Prognostic value of coronary artery calcium scoring and computed tomography coronary angiography in remote Indigenous and non-Indigenous Australians

Abstract

BackgroundThe long-term prognostic utility of coronary calcification and coronary artery disease on computed tomography coronary angiography (CTCA) in remote Indigenous and non-Indigenous Australians is not known. MethodsConsecutive patients undergoing CTCA from 2013 to 2017 in Central Australia were followed-up for major adverse cardiovascular events (MACE). Results347 patients were included (50 ± 12 years; 47% female; 39% Indigenous). 172 (50.0%) exhibited coronary calcification. CTCA demonstrated no coronary artery disease (CAD) in 137 (39.5%), non-obstructive CAD in 149 (42.9%), and obstructive CAD in 61 (17.6%) patients. Although Indigenous ethnicity was associated with coronary calcification and baseline CAD in age- and gender-adjusted models, this association was non-significant after accounting for comorbidities. Over 4.6 years (IQR 3.52–5.68) of follow-up, MACE incidence rates per 100 person-years were 2.92 (CI 1.92–4.44) and 0.48 (CI 0.18–1.27) in those with and without calcification respectively (p = 0.001), and 0.15 (CI 0.02–1.09), 1.32 (CI 0.69–2.54), and 6.23 (CI 3.81–10.16) in patients with no, non-obstructive, and obstructive CAD respectively (p < 0.001). Coronary calcification and obstructive CAD were associated with 5-fold (HR 5.25, 95% CI 1.66–16.59, p = 0.005) and 6-fold (HR 6.35, 95% CI 2.70–14.89, p < 0.001) greater hazards of MACE respectively in multivariable models, with no significant interaction by ethnicity in these associations seen. ConclusionsThe prognostic value of coronary calcification and CAD on CTCA amongst remote Indigenous individuals appears similar to that seen in non-Indigenous populations. Our data suggest that coronary artery calcium scoring and CTCA can be used to risk-stratify in remote settings where a normal study is associated with an excellent prognosis for at least two years.