A new testing method may be able to quickly rule out acute myocardial infarction (AMI) in patients presenting to the ED with chest pain. Research suggests that combining an ECG with a high-sensitivity cardiac troponin T (hs-cTnT) test below the level of detection can identify those patients at sufficiently low risk for AMI, allowing them to be released to outpatient care sooner.
The findings of the meta-analysis were reported online in Annals of Internal Medicine on April 17, 2017. The study authors point out that a second test should be repeated approximately 3 hours after initial onset of symptoms, since troponin is not always detectable in circulation of patients who arrive quickly after onset of pain.
According to an article posted on Medscape, the researchers wrote that they “observed that 50% of patients with false-negative results had blood sampling within 3 hours of symptom onset and [we] therefore recommend a cautious approach to implementation to exclude patients presenting soon after symptom onset. Data are currently insufficient to establish a minimum safe duration below 3 hours."
The meta-analysis included data from 11 geographically diverse cohorts, studying 9241 patients in total. Use of the hs-cTnT test plus ECG showed that, on average, 30.6% of patients were at low risk for AMI. The sensitivity estimate of this method was 98.7% (95% confidence interval [CI], 96.6% - 99.5%). Cohort sensitivities ranged from 87.5% to 100% (P < .001).
Fourteen of the 9241 patients had AMI despite classification of low risk with hs-cTnT and ECG. It was noted that 7 of those 14 took the blood test earlier than 3 hours since symptom onset, and 4 of them did so earlier than 2 hours. This further emphasizes the importance of repeating the test 3 hours after initial presentation to the ED.Using a combined hs-cTnT test and ECG to identify patients who can safely be released to outpatient care not only saves time and money for those patients, but can also free up resources that may be of greater need and benefit to other patients, such as those at higher risk of AMI. Check out the full abstract of the meta-analysis right here.