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


Therapeutics

Invasive and conservative management after myocardial infarction were equivalent at 1 year

ACP J Club. 1992 May-June;116:67. doi:10.7326/ACPJC-1992-116-3-067


Source Citation

Williams DO, Braunwald E, Knatterud G, et al. One-year results of the Thrombolysis in Myocardial Infarction Investigation (TIMI) Phase II Trial. Circulation. 1992 Feb;85:533-42.


Abstract

Objective

To assess the effects on mortality and re-infarction of an invasive therapeutic strategy compared with conservative management after recombinant tissue-type plasminogen activator (rt-PA) therapy for acute myocardial infarction.

Design

Randomized controlled trial with 1-year follow-up.

Setting

Multicenter trial in the United States.

Patients

3339 patients < 76 years of age, with > 30 minutes of ischemic chest pain, electrocardiographic ST-segment elevation diagnostic of myocardial infarction, presentation ≥ 70 years of age, and 14% had had a previous infarction. 98% of patients were followed for 1 year.

Intervention

All patients received a 6-hour infusion of rt-PA (alteplase), heparin, and aspirin. 1681 patients were randomized to the invasive strategy arm (routine cardiac catheterization within 18 to 48 hours of infarction and, when appropriate, percutaneous transluminal coronary angioplasty [PTCA] or coronary artery bypass grafting [CABG]). 1658 patients were assigned to conservative management (catheterization and PTCA or CABG done only in response to either spontaneous or provoked myocardial ischemia).

Main outcome measures

1-year, all-cause mortality including fatal myocardial infarction. Secondary end points were recurrent chest pain, severe ischemic events (chest pain with or without myocardial infarction), myocardial re-infarction (chest pain with electrocardiographic or confirmatory cardiac enzymatic changes), and stroke. Events were classified by independent, blinded cardiologists.

Main results

1 year after the infarction, no significant differences between patients assigned to the invasive or conservative strategies were seen in rates of death (6.9% vs 7.4%, respectively), fatal and nonfatal re-infarction (9.4% vs 9.8%), death and re-infarction (14.7% vs 15.2% {95% CI for the 0.5% difference -1.2% to 2.3%}*), recurrent severe ischemic events (24.3% vs 27.6%), or stroke (2% for each group). Patients in the invasive strategy group were more likely than those treated conservatively to have had cardiac catheterization (98% vs 45%, respectively) and either PTCA or CABG (72% vs 36%). Baseline demographic and clinical factors were not associated with differences in outcome.

Conclusion

Thrombolytic therapy, followed by cardiac catheterization and revascularization in response to ischemia, was associated with the same mortality and morbidity 1 year after myocardial infarction as the strategy of routine early invasive diagnostic and therapeutic intervention.

Source of funding: National Heart, Lung, and Blood Institute.

Address for article reprint: Dr. D.O. Williams, Division of Cardiology, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA.

*Numbers calculated from data in article.


Commentary

Trials evaluating the strategies of routine immediate angiography or routine delayed angiography and angioplasty after thrombolytic therapy have not found improvements in left ventricular function or patient outcomes. Earlier reports of follow-up in most of these trials have been short-term (1).

This important 1-year follow-up of the TIMI Phase II trial has shown that both the invasive and conservative strategies result in favorable outcomes, with no differences detected in the rates of death or re-infarction. This study supports the results of a similar trial showing a lack of benefit at 1 year from an invasive as compared with a conservative management strategy (2).

Is the issue finally settled? Probably not. Despite the impressive size of the TIMI Phase II Trial, modest benefits (15% to 20% relative risk reductions) could possibly have been missed. In addition, there may be subgroups of patients (those at particulary high risk) who derive benefit from the invasive strategy. These subgroups will undoubtedly be the focus of future investigations.

For the present, a conservative approach is advocated for most patients with myocardial infarction after thrombolytic therapy. Coronary angiography as a preliminary to revascularization can be reserved for patients with spontaneous or exercise-induced ischemia.

David Massel, MD
Victoria General HospitalLondon, Ontario, Canada

David Massel, MD
Victoria General Hospital
London, Ontario, Canada


References

1. TIMI Research Group. Comparison of invasive and conservative strategies after treatment with intravenous tissue plasminogen activator in acute myocardial infarction: Results of the Thrombolysis in Myocardial Ischemia (TIMI) II trial. N Engl J Med. 1989;320:618-27.

2. SWIFT (Should we intervene following thrombolysis?) Trial Study Group. SWIFT Trial of delayed elective intervention v. conservative treatment after thrombolysis with anistreplase in acute myocardial infarction. BMJ. 1991;302:555-60.