Heart failure in beta-thalassemia syndromes: a decade of progress.
The thalassemias are common monogenic disorders of hemoglobin synthesis. beta-thalassemias are the most important among the thalassemia syndromes and have become a worldwide clinical problem due to an increasing immigrant population. In beta-thalassemia major, regular blood transfusions are necessary early in life. Beta-thalassemia intermedia refers to a less severe phenotype, whereas beta-thalassemia/hemoglobin E disease encompasses a broad phenotypic spectrum. Blood transfusions and increased gastrointestinal iron absorption result in iron overload and tissue damage. Among patients with beta-thalassemia major, biventricular, dilated cardiomyopathy remains the leading cause of mortality. In some patients, a restrictive type of left ventricular cardiomyopathy or pulmonary hypertension is noted. The clinical course, although variable and occasionally fulminant, is more benign in recent than in older series. Myocarditis has been described as a cause of left-sided heart failure in younger patients. Pulmonary arterial hypertension is the principal cause of heart failure in beta-thalassemia intermedia. Chelation therapy has improved prognosis in beta-thalassemia major both by reducing the incidence of heart failure and by reversing cardiomyopathy. Estimation of the patient's cardiac risk is mainly based on clinical criteria and serial echocardiography. A new cardiovascular magnetic resonance technique will probably fulfill the need for more precise risk stratification in beta-thalassemia syndromes. By increasing the proportion of patients on optimal chelation, survival in beta-thalassemia major may further improve. Recent advances in gene therapy are expected to result in the long-awaited cure of this disease.