Angina is the initial manifestation in approximately half of all patients who present with coronary artery disease. The presence of chronic angina approximately doubles the risk of major cardiovascular events.
Management of angina includes lifestyle changes and pharmacologic treatment to reduce cardiovascular risks, antianginal therapies (beta-blockers, long-acting nitrates, calcium-channel blockers, and — recently in the United States — ranolazine), and revascularization. A new Clinical Practice article summarizes.
Clinical Pearl
• Do diagnostic tests for coronary artery disease also provide prognostic information?
Several tests that are used to diagnose coronary artery disease can also provide prognostic information. The standard exercise ECG stress test is the least sensitive test for coronary artery disease and cannot define its extent, but the duration of exercise, presence of ST-segment changes, and occurrence of angina confer prognostic information. As compared with the routine exercise ECG stress test, stress tests that involve imaging typically have a superior ability to detect coronary artery disease without an appreciable loss of specificity. The exercise ejection fraction is one of the most important prognostic variables in patients with coronary artery disease. Imaging stress tests allow evaluation of left ventricular performance and assessment of the extent of ischemia during stress.
Table 1. Tests to Diagnose and Assess the Prognosis of Clinically Significant Coronary Disease.
Clinical Pearl
• What are some of the general guidelines for the management of suspected chronic angina?
Establishing a diagnosis of chronic angina should be pursued in parallel with managing symptoms and initiating preventive therapies. In patients in whom stable angina is suspected, preventive therapies, including aspirin, should be started immediately if they are not already in use. Blood pressure should be reduced to below 120/85 mm Hg if possible, and a moderate-to-high-intensity statin (that reduces low-density lipoprotein [LDL] cholesterol levels by >30% from pretreatment levels) should be used. Changes in lifestyle behaviors should also be recommended. These changes include weight loss in overweight or obese patients, dietary changes to reduce fat and sugar intake, and smoking cessation. Antianginal therapy should be initiated as soon as the diagnosis is suspected. In patients with stable angina, beta-blockers, calcium-channel blockers, and long-acting nitrates reduce angina similarly and appear to have a similar safety profile (except for short-acting calcium-channel blockers).
Morning Report Questions
Q: What are some of the newer medical therapies for chronic angina?
A: Ranolazine is a metabolic antianginal agent that is approved for the treatment of chronic angina. It diminishes myocardial ischemia by reducing calcium overload caused by inhibition of the late sodium current. It does not affect heart rate or blood pressure and thus may be considered as a first-line agent for patients with slow heart rate or low blood pressure. It has been evaluated in two studies of outcomes in patients with angina, with mixed results. Ranolazine prolongs the QT interval in a dose-dependent manner; however, no increase in significant arrhythmias has been observed with its use in multiple safety studies. Still, caution is warranted regarding prescription of other drugs that cause QT-interval prolongation, as well as regarding other drug–drug interactions. Ivabradine is a selective heart-rate–lowering (physiological) agent that inhibits the If current in the pacemaker cells in the sino-atrial node. It is approved for treatment of heart failure with a goal of preventing hospitalization in patients who have an increased heart rate despite adequate beta-blocker therapy. It has also been reported to be effective in improving exercise duration in patients with chronic angina who are not receiving background therapy. However, the results of a large randomized trial involving patients who had both stable coronary artery disease without heart failure and a resting heart rate of 70 beats per minute or more have aroused concern about the use of ivabradine for chronic angina. Ivabradine should not be used to treat angina in the absence of heart failure.
Table 2. Antianginal Agents.
Q: When would you consider revascularization for a patient with chronic stable angina?
A: The decision regarding whether and how to revascularize (with percutaneous coronary intervention [PCI] or coronary-artery bypass grafting [CABG]) or whether to continue medical therapy should ideally involve a heart-team approach incorporating input from interventional cardiologists and cardiothoracic surgeons. The decision should take into account clinical risk factors, characteristics of the lesion, and hemodynamic factors, and it may be informed by the use of validated risk scores to refine the selection of patients for PCI versus CABG. Randomized trials involving patients who were eligible for either medical therapy or revascularization have shown that PCI is effective in reducing angina in patients with chronic angina, but it does not result in a lower risk of death or myocardial infarction than that with medical therapy. These observations suggest that medical therapy alone is a reasonable starting point if it has an acceptable side-effect profile. Revascularization should be considered for patients who have ongoing angina despite adequate medical therapy; this group includes as many as 50% of patients with chronic angina.