Imaging-defined subclinical atherosclerosis in subclinical hypothyroidism: Prevalence, associated factors, and...

Subclinical hypothyroidism (SCH) has been linked to adverse cardiovascular profiles; however, the burden of subclinical atherosclerosis detected by imaging and its associated drivers remain insufficiently characterized, particularly in real-world Middle Eastern populations.

To quantify the prevalence of imaging-defined subclinical atherosclerosis in adults with SCH and to identify clinical and biochemical factors independently associated with its presence.

We conducted a cross-sectional study of 500 adults with SCH (TSH 4.5-10 mIU/L with normal free T4) evaluated at a tertiary cardiac center in Oman (December 2023-September 2025). Participants underwent fasting lipid assessment, high-sensitivity C-reactive protein (hs-CRP), carotid ultrasound (carotid plaque and intima-media thickness [CIMT]), and coronary artery calcium (CAC) scoring. The primary outcome was imaging-defined subclinical atherosclerosis, defined as the presence of at least one of the following: CIMT >1.0 mm, carotid plaque, or CAC >100. Multivariable logistic regression was performed using prespecified clinically relevant covariates, including age, sex, body mass index, metabolic syndrome, LDL-C, hs-CRP, and TSH category.

Overall, 46% of patients demonstrated imaging-defined subclinical atherosclerosis. The prevalence of CIMT >1.0 mm, carotid plaque, and CAC >100 was 26%, 29%, and 22%, respectively. Imaging-defined subclinical atherosclerosis was substantially more frequent among individuals with metabolic syndrome (72% vs. 33%, p < 0.001). In adjusted models, LDL-C > 160 mg/dL (OR 2.1, 95% CI 1.5-2.9), hs-CRP >3 mg/L (OR 1.9, 95% CI 1.4-2.5), TSH >7 mIU/L (OR 1.7, 95% CI 1.2-2.3), and metabolic syndrome (OR 2.5, 95% CI 1.8-3.5) were independently associated with imaging-defined subclinical atherosclerosis.

Nearly half of adults with SCH exhibit imaging evidence of subclinical atherosclerosis. Higher LDL-C, systemic inflammation, higher TSH, and metabolic syndrome identified a subgroup with a disproportionately greater burden of imaging-defined subclinical atherosclerosis. These findings support a more individualized cardiometabolic risk assessment strategy in SCH and justify prospective studies evaluating whether targeted preventive strategies improve long-term outcomes.