Coronary Artery Calcification on Prior Non-Gated Chest CT in Patients With Myocardial Infarction: Reporting Rates and Implications for Cardiovascular Risk Stratification.

BACKGROUND

Coronary artery calcification (CAC) is a strong independent predictor of cardiovascular events and can be reliably identified on non-gated thoracic CT (NGTCT). International consensus statements recommend routine reporting of incidental CAC with visual grading and management prompts. However, real-world adherence to these recommendations remains variable, and no data currently exist for New Zealand.

METHODS

We conducted a retrospective observational study of patients presenting with acute myocardial infarction (MI) to Tauranga and Whakatāne Hospitals between January 2021 and December 2023. Patients with ST-elevation or non-ST-elevation MI were included; type 2 MI was excluded. Radiology reports from prior NGTCT performed within 5 years of admission were reviewed to assess CAC reporting and grading. Demographic data were obtained from local electronic health records, and cardiovascular risk factors were extracted from the Aotearoa New Zealand All Cardiology Services Quality Improvement registry.

RESULTS

After exclusions, 1602 patients were admitted with acute MI, of whom 269 (16.8%) had a prior non-cardiac NGTCT. CAC was reported in 70 reports (26%), with visual severity grading provided in 14 (20%). Only two reports (3%) mentioned CAC in the conclusion, and none included a management recommendation. Most ungraded reports used descriptive terminology rather than standardised severity categories. Modifiable cardiovascular risk factors among those with unreported CAC were common, including current or former smoking (83%), hypertension (57%), elevated total cholesterol (41%), elevated LDL cholesterol (41%) and raised HbA1c (27%). CAC reporting was lower in patients aged < 55 years and did not differ between Māori and New Zealand European/Pākehā patients.

CONCLUSION

CAC is infrequently reported and rarely graded on NGTCT in regional New Zealand patients who later present with MI, despite strong international recommendations. Given the high prevalence of modifiable risk factors and the potential impact on cardiovascular risk stratification and prevention, routine standardised CAC reporting with inclusion of brief management guidance should be implemented.