Early revascularization and long-term survival in cardiogenic shock complicating acute myocardial infarction

Abstract

Context: Cardiogenic shock remains the major cause of death for patients hospitalized with acute myocardial infarction (MI). Although survival in patients with cardiogenic shock complicating acute MI has been shown to be significantly higher at 1 year in those receiving early revascularization vs initial medical stabilization, data demonstrating long-term survival are lacking.

Objective: To determine if early revascularization affects long-term survival of patients with cardiogenic shock complicating acute MI.

Design, setting, and patients: The Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial, an international randomized clinical trial enrolling 302 patients from April 1993 through November 1998 with acute myocardial infarction complicated by cardiogenic shock (mean [SD] age at randomization, 66 [11] years); long-term follow-up of vital status, conducted annually until 2005, ranged from 1 to 11 years (median for survivors, 6 years).

Main outcome measures: All-cause mortality during long-term follow-up.

Results: The group difference in survival of 13 absolute percentage points at 1 year favoring those assigned to early revascularization remained stable at 3 and 6 years (13.1% and 13.2%, respectively; hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.57-0.97; log-rank P = .03). At 6 years, overall survival rates were 32.8% and 19.6% in the early revascularization and initial medical stabilization groups, respectively. Among the 143 hospital survivors, a group difference in survival also was observed (HR, 0.59; 95% CI, 0.36-0.95; P = .03). The 6-year survival rates for the hospital survivors were 62.4% vs 44.4% for the early revascularization and initial medical stabilization groups, respectively, with annualized death rates of 8.3% vs 14.3% and, for the 1-year survivors, 8.0% vs 10.7%. There was no significant interaction between any subgroup and treatment effect.

Conclusions: In this randomized trial, almost two thirds of hospital survivors with cardiogenic shock who were treated with early revascularization were alive 6 years later. A strategy of early revascularization resulted in a 13.2% absolute and a 67% relative improvement in 6-year survival compared with initial medical stabilization. Early revascularization should be used for patients with acute MI complicated by cardiogenic shock due to left ventricular failure.

Trial registration: clinicaltrials.gov Identifier: NCT00000552.

Figure 1

Study Flow Diagram IABP = Intra-aortic balloon pump *Survivors count excludes 1 patient in ERV group who underwent heart transplantation and was discharged alive from the hospitalization for shock. **One patient in the IMS group who successfully underwent heart transplantation after discharge but prior to one year post-randomization was censored at the date of transplantation.

Figure 2

Kaplan-Meier long term survival of 152 patients assigned to emergency early revascularization and 150 patients assigned to initial medical stabilization. Logrank test P= 0.028. Risk set sizes are shown at bottom. The survival rates in the ERV and IMS groups, respectively, were 41.4% vs 28.3% at 3 years and 32.8% vs. 19.6% at 6 years. With exclusion of 8 patients with aortic dissection, tamponade, or severe mitral regurgitation identified shortly after randomization, the survival curves remained significantly different (P=0.023) with a 14.0% absolute difference at 6 years.

Figure 3

Kaplan-Meier long term survival based on 143 patients discharged alive following the hospitalization for shock, stratified by emergency early revascularization vs. initial medical stabilization groups. Logrank test P= 0.029. Risk set sizes are shown at bottom. The survival rates in the ERV and IMS groups, respectively, were 78.8% vs 64.3% at 3 years and 62.4% vs. 44.4% at 6 years.