Purpose:
To investigate the association between myocardial hypodensity on standard coronary computed tomography angiography (CCTA) and echocardiographic diastolic dysfunction (DD) grade, and to evaluate correlations between hypodensity percentage and CT-derived left atrium (LA) and left ventricular (LV) functional parameters.

Material and methods:
This retrospective study included 156 patients (mean age 47.9 ± 11.4 years, 86 men) who underwent CCTA for suspected coronary artery disease and had comprehensive echocardiographic data. Myocardial hypodensity was quantified as the percentage of LV myocardium with attenuation < 46 HU using semi-automated, patient-specific attenuation mapping. Left atrial ejection fraction (LAEF) and volumes were derived from multi­phase CCTA reconstructions, and echocardiographic diastolic dysfunction was classified as per American Society of Echocardiography and the European Association of Cardiovascular Imaging (ASE/EACVI) 2016 guidelines. Coro­nary artery disease (CAD) severity (CAD-RADS 2.0) and cardiovascular risk (SMART score) were also recorded. Correlation, ROC, and multivariate regression analyses were performed; a data-driven LAEF threshold was used to stratify impaired atrial function.

Results:
Hypodensity percentage correlated inversely with LAEF (ρ = –0.41, p < 0.001) and left ventricle ejection fraction (LVEF) (ρ = –0.29, p = 0.006), and positively with LA volume (ρ = 0.34, p = 0.002). ROC analysis showed that a hypo­density threshold of 9.5% predicted reduced LAEF (< 47%) with 36% sensitivity and 71% specificity (AUC = 0.67, ρ < 0.05). Hypodensity increased across DD grades: 5.7% (grade 1), 12.6% (grade 2), and 24.8% (grade 3), ρ < 0.001.

Conclusions:
Quantitative myocardial hypodensity on CCTA correlates with subclinical diastolic dysfunction and LA functional impairment. These findings support the potential of incorporating perfusion metrics into routine CCTA workflows to improve early diastolic assessment.