the composite primary endpoint (death from any cause, stroke, MI, or repeat revascularization) remained significantly higher (37.3% vs 26.9%) in the PCI group due primarily to the higher rates of repeat revascularization and myocardial infarction. The rates of all‐cause death and stroke were not different [48]. When analyzed by SYNTAX score, those with a score of <23, inclusive of left main patients, there was no difference in the composite primary endpoint (32.1% vs 28.6%; p = 0.43). In those with a SYNTAX score of 23–32 with unprotected left main disease, the outcomes were similar (32.7% vs 32.3%; p = 0.88); but not in patients with three vessel disease in whom PCI had higher event rates for the primary composite endpoint (37.9% vs 22.6%; p = 0.0008). For patients with a SYNTAX score ≥33, the rates were higher in patients with left main disease (46.5% vs 29.7%; p = 0.003) and those with three vessel disease without (41.9% vs 24.1%; p = 0.0005) unprotected left main disease. At 10 years follow‐up, CABG was associated with a survival benefit in patients with three‐vessel disease [49]. The results of the SYNTAX trial indicate that CABG remains the standard for patients with complex three vessel disease. However, in patients with less complex disease (i.e., left main coronary disease with low and possibly intermediate SYNTAX scores, or three vessel disease with low SYNTAX scores), PCI is a reasonable alternative treatment to CABG. In patients with a high SYNTAX score, the potential advantages of surgery should be stressed, but PCI should not be denied to patients who have a strong preference or a very high surgical risk. However, these conclusions must be interpreted in the context of the trial’s limitations, such as the use of a first generation (paclitaxel‐eluting) stent, which has a higher rate of restenosis than current second generation drug‐eluting stents. Also, the analyses of subgroups by SYNTAX score was not pre‐specified or adequately powered, and therefore the findings should be considered hypothesis generating.
In the Coronary Artery Revascularization in Diabetes (CARDia) trial, 510 diabetic patients with multivessel or complex single vessel coronary disease were randomized to PCI using a stent (and routine abciximab) or CABG. The trial was underpowered for the primary endpoint (composite of all‐cause mortality, myocardial infarction, and stroke), and at one year there was no difference between CABG and the 69% of patients who received a DES (12.4% and 11.6%; p = 0.82) [46]. In the Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multivessel Disease (FREEDOM) trial, 1900 patients with diabetes and multivessel (83% with three vessel) disease (median SYNTAX score of 26) were randomized to either PCI with a first generation (paclitaxel or sirolimus‐eluting) stent or CABG. Both groups received optimal medical therapy [47]. At a median follow‐up of 3.8 years, the primary composite endpoint death from any cause, non‐fatal myocardial infarction, or non‐fatal stroke was more frequent in the PCI group (26.6% vs 18.7%; p = 0.005). The benefit of CABG was predominantly because of lower rates of myocardial infarction and death from any cause while stroke was more frequent in the CABG group (2.4% vs 5.2%; p = 0.03 at 5 years). The findings of FREEDOM suggest that in patients with diabetes and advanced CAD, CABG is superior to PCI using first generation stents.
Comparison of coronary artery bypass surgery with medical therapy for stable angina
The European Coronary Surgery Study (ECSS), Coronary Artery Surgery Study (CASS), and Veterans Administration Cooperative Study (VA Study) are relatively small, randomized trials that have compared CABG with medical therapy among patients with mild to moderate angina [50–52]. They were conduced over 35 years ago in an era when there was no effective medical therapy for CAD. The consistent finding from these studies was that surgical revascularization provides better symptomatic relief from angina, but the benefit is lost over time, most likely because of vein graft failure and subsequent crossover to CABG in the medical treatment arm. The randomized trials and a meta‐analysis [53] indicate that an initial strategy of surgical revascularization does not improve survival in the general population of CAD, but that there are specific subsets that either have a large amount of ischemic myocardium or significant LV dysfunction. Thus, patients with three vessel disease (especially in those with abnormal LV function), two or three vessels disease with >75% stenosis of the LAD or a markedly positive stress test derive prognostic benefit from CABG. In general, patients with severe symptoms have been excluded from the trials, but an analysis from registry data of the CASS study indicates that surgical revascularization probably improves prognosis in patients with severe angina who have multivessel disease, even in the absence of LV dysfunction or proximal LAD stenosis [54]. It is important to be aware that this evidence, which has been used to craft current guidelines, is limited by the fact that the randomized trials were all conducted in the early years of bypass surgery, and are not representative of the contemporary surgical techniques such as the routine use of internal mammary grafts or minimally invasive and off‐pump surgery. Conversely, the medical group did not benefit from the aggressive preventive measures which are now routine nor did they consistently receive beta‐blockers or angiotensin‐converting enzyme (ACE) inhibitors. Furthermore, the general applicability of these trials is limited by the fact that they did not enrol many women or patients over 65 years old.
The STICH trial has reported outcomes in stable multivessel CAD (excluding significant left main or CCS III/IV angina) in the presence of reduced left ventricular function (EF≤35%). The intial data showed no benefit of CABG compared to medical therapy alone, but in the 10‐year follow‐up (STICHES) analysis, cardiovascular and all‐cause mortality was lower with CABG [55,56]. In a substudy of the STICH trial, detection of myocardial viability using SPECT perfusion imaging or dobutamine echocardiography did not identify patients who would benefit from CABG surgery. There are no randomized trials comparing PCI with CABG in this patient subset, and hence current evidence supports CABG over PCI.
Recommendations for revascularization in stable angina
Broadly speaking, revascularization is appropriate for patients with limiting symptoms despite optimal medical therapy, as well as those with strongly positive stress tests, proximal multivessel disease, and active patients who prefer an interventional approach over medical therapy. The choice between PCI and CABG in any one patient is determined by extent of disease, the risks of the procedure, likelihood of success, and ability to achieve complete revascularization with the two strategies as well as diabetic status and patient preference. While medical therapy is the cornerstone of treatment of stable angina, it is important to remember that there is no evidence that medical therapy alone improves prognosis in high risk patients, as defined in the clinical trials of medical treatment vs CABG.
Patients with significant proximal LAD artery disease have a survival advantage with CABG over medical therapy, even in the absence of severe symptoms, LV dysfunction, or other lesions. PCI provides similar results among patients who have suitable anatomy for PCI of the proximal LAD and normal LV function (Tables 11.2 and 11.3).
CABG offers a survival advantage over medical therapy in patients with severe symptoms and three vessel disease, even in the absence of proximal LAD involvement or LV dysfunction. Patients with three vessel disease and LV dysfunction should have CABG. PCI is an alternative to CABG for three vessel disease in those with angiographically suitable targets and normal LV function (e.g., SYNTAX score ≤22; Tables 11.2 and 11.3). Surgical revascularization is recommended for significant left main disease though PCI is an alternative in patients with SYNTAX score of ≤22, and may be considered for those with a SYNTAX score of 23–32 (Tables 11.2 and 11.3).
In patients with diabetes mellitus, in the setting of multivessel or diffuse disease, there is a survival advantage with CABG over PCI. PCI is reasonable for diabetics with discrete two vessel disease (e.g., SYNTAX score ≤22) and preserved LV function.
For
