ACEI: A maximally tolerated dose of the angiotensin converting enzyme inhibitor, lisinopril will be attempted in three steps at two-week intervals. The target maintenance dose ranges from 0.4 mg/kg to 0.6 mg/kg depending on the patient's weight. Patients who are unable to tolerate treatment with ACEI or who have been previously intolerant of ACEI will receive the angiotensin receptor blocker (ARB) losartan. The duration for the ACEI or ARB therapy is 18 months.