Myocardial infarction often develops when thrombosis occurs at lesions that have not previously been flow limiting. However, the development of cardiogenic shock complicating acute myocardial infarction in such circumstances has received little attention. The characteristics of 15 patients with cardiogenic shock who had no flow-limiting angiographic stenoses were compared with those of 767 patients with > or =1 stenosis who were enrolled in the Should We Emergently Revascularize Occluded Coronary Arteries for Cardiogenic Shock (SHOCK) trial and registry. Compared with patients with > or =1 flow-limiting stenosis, patients with no flow-limiting stenoses were less likely to have pulmonary edema on chest x-ray (29% vs 62%, p = 0.008) and to be white (53% vs 82%, p = 0.011), and they had lower median highest creatine kinase levels (702 vs 2,731 U/L, p = 0.018). For SHOCK trial patients, 1-year survival was 49% for patients with > or =1 flow-limiting stenosis and 71% for those with no flow-limiting stenoses (p = 0.268). In conclusion, patients with cardiogenic shock without flow-limiting stenosis have different characteristics, and potentially disease mechanisms, and they do not require revascularization.