Current issues of ACP Journal Club are published in Annals of Internal Medicine


Prognosis

Catherization was not required after first MI in patients without angina or < 2 mm of ST depression on exercise testing

ACP J Club. 1994 May-June;120:78. doi:10.7326/ACPJC-1994-120-3-078


Source Citation

Cross SJ, Lee HS, Kenmure A, Walton S, Jennings K. First myocardial infarction in patients under 60 years old: the role of exercise tests and symptoms in deciding whom to catheterise. Br Heart J. 1993 Nov;70:428-32.


Abstract

Objectives

To determine the role of exercise tests and angina assessment in detecting multivessel coronary artery disease (CAD) after first myocardial infarction (MI) in patients aged < 60 years. The need for coronary revascularization was considered.

Design

Inception cohort followed for a mean of 16 months.

Setting

Cardiology department of a teaching hospital in Scotland.

Patients

191 consecutive patients (mean age 51 y, 75% men) who were discharged after their first acute MI. Diagnosis was made by the presence of 2 of the following criteria: development of new Q waves or the evolution of characteristic ST-segment changes, chest pain ≥ 30 minutes, and an increase in cardiac enzyme concentration to twice the normal level.

Assessment of prognostic factors

All patients had angina assessment by the Rose questionnaire (exercise-induced chest pain that resolved on stopping or slowing down). Exercise tests were done according to the Bruce Protocol in 173 patients. All patients had coronary arteriography.

Main outcome measures

Death, rehospitalization for further MI, bypass surgery, or angioplasty.

Main results

5 patients died shortly after discharge. Of the 186 patients followed, 5 died, 7 were referred for surgery or angioplasty, and 1 had a nonfatal MI. Exercise tests could not be done for 13 (7%) and were inadequate for another fifth of patients, unrelated to the extent of CAD. None of the 55 patients without angina or with < 2 mm of ST depression during the exercise test died, had an MI, or was referred for surgery or angioplasty. Increasing extent of CAD was more likely with a positive exercise test (P < 0.01 for both 1 and 2 mm of ST depression). Angina alone did not predict the severity of CAD but, with increasing extent of CAD, more patients had ischemia according to exercise tests and angina combined (P < 0.01 for 1 mm, P < 0.05 for 2 mm of ST depression or angina). 80% of patients with 3-vessel or left main-stem disease had either a positive exercise test or angina.

Conclusion

After a first myocardial infarction, patients without pain or with < 2 mm of ST depression on exercise testing did not appear to need catheterization.

Source of funding: Not stated.

For article reprint: Dr. S. Cross, Cardiac Department, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB9 2ZD, United Kingdom. FAX 44-224-685-307.


Commentary

The study by Cross and colleagues evaluated the combined role of a classic history of angina and standard exercise testing to stratify patients after MI for prognosis. The authors purport to show that these 2 factors can be used to define a subgroup that is at low risk for developing complications and, therefore, would not need coronary arteriography. Because angiography is offered routinely to patients after MI in many institutions, such a conclusion could reduce unnecessary costs.

Because the sample size was modest (n = 186 patients), however, and the follow-up period was short (18 months) and subject to diagnostic suspicion bias, the ability to draw conclusions on death and second MI are limited. Referral for angioplasty and bypass surgery are based on clinical judgment that is influenced by the results of angiography, ischemic response to exercise stress tests, and patients' anginal history and, therefore, are questionable outcomes for comparison of a predictive test.

Perhaps a better way to understand the clinical usefulness of exercise testing and anginal symptoms is to evaluate the sensitivity, specificity, and predictive values of the combined factors in predicting CAD that has been shown to benefit from bypass surgery, specifically 3-vessel disease, left main-stem disease, and left anterior descending artery disease (LAD) combined with an additional artery (1, 2). Using the most sensitive test of angina or > 1 mm of ST depression, 4 patients with LAD and 1-vessel disease and 4 with 3-vessel disease would have been missed. Studies of the efficacy of radionucleotide imaging combined with anginal history in defining the need for coronary angiography in patients after MI might be more fruitful for future research because of their higher sensitivity and specificity for multiple-vessel disease in other settings (3).

More recent data, such as the evidence provided by the DANAMI study (4), suggests that patients with recurrent chest pain or positive study test after myocardial infarction benefit from coronary revascularization. Such patients should therefore undergo coronary angiography.

Charles B. Eaton, MD
Memorial Hospital of Rhode IslandPawtucket, Rhode Island, USA


References

1. European Coronary Surgery Study Group. Long-term results of prospective randomised study of coronary artery bypass surgery in stable angina pectoris. Lancet. 1982;2:1173-80.

2. Passamani E, Davis KB, Gillespie MJ, Kilip T. A randomized trial of coronary artery bypass surgery. Survival of patients with a low ejection fraction. N Engl J Med. 1985;312:1665-71.

3. Carillo AP, Marks DS, Pickard SD, Khaja F, Goldstein S. Correlation of exercise 201thallium myocardial scan with coronary arteriograms and the maximal exercise test. Chest. 1978;73:321-6.

4. Madsen JK, Grande P, Saunamäki K, et al. Danish multicenter randomized study of invasive versus conservative treatment in patients with inducible ischemia after thrombolysis in acute myocardial infarction (DANAMI). DANish trial in Acute Myocardial Infarction. Circulation. 1997;96:748-55.