Sex differences in photon-counting CT findings across hypertrophic phenotypes

Abstract Background Photon-counting computed tomography (PCCT) enables simultaneous assessment of left ventricular morphology, function, and myocardial tissue characterization. Whether sex influences PCCT findings across hypertrophic phenotypes remains uncertain. Methods We studied consecutive adults with a left ventricular hypertrophic phenotype undergoing PCCT. Patients were classified as hypertrophic cardiomyopathy (HCM), transthyretin amyloid cardiomyopathy (ATTR-CM), or secondary left ventricular hypertrophy (LVH). Sex differences in PCCT-derived left ventricular mass index, volumes, ejection fraction, late iodine enhancement (LIE), and extracellular volume (ECV) were assessed overall and by etiology. In patients with clinically indicated cardiovascular magnetic resonance (CMR) within ±12 months, sex effects on CT-CMR agreement were also evaluated. Results Among 182 patients, 50 were women and 132 were men; 83 had paired PCCT-CMR data. In the overall cohort, women had lower left ventricular mass index, smaller left ventricular volumes, higher ejection fraction, slightly lower ECV, and lower LIE extent than men. In HCM, women and men showed similar wall thickness, left ventricular mass, LIE burden, and ECV. In secondary LVH, women had smaller volumes and higher ejection fraction, without meaningful differences in tissue markers. In ATTR-CM, women appeared less remodeled and less infiltrative, although only four women were included. CT-CMR agreement for wall thickness, left ventricular mass, ejection fraction, scar extent, and ECV was similar in women and men. Diagnostic ECV thresholds were also consistent across sexes. Conclusions Sex influences PCCT hypertrophic phenotypes mainly through remodeling and functional adaptation rather than major differences in tissue characterization. CT-CMR agreement and diagnostic ECV thresholds appear robust across sexes.