LAUSR

Mucopolysaccharidosis type III (MPS III; Sanfilippo disease) is primarily characterized by neurocognitive decline with limited somatic disease. Only few reports addressed cardiac disease (CD) in MPS III. We investigated the prevalence of CD in a relatively large cohort of patients. In this cross‐sectional study, extensive echocardiographic studies were performed in 30 MPS III patients (16 patients <18 years), all without clinical symptoms of CD. Results were compared to data from matched controls. The mean global longitudinal strain on speckle‐tracking echocardiography (STE) was impaired in both pediatric and adult patients vs controls (resp. −18.4% vs −20.7%; mean difference 2.25, 95% CI 0.61‐3.89, P = 0.009 and −16.9% vs −19.5%; mean difference 2.64, 95% CI 0.78‐4.49, P = 0.007), indicating early systolic dysfunction. Left ventricle ejection fraction (LVEF) was normal in pediatric patients and (slightly) impaired in adult patients vs controls (48.7% vs 55.8%, P = 0.002). Tissue Doppler imaging (TDI) showed significantly slower early diastolic velocities (e′) compared to controls indicative for diastolic dysfunction. Furthermore, mitral and aortic valve abnormalities were prevalent (43% and 33% of patients, respectively). Finally, 15.6% of the patients had a first‐degree atrioventricular block on electrocardiography (ECG). The impaired STE reveals early, subclinical LV dysfunction which is supported by results of TDI. In addition, mild valvular disease and ECG abnormalities are prevalent. The lowered LVEF in adult patients suggests that the LV dysfunction is progressive, and may ultimately lead to clinical myocardial disease when patients live longer due to an effective disease‐modifying treatment of which a number of options are now in clinical trials.