Decision analysis in the evaluation of revascularization

Article Abstract:

A paper in the December 1, 1990 issue of the Annals of Internal Medicine by J.B. Wong and colleagues evaluates the effectiveness of revascularization by means a mathematical model. Revascularization refers to methods that restore blood flow to the heart after it has been seriously reduced by the accumulation of atherosclerotic plaque in the coronary arteries. It may be accomplished by percutaneous transluminal coronary angioplasty (PTCA, where a small balloon is inserted into the damaged vessel, then inflated to enlarge the opening) or by coronary artery bypass graft surgery (CABG, insertion of a grafted vessel segment to bypass the damaged one). Analysis of data from many sources, however, is complicated by variability in studies' assumptions and methods of data collection. Some of these differences are discussed. The Coronary Artery Surgery Study (CASS), one of three analyzed in Wong's paper, reported several interesting findings, all of which differed from the conclusions reached by the paper's authors. Overall, though, some conclusions can be reached. Patients with disease of the left main coronary artery have an increased chance of survival if they undergo surgery, as do those with disease of three vessels, with or without good ventricular function. Patients with disease affecting two vessels live longer after surgery than without it when their disease includes the proximal left anterior descending coronary artery. Certain considerations need to be considered when recommending PTCA over CABG. Wong and colleagues have not built a convincing argument for their viewpoints. Moreover, they do not distinguish between cost effectiveness accomplished through improved efficiency and that achieved through rationing of services, an option that should only be considered when all else has failed. (Consumer Summary produced by Reliance Medical Information, Inc.)

editorial

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Myocardial revascularization for chronic stable angina: analysis of the role of percutaneous transluminal coronary angioplasty based on data available in 1989

Article Abstract:

When coronary arteries are severely damaged, the heart requires revascularization (restoration of normal blood flow). This may be done by means of a coronary artery bypass graft (CABG, the surgical insertion of a graft so blood can flow around the damaged part), or via percutaneous transluminal coronary angioplasty (PTCA, where a small balloon is inserted into the damaged artery, and gradually enlarged until blood can flow again). In spite of the growth of PTCA since its introduction in 1977, the number of patients who undergo CABG has not changed significantly. No randomized, controlled study to compare the effectiveness of the two approaches has yet been reported. To learn more about the relative effectiveness of CABG and PTCA, a decision analytic model was constructed and tested with data from the Coronary Artery Surgery Study (CASS). Short- and long-term risks, short-term success and survival, late myocardial infarction (heart attack), and symptoms and costs, were all compared. The results indicate that revascularization is not needed unless severe symptoms or extensive ischemia (inadequate blood supply) are present, or disease is apparent in several vessels. Angioplasty is preferable in such cases if it can lead to the same degree of revascularization as CABG. Recommendations are made for specific conditions (such as single-vessel disease). Bypass surgery is somewhat better than PTCA for people with three-vessel disease. An extensive discussion and literature review are included. (Consumer Summary produced by Reliance Medical Information, Inc.)

Models, Mathematical models

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Management of chronic stable angina: medical therapy, percutaneous transluminal coronary angioplasty, and coronary bypass graft surgery

Article Abstract:

The treatment of chronic chest pain should be tailored to individual patients depending on how severe their coronary artery disease is. Researchers analyzed three clinical trials comparing drug therapy with angioplasty, seven trials comparing drug therapy with bypass surgery, and nine trials comparing angioplasty with bypass surgery. Patients with mild disease benefitted from angioplasty and drug therapy. Those with moderate risk required angioplasty or bypass surgery and those with severe disease benefitted most from bypass surgery.

Angina pectoris

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