in-hospital mortality of 7 % in a series of 141 patients with poor LV dysfunction. In some previous studies, the incidence of in-hospital mortality was reported as ranging from 4.7 to 15.0 % in these groups [6–9]. For patients with congestive heart failure, mortality is directly related to the severity of their ventricular systolic dysfunction.

There have been several controversies surrounding the choice of the optimal surgical strategy in patients with reduced ejection fraction. Many surgeons prefer using CPB because hemodynamic instability, hypotension induced by ventricular arrhythmias, or cardiac arrests are frequent problems encountered in this specific group of patients. CABG using CPB has been safe due to recent development in myocardial protection techniques, and in majority of patients its damaging effect on myocardium is minimal and reversible, but patients with LV dysfunction have very poor reserve, and even slight damage to myocardium may have significant consequences.

Good midterm surgical results reported with OPCAB surgery were associated with an increased popularity of this revascularization technique, especially in this category of high-risk patients with poor LV function. Hemodynamic deterioration is the greatest concern during displacement of the heart in OPCAB surgery. A good hemodynamic monitoring and more attention to minor details during OPCAB are very important in this group of patients. TEE gives us good information about the wall motion and chamber filling of the left ventricle, and the heart can be displaced in a direction so that there is minimal compression of the right ventricular outflow tract and minimal hemodynamic compromise. Poor LV function is sometimes an exclusion criterion for the OPCAB approach because of the technical difficulty of safely displacing the heart under condition of hemodynamic stability. Displacement of the beating heart may be well tolerated with good LV function, but hemodynamic compromise occurs more often in patients with severe LV dysfunction, making it difficult to achieve complete revascularization in these patients using the OPCAB technique. However, several pioneer surgeons have challenged to adopt beating heart technique to these high-risk patients. Multiple single-center reports have been published detailing outcomes of OPCAB for patients with a low EF. Ascione and coworkers [4] reported an operative mortality of 7 % in a series of 74 OPCAB patients with EF <30 %. Arom and colleagues [10] found an operative mortality of 2 % in their series of 45 OPCAB patients with low EF (<30 %). Shennib and coworkers [11] compared the clinical outcome of OPCAB and conventional CABG in patients with poor LV function (EF <35 %) and reported that operative mortality was lower in the former group (3.2 % vs. 10.9 %). However, there were fewer distal anastomoses per patient (2.8 vs. 3.9) in the OPCAB group. Recently, Keeling and coworkers [12] reported a large and propensity-matched OPCAB trial. They analyzed the effect of off-pump versus on-pump coronary revascularization in patients with low ejection fraction with propensity score matching technique. They showed that patients undergoing scheduled OPCAB were older, more frequently female than those who underwent ONCAB. OPCAB was associated with a significant lower adjusted risk of death, stroke, major adverse cardiac events, and prolonged intubation, and postoperative transfusion rates were significantly lower in the OPCAB group.

We have performed OPCAB surgery in all CABG cases with no exclusion criteria since 2001 [13]. Our technical knack for the safe exposure of the heart is shown. After midline pericardiotomy, the left side of pericardium is incised from the apex to the back of the pericardial sac to the anterior of the phrenic nerve, in order that it must not be injured. The other pericardiotomy is at the level of the left atrial appendage. The right side of the pericardium is incised longitudinally around the superior vena cava. This maneuver prevents the SVC from being compressed by the pericardium and prevents disruption of venous return when the heart is lifted. Hemodynamic compromise during displacement of the heart is likely to be caused by inadequate ventricular filling due to disturbance of venous return. The incised left side of the pericardium is pulled up and retracted over the sternal retractor. The right side of the pericardium should be free for easy rotation of the heart into the free space beneath the right sternum. We also use two deep pericardial sutures which are put in the bottom of the pericardium beside the IVC and left lower pulmonary vein. The most important point for comfortable surgical view without disturbing the beating heart is that the cardiac base is rotated right-side down and left-side up and to move the center of gravity of the heart toward the right [14].

Revascularization on the branches of the circumflex and right coronary systems require a more vertical displacement that is even more pronounced in the posterolateral system. Hemodynamic instability was minimized with the patient in a Trendelenburg position, which creates bilateral filling pressures to reach adequate level. The most important is the presence of a dedicated cardiac anesthesiologist constantly vigilant of hemodynamic and progress of the operation who can alert the surgeon of the need to return the verticalized heart to a more physiological position and to rapidly create a proximal anastomosis or to insert a shunt for hemodynamically compromising ischemia. The experienced off-pump anesthesiologist is adept at using inotropes and pressors as necessary based on hemodynamics and continuous TEE evaluation of the degree of mitral regurgitation and can anticipate the next step in the operation and adjust vasoactive drips and bed positioning as necessary to ensure a smooth operation.

In actuality, a skilled OPCAB surgeon does not feel difficulty in case of enlarged heart or LV dysfunction. The change of ventricular filling volume during displacement of the heart has only a marginal effect on enlarged heart. A concentric hypertrophic heart is more irritably affected by change of filling volume. Enlarged ventricular chamber does play a buffer action against the change of filling volume that makes a little impact for hemodynamic stability. Furthermore, regional motion of the ventricular wall of an enlarged heart is smaller than normal heart that facilitates for surgeons further comfortable coronary artery anastomosis. Mitral regurgitation during displacement of the heart sometime becomes a problem in OPCAB surgery. When increases in the PAP and the CVP are observed, a TEE examination of the mitral valve can be very helpful in the diagnosis. A tethering mitral valve of enlarged heart often causes mitral regurgitation when the heart is forced to lift up and compress. However, in almost all cases of enlarged heart, acute position-related mitral regurgitation may be resolved with appropriate repositioning.

When comfort with OPCAB technique grew, data began to emerge citing the potential benefits of avoidance of CPB for high-risk subgroup. We feel that the greatest benefits derived from avoidance of extracorporeal circulation will become manifest not in low-risk individuals, but in patients with significant comorbidities, but this remains unproven.

Several large series of surgical intervention for an acute myocardial infarction (AMI) were reported in the beginning of the 1970s. In the early days of coronary artery bypass grafting (CABG), surgical intervention within the first months of an acute myocardial infarction was associated with increased mortality rate. Early reports suggested that emergency CABG for AMI was associated with a high operative mortality rate, ranging from 9 % to as high as 60 % [15–17]. More recently, with improved anesthetic and surgical techniques, supportive pharmacologic therapy, and myocardial preservation, the perioperative mortality rate associated with emergency CABG in selected patients with AMI has fallen markedly [18].

Patients with evolving acute coronary syndrome defined as continuum from unstable angina to non-ST-segment elevation MI to ST-segment elevation MI display a high-risk entry in CABG surgery. Perioperative mortality is increased severalfold compared with patients with stable angina, and it may be advisable to delay surgical intervention whenever possible. However, in the presence of refractory symptoms, hemodynamic alterations, or in STEMI patients, emergency surgical therapy within the first hours is indicated. Current indication [19, 20] for emergency CABG surgery in ASC patients is limited to those presenting with evolving myocardial ischemia refractory to optimal medical therapy, presence of left main stenosis (≧50 %) and 3-vessel disease, ongoing ischemia despite successful or failed PCI, complicated PCI, cardiogenic shock accompanied by complex coronary anatomy, or life-threatening ventricular arrhythmias thought to be caused by myocardial ischemia. Patients that meet these indications are relatively rare. An aggressive surgical approach, when appropriate, has been shown to be the superior approach for patients presenting with moderate- to high-risk ACS and is recommended by US and European guidelines for treating these patients.