Cardiogenic shock complicating acute myocardial infarction in patients without heart failure on admission: incidence, risk factors, and outcome. SPRINT Study Group.

Purpose: Patients with large myocardial infarction (MI) presenting with clinical signs of heart failure are at increased risk for subsequent development of cardiogenic shock and death. Little is known, however, about the development of cardiogenic shock among patients with acute MI presenting without clinical signs of heart failure. The aim of the present study was to examine the incidence, predictors for occurrence, and outcome of in-hospital development of cardiogenic shock among patients with acute MI without heart failure on admission.

Patients And Methods: Clinical data of 5,839 consecutive patients hospitalized with acute MI were analyzed.

Results: Of 3,465 (59%) patients without heart failure on admission (Killip class I), 89 (2.6%) developed cardiogenic shock during their hospital stay. This represented 24% of all cases of in-hospital cardiogenic shock in the entire group. Cardiogenic shock developed more than 24 hours after admission in 66% of cases. All but three patients with cardiogenic shock died whereas a 5% in-hospital mortality was found among patients without cardiogenic shock. Independent predictors for in-hospital shock were age (for a 10-year increment, adjusted relative odds [RO] = 2.45, 90% confidence interval [CI] = 1.50 to 4.02); female gender (RO = 1.51, 90% CI = 0.91 to 2.50); history of angina (RO = 2.64, 90% CI = 1.36 to 3.76); history of stroke (RO = 2.12, 90% CI = 1.26 to 6.35); peripheral vascular disease (RO = 1.99, 90% CI = 0.95 to 4.18); peak lactate dehydrogenase (LDH) greater than four times the normal (RO = 3.16, 90% CI = 1.79 to 5.57); and hyperglycemia on admission (RO = 3.52, 90% CI = 2.13 to 5.84). Patients with six risk factors (excluding LDH values) had an estimated probability of 35% for developing in-hospital cardiogenic shock.

Conclusions: (1) A significant proportion of MI patients who developed cardiogenic shock during hospitalization were free of heart failure on admission. (2) Our study identified several risk factors facilitating early identification of subgroups at risk for cardiogenic shock within otherwise low-risk patients.