Angiographic prevalence of occlusion myocardial infarction and the limited value of serial troponin in patients with non-ST-segment elevation acute coronary syndrome.

Abstract

Background: An estimated 25%-34% of patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) are diagnosed with an occluded culprit artery during catheterization. Whether early serial troponin kinetics discriminate angiographically defined occlusion myocardial infarction (OMI) in catheterized patients with NSTE-ACS remains uncertain.

Methods: We conducted a single-center retrospective cohort study of 481 patients with NSTE-ACS who underwent coronary catheterization between 2017 and 2023. OMI was defined by a purely angiographic criterion: >90% culprit-vessel stenosis with Thrombolysis in Myocardial Infarction flow grade 0, 1, or 2. Seven contemporary sensitivity troponin I metrics (absolute values at 0, 3, and 6 h; deltas; and ratios) were evaluated by receiver operating characteristic analysis. Operating characteristics are reported with 95% confidence intervals (CIs) and likelihood ratios.

Results: Ninety-eight patients (20.4%) met the angiographic definition of OMI. These patients were younger (median, 65.5 vs. 70.0 years; p = 0.025), had fewer comorbidities, and more often presented with chest pain (92.9% vs. 82.8%; p = 0.013). The left circumflex artery was the most common culprit in OMI (36.7%). Twenty-nine patients with OMI (29.6%) had a presentation ECG classified as normal (no ST-T change or bundle branch block. No troponin metric reliably discriminated OMI from non-occlusion MI. The prespecified primary predictor, the 0-6-h change in troponin concentration, had an area under the curve (AUC) of 0.623 (95% CI, 0.544-0.703) and the best single metric, the 6-h value, of 0.654 (0.580-0.727); all seven unadjusted troponin-metric AUCs were under 0.66. At its Youden cutoff (≥0.379 ng/mL), the 6-h troponin had a sensitivity of 69.4%, a specificity of 57.7%, a positive predictive value of 27.2%, and a negative predictive value of 89.3%. The highest positive predictive value of any metric was 41.3%, the first troponin (at 0 h) identified fewer than 40% of patients with OMI at its optimal threshold, and likelihood ratios produced only limited shifts in post-test probability.

Conclusion: Among analyzable patients with NSTE-ACS undergoing catheterization, approximately one in five met the study-defined angiographic criteria for OMI. Early serial troponin kinetics showed only modest discrimination, and upper confidence bounds fell below levels expected of a standalone triage biomarker. Complementary strategies for identifying these patients, including expert ECG interpretation, warrant further study.