Objective: To determine prognostic factors associated with death in patients with complicated acute myocardial infarction requiring mechanical ventilation.
Design: Retrospective chart-based analysis.
Setting: A 22-bed medical intensive care unit in a university hospital.
Patients: A total of 157 consecutive patients with acute myocardial infarction requiring endotracheal intubation and mechanical ventilation admitted to an intensive care unit during a 6-yr period.
Interventions: Coronary reperfusion strategy within 12 hrs following symptom onset.
Measurements and main results: Clinical characteristics at admission of survivors (n = 77) and nonsurvivors (n = 80) were similar regarding demographics, medical history, and Glasgow Coma Scale score. Twenty-eight-day intensive care unit mortality rate was 51%. The following criteria were higher for nonsurvivors: Simplified Acute Severity Score II, 79 +/- 18 vs. 64 +/- 17 (p <.0001); Acute Physiology and Chronic Health Evaluation (APACHE) II, 33 +/- 13 vs. 25 +/- 6 (p <.0001); incidence of cardiogenic shock (p =.0085) and failing organs (p <.0001); coronary artery disease extension (p =.045); and delay between symptom onset and coronary reperfusion (p =.0348). Nonsurvivors also had higher serum urea and creatinine and lower urine output, arterial pH, and left ventricular ejection fraction (p <.05). Mortality rate was higher in patients with PaO2/FiO2 ratio <200 than in patients with PaO2/FiO2 ratio >200 at admission (log-rank, 5.016; p =.0251). By multivariate analysis, only three factors were independently associated with death: APACHE II >29 (odds ratio, 1.132; 95% confidence interval, 1.013-1.265, p =.0287), serum creatinine >180 micromol/L (odds ratio, 6.151; 95% confidence interval, 1.446-26.166, p =.0139), and initial left ventricular ejection fraction <0.4 (odds ratio, 1.121; 95% confidence interval, 1.049-1.347, p =.0316). Overall, good discrimination was achieved for the risk score model (c-index, 0.852).
Conclusions: We confirmed the high mortality rate of patients admitted to an intensive care unit with acute myocardial infarction requiring mechanical ventilation. In these patients, the main risk factors for death found, namely high APACHE II, early development of acute renal failure, and low resting left ventricular function, reflected the severity of the myocardial infarction.