Cardiac computed tomography-derived coronary artery volume to myocardial mass in patients with severe coronary artery disease

Background: Coronary artery lumen volume (V) to myocardial mass (M) ratio (V/M) can show the mismatch between epicardial coronary arteries and the underlying myocardium. Methods: The V, M and V/M were obtained from the coronary computed tomography angiography (CCTA) of patients in the FAST-TRACK CABG study, the first-in-human trial of coronary artery bypass grafting (CABG) guided solely by CCTA and fractional flow reserve derived from CCTA (FFRCT) in patients with complex coronary artery disease (CAD). The correlations between V/M ratios and baseline characteristics were determined and compared with those from the ADVANCE registry, an unselected cohort of historical controls with chronic CAD. Results: The V/M ratio was obtained in 106 of the 114 pre-CABG CCTAs. Mean age was 65.6 years and 87% of them were male. The anatomical SYNTAX score from CCTA was significantly higher than the functional SYNTAX score derived using FFRCT [43.1 (15.2) vs 41.1 (16.5), p < 0.001]. Mean V, M, and V/M were 2204 mm(3), 137 g, and 16.5 mm(3)/g, respectively. There were weak negative correlations between V and anatomical and functional SYNTAX scores (Pearson's r = -0.26 and -0.34). V and V/M had a strong correlation (r = 0.82). The V/M ratio in the current study was significantly lower than that in the ADVANCE registry (median 16.1 vs. 24.8 [1st quartile 20.1]). Conclusion: Systematically smaller V/M ratios were found in this population with severe CAD requiring CABG compared to an unselected cohort with chronic CAD. The V/M ratio could provide additional non-invasive assessment of CAD especially when combined with FFRCT.