Chronic stable angina percutaneous coronary intervention versus medical therapy
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Chronic stable angina Microchapters | ||
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Differentiating Chronic Stable Angina from Acute Coronary Syndromes | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; John Fani Srour, M.D.; Jinhui Wu, M.D.
Overview
An increased risk of mortality and morbidity is associated with untreated coronary artery disease.[1] The main aim of therapy in patients with chronic stable angina is to alleviate symptoms, delay the progression of atherosclerosis, reduce the incidence of adverse coronary events and improve prognosis. This is achieved either by medical therapy or by revascularization procedures such as percutaneous coronary intervention or coronary artery bypass grafting. Medical therapy alleviates symptom and improves prognosis; however, on the contrary, revascularization procedures provide symptomatic relief but generally does not improve mortality.
Limitations of Older Trials
There are some reservations to the application of results from older trials to the current clinical practice. Listed below are a few of the important limitations.
- The patient population evaluated in older trials was confined to patients with preserved left ventricular function and focal coronary artery disease and hence, its difficult to conclude the same results in patients with diffuse coronary artery disease and/or patients with left ventricular dysfunction.
- Majority of the patients evaluated in earlier trials underwent coronary angioplasty alone without stenting and even in a few trials that compared the benefit of PCI with concurrent bare-metal stent; involved patients who did not receive the current anti-thrombotic regimen.
Clinical trials comparing PCI versus Medical therapy
- In the ACME trial (1992), approximately 213 patients with stable single-vessel CAD were assessed to compare the effects of PCI with medical therapy on angina and exercise tolerance. The study demonstrated that PCI significantly reduced the incidence of anginal symptoms compared to medical therapy (50% angina free in PCI group versus 24% in medically treated group) at one month and a sustained significant benefit was observed at 6 month follow-up (64% angina free in PCI group versus 46% in medically treated group; p=less than 0.01). Patients treated with PCI were associated with better exercise duration of 2.1 minutes which was significantly greater than the 0.5 minute experienced in the medically treated group (p=less than 0.0001). Thus, the study concluded that PCI offered earlier and more complete relief of angina than medical therapy and was associated with a better exercise tolerance.[2]
- Other older trials compared PTCA to both limited (AVERT trial) and optimal medical interventions (RITA-2 and MASS II). The findings of these trials were that patients undergoing PTCA had similar rates of death and myocardial infarction as those on medical therapy and were less likely to have angina during the first few years.
- More recent literature provides comparison between the use of stents and medical management, however, there is few data examining the extensive use of drug eluting stents and current extensive antithrombotic regimens (clopidogrel and GP IIb/IIIa inhibitors). In the most recent trial, COURAGE[3], drug-eluting stents were used in only 15 percent of patients. However, the COURAGE trial has the data most applicable to current practice. In this study 2287 patients were randomized to either aggressive medical therapy alone or aggressive medical therapy plus PCI with bare metal stenting. Patients were required to have both objective evidence of ischemia and significant CHD in a least one vessel; 87 percent were symptomatic and 58 percent had Canadian Cardiovascular Society CCS class II or III angina. Patients were excluded if they had CCS class IV angina, ≥50 percent left main disease, a markedly positive treadmill test (significant ST segment depressions and/or a hypotensive response during stage I of the Bruce protocol), an LVEF less than 30 percent, or coronary lesions deemed unsuitable for PCI. All patients received optimal medical therapy with beta blockers, calcium channel blockers, nitrates, antiplatelet therapy (either aspirin or clopidogrel), and aggressive lipid-lowering therapy with statin (attained median LDL-cholesterol was 72 mg/dL at five years). Exercise was recommended to achieve further improvements in the lipid profile when necessary. The results were published at a median follow-up of 4.6 years. There was no significant difference between the two treatment strategies for the primary end point of death from any cause and non-fatal MI. There was no significant difference in the rates of hospitalization for ACS. Patients in the PCI group underwent significantly fewer subsequent revascularization procedures (21 versus 33 percent, HR 0.60, 95% CI 0.51-71).
- The issue of whether patients who receive PCI plus optimal medical therapy have a better quality of life and less angina than those who receive optimal medical therapy was addressed in COURAGE as well: At baseline, 22 percent of patients were free of angina. At three months, significantly more patients who received PCI were angina free (53 versus 42 percent), but at 36 months there was no significant difference (59 versus 56 percent). Patients in both groups showed significant improvements from baseline values in various measures of quality of life. The percent of patients with clinically significant improvement in parameters such as physical limitation, angina stability, angina frequency, and overall quality of life was significantly higher in the PCI group by the sixth months. However, there was no significant difference in these rates at 36 months. The results of COURAGE demonstrate that PCI with bare metal stents plus optimal medical therapy and initial, optimal medical therapy with revascularization as necessary are comparable strategies.
References
- ↑ Moliterno DJ, Elliott JM (1995) Randomized trials of myocardial revascularization. Curr Probl Cardiol 20 (3):125-90. PMID: 7600846
- ↑ Parisi AF, Folland ED, Hartigan P (1992) A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. Veterans Affairs ACME Investigators. N Engl J Med 326 (1):10-6. DOI:10.1056/NEJM199201023260102 PMID: 1345754
- ↑ Optimal medical therapy with or without PCI for stable coronary disease. Boden WE, O'Rourke RA, Teo KK, Hartigan PM, Maron DJ, Kostuk WJ, Knudtson M, Dada M, Casperson P, Harris CL, Chaitman BR, Shaw L, Gosselin G, Nawaz S, Title LM, Gau G, Blaustein AS, Booth DC, Bates ER, Spertus JA, Berman DS, Mancini GB, Weintraub WS; COURAGE Trial Research Group. N Engl J Med. 2007 Apr 12;356(15):1503-16. Epub 2007 Mar 26. PMID: 17387127