People with systemic lupus erythematosus (SLE) taking antimalarials, particularly for prolonged periods, could be at risk for cardiomyopathy, and measuring specific myocardial biomarkers could help identify patients at particularly high risk, researchers have suggested.
Writing in the Journal of Rheumatology, the research team led by Konstantinos Tselios, MD, PhD, of the University of Toronto Lupus Clinic at the Centre for Prognosis Studies in the Rheumatic Diseases, noted that antimalarial-induced cardiomyopathy (AMIC) had been reported in 47 patients to date, 19 of whom had SLE, with duration and cumulative use of antimalarials thought to be the cause.
The authors suggested that AMIC could be underrecognized because antimalarials were currently recommended for all patients with SLE (without known contraindications) for prolonged periods. It was speculated that the mechanism by which AMIC occurred involved the deposition of antimalarials in the myocardial fibers and that this could lead to chronic, subclinical tissue necrosis, a process which, if not reversed, could lead to heart failure.
“Heart-specific biomarkers, such as cardiac troponin (for the assessment of myocardial necrosis) and brain natriuretic peptide (BNP; for the assessment of volume and/or pressure overload), may be of value in identifying subclinical heart damage,” the research team suggested.
The current study involved 151 consecutive patients with SLE who had no prior cardiac disease and were attending the University of Toronto Lupus Clinic from March to May 2016.
During the course of the disease, 28 of the patients had been taking chloroquine, and 137 had been taking hydroxychloroquine (14 patients had been treated with both drugs at different time periods). In the study, normal range was less than 26 ng/mL for high-sensitivity cardiac troponin I (cTnI) and less than 100 pg/mL for BNP.
Overall, 16 patients (10.6%) had abnormal BNP, of whom 9 (6%) also had abnormal cTnI. Prolonged antimalarial use (greater than 5.6 yrs) was associated with increased risk for these elevated biomarkers, regardless of age and SLE disease duration.
“Because duration of AM [antimalarial] treatment is the critical predictor of AMIC, the majority of patients with SLE should be considered at risk because most of them receive long-term maintenance therapy,” the researchers wrote.
They said that elevations of the biomarkers implicated possible active myocardial necrosis (elevated cTnI) and/or increased intracardiac ventricular pressure (elevated BNP).
“In this context, AM deposition in the myocardium, leading over time to overt cardiomyopathy, may be an important contributing factor. Indeed, 6 out of 16 of these patients were ultimately diagnosed with definite or possible AMIC, while 3 of them were completely asymptomatic, and their investigation was initiated because of the abnormal biomarkers,” they wrote.
The researchers also found that persistent creatine phosphokinase (CPK) elevation was also an important predictor for elevated cardiac biomarkers.
“We showed that chronic AM use is associated with a more than threefold increased risk for elevated CPK (after excluding patients with active myositis and statin therapy). ... It is not known whether elevated CPK may predict patients at risk for development of AMIC or whether certain patients are predisposed to AM-related muscle damage,” they said.
“Prolonged AM therapy and persistent CPK elevation conferred an increased risk for abnormal BNP and cTnI, which might predict AMIC,” they concluded.
Nevertheless, the authors acknowledged that expensive and invasive investigation was unjustified in asymptomatic individuals. They therefore suggested that identifying heart-specific biomarkers for the detection of subclinical heart damage could allow patients to be stratified according to their risk.
“Cardiac biomarkers could become a screening test for patients with SLE using AM for longer than 5.6 years and/or who have persistently elevated CPK levels. Further research is needed to delineate the differential toxicity of CQ [chloroquine] and HCQ [hydroxychloroquine],” they suggested.
The University of Toronto Lupus Research Program is supported by the University Health Network, Lou and Marissa Rocca, and the Lupus Foundation of Ontario. Dr. Tselios is financially supported by Lupus Ontario.
SOURCE: Tselios K et al. J Rheumatol. 2018. doi: 10.3899/jrheum.171436.