Scleraxis as a prognostic marker of myocardial fibrosis in hypertrophic cardiomyopathy (SPARC) study.

Interstitial fibrosis is a histopathological hallmark of hypertrophic cardiomyopathy (HCM). Although extracellular matrix (ECM) biomarkers, including matrix metalloproteinases, are overexpressed in HCM patients, they do not correlate with sudden cardiac death (SCD) risk. The objective of this study was to determine whether scleraxis, a transcription factor that regulates collagen gene expression, is detectable in HCM patients and correlates with disease burden. Between 2017 and 2018, a total of 46 HCM patients were enrolled (58 ± 14 years (31 males, 15 females)) with a mean 5 year SCD risk of 2.3% ± 1.3%. Cardiac MRI confirmed HCM in all patients with a mean interventricular septal thickness of 20 ± 2 mm. Late gadolinium enhancement (LGE) was present in 32 (70%) study participants occupying 18% ± 7% of the left ventricular (LV) myocardium. Serum scleraxis levels were significantly higher in the HCM patients by approximately twofold as compared to controls (0.76 ± 0.06 versus 0.32 ± 0.02 ng/mL, p < 0.05). No correlation was demonstrated between serum scleraxis levels and markers of disease severity in HCM patients, including maximum LV wall thickness, %LGE, and SCD risk factors. Serum scleraxis is elevated in the HCM population. Future studies are warranted to evaluate the prognostic value of scleraxis in identifying high-risk HCM patients who require aggressive management for prevention of SCD.