High sensitivity troponin T (hsTnT) can be a reliable tool for excluding acute coronary syndrome (ACS) in very low-risk patients, according to a recent study published in the Journal of American Medical Association.
The study, which was performed in 15 emergency departments in the United States, recorded serial hsTnT measurements in patients suspected to have ACS. The upper reference level was set as 19 ng/L (which is the 99th percentile for a healthy US cohort).
Among patients suspected to have ACS, the presence of an hsTnT level less than 6 ng/L ruled out the presence of acute myocardial infarction with a negative predictive value of 99.4% while those who had an hsTnT level of 19 ng/L or less in the first three hours of the presentation did not have acute cardiac events (acute myocardial infarction, urgent revascularization, or death) in the following thirty days with a negative predictive value of 99.3%.
Previous studies have suggested the use of a single hsTnT measurement with a lower cutoff to rule out ACS in suspected patients. However, when this was applied to the study population, the results were unsatisfactory. As a result, the study recommends the use of serial hsTnT at 0 and 3 hours.
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]“Identifying a low-risk cohort may permit early emergency department discharge and avoid unnecessary hospitalization.” [/perfectpullquote]
The study also shows no sex difference in the diagnostic value when sex-specific cutoffs were used. This refutes previous evidence that females are more likely to develop acute myocardial infarction when applying a sex-specific cutoff value.
According to the authors, the use of this diagnostic tool will help ruling out ACS in very low-risk patients and thus will help to discharge them sooner. This will decrease the load on the emergency departments and will have a positive impact on both the patients and the physicians.
The authors acknowledge some limitations of the study such as being observational in nature, and thus the impact on the outcome could not be fully assessed. Also, patients with elevated hsTnT due to non-cardiac causes (such as renal failure) were excluded from the study while these patients might be at increased risk of having acute cardiac events. Lastly, the results of this study cannot be generalized to centers using high sensitivity troponin I to test for the presence of myocardial injury.