Outcome of patients aged >or=75 years in the SHould we emergently revascularize Occluded Coronaries in cardiogenic shocK (SHOCK) trial: do elderly patients with acute myocardial infarction complicated by cardiogenic shock respond differently to emergent revascularization?

Abstract

Background: In the SHOCK trial, the group of patients aged >or=75 years did not appear to derive the mortality benefit from early revascularization (ERV) versus initial medical stabilization (IMS) that was seen in patients aged <75 years. We sought to determine the reason for this finding by examining the baseline characteristics and outcomes of the 2 treatment groups by age.

Methods: Patients with cardiogenic shock (CS) secondary to left ventricular (LV) failure were randomized to ERV within 6 hours or to a period of IMS. We compared the characteristics by treatment group of patients aged >or=75 years and of their younger counterparts.

Results: Of the 56 enrolled patients aged >or=75 years, those assigned to ERV had lower LV ejection fraction at baseline than IMS-assigned patients (27.5% +/- 12.7% vs 35.6% +/- 11.6%, P = .051). In the elderly ERV and IMS groups, 54.2% and 31.3%, respectively, were women ( P = .105) and 62.5% and 40.6%, respectively, had an anterior infarction (P = .177). The 30-day mortality rate in the ERV group was 75.0% in patients aged >or=75 years and 41.4% in those aged <75 years. In the IMS group, 30-day mortality was 53.1% for those aged >or=75 years, similar to the 56.8% for patients aged <75 years.

Conclusions: Overall, the elderly randomized to ERV did not have better survival than elderly IMS patients. Despite the strong association of age and death post-CS, elderly patients assigned to IMS had a 30-day mortality rate similar to that of IMS patients aged <75 years, suggesting that this was a lower-risk group with more favorable baseline characteristics. The lack of apparent benefit from ERV in elderly patients in the SHOCK trial may thus be due to differences in important baseline characteristics, specifically LV function, and play of chance arising from the small sample size. Therefore, the SHOCK trial overall finding of a 12-month survival benefit for ERV should be viewed as applicable to all patients, including those >or=75 years of age, with acute myocardial infarction complicated by CS.