April 1, 1995
View Full PaperEarly diagnosis and exclusion of acute myocardial infarction using biochemical monitoring
Key Result
Monitoring a combination of myoglobin and CK-MB achieved 98% sensitivity and 93% specificity for detecting acute myocardial infarction within 6 hours in patients with non-diagnostic ECGs.
Study Design
Type
Observational (n=142)
Structured PICO
Does frequent monitoring of CK-MB, myoglobin, and troponin T accurately confirm or exclude acute myocardial infarction in patients with chest pain and a non-diagnostic ECG?
P
Population
142 patients with chest pain for ≤12 hours and a non-diagnostic ECG, monitored with frequent blood sampling for 3-6 hours.
E
Exposure
Frequent analysis of creatine kinase MB (CK-MB), myoglobin and troponin T alone or in combination (blood samples obtained every 30 min during the first 3 h and thereafter at longer intervals)
O
Outcome
Ability to detect or exclude acute myocardial infarction (AMI) during the first 6 h after admissionsurrogate
Frequent monitoring of myoglobin combined with CK-MB or troponin T enables rapid confirmation or exclusion of AMI within 3-6 hours in patients with non-diagnostic ECGs.
Abstract
Background The aim was to evaluate whether frequent analysis of creatine kinase MB (CK-MB), myoglobin and troponin T alone or in combination could either confirm or exclude acute myocardial infraction (AMI) within the first few hours after patients were admitted to hospital with chest pain and a non-diagnostic ECG. Methods One hundred and forty-two patients with chest pain (≤12h) and a non-diagnostic ECG were included in the study. Blood samples were obtained every 30 min during the first 3 h and thereafter at longer intervals. Different discriminatory levels and combinations of markers were tested for their ability to detect (n = 59) or exclude (n = 83) AMI during the first 6 h after admission. Results No single marker adequately combined high early sensitivity and specificity. However, a combination of myoglobin and CK-MB analyses had a sensitivity at entry of 59%, which increased by 5–10% every 30 min and reached 92% after 2 h and 98% after 6 h with a specificity of 93%. A combination of myoglobin and troponin T analyses showed identical sensitivity but a slightly inferior specificity. In the patients with no AMI it was possible to exclude AMI in 64% within 3 h by using myoglobin and within 6 h in approximately 70% by using CK-MB or troponin T. Conclusions Monitoring of a combination of myoglobin and CK-MB or troponin T will allow confirmation or exclusion of AMI within 3–6 h in almost all patients. This method will have a large impact on the handling of patients with suspected AMI without a diagnostic ECG.