Validation of a clinical prediction rule for left ventricular ejection fraction after myocardial infarction in patients ≥ 65 years old

We sought to validate a previously described clinical prediction rule for classifying left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI). As part of the Connecticut cohort of the Cooperative Cardiovascular Project (CCP) pilot study, we identified 3,093 Medicare patients who had been admitted to hospitals throughout Connecticut with an AMI in 1992 and 1993. Retrospective chart review and detailed electrocardiogram interpretation were performed. Of the 1,891 patients with an interpretable EF, 1,378 (73%) had > or = 1 of the rule's exclusion criteria. Of the remaining 513 patients, the clinical prediction rule had a positive predictive value of 89% (i.e., 456 of 513 patients had an EF > or = 40%). In a multivariate model, presentation > 6 hours after the onset of chest pain, a history of bypass surgery, and diabetes mellitus were associated with patients in whom the rule did not correctly predict an EF > or = 40%. Excluding patients with these characteristics from the rule increased the positive predictive value from 89% to 93% and excluded an additional 239 patients. The EF could not be predicted among the patients who did not meet the rule's criteria. In conclusion, a previously published clinical prediction rule for the classification of the EF in patients after an AMI correctly classified 8 of every 9 eligible elderly patients as having an EF > or = 40%. Thus, while not performing as well as it did in the original study, our findings support the use of this rule in providing clinicians with an objective method for estimating an EF > or = 40% in a specific subset of elderly patients.