The following are key points to remember about medical therapy with versus without revascularization in stable patients with moderate and severe ischemia:

1. All patients with stable ischemic heart disease (SIHD) should be managed with guideline-directed medical therapy (GDMT), which reduces progression of atherosclerosis and prevents coronary thrombosis.
2. Revascularization is also indicated in patients with SIHD and progressive or refractory symptoms, despite medical management.
3. Early randomized trials of coronary artery bypass grafting (CABG) versus conservative care in patents with SIHD performed several decades ago suggested a survival benefit for CABG in patients with extensive anatomic disease, in whom a large amount of myocardium was at risk (left main disease, three-vessel disease, and possibly two-vessel disease involving the proximal left anterior descending coronary artery).
4. These earlier randomized trials of CABG versus medical therapy (MT), however, antedated the more contemporary use of "disease-modifying" pharmacological interventions, including statins, inhibitors of the renin-angiotensin-aldosterone axis, and antiplatelet agents that individually have been shown to reduce death and myocardial infarction (MI) in placebo-controlled trials.
5. More recently, the benefits of routine revascularization in SIHD have been questioned by the similar rates of death and MI observed in optimal medical therapy (OMT)-treated patients with and without percutaneous coronary intervention (PCI) in the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial, and with and without PCI or CABG in the BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial.
6. Whether a strategy of routine revascularization (with PCI or CABG as appropriate) plus GDMT reduces rates of death or MI, or improves quality of life compared to an initial approach of GDMT alone in patients with substantial ischemia is uncertain. Careful review of the data demonstrates the limitations of our current knowledge, resulting in a state of community equipoise.
7. Recent clinical practice guidelines from the United States and Europe, as well as US appropriate use criteria, endorse GDMT for all patients with SIHD, but recommend (with variable levels of certainty) consideration of revascularization in patients with significant ischemia or symptoms that persist despite MT.
8. The optimal approach to patients with SIHD remains unsettled because all prior randomized trials, either by design or execution, have limitations. An adequately powered, randomized trial of contemporary conservative versus invasive approaches is greatly needed to provide guidance for the optimal approach in patients with SIHD, moderate or severe ischemia, and symptoms that can be controlled with MT.
9. The primary aim of the ISCHEMIA trial (ClinicalTrials.gov Identifier: NCT01471522) is to determine whether an initial invasive strategy of cardiac catheterization and optimal revascularization (with PCI or CABG, as determined by the local heart team) plus GDMT will reduce the primary composite endpoint of cardiovascular death or nonfatal MI in SIHD patients with moderate or severe ischemia and medically controllable or absent symptoms, as compared with an initial conservative strategy of GDMT alone, with catheterization reserved for failure of GDMT.
10. The results of the ISCHEMIA trial will have important implications regarding global guidelines for performance and reimbursement of revascularization procedures in patients with SIHD. Primary care providers, cardiologists, and cardiac surgeons around the world should enthusiastically support enrollment of their patients into ISCHEMIA, so that it may provide much needed prospective evidence to inform the optimal management of patients with SIHD, substantial myocardial ischemia, and angina symptoms that are controlled or absent.

Keywords: Angina, Stable, Atherosclerosis, Cardiac Catheterization, Coronary Artery Bypass, Coronary Thrombosis, Myocardial Infarction, Myocardial Ischemia, Myocardium, Percutaneous Coronary Intervention, Practice Management, Medical

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