Unstable Angina Risk Stratification using High-sensitivity Cardiac Troponin and Coronary Angiography

Abstract

Patients formerly diagnosed with unstable angina (UA) are being reclassified as non-ST-elevation myocardial infarction (NSTEMI) with the widespread adoption of sensitive troponin assays (hsTn), leading to significant changes in the incidence and prognosis of UA. The main purpose of this study was to evaluate the value of hsTn and the presence of significant obstructive CAD in the risk stratification of patients with unstable angina. We conducted a retrospective, single-centre study of 742 patients hospitalized for UA between 2016-2021. The primary endpoint of this study was all-cause mortality. The secondary outcome (MACE) was defined as a composite of nonfatal myocardial infarction (MI), hospitalization for heart failure (hHF), and repeated coronary angiography due to recurring UA (rUA) after the index event. Outcomes were assessed within one month, one year, and up to 5 years of follow-up. The average follow-up duration was 45±24 months, and 37.2% (N=276) of patients completed a 5-year follow-up. No in-hospital death was observed, and 6.9% of patients died during follow-up, which was more commonly a late event (>12 months). The composite secondary endpoint (MI+hHF+rUA) was observed in 16.7% of the patients. There was 3.2% nonfatal MI, 2.3% hHF, and 11.6% rUA during follow-up. We developed a risk model (UA Mortality Risk) using variables with the highest discriminatory power: age, hsTn, and ST-segment deviation. Our model performed well against the GRACE and TIMI risk scores in predicting death during follow-up. Obstructive CAD on coronary angiography was the only independent predictor of MACE during follow-up. In conclusion, a contemporary cohort of patients with UA presented with favourable prognosis, particularly within the first year after the index event. Non-significant increases in HsTn levels add to the risk stratification of UA patients, and the presence of obstructive CAD was the only independent predictor of MACE, highlighting the potential importance of assessing coronary anatomy.