Impact of Zero Coronary Artery Calcium Scoring on Downstream Cardiac Testing and Cardiac Outcomes Compared With No Testing.

Background: The impact of coronary artery calcium (CAC) scoring on downstream resource utilisation and outcomes remains unclear, especially in those with zero CAC.

Methods: Consecutive CAC scores from two academic hospitals in Toronto, Ontario, were linked to population-based databases. Subjects with zero CAC without previous cardiovascular disease were propensity score matched with a non-CAC-tested control group for age, sex, cardiovascular risk factors, and comorbidities. Downstream cardiac testing, acute myocardial infarction, heart failure (HF) hospitalisations, and HF emergency department (ED) visits were compared between the 2 groups.

Results: A total of 4884 patients underwent CAC scoring, of whom 2709 had zero CAC (mean 52.9 ± 10.6 years), 55.4% women. At 3.4 years, graded-stress testing (hazard ratio [HR] 1.24, 95% confidence interval [95% CI] 1.14-1.35), stress echocardiography (HR 1.80, 95% CI 1.59-2.05), and cardiac magnetic resonance imaging (HR 3.40, 95% CI 2.55-4.53) use was higher in the zero CAC group, whereas myocardial perfusion scintigraphy (HR 1.08, 95% CI 0.97-1.21) and catheterisation (HR 1.14, 95% CI 0.91-1.44) were similar and percutaneous coronary intervention (HR 0.58, 95% CI 0.35-0.98) and coronary artery bypass grafting (HR 0.14, 95% CI 0.03-0.61) were lower. There was an approximately 5-fold lower rate of myocardial infarction (HR 0.22, 95% CI 0.10-0.51) in the zero CAC group and no difference in HF hospitalisations (HR 1.15, CI 95% 0.53-2.48) or ED admissions (HR 1.21, 95% CI 0.58-2.52).

Conclusions: Our results support the utility of zero CAC in limiting interventional cardiovascular procedures while maintaining an association with reduced downstream cardiovascular events.