Coronary Artery Dimension-Adjusted Subtended Myocardial Mass Obtained With Coronary CT Angiography as a Potential Biomarker of Myocardial Ischemia in Patients With Hypertrophic Cardiomyopathy

Objective To compare coronary artery dimension-adjusted subtended myocardial mass between patients with hypertrophic cardiomyopathy (HCM) and a normal population without detectable atherosclerosis, and between HCM patients with and without chest pain. Materials and Methods Twenty-five patients with HCM but no detectable atherosclerosis on coronary computed tomography angiography (CCTA) were included in the study. This group comprised 14 patients with chest pain and 11 patients without chest pain. They were matched with 25 healthy participants based on sex, age, coronary dominance pattern, and body surface area. The minimal lumen area (MLA) and subtended myocardial volume (V-sub) were assessed in the left main (LM), proximal left anterior descending (pLAD), proximal left circumflex (pLCx), and proximal right coronary (pRCA) arteries. Additionally, an index of the subtended myocardial mass adjusted for the MLA, calculated as V-sub/MLA(2), was determined. Results MLA was significantly larger in patients with HCM compared to the control group in LM (20.93 +/- 6.31 mm(2) vs. 15.24 +/- 3.90 mm(2),P < 0.001), pLAD (14.28 +/- 3.55 mm(2) vs. 11.36 +/- 2.07 mm(2),P = 0.001), pLCx (10.94 +/- 3.60 mm(2) vs. 9.15 +/- 2.93 mm(2),P = 0.045), and pRCA (13.41 +/- 4.85 mm(2) vs. 11.22 +/- 3.20 mm(2),P = 0.018). Despite an increase in coronary luminal area, patients with HCM exhibited significantly higher V-sub/MLA(2) compared to the control group in both the pLAD (403.56 +/- 200.35 mm(-1) vs. 241.70 +/- 85.87 mm(-1),P < 0.001) and the pRCA (186.06 +/- 95.07 mm(-1) vs. 125.07 +/- 70.18 mm(-1),P = 0.007). V-sub/MLA(2) was significantly elevated in patients with chest pain compared to those without in the pLAD (473.75 +/- 227.38 mm(-1) vs. 314.24 +/- 110.74 mm(-1),P = 0.018) and the pLCx (417.04 +/- 182.65 mm(-1) vs. 275.29 +/- 112.97 mm(-1),P = 0.044). Conclusion CCTA-derived V-sub/MLA(2) may more accurately reflect the balance between myocardial blood supply and demand, offering insights into the occurrence of demand angina in patients with HCM without obstructive coronary artery disease.