Patients with unstable angina or non-ST-segment elevation myocardial infarction (MI) may be managed with either an “invasive” or “conservative” strategy. It is unclear which of these strategies is superior.

We identified studies with MEDLINE and EMBASE searches (1966-September 2003) and by reviewing reference lists. Studies were included if they were randomized controlled trials comparing management strategies for patients in the early post-unstable angina/non-ST-segment elevation MI period and had follow-up data for at least 3 months.

Seven trials that randomized a total of 9212 patients were included. The pooled odds ratio (OR) for all-cause mortality was 0.96 (95% confidence interval [CI]: 0.72 to 1.27). The occurrence of fatal or nonfatal re-infarction was reduced with an invasive strategy (OR 0.73; 95% CI: 0.61 to 0.88) as was readmission to hospital (OR 0.67; 95% CI: 0.48 to 0.94). The endpoints of nonfatal MI and the composite of death or nonfatal MI showed nonsignificant trends favoring an invasive strategy. Trials that included a higher proportion of patients with ST-segment depression on admission and trials in which a larger proportion of patients underwent revascularization showed a greater magnitude of benefit for an invasive strategy.

For patients with unstable angina/non-ST-segment elevation MI, an invasive strategy reduces rates of fatal or nonfatal re-infarction and hospital readmission, but not all-cause mortality, when compared with a noninvasive strategy. These results suggest that an invasive management strategy should be considered for all patients with unstable angina/non-ST-segment elevation MI and perhaps in particular those with ST-segment depression.