Prognostic differences between routine invasive and conservative strategies for the management of high-risk, non-ST segment acute coronary syndromes: Experience from two consecutive periods in a single center.

Background: The optimal revascularization strategy for non-ST elevation acute coronary syndromes (NSTE-ACS) remains controversial, especially in a real world context. The objective of this work was to assess differences at 1 year in all-cause mortality and the composite endpoint of mortality or acute myocardial infarction (MI) between two management strategies for NSTE-ACS: a conservative strategy (CS) versus a routine invasive strategy (RIS).

Methods: Of 799 consecutive patients admitted to our institution, 369 were treated with CS (from January 2001 to October 2002); 430 patients admitted with the same diagnosis were treated with RIS (from November 2002 to November 2004). A propensity score (PS) matched sample was created and included 694 patients (87% of the original population). The event rate was compared between each paired member of the PS-matched sample, one receiving RIS and the other CS, and their differences were tested by Cox proportional analysis.

Results: No significant differences in baseline characteristics were noted between the two management cohorts. By design, the rate of in-hospital catheterization and revascularization procedures increased in RIS compared with CS. The mortality rate was lower, but not significant, in RIS (HR: 0.76, 95% CI=0.51-1.11; p=0.155). For the composite of death or MI, RIS showed a relative risk reduction of 29% (HR: 0.71, 95% CI=0.53-0.94); p=0.018) compared with CS, differences that become non-significant (p=0.680) if we adjust for differences in rate of revascularization procedures and changes in medication prescription.

Conclusions: RIS was associated with a 1-year lower risk of the combined endpoint of all-cause death and MI in patients with NSTE-ACS, attributable to changes in frequency of revascularization procedures and in medical treatment.