What was the conclusion of the SHOCK (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) trial?

Conclusion of the SHOCK Trial

The SHOCK (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) trial concluded that emergency revascularization with either PCI or CABG significantly reduced mortality at 6 months and beyond in patients with acute myocardial infarction complicated by cardiogenic shock, despite not showing a significant difference in the primary endpoint of 30-day mortality. 1

Key Findings of the SHOCK Trial

• The trial randomized patients with AMI and cardiogenic shock to either emergency revascularization or initial medical stabilization 1
• Among patients randomized to revascularization, 64% underwent PCI and 36% underwent CABG 1
• Median time from randomization to revascularization was 0.9 hours for PCI and 2.7 hours for CABG 1
• No significant difference was found in the primary endpoint of 30-day mortality between the two groups 2
• A significant survival benefit emerged at 6 months (50% vs. 37%, p=0.027) 2, 3
• The survival benefit was maintained through 1 year (47% vs. 34%, p=0.025) and extended to 6 years (32.8% vs. 19.6%) 4, 2
• The benefit appeared greatest for patients younger than 75 years of age 2, 3

Study Design and Population

• The SHOCK trial was a multicenter, randomized, unblinded study with 302 patients enrolled from April 1993 through November 1998 5, 4
• Eligibility criteria included development of cardiogenic shock within 36 hours of acute transmural MI with ST elevation or new LBBB 5
• Clinical criteria for shock included SBP <90 mmHg for ≥30 minutes or need for supportive measures to maintain SBP ≥90 mmHg 1
• Hemodynamic criteria included cardiac index ≤2.2 L/min/m² and PCWP >15 mmHg 1

Impact on Clinical Practice

• Based on the SHOCK trial results, current guidelines recommend immediate revascularization for patients with STEMI complicated by cardiogenic shock 1
• The American College of Cardiology/American Heart Association guidelines recommend emergency revascularization for patients with AMI and cardiogenic shock, particularly those younger than 75 years 2
• The mode of revascularization (PCI or CABG) should be based on coronary anatomy, with similar survival outcomes regardless of revascularization method 1
• For patients with multivessel disease and cardiogenic shock, current evidence supports culprit-lesion-only PCI rather than immediate multivessel PCI 1

Clinical Implications and Caveats

• Despite the benefits of early revascularization, mortality in cardiogenic shock remains substantial at 40-50% after 30 days 6
• Mechanical circulatory support devices may be beneficial before revascularization, especially if CABG is planned 1, 7
• The routine use of intra-aortic balloon pump (IABP) is not recommended due to lack of survival benefit 1
• A multidisciplinary shock team approach with standardized protocols is recommended for optimal outcomes 7, 8
• Rapid transfer of patients with AMI complicated by cardiogenic shock to centers capable of early angiography and revascularization is recommended 1, 3

Long-term Outcomes

• Almost two-thirds of hospital survivors with cardiogenic shock who received early revascularization were alive 6 years later 4
• Early revascularization resulted in a 13.2% absolute and 67% relative improvement in 6-year survival compared to initial medical stabilization 4
• Among hospital survivors, 6-year survival rates were 62.4% vs. 44.4% for early revascularization vs. initial medical stabilization groups 4
• The majority of survivors (83%) at 1 year were in New York Heart Association functional class I or II 3