Is there a benefit to early angiography in patients with ST-segment depression myocardial infarction? An observational study.

BACKGROUND AND OBJECTIVE

Patients with ST-segment depression myocardial infarction (MI) have a similar long-term outcome compared with those who have ST-segment elevation. It remains unclear whether an aggressive treatment approach with very early (<6 hours) angiography and revascularization improves outcome over an early conservative approach. We compared the short-term outcome of patients who received very early (<6 hours) angiography with patients who received early conservative therapy for ST-segment depression MI.

METHODS

Patients seen within 12 hours with ST-segment depression on the initial electrocardiogram (ECG) were identified from the National Registry of Myocardial Infarction 2 (NRMI) database, which collected information from 1994 to 1998. Those who received very early (<6 hours) angiography were compared with those who received early conservative therapy. The short-term outcomes, including major bleeding episodes, cerebral vascular events, recurrent ischemia and angina, MI, and death, were compared on the basis of the initial therapy received.

RESULTS

Patients treated with very early angiography (2402) were younger, more likely to be males, smokers, and have less of a cardiac history (angina, MI, congestive heart failure, aortocoronary bypass surgery) and less likely to have diabetes mellitus than those who received early conservative therapy (17,735). Hospital outcome in the very early angiography group was similar to the early conservative therapy group in terms of cerebral vascular events (0.8% vs 1.0%, P =.27), major bleeding events (2.8% vs 2.4%, P =.25), and recurrent MI (2.1% vs 2.3%, P =.57) but was associated with lower recurrent ischemia or angina (11.4% vs 16.7%, P <.001) and improved survival (death, 4.9% vs 7.3%, P <.001). Multivariate analysis suggested that patients receiving very early angiography had lower mortality compared with those receiving early conservative therapy (odds ratio [OR] = 0.76; 95% CI 0.60-0.95). However, comparing patients matched on propensity score (1405) showed mortality was similar in both treatment groups (5.6% vs 5.4%, P =.87), with no significant inhospital mortality benefit of very early angiography (OR = 0.89; 95% CI 0.71-1.13).

CONCLUSIONS

The apparent mortality benefit of very early angiography in patients with ST-segment depression MI is a reflection of bias by confounding. Controlling for baseline differences using propensity score methods in this observational study indicated no inhospital mortality benefit of a very early aggressive approach compared with a conservative approach.