Low-risk Non-ST-Elevation Acute Coronary Syndrome and Normal Troponin: Do We Need Further Evaluation?

With the recent introduction of high-sensitivity troponin (hsTn), the incremental benefit of stress myocardial perfusion imaging (MPI) in the evaluation of patients who present to the emergency department (ED) with acute coronary syndrome (ACS) is unclear.

To assess the added value of stress MPI in low-risk ACS patients with normal range hsTnI.

We analyzed all patients who were hospitalized at our medical center from February 2016 to November 2017, who presented with low-risk ACS and underwent stress MPI, and in whom hsTnI was in the normal range after the introduction of hsTnI.

During the study period, 161 patients were admitted with a diagnosis of unstable angina (i.e., ACS with normal range hsTnI) and underwent stress MPI during index admission. The study population included 52/161 patients (31.7%) with low-risk ACS who had no indication for initial invasive strategy. No patients had positive MPI. One patient underwent coronary angiography due to suggestive history; however, he did not have a significant coronary artery disease and had no indication for percutaneous coronary intervention.

In patients with low-risk ACS and normal range hsTnI without additional high-risk features, stress MPI has little additional value for the correct diagnosis and management. Prospective studies are warranted to confirm whether resting hsTnI could serve as a powerful triage tool in chest pain patients in the ED before diagnostic testing and thus, improve patient management.