Algorithm rules in or rules out heart attacks within 1 hour

CHICAGO, IL – An algorithm that incorporates high-sensitivity cardiac troponin T (hs-cTnT) values may be associated with ruling-out or ruling-in myocardial infarction (heart attack) within one hour in 77% of patients with acute chest pain who presented to an emergency department.

Tobias Reichlin, M.D., of University Hospital Basel, Switzerland, and colleagues sought to develop and validate an algorithm to rapidly rule-in or rule-out an AMI, in a  report posted Online First by Archives of Internal Medicine.

Patients with symptoms that suggest an acute myocardial infarction (AMI) account for about 10% of all emergency department consultations, the study background states. Standard diagnostic procedures include electrocardiography and measurement of cardiac troponin (cTn) levels. High-sensitivity cardiac troponin (hs-cTn) tests appear to have improved the early diagnosis of AMI, but how usage of the assays in clinical practice is not clear because they have increased the number of positive results in conditions other than AMI.

The prospective study enrolled 872 patients with acute chest pain presenting to the emergency department and AMI was the final diagnosis in 147 patients (17%).

The algorithm incorporated (high-sensitivity cardiac troponin T) hs-cTnT baseline values and absolute changes within the first hour. It was developed in a sample of 436 patients and validated in the remaining 436 patients.

Applying the algorithm to the validation cohort, 259 patients (60%) could be classified as rule-out, 76 patients (17%) as rule-in and 101 patients (23%) as being in the observational zone within one hour. Results showed that the cumulative 30-day survival was 99.8%, 98.6% and 95.3% in patients classified as rule-out, observational zone and rule-in, respectively.

“The use of this algorithm seems to be safe, significantly shortens the time needed for rule-out and rule-in of AMI, and may obviate the need for prolonged monitoring and serial blood sampling in 3 of 4 patients with chest pain,” the authors conclude.