Coronary artery calcification is prevalent in systemic sclerosis and is associated with adverse prognosis.

Objective: Coronary artery calcification assessed on thoracic computed tomography represents the calcific component of established coronary artery disease, is a biomarker of total atheromatous plaque burden and predicts mortality. Systemic sclerosis is a pro-inflammatory condition, and inflammation is also a driver of coronary artery disease. We assessed coronary artery calcification prevalence, mortality risk and potential clinical impact on primary prevention in a cohort of patients with systemic sclerosis, differentiated by clinical phenotype including the presence of interstitial lung disease and pulmonary arterial hypertension.

Methods: Retrospective analysis of 258 computed tomographies in systemic sclerosis patients from three prospectively maintained clinical and research databases at a single tertiary rheumatology/pulmonary hypertension (PH) service between March 2007 and September 2020 (mean age = 65 ± 12, 14% male). Co-morbidities, statin prescription and all-cause mortality were recorded. Patients were subtyped according to underlying systemic sclerosis complications. Computed tomographies were re-reviewed for coronary artery calcification; severity was graded using a 4-point scale per vessel and summed for total coronary artery calcification score. The impact of reporting coronary artery calcification was assessed against pre-existing statin prescriptions.

Results: Coronary artery calcification was present in 58% (149/258). Coronary artery calcification was more prevalent in systemic sclerosis-pulmonary arterial hypertension than in systemic sclerosis subgroups with interstitial lung disease or without pulmonary arterial hypertension, controlling for age, sex, co-morbidities and smoking status (71%; χ ²(13) = 81.4; p < 0.001). The presence and severity of coronary artery calcification were associated with increased risk of mortality independently of age and co-morbidities (hazard ratio = 2.8; 95% confidence interval = 1.2-6.6; p = 0.018). The 'number needed to report' coronary artery calcification presence to potentially impact management was 3.

Conclusions: Coronary artery calcification is common in systemic sclerosis. Coronary artery calcification predicts mortality independently of age and confounding co-morbidities which suggests this finding has clinical relevance and is a potential target for screening and therapeutic intervention.