The clinical significance of misleading troponin elevations: is macrotroponin a culprit for unnecessary invasive coronary angiography?

Background Cardiac troponin (cTn) assays can yield elevated results unrelated to true myocardial ischemia when interfered by complexes of cTn and anti-cTn antibodies, called macrotroponin. Elevation of cTn above the 99th percentile is the central criterion in diagnosing myocardial injury and acute myocardial infarction. The study aimed to explore the clinical significance of macrotroponin. We hypothesized that macrotroponin may prompt unnecessary invasive coronary angiographies (CAG) in patients presenting with symptoms of acute myocardial infarction. This study assessed whether macrotroponin presence is associated with CAG outcomes. Method This cross-sectional study collected plasma from patients suspected of acute coronary syndrome at our hospital from January 1st, 2021, until December 10th, 2023. We included patients who underwent CAG for suspected non-ST elevation myocardial infarction and had at least one pre-procedure cTn sample exceeding the sex-specific upper reference limit. We used Protein A/G depletion and Siemens Atellica hs-cTnI reanalysis with a 40% troponin recovery threshold. CAG results were retrieved from medical records, and Fischer's exact test determined statistical significance, odds ratio, and confidence interval. Results Among 145 patients, 34 (23.4%) showed no stenosis on CAG, whereas 111 (76.6%) had significant stenosis. Of the 34 patients without stenosis, 11 (32.4%) had macrotroponin, compared to 7 (6.3%) of the 111 patients with stenosis (Odds ratio 6.97, 95% CI 2.2-23.7). Among those 11 patients with macrotroponin and no stenosis, 5 (3.4% of the study population) displayed stable elevations attributed to macrotroponin buildup. The remaining 6 patients had strong dynamic changes in serial measurements or were later diagnosed with cardiac sarcoidosis or amyloidosis. Conclusion The presence of macrotroponin was significantly associated with a CAG outcome without stenosis, suggesting macrotroponin may lead to unnecessary invasive procedures. Further research and careful interpretation of troponin results are warranted in clinical practice.