Background Patients with Systemic Lupus Erythematosus (SLE) are at increased risk of premature mortality due to myocardial infarction (MI). The underlying mechanisms are not fully understood. This study aims to generate new hypothesizes on these mechanisms through description of MI subtypes and locations and by identifying risk factors for MI.

Methods We identified 35 SLE patients with and a first-time non-procedural MI (MI-SLE). We matched these 35 MI-SLE patients to 35 patients with MI but not SLE (MI-nonSLE) and 35 patients with SLE but not MI (nonMI-SLE) for gender, age and geographical location. Patients and controls were matched individually (1:1:1). Detailed retrospective medical file review was performed.

Results Median age was 62 years and 89% were female in all groups. Prevalence of ST-elevation MI was similar in MI-SLE patients and MI-nonSLE patients (27% vs 36%; p=0.80). The left ventricle was the most commonly infarcted in both MI-SLE and MI-nonSLE - 77% vs 59% according to coronary angiography and 42% vs 55% according to echocardiography. The left ventricular ejection fraction was similar in MI-SLE and MI-nonSLE patients (p=0.62). MI with coronary atherosclerosis was trends wise more common in MI-SLE patients compared to MI-nonSLE patients (88% vs 66%; p=0.065). Previous cardiovascular disease (43%, 5.7%, 14%; p<0.001), coronary artery disease (31%, 2.9%, 2.9%; p<0.001) and low plasma albumin levels (35 g/L, 40 g/L, not determined; p=0.001) distinguished MI-SLE patients from MI-nonSLE and nonMI-SLE patients.

Conclusion Coronary atherosclerosis was present in a large majority of MI-SLE patients at the event of MI. In addition, coronary artery disease preceding MI was more prevalent in SLE patients than in the general population, indicating accelerated coronary atherosclerosis as a cause of increased MI prevalence in SLE. Among SLE patients, low albumin levels were a risk factor for MI.