Myocarditis in beta-thalassemia major. A cause of heart failure.

BACKGROUND

Although acute pericarditis is a common complication of beta-thalassemia major, the prevalence and consequences of myocarditis in this disease have not been investigated.

METHODS AND RESULTS

A prospective 5-year follow-up study was carried out in all patients with beta-thalassemia major in whom the diagnosis of acute infectious myocarditis could be established between 1977 and 1986. A similar number of age- and sex-matched control subjects with beta-thalassemia and normal left ventricular function and no evidence of myocarditis were also followed for 5 years. Of 1048 patients with beta-thalassemia major, 47 patients (age, 15 +/- 2.5 years) with precordial chest pain were diagnosed as having acute infectious myocarditis. Myocardial biopsy was diagnostic in 26 patients, border-line in 14 patients, and nondiagnostic in 7 patients. Acute heart failure with left ventricular dysfunction (left ventricular ejection fraction, 25 +/- 11%) developed in 11 patients (23.4%) with myocarditis, and 8 of them died within 1 month to 1 year after diagnosis. Thirteen patients with myocarditis (27.6%) developed chronic heart failure (left ventricular ejection fraction, 26 +/- 13%) within 3 +/- 1.3 years, and 10 of them died within 8 +/- 3 months. Left ventricular systolic and diastolic functions of the control subjects did not change significantly during the 5-year period (left ventricular ejection fraction, 63 +/- 11% versus 65 +/- 7%; P = NS). However, left ventricular restrictive abnormalities (early diastole/late diastole, > 2.2; deceleration time, < 110 milliseconds) combined with right ventricular dilatation (> 30 mm internal diameter) and right-sided heart failure developed in 3 patients with extremely high mean serum ferritin levels. No significant difference was found in mean levels of serum ferritin and pretransfusion hemoglobin between patients with and those without myocarditis.

CONCLUSIONS

In patients with beta-thalassemia, myocarditis appears to be involved in the pathogenesis of left ventricular systolic dysfunction, being the main cause of death. Iron overload appears to provoke left ventricular restrictive abnormalities combined with right ventricular enlargement and dysfunction.