Incidental CAC on non-gated chest CT: prognostic value for cardiovascular events in patients without prior cardiovascular disease

Abstract

Background: Non-gated chest computed tomography (CT) is routinely performed for the evaluation of thoracic conditions. Although the heart is not the primary focus of this examination, coronary artery calcification (CAC) is frequently encountered as an incidental finding and reflects underlying atherosclerotic burden.

Objective: The study aimed to assess whether incidentally detected CAC on non-gated chest CT is associated with fiveyear cardiovascular outcomes in patients without prior cardiovascular disease (CVD).

Methods: We conducted a retrospective cohort study of adults aged 40-70 years who underwent non-gated chest CT at Bangkok Metropolitan Administration (BMA) General Hospital between July 2019 and June 2020. CAC was assessed using a visual coronary artery calcium (vCAC) scoring system. Demographic characteristics, cardiovascular risk factors, and cardiovascular events occurring within five years after the index CT were obtained from electronic medical records.

Results: Incidental CAC (vCAC ≥1) was present in 54.3% of patients. Individuals with CAC were significantly older and had a higher burden of cardiometabolic risk factors. Cardiovascular events occurred more frequently in patients with CAC than in those without CAC (14.6% vs. 3.3%), corresponding to an approximately fourfold higher event rate. Event rates also increased with CAC severity (P < 0.001 for trend), with a notable increase observed among patients with vCAC scores ≥ 2.

Conclusion: Incidental CAC on routine non-gated chest CT is associated with future cardiovascular events in patients without known CVD. Visual CAC assessment may provide clinically useful prognostic information and support opportunistic cardiovascular risk stratification in routine radiology practice.