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Therapeutics

Conservative management was more effective than invasive management in acute non-Q-wave MI

ACP J Club. 1998 Nov-Dec; 129:63. doi:10.7326/ACPJC-1998-129-3-063

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Source Citation

Boden WE, O'Rourke RA, Crawford MH, et al., for the Veterans Affairs Non-Q-Wave Infarction Strategies in Hospital (VANQWISH) Trial Investigators. Outcomes in patients with acute non-Q-wave myocardial infarction randomly assigned to an invasive as compared with a conservative management strategy. N Engl J Med. 1998 Jun 18;338:1785-92.


Abstract

Question

In patients with acute non-Q-wave myocardial infarction (MI), is a conservative management strategy as effective as an invasive management strategy at reducing deaths and nonfatal infarctions?

Design

Randomized controlled trial with a mean follow-up of 23 months.

Setting

17 clinical centers in the United States.

Patients

920 patients (mean age 62 y, 97% men) who had evolving acute MI, creatine kinase-MB isoenzyme levels > 1.5 times the upper limit of normal and no new abnormal Q waves (or R waves) on serial electrocardiograms (ECGs). Exclusion criteria were serious comorbid conditions or ischemic complications that placed patients at high risk while they were in the coronary care unit.

Intervention

Patients were allocated to an invasive management strategy (n = 462) or a conservative management strategy (n = 458). 96% of patients in the invasive strategy group had coronary angiography as the initial test; revascularization was done in 44% of patients. In the conservative strategy group, radionuclide ventriculography and thallium stress testing were done; invasive management was considered for patients with ischemia (recurrent postinfarction angina, ≥ 2-mm ST-segment depression on stress test, or ≥ 2 vascular regions with re-distribution defects on thallium scintigraphy [or 1 with increased uptake of thallium by the lung]). Coronary angiography was done in 48% of patients in the conservative strategy group; revascularization was done in 33%. All patients received aspirin, 325 mg/d, and long-acting diltiazem, 180 to 300 mg/d.

Main outcome measure

Combined end point of death and nonfatal MI.

Main results

Analysis was by intention to treat. During a mean follow-up of 23 months (range 12 to 44 mo), the combined end point of death and nonfatal infarction did not differ between groups (P > 0.2) (Table). Patients in the invasive strategy group had more combined deaths and nonfatal infarctions during the first 12 months of follow-up than did patients in the conservative strategy group {P = 0.002}* (Table).

Conclusion

In patients with acute non-Q-wave myocardial infarction, conservative management reduced deaths plus nonfatal infarctions in the first 12 months and was as effective as invasive management over the long term.

Sources of funding: Department of Veterans Affairs Cooperative Studies Program and Hoechst Marion Roussel.

For correspondence: Dr. W.E. Boden, The Medical Service, Veterans Affairs Healthcare Network of Upstate New York, 800 Irving Avenue, Syracuse, NY 13210, USA. FAX 315-477-4547.

*P value calculated from data in article.


Table. Effect of conservative vs invasive management on nonfatal infarctions plus deaths in patients with acute non-Q-wave MI†

Length of follow-up Conservative management Invasive management RRR (95% CI) NNT (CI)
12 mo 14% 22% 36% (15 to 52) 13 (8 to 35)
12 to 44 mo 27% 30% 10% (-10 to 27) Not significant

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


Commentary

The Veterans Affairs Non-Q-Wave Infarction Strategies in Hospital (VANQWISH) trial is another post-MI trial confirming the adage that “more is not always better” (1, 2). In this case, “more” refers to more angiography and subsequent revascularization. In the VANQWISH trial, outcomes, including mortality, were better in the conservative strategy group than in the invasive strategy group and this finding was consistent across various subgroups.

The results support a previous recommendation for an initial conservative, but not lackadaisical, approach for many patients with MI (3). Early coronary angiography with a view to appropriate revascularization can be considered for patients with MI and recurrent or persistent ischemia at rest or severe persistent heart failure despite aggressive medical therapy; these patients were excluded from the VANQWISH trial. As the trial shows, an early aggressive approach is also warranted for patients with exercise-induced ischemia and indicators of multi-vessel disease or poor prognosis, defined in the VANQWISH trial as increased lung uptake or involvement of ≥ 2 vascular territories on thallium scans or ≥ 2-mm ST-segment depression on the stress ECG.

David Massel, MD
London Health Sciences CentreLondon, Ontario, Canada

David Massel, MD
London Health Sciences Centre
London, Ontario, Canada


References

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

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

3. Massel D.Invasive and conservative management after myocardial infarction were equivalent at 1 year. ACP J Club. 1992 May-Jun:67 (Ann Intern Med. vol 116, suppl 3). Comment on: Williams DO, Braunwald E, Knatterud G,et al. Circulation. 1992;85:533-42.