Cardiovascular outcome in hospitalized patients with minimal troponin I elevation and normal creatine phosphokinase

Background: Among patients with acute coronary syndrome, elevated cardiac troponin and creatine phosphokinase MB fraction levels have both prognostic and diagnostic values. However, in hospitalized patients, cardiac biomarkers are measured in a variety of clinical situations including but not limited to acute coronary syndrome. Moreover, these patients may have elevated troponin levels with no increase in creatine phosphokinase MB fraction levels. Objective: To evaluate the cardiovascular outcome of acutely ill, hospitalized patients with minimal troponin I increase with normal creatine phosphokinase MB fraction. Methods: We identified 64 patients retrospectively from our database with minimal troponin I increase and normal creatine phosphokinase MB fraction hospitalized between November 1998 and April 2000. Discharged patients were questioned about re-hospitalization for myocardial infarction, unstable coronary syndrome, congestive heart failure and percutaneous coronary intervention by means of a structured questionnaire. For those patients who died during hospitalization, data were collected from hospital records. For patients who died at home or at a different institution, a surviving relative completed the questionnaire. Primary outcomes were death, myocardial infarction and the need for revascularization or re-hospitalization. Results: Composite endpoint of death, myocardial infarction, percutaneous coronary intervention or coronary artery bypass grafting and re-hospitalization for cardiac cause occurred in 35.95% of patients within 1 year. Conclusions: There is a significant composite event rate of death, myocardial infarction or re-hospitalization for cardiac causes in acutely ill, hospitalized patients with normal creatine phosphokinase MB fraction and minimally elevated troponin I, regardless of the cause for hospitalization.