Efficacy of Carvedilol in Patients with Dilated Cardiomyopathy due to Beta-thalassemia major; a Double-blind Randomized Controlled Trial

Objective: Dilated cardiomyopathy is the end result of chronic iron overload in patients with beta thalassemia major. The objective of the present study was to evaluate the safety and efficacy of Carvedilol in patients with beta thalassemia major and dilated cardiomyopathy.
Methods: During a six-month period, fourteen patients with beta-thalassemia major and heart failure without diabetes mellitus referred to pediatric cardiology clinic enrolled in this double blind, randomly assigned study. All patients were on anti failure therapy with Digoxin, Captopril and Furosemide. Carvedilol was started at a dosage of 3.12 mg bid and for patients who had a systolic blood pressure >100 mmHg, heart rate >60/min and no signs of low cardiac output the dosage was increased every two weeks to a maximum of 25 mg bid. Clinical signs and symptoms, systolic and diastolic echocardiographic indexes and Tissue Doppler Imaging (TDI) data were collected from each patient.
Findings: Eight patients received Carvedilol (Group 1) and six received placebo (Group 2). The mean age of patients in Group1 and 2 were 16±0.7 years and 17±3 years respectively. Only one patent in Group 1 tolerated increasing Carvedilol dosage to more than 6.25 mg bid. Changes in New York Heart Association (NYHA) classification, Ejection fraction, End diastolic dimension changes, TDI systolic(S), early (Ea) and late (Aa) diastolic waves were not statistically significant in these two Groups (P>0.05). Pulse Doppler E/A wave ratio of mitral valve in Group1 and Group 2 changed from 1.1±0.37 m/s to 1.8±0.40 m/s and from 1.34±0.30 m/s to 2.6±0.23m/s respectively (P=0.04).
Conclusion: Patients with thalassemia and dilated cardiomyopathy have poor tolerance to increasing Carvedilol dosage and develop decreased systolic blood pressure during advancement of the drug dosage. Carvedilol can be effective in prevention of progression of diastolic dysfunction in these patients.

Keywords
Beta thalassemia major; Carvedilol; Heart filure; Dilated cardiomyopathy