High-sensitivity cardiac troponin I to predict obstructive coronary artery disease and revascularisation in rural patients with non-st-elevation myocardial infarction transferred for invasive coronary angiogram.

Abstract

Introduction: Rural patients with non-ST-elevation myocardial infarction (NSTEMI) are often transferred for invasive coronary angiography (ICA), incurring substantial costs, procedural risks and inconvenience. Yet, many do not have obstructive coronary artery disease (CAD) or undergo revascularisation. We hypothesised that low-level elevations [<=5 times upper reference limit (URL)] of high-sensitivity cardiac troponin I (hs-cTnI) may assist risk-stratification. Method(s): A retrospective analysis using electronic records was conducted on rural patients with NSTEMI transferred to Western Australian metropolitan hospitals for ICA in 2019. Patients with cardiac arrest, cardiogenic shock, or unstable arrhythmias were excluded. Obstructive CAD was defined as >=50% stenosis. Multivariate logistic regression was used to identify predictors of obstructive CAD or revascularisation. Result(s): Of 438 patients [60.6+/-13.2 years, 252 (77.1%) male sex], 327 (75.2%) had obstructive CAD and 241 (55.0%) underwent revascularisation. Hs-cTnI was significantly higher in patients with obstructive CAD (median 1510 ng/L vs 503 ng/L; p<0.001) and who underwent revascularisation (1,765 ng/L vs 516 ng/L; p<0.001). Of 88 (20.1%) patients with hs-cTnI <=5 times URL, 58 (65.9%) had obstructive CAD and 39 (44.3%) underwent revascularisation. Multivariate predictors of obstructive CAD were age (p<0.001), male sex (p<0.001), diabetes (p<0.001), ever-smoking (p=0.024), prior revascularisation (p=0.006) and hs-cTnI >5 times URL (p=0.006). Multivariate predictors of revascularisation were age (p=0.033), male sex (p<0.001), diabetes (p=0.004) and hs-cTnI >5 times URL (p=0.007). Conclusion(s): In rural patients with NSTEMI, low-level elevations in hs-cTnI (<=5 times URL) were associated with less obstructive CAD and revascularisation and may help identify patients that may not require transfer to metropolitan centres for ICA.Copyright © 2024