Asymptomatic cardiac involvement in Thai systemic sclerosis: prevalence and clinical correlations with non-cardiac manifestations (preliminary report)

Objective. To determine the prevalence of asymptomatic cardiac involvement and its correlation with non-cardiac manifestation in Thai SSc patients. Methods. A cross-sectional study was carried out between January 2012 and June 2013 at Srinagarind Hospital, Khon Kaen University, Thailand, on adult SSc patients without signs or symptoms suggestive of cardiac involvement. We excluded those with overlap syndrome, having serum creatinine >123.8 mu mol/l, history of cardiac diseases, any atherosclerosis risk factors and receiving angiotensin-converting enzyme inhibitors. Non-invasive tests related to cardiac involvement were performed, including: echocardiography, ECG, chest X-ray, inflammatory biomarkers, cardiac enzymes and N-terminal prohormone of brain natriuretic peptide. Results. A total of 103 SSc patients were enrolled, 61.2% of whom were in the subset. Of these, 63 patients had at least one test abnormality (prevalence 61.2%; 95% CI 51.6, 70.7). The two leading cardiac abnormalities were diastolic dysfunction (44.7%) and elevation of cardiac enzymes (36.9%). The only predictor for cardiac involvement per multivariate analysis was the dcSSc subtype with a higher modified Rodnan skin score, and shorter disease duration (odds ratio = 3.37; 95% CI 1.07, 10.65). Compared with the limited subtype, dcSSc was also significantly associated with elevated cardiac enzyme and prolonged distance between a Q wave and T wave in an ECG (QT interval). Conclusion. Asymptomatic cardiac involvement in Thai SSc was not uncommon, and the most common finding was diastolic dysfunction. Elevated cardiac enzymes were found in one-third of the patients, which correlated with the dcSSc subtype with a higher modified Rodnan skin score and shorter disease duration, suggestive of early myocardial microcirculation disruption. Long-term follow-up was performed to elucidate the clinical implication of these abnormalities.