Influence of thrombolytic therapy, with or without intra-aortic balloon counterpulsation, on 12-month survival in the SHOCK trial

Background The enhancement of diastolic coronary blood flow by the combination of thrombolytic therapy (TT) and intra-aortic balloon counterpulsation (IABP) in experimental studies provides a rationale for their combined use in acute myocardial infarction (MI) complicated by cardiogenic shock. We examined the relation between TT (with and without IABP) and 12-month survival in the SHould We Emergently Revascularize Occluded Coronaries for Cardiogenic ShocK (SHOCK) Trial. Methods and results Among 302 patients with myocardial infarction and cardiogenic shock who were randomized in the SHOCK Trial, 16 had absolute contraindications to TT. Among 150 patients randomly assigned to initial medical stabilization (IMS), 63% received TT, as recommended per protocol, compared with 49% of 152 patients randomly assigned to emergency revascularization, in whom TT was not recommended if immediate angiography was available. IABP deployment, which was protocol-recommended, was used in 86% of patients. The rate of severe bleeding was similar in patients receiving TT and in those not receiving TT (31% vs 26%, P = .37). Among patients randomly assigned to IMS, TT was associated with improved 12-month survival (unadjusted mortality hazard ratio, 0.59; P = .01; mortality hazard ratio adjusted for age and prior MI, 0.62; P = .02). TT was not associated with improved 12-month survival among patients randomly assigned to emergency revascularization (unadjusted mortality hazard ratio, 0.93; P = .76; mortality hazard ratio adjusted for age and prior MI, 1.06, P = .81). The test for interaction of TT and randomization group P value was .16, and there was insufficient statistical power to demonstrate a differential effect of TT on 12-month survival by treatment group assignment. Conclusions Among patients randomly assigned to IMS in the SHOCK Trial, TT was associated with improved 12-month survival and did not significantly increase the risk of severe bleeding.