Introduction Patients with systemic lupus erythematosus (SLE) are affected by morbidity and premature mortality from cardiovascular disease (CVD) – commonly defined as myocardial infarction (MI), coronary artery disease (CAD), stroke and/or peripheral arterial disease (PAD). To date, neither MI subtypes, locations nor risk factors for MI specifically have been fully investigated in SLE.

Aims To study the subtypes, locations and risk factors of the first-time MI in patients with SLE.

Material and methods SLE patients with a first-time MI (SLE-MI), meeting the Third Universal Definition of MI, were included in a cross-sectional investigation of our SLE cohort (n=650). As comparators, MI-free SLE patients (SLE-nonMI) from the same cohort were individually matched for age and gender. Data were collected through retrospective medical record review, including reports on ECG, echocardiography and coronary angiography. Potential risk factors for MI were investigated; previous CVD, including CAD (comprising stable CAD and unstable angina), ischaemic stroke and PAD, venous thromboembolism, diabetes, smoking habits, anti-phospholipid syndrome (APS), lupus nephritis, estimated glomerular filtration rate, prednisone equivalent dosage at MI, plasma/serum albumin, CRP and erythrocyte sedimentation rate. Paired tests, McNemar’s and Wilcoxon’s signed rank tests, were used as appropriate.

Results MI was diagnosed in 43/650 patients, 41/43 had a non-iatrogenic MI – i.e. MI not related to percutaneous coronary intervention, stent thrombosis or coronary artery bypass grafting. Of these, non-ST-elevation MI (NSTEMI) and MI with significant coronary atherosclerosis were the most prevalent subtypes (69% and 89%, respectively). Furthermore, atherosclerosis in the left anterior descending artery (LAD) was present in 75% of patients. The following factors differed between SLE-MI and SLE-nonMI: CVD (43% versus 20%; p=0.03), CAD (30% versus 0%; p=0.0002), diabetes (15% versus 0%; p=0.001), and albumin levels (35 g/L versus 40 g/L; p=0.0004). 23% of SLE-MI and 10% of SLE-nonMI patients met the criteria for definite APS prior to MI (p=0.17); post-MI, APS prevalence increased in patients with SLE-MI (43% versus 10%; p=0.0009).

Conclusions NSTEMI with angiography-verified atherosclerosis, most commonly in LAD, was the most prevalent MI subtype. Previous CVD (especially CAD), APS, diabetes, and decreased albumin levels distinguished SLE patients with MI from SLE patients without MI.