Abstract
BackgroundHeart failure remains a major cause of mortality in thalassaemia major. The possible role of cardiac fibrosis in thalassemia major in the genesis of heart failure is not clear. It is also unclear whether cardiac fibrosis might arise as a result of heart failure.MethodsWe studied 45 patients with thalassaemia major who had a wide range of current cardiac iron loading and included patients with prior and current heart failure. Myocardial iron was measured using T2* cardiovascular magnetic resonance (CMR), and following this, late gadolinium enhancement (LGE) was used to determine the presence of macroscopic myocardial fibrosis.ResultsThe median myocardial T2* in all patients was 22.6 ms (range 5.3-58.8 ms). Fibrosis was detected in only one patient, whose myocardial T2* was 20.1 ms and left ventricular ejection fraction 57%. No fibrosis was identified in 5 patients with a history of heart failure with full recovery, in 3 patients with current left ventricular dysfunction undergoing treatment, or in 18 patients with myocardial iron loading with cardiacT2* < 20 ms at the time of scan.ConclusionThis study shows that macroscopic myocardial fibrosis is uncommon in thalassemia major across a broad spectrum of myocardial iron loading. Importantly, there was no macroscopic fibrosis in patients with current or prior heart failure, or in patients with myocardial iron loading without heart failure. Therefore if myocardial fibrosis indeed contributes to myocardial dysfunction in thalassemia, our data combined with the knowledge that the myocardial dysfunction of iron overload can be reversed, indicates that any such fibrosis would need to be both microscopic and reversible.
Highlights
Thalassaemia is the commonest single gene disorder worldwide, with approximately 94 million heterozygotes for beta thalassaemia and 60,000 homozygotes born each year [1]
Heart failure is clearly related to intracardiac iron, it is less clear whether there is an additional contribution from myocardial fibrosis
In dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM), the fibrosis is a driver of the development of left ventricular (LV) dysfunction, and is directly linked to adverse cardiac outcomes such as heart failure and arrhythmias [15,17]
Summary
Thalassaemia is the commonest single gene disorder worldwide, with approximately 94 million heterozygotes for beta thalassaemia and 60,000 homozygotes born each year [1]. Myocardial siderosis is the major cause of mortality and is dominantly manifested as heart failure [2], which typically has a disguised onset that may deteriorate catastrophically as a result of a vicious cycle of increasing intracellular iron levels. This toxic cardiomyopathy can be reversible if chelation is commenced early [3], it may take years to reduce cardiac storage iron levels to normal. It is unclear whether cardiac fibrosis might arise as a result of heart failure
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