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


Therapeutics

Invasive treatment reduced reinfarctions and admissions for unstable angina in patients with ischemia after MI

ACP J Club. 1998 Jan-Feb;128:4. doi:10.7326/ACPJC-1998-128-1-004


Source Citation

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). Circulation. 1997 Aug 5;96:748-55.


Abstract

Objective

To compare the effectiveness of deferred invasive treatment (percutaneous transluminal coronary angioplasty or coronary artery bypass grafting [CABG]) with conservative treatment for patients with myocardial ischemia after acute myocardial infarction (MI) treated with thrombolytics.

Design

Randomized controlled trial.

Setting

43 hospitals in Denmark.

Patients

1008 patients aged ≤ 69 years (82% men) who were hospitalized with definite MI, had either symptomatic angina > 36 hours after MI or a predischarge exercise test positive for ischemia, and had initiation of thrombolytic treatment within 12 hours of symptom onset. Exclusion criteria were previous MI, angioplasty, or CABG; administration of < 50% of the thrombolytic dose; need for immediate invasive treatment; decreased systolic blood pressure during exercise; substantial noncoronary disease; inability to perform a bicycle exercise test; and electrocardiographic abnormalities that precluded ST-segment evaluation during exercise.

Intervention

503 patients were allocated to invasive treatment (angioplasty without stent implantation within 2 wk of randomization or CABG within 5 wk of randomization). 505 patients were allocated to conservative treatment (including anti-ischemic medication). Both groups received aspirin, 150 mg/d.

Main outcome measures

Mortality, reinfarction, and hospitalization for unstable angina.

Main results

Analysis was by intention to treat. At median follow-up of 2.4 years, there were fewer reinfarctions (28 vs 53, P = 0.004) and fewer hospitalizations for unstable angina (90 vs 149, P < 0.001) in the invasive group compared with the conservative group, but there was no difference in deaths (18 vs 22, P = 0.45) (Table).

Conclusion

Invasive treatment (percutaneous transluminal coronary angioplasty or coronary artery bypass grafting) reduced reinfarctions and hospitalizations for unstable angina, but not deaths, in patients with myocardial ischemia after acute myocardial infarction treated with thrombolytic drugs.

Source of funding: The Danish Heart Foundation.

For article reprint: Dr. J.K. Madsen, The DANAMI Study, Department of Medicine B 2141, The Heart Centre, Rigshospitalet, National University Hospital, DK-2100 Copenhagen, Denmark. FAX 45-3545-1949.


Table. Invasive vs conservative treatment for ischemia after myocardial infarction*

Outcomes Invasive EER Conservative CER RRR (95% CI) ARR |EER-CER| NNT (CI)
Reinfarction 5.6% 10.5% 47% (18 to 66) 4.9% 21 (12 to 62)
Admission for unstable angina 17.9% 29.5% 39% (24 to 52) 11.6% 9 (6 to 16)

*Abbreviations defined in Glossary; RRR, ARR, NNT, and CI calculated from data in article.


Commentary

Compared with previous studies of the management of patients after thrombolysis for MI, the study by Madsen and colleagues only included patients with well-documented postinfarction ischemia who were randomly assigned to early revascularization or medical therapy. The criteria for postinfarction ischemia were also relatively conservative, requiring either spontaneous angina, or inducible ischemic symptoms or ST-segment changes during a symptom-limited exercise test. Postinfarction ischemia defined in this manner is a known risk factor for recurrent ischemic events and has been suggested to be a criterion for early cardiac catheterization and possible revascularization (1, 2). In this study, patients with postinfarction ischemia treated with medical therapy had a higher incidence of recurrent ischemic events than revascularized patients. The mortality rate with medical therapy was only 4.4%; thus, the number of patients included was insufficient to determine whether revascularization improved survival.

The important question is whether an aggressive strategy to evaluate and treat postinfarction ischemia with coronary revascularization is cost-effective. Although not specifically addressed in this report, it is reasonable to assume that it is cost-effective to implement a diagnostic and early revascularization strategy that targets patients who are likely to require revascularization within 6 months of MI for recurrent ischemia. The risk is in an overly aggressive strategy that includes patients who are unlikely to have recurrent events. Revascularization by the routine use of coronary angiography and angioplasty in such patients has previously been shown not to improve outcome. The important finding of this study is that when postinfarction ischemia is well documented, early revascularization seems to improve outcome compared with medical therapy.

Paul R. Eisenberg, MD, MPH
Washington University School of MedicineSt. Louis, Missouri, USA


References

1. Ryan TJ, Anderson JL, Antman EM, et al. ACC/AHA guidelines for the management of patients with acute myocardial infarction: executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Mocardial Infarction). Circulation. 1996;94:2341-50.

2. Gibbons RJ, Balady GJ, Beasley JW, et al. ACC/AHA guidelines for exercise testing: executive summary. A report of the American College Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Exercise Testing). Circulation. 1997;96:345-54.