While many of the observational studies excluded patients with recent myocardial infarction or worsening heart failure, some have included patients who had more acute presentations. Elefteriades et al. [33] reported on 83 patients with ischemic cardiomyopathy (EF ≤ 30 %) who underwent CABG. While the overall mortality rate was 8.4 %, it was 22.7 % in patients who were admitted to the ICU immediately before operation due to cardiogenic shock compared to 3.3 % in those who were stable prior to operation. Emergency operation was also cited as a risk factor for perioperative death by others [11, 29, 35, 39]. In the study by Bouchart et al. [39], 49 of 141 patients with an EF ≤ 25 % had a transmural infarction within 30 days of operation and 37 patients underwent operation within 24 h of catheterization due to clinical need. The operative mortality was 25 % in those patients requiring operation within 12 h of catheterization. Pocar et al. [40] studied 45 patients with significant heart failure (NYHA Class III–IV) who had undergone preoperative PET scanning prior to elective CABG. While these patients were clinically stable, the preoperative hemodynamics demonstrated a degree of decompensation in many of them. An LVEDP ≥ 25 mmHg was associated with a threefold increase in the risk of death and an LVEDP ≥ 20 mmHg was associated with an increased need for IABP support. None of the patients with an LVEDP ≥ 25 mmHg improved to NYHA Class I. A high operative mortality was also seen by Bouchart et al. [39] where patients with an LVEDP ≥ 23 mmHg had a mortality of 20 % compared to 2.7 % without this risk factor. One theory is that an elevated LVEDP inhibits diastolic flow of the subendocardium and this is responsible for the poor results seen with an elevated LVEDP. Thus, patients who are unstable should be stabilized and optimized if possible before undergoing revascularization. Alternatively, high LVEDP may be a marker for more advanced cardiac injury, decompensation or remodeling, and should prompt consideration for other therapies.

Elevated pulmonary artery pressure has also been indicted as a significant risk factor in patients undergoing revascularization. Hovnanian et al. [34] reported on 244 patients with an EF ≤ 35 % who had viability by thallium scanning. In-hospital mortality was 3.7 %, but was 25 % in those patients with a pulmonary artery systolic pressure (PAsP) >70 mmHg. However, 17 % of the patients had a mitral valve intervention as well as CABG, making it more difficult to apply these data to patients with coronary disease alone. Selim Isbir et al. [41] also reported a negative survival effect with an elevated pulmonary artery pressure by multivariate analysis, but no value was given above which the risk rises and pulmonary artery catheters were not placed preoperatively on a routine basis.

Many of the patients with ischemic cardiomyopathy have symptoms of CHF. Those with important angina in addition to heart failure symptoms have good survival and symptom relief with revascularization. However, patients with predominantly Class IV CHF symptoms are at higher operative risk [29, 34, 39], have lower long-term survival [34, 35, 39] and have less resolution of their symptoms [37]. It may be difficult to opt for revascularization in a patient with no angina and Class IV heart failure symptoms, especially when the operative mortality can reach 29 % [39], but these same patients are also at high risk for death with medical management alone. Choosing the patient with stable Class IV heart failure symptoms for revascularization and directing the decompensated patients towards medical management, heart transplantation or ventricular assist device therapy may minimize the operative risk and maximize outcomes.

The best results are clearly seen in patients who can undergo elective operation and those with compensated symptoms. Appropriate patient selection is the single greatest factor in achieving low operative mortality. In terms of conduct of the operation, myocardial protection is critical to limit additional ischemic damage. Complete revascularization is important in all patients, especially those with ischemic cardiomyopathy [29]. Perioperative management with an intra-aortic balloon pump (IABP) has been shown to be beneficial [41]. The operation also needs to be conducted in a time-efficient manner as longer cross-clamp and bypass times have been associated with lower survival [41]. Choice of conduit may not be as important in ischemic cardiomyopathy as it is with a normal ventricle. Selim Isbir et al. [41] used the left internal mammary artery (IMA) in only 50.4 % of patients and found no correlation between IMA use and outcome out to 4 years. Even though there is evidence that some patients without ischemic cardiomyopathy may benefit from the use of bilateral IMA grafts, it was not better than the use of single IMAs in patients with an ejection fraction <30 %, although there was slightly better outcome with bilateral IMAs seen in patients with an EF ≥ 30 % [42]. While these results may be influenced by patient selection in that patients with lower risk may have received bilateral IMAs, these results probably reflect the relative dominance of the cardiomyopathy in determining long-term outcomes rather than the details of the revascularization.

Yoon et al. reported their results in 1468 patients with an EF < 30 %. Patients were either treated with CABG, CABG with mitral valve repair or replacement, CABG with SVR or listing for transplantation. Viability testing was performed in only about 20 % of the patients. The treatment plan was based on the clinical situation. In their retrospective analysis, they determined that most patients would have benefited most with either CABG or listing for transplantation, despite the 18 % mortality seen on the waiting list in this cohort. The authors believe that mitral repair in ischemic cardiomyopathy provides few benefits to most patients. The addition of mitral repair to CABG in patients with 3+ or 4+ mitral regurgitation has been shown to produce no survival benefit and no long-term relief from significant heart failure over CABG alone [45]. Left ventricular reconstruction is, at best, useful in a limited number of patients with ischemic cardiomyopathy as it works best in the setting of an anterior-septal infarct. Although the STICH Trial has cast some doubt about its use in a larger patient population, other data document marked symptomatic improvement and survival benefit when compared with historic controls [46, 47]. If patients are deemed extraordinarily high risk for CABG with little probability of symptomatic or survival benefit, then transplantation is a reasonable option with excellent results. However, despite the potential favorable outcome with transplantation, donor shortages have resulted in long wait lists with the potential for significant mortality while awaiting transplantation, eliminating this as an option for many patients who are in need of timely intervention. In addition, the use of organs for patients who have other treatment options may deny patients who require transplant a chance at life.

With the advent of smaller, more durable left ventricular assist devices (LVADs), this may be a better option than revascularization for many of these high-risk patients. In the elective setting and good patient selection, LVAD therapy can achieve 95.8 % 3-year survival [48]. Even in a broader group of patients, therapy with modern LVADs achieves better survival than medical therapy in end-stage cardiomyopathy [49, 50]. In addition, heart failure symptoms are greatly improved and the results seem to be durable with more consistent relief of heart failure symptoms than seen in patients undergoing revascularization. This therapy is particularly suited for many of the patients who are considered high risk for revascularization alone – those with very large ventricles, NYHA Class IV symptoms, low cardiac index, high LVEDP and significant mitral regurgitation. In addition, since LVAD therapy does not rely on the adequacy of LV function, the presence of viability is not a concern. As devices continue to improve and costs are lowered, this will likely become the treatment of choice for patients with ischemic cardiomyopathy with important risk factors for revascularization alone.