To assess the efficacy of angiotensin II receptor blocker, Losartan, to prevent progressive dilation of aortic root in patients with Marfan syndrome.

Marfan syndrome (MFS) is a multisystem connective tissue disorder of autosomal dominant inheritance1. The cardinal features are noted in the cardiovascular, ocular, and skeletal system. The most life-threatening complication of MFS is progressive aortic root dilation leading to aortic dissection or rupture. Losartan, an angiotensin II type I receptor (AT1) antagonist, is a drug already in clinical use for hypertension and type II diabetic nephropathy. A recent study showed that Losartan prevents aortic root dilation and lung problem in a mouse model of MFS. Therefore, the goals of this clinical trial are to examine the efficacy and safety of Losartan in patients with Marfan syndrome for aortic root dilation prevention.

Inclusion criteria

• Marfan syndrome with recognized aortic root dilation
• Patients must be older than one year of age
• Beta-blocker treatment at least three months
• Must sign an informed consent form

Exclusion criteria

• Prior to aortic root surgery
• Aortic root dimension more than 5.5cm
• Aortic surgery within 6 months
• Diabetes mellitus or liver and renal dysfunction or asthma
• Pregnancy
• Intolerance to Losartan therapy