Cardiac involvement in systemic lupus erythematosus (SLE) is often undiagnosed in its early phases. Specific heart biomarkers may identify patients at risk. We sought to investigate the prevalence and associated factors for such biomarkers in SLE.
Brain natriuretic peptide (BNP) and cardiac troponin I (cTnI) were measured simultaneously in 151 consecutive patients with no history of heart disease or pulmonary arterial hypertension (PAH). None had electrocardiographic abnormalities suggestive of acute coronary syndrome. Cross-sectional comparisons and logistic regression analyses were performed. Patients with abnormal biomarkers were investigated to delineate the specific cause.
Sixteen patients (16/151, 10.6%) had elevated BNP, and 9 of them also had abnormal cTnI. Compared to subjects with normal biomarkers, they were older, had longer disease and antimalarial (AM) use duration, and more frequently persistent creatine phosphokinase (CPK) elevation. Multivariable regression analysis showed prolonged AM treatment (> 5.6 yrs) and persistent CPK elevation to be important predictors for elevated cardiac biomarkers. Six patients were diagnosed with definite (based on endomyocardial biopsy, n = 2) or possible (based on cardiac magnetic resonance after exclusion of other causes) AM-induced cardiomyopathy (AMIC); all had both BNP and cTnI elevated. Alternative causes were identified in 5, while no definitive diagnosis could be made in the remaining patients.
About 10% of patients with SLE had elevated myocardial biomarkers, in the absence of prior cardiac disease or PAH. One-third of them were diagnosed with AMIC. Prolonged AM therapy and persistent CPK elevation conferred an increased risk for abnormal BNP and cTnI, which might predict AMIC.