Prognostic efficacy of early clinical categorization of myocardial infarction patients.

To assess the prognostic validity of "low risk" classification at 24-36 hours as the basis for early transfer to an intermediate coronary care unit, Killip and Hutter/Sidel criteria for risk classicication were applied to 410 patients with acute myocardial infarction (MI) and prospectively compared with respect to mortality and morbidity. Six percent of "low risk" patients by the Killip classification subsequently died and were therefore misclassified. No patients in the group classified as "low risk" by the Hutter/Sidel criteria died; however, more than two and a half times as many potentially "low risk" patients were excluded from this group. With respect to morbidity, 35 of 87 patients (40%) classified as "low risk" by Hutter/Sidel criteria developed 43 major complications during their hospitalization. Nine of these patients developed 11 of the 43 complications (26%) on day six or later, and for five of these patients, this was their first major complication during hospitalization. This significant incidence of morbidity in "low risk" patients, despite their low mortality rates as a group, must be taken into account in developing intermediate coronary care units.