Determinants of extracellular volume fraction on computed tomography angiography in patients with acute coronary syndrome

Background Coronary computed tomography angiography (CCTA) has been proposed to estimate myocardial extracellular volume (ECV) fraction, reflecting myocardial edema or fibrosis. Purpose We aimed to explore the clinical determinants of CCTA-derived ECV in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Methods We retrospectively enrolled patients with NSTE-ACS who underwent CCTA on ECV protocol with subtraction method before catheterization. Patients with prior history of revascularization, known myocardial infarction, hemodialysis were excluded. Results A total of 172 patients were studied. Among them, 99 showed epicardial obstructive stenosis requiring revascularization, while 63 did not. Median age was 72 [61-79] years and 65.1% (112/172) were man. Median global ECV value was 32.8 [29.6-37.8] %. Univariable logistic regression analysis showed that women, diabetes mellitus, statin-naïve, high NT-pro BNP level, multivessel disease, low left ventricular ejection fraction (LVEF) and high E/e’ ratio were associated with the highest global ECV tertile, while the presence of epicardial stenosis was not. Multivariable logistic regression analysis revealed that the independent determinants of global ECV value were women (adjusted odds ratio [OR] 0.34, 95% confidence interval [CI] 0.122-0.944, P=0.038), high E/e’ ratio (adjusted OR 1.13, 95% CI x1.01-1.27, P=0.033), and LVEF (adjusted OR 0.929, 95% CI 0.88-0.981, P=0.008). Furthermore, the same procedure was performed on 67 patients diagnosed with MINOCA out of 172 patients. Median age was 72 [61-79] years and 46.3% (31/67) were man. Median global ECV value was 32.9 [29.6-37.8] %. Univariable logistic regression analysis showed that women, renal function decline, Takotsubo cardiomyopathy, high NT-pro BNP level and high E/e’ ratio were associated with the highest global ECV tertile, while the presence of epicardial stenosis was not. Multivariable logistic regression analysis revealed that the independent determinants of global ECV value were women (adjusted odds ratio [OR] 0.162, 95% confidence interval [CI] 0.025-1.02, P=0.0525), high E/e’ ratio (adjusted OR 1.12, 95% CI 0.945-1.32, P=0.194), and Takotsubo cardiomyopathy (adjusted OR 4.99, 95% CI 0.565-44.10, P=0.148). Conclusions In patients with NSTE-ACS, global ECV was associated with multiple clinical characteristics, echocardiographic and angiographic factors. Our results suggest that clinical factors such as sex, left ventricular systolic or diastolic function should be taken into account in the assessment of ECV fraction using CCTA.