Does modifying the Thrombolysis in Myocardial Infarction risk score (by adding diabetes and ejection fraction) improve the ability to predict coronary events in patients with chest pain?

In this developmental study, a modified Thrombolysis in Myocardial Infarction (TIMI) risk score was better at predicting coronary events 6 months after patients present with chest pain suspected to be ischemic in origin. Since models generally perform better in developmental studies than in subsequent testing, the new score needs independent validation. (LOE = 2b-)

García-Almagro FJ, Gimeno JR, Villegas M, et al. Prognostic value of the Thrombolysis in Myocardial Infarction risk score in a unselected population with chest pain. Construction of a new predictive model. Am J Emerg Med 2008;26:439-445.  [PMID:18410812]

Cohort (prospective)

Industry

Inpatient (any location) with outpatient follow-up

These researchers evaluated 711 consecutive patients coming to a cardiology unit complaining of chest pain suggestive of cardiac ischemia. They excluded patients with persistent ST-segment elevation. All patients had serial electrocardiograms, blood tests, and an echocardiogram within 72 hours of admission. The researchers contacted each patient 1 month and 6 months later. The primary outcomes of interest were: cardiovascular death (sudden death, death from heart failure, or procedure-related death), revascularization, myocardial infarction, and a combination of the 3. Additionally, a TIMI risk score, from 0 to 7, was calculated for each patient. The TIMI risk score assigns 1 point when each of the following are present: 65 years or older; 3 or more classical risk factors (hypertension, hypercholesterolemia, diabetes mellitus, smoking, or family history of ischemic heart disease); previous significant coronary disease (stenosis of at least 50%); aspirin use in the previous 7 days; at least 2 episodes of angina in the previous 24 hours; elevation of cardiac enzymes; and ST deviations of at least 0.5 mm. Finally, the researchers assessed the predictive ability of the TIMI risk score combined with other clinical factors. They had follow up information on 93% of the patients. By 6 months, 15.1% of patients were readmitted. Additionally, 5.1% had revascularization procedures, 1.4% had myocardial infarctions, 3.5% died from cardiovascular causes, and 9.8% experienced the combined end point. The authors developed a modified risk score using the following schema: 1 point for 65 years or older; 3 or more classical risk factors; previous significant coronary disease; aspirin use; elevated cardiac enzymes; ST deviations of at least 0.5 mm, and diabetes. Additionally the modified score assigned 2 points if the ejection fraction was less than 35% and 1 point if it was between 35% and 45%. At 6 months, 2.3% of patients with cardiovascular outcomes had a TIMI risk score of 0 or 1, 4.2% for 2, 10.2% for 3, 11.0% for 4, and 18.7% for a score of more than 5. The original TIMI score found an average 33% increase for each additional point increase, but these researchers found an average 44% increase in the combined outcome rate for each 1-point increase in the modified TIMI score.