Prevalence and characterization of cardiac involvement in Hunter syndrome

To assess the prevalence of cardiovascular signs and symptoms in a large group of patients with Hunter syndrome, an X-linked metabolic disorder caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase.

The Hunter Outcome Survey was established to characterize the natural history of Hunter syndrome and to assess the response to enzyme replacement therapy. Echocardiographic and electrocardiographic examination results were available for 102 patients who were enzyme replacement therapy-naïve in the Hunter Outcome Survey (median age at examination, approximately 8 years) as of Jan 23, 2009.

The most common cardiovascular finding was valve disease, which was present in 63% of patients. Left ventricular hypertrophy (defined as left ventricular mass indexed to height(2.7) ≥50 g/m(2.7)) was found in 48% of patients <18 years old. Elevated blood pressure (defined as a Z score ≥2 for systolic blood pressure or diastolic blood pressure) was present in 25% of patients <18 years old. Other findings included abnormal heart frequency (7%), arrhythmia (5%), and congestive heart failure (6%).

Treating physicians should be aware of the early emergence of cardiovascular manifestations in patients with Hunter syndrome so that appropriate treatment can be initiated.