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 (FFR_CT) 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 FFR_CT [43.1 (15.2) vs 41.1 (16.5), p ​< ​0.001]. Mean V, M, and V/M were 2204 ​mm³, 137 ​g, and 16.5 ​mm³/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 FFR_CT.