Pilot Study of Perindopril in Childhood Cancer Survivors

Inclusion Criteria: 1. Enrolled in the Survivor Cohort of the PCS2 study at The Hospital for Sick Children at the time of enrollment. 2. Aged \< 20 years at enrollment. 3. Weight ≥ 25kg at enrollment 4. LVPW Z-score ≤-2.0 at any of the 0, 12 or 24 month PCS2 echocardiography assessments, on two consecutive echocardiograms at least 3 but no more than 15 months apart. 5. EF greater than 50% at enrollment 6. Serum potassium (to be ˃5.0mMol/l) at Initiation Exclusion Criteria: 1. Known associated cardiac conditions for which angiotensin converting enzyme therapy is contraindicated (such as aortic stenosis, severe coarctation of the aorta, or hypertrophic cardiomyopathy with LV outflow tract obstruction) 2. Active malignancy detected within last 2 years (i.e. must be at least 2 years in remission) 3. Prior radiation therapy to a field that involved the heart 4. Prior symptomatic heart failure, or prior reduction in EF below 50% detected on surveillance echocardiography. 5. Use of any cardioactive medications including diuretics within the last 6 months 6. Concurrent serious or life threatening disease or extracardiac organ compromise which would limit participation in the trial or potentially have secondary effects on cardiac function, as determined by the treating physician. 7. Renal dysfunction precluding ACEi therapy, defined as serum creatinine greater than the 95th percentile for age or eGFR by the modified Schwartz formula of less than the 5th percentile prior to recruitment to the interventional trial (within 30 days of recruitment date) 8. Hypertension requiring treatment. 9. History of angioedema or ACEi hypersensitivity 10. Patients with hereditary problems of galactose intolerance, glucose-galactose malabsorption, or the Lapp lactase deficiency. 11. Upper airway obstructive lesions 12. Pregnancy 13. Breast-feeding