Predictive Value of the Electrocardiogram in Acute Myocardial Infarction

To the Editor: Dr Welch and colleagues¹ reported that patients with acute myocardial infarction (AMI) with initially normal or nonspecific initial electrocardiogram (ECG) results had lower mortality rates than those who presented with diagnostic ECG results. These conclusions are based on odds ratios derived from models comparing mortality in patients with normal or nonspecific ECG results and in patients with ECG signs specific to AMI. Although odds ratios are important measures of association, they do not describe the ability of information—here normal, nonspecific, or specific ECG results—to help the clinician predict the death or survival of a given patient.² To provide this information, the authors should have focused on the positive and negative predictive values.³ The relevant positive predictive value is the proportion of patients dying in the diagnostic ECG group (11.5%); the relevant negative predictive values would be the proportions of patients surviving in the normal (94.3%) and the nonspecific (91.3%) groups. These predictive values are not impressive.