Troponin Elevation in 20.4% of NSTE-ACS Patients

Out of 481 patients with non–ST-segment elevation acute coronary syndrome, 98 individuals—representing 20.4% of the cohort—met angiographic criteria for occlusion myocardial infarction, while early serial troponin kinetics yielded an area under the curve of just 0.623. Meanwhile, major cardiac societies revised universal definitions to separate myocardial injury from infarction.

The investigation set out to determine whether early serial troponin kinetics could reliably discriminate angiographically defined occlusion myocardial infarction among these catheterized patients, evaluating troponin as a candidate risk-enrichment marker rather than a standalone rule-in or rule-out test.

Out of 1,260 coronary catheterization records reviewed from January 2017 to December 2023, 721 represented non–ST-segment elevation acute coronary syndrome with culprit-vessel characterization after exclusions. Following the removal of cases with uncollected or incomplete serial troponin sampling or missing catheterization data, the final analytic cohort comprised 481 patients. Among these individuals, 98 patients—representing 20.4% of the group—met that angiographic definition of occlusion myocardial infarction, while 383 patients (79.6%) were classified as having non-occlusion myocardial infarction. Abstractors recorded raw clinical and angiographic fields while not blinded to troponin values, and occlusion status was computed afterward from the abstracted stenosis and Thrombolysis in Myocardial Infarction flow fields.

Troponin Fork: The NSTE Decision

Culprit Vessel Distribution and Troponin Limitations

Anatomical review of the 98 occlusion cases revealed that the circumflex or obtuse marginal territory served as the most frequent culprit vessel, accounting for 36 cases (36.7%). The right coronary artery followed with 31 cases (31.6%), while the left anterior descending artery accounted for 27 cases (27.6%). Three patients (3.1%) exhibited ramus involvement, and one patient (1.0%) involved left main disease. Multivessel coronary artery disease appeared in 37.2% of the occlusion group and 44.7% of the non-occlusion group, with a p-value of 0.192.

When researchers evaluated serial troponin kinetics, the prespecified primary predictor—the 0-to-6-hour change in troponin concentration—had an area under the curve of 0.623 with a 95% confidence interval ranging from 0.544 to 0.703. The 6-hour value yielded an area under the curve of 0.654 with a 95% confidence interval of 0.580 to 0.727; all seven unadjusted troponin-metric areas under the curve remained under 0.66. At a 6-hour troponin Youden cutoff of 0.379 nanograms per milliliter or higher, the test achieved a specificity of 57.7%, a sensitivity of 69.4%, a negative predictive value of 89.3%, and a positive predictive value of 27.2%.

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Cause-specific cardiovascular mortality was not reported because retrospective cause-of-death attribution was unreliable in this dataset. This made all mortality analyses exploratory, as the cohort was not powered for mortality endpoints. Consequently, the findings indicate that early serial troponin kinetics do not reliably discriminate occlusion myocardial infarction in this patient population.

Troponin Elevation and Type 2 Myocardial Infarction Mechanisms

High-sensitivity assays facilitate the detection of small degrees of myocardial injury, yet an elevated result does not identify its underlying mechanism.

A systematic review evaluated the prevalence, clinical predictors, and potential management implications of obstructive coronary artery disease in adults with type 2 myocardial infarction or closely related troponin-positive supply-demand ischemic presentations. This review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. Information sources included PubMed/MEDLINE, Embase, Scopus, and Web of Science, which were searched for studies published from January 1, 2007, through September 20, 2026. Eligible designs encompassed prospective and retrospective cohort studies, registry-based analyses, cross-sectional prevalence studies, and comparative diagnostic or prognostic studies, while applying the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data to systematic imaging prevalence studies and the Joanna Briggs Institute Cohort Checklist for comparative cohort and registry studies.

Among analyzed literature, a prespecified analysis of a prospective multicenter registry published in 2026 evaluated 774 angiographed patients with confirmed type 2 myocardial infarction who had greater than or equal to 1-year follow-up under the Fourth Universal Definition. Independent adjudication was performed by two cardiologists, revealing a median peak cardiac troponin I of 19.7 times the upper reference limit, with all patients undergoing invasive angiography where obstructive coronary artery disease was defined as greater than or equal to 50% stenosis in at least one major epicardial vessel. Conversely, a 2013 study evaluated using the Joanna Briggs Institute Prevalence Checklist exhibited high, moderate, and moderate-high domain ratings, though the initial troponin-tested cohort was broad and coronary artery disease status was available for only 31 out of 144 patients with type 2 myocardial infarction, creating major partial verification and referral selection bias as noted by authors such as Allou et al.

Universal Definition Updates and Pathophysiological Classification

Kiyan Heybati from the Department of Internal Medicine at the Mayo Clinic in Rochester, Minnesota, USA, and Harish Ramakrishna from the Department of Anesthesiology and Perioperative Medicine at the Mayo Clinic in Rochester, Minnesota, USA, outlined key updates regarding myocardial infarction definitions. Released in 2026 within EMJ Cardiology, the review points out that the fourth version established a clear separation between myocardial injury and infarction, noting that an elevated troponin level in the absence of other ischemia signs should be classified as injury rather than infarction, which may present as either acute or chronic.

The Fifth Universal Definition of Myocardial Infarction establishes a classification system focusing on primary, secondary, and procedure-related myocardial infarction. Procedure-related events include Type 4, which relates to percutaneous coronary intervention with subtypes for stent thrombosis and restenosis, and Type 5, which relates to coronary artery bypass graft surgery. Type 3 myocardial infarction has been removed. Cardiac death before testing is now classified by setting or post-mortem findings into one of the other clinical categories. Myocardial infarction with non-obstructive coronary arteries has been redefined as 'myocardial injury with non-obstructive coronary arteries'.

Authors emphasize that even in acute illnesses such as sepsis or haemorrhage, primary myocardial infarction should be considered as a differential diagnosis given their tendency to trigger an atherothrombotic event. When primary myocardial infarction is suspected or signs of ongoing myocardial ischaemia are present, coronary angiography is required, followed by case reclassification if an acute coronary abnormality is identified. To support epidemiological tracking and appropriate management including risk factor modification and rehabilitation, a set of International Classification of Diseases 11th Revision codes has been proposed.