P1454: clinical determinants of cardiac iron in regularly transfused thalassemia intermedia patients

Topic: 27. Thalassemias Background: In sporadically transfused or transfusion naïve thalassemia intermedia (TI) patients, myocardial iron overload (MIO) by T2* cardiac magnetic resonance (CMR) was demonstrated to be a highly rare finding, despite the significant hepatic iron accumulation. Studies specifically addressing this issue or the clinical correlates of cardiac T2* values only in regularly transfused TI patients are lacking. Aims: We assessed the clinical determinants of global heart T2* values in regularly transfused TI patients. Methods: We considered 154 beta-TI patients (42.53±13.83years, 88 females) consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia project. Iron overload was quantified by a multiecho T2* technique. Results: Global heart T2* values were comparable between males and females as well as between patients without and with the spleen, but showed a weak positive correlation with aging (R=0.215, p=0.007). Global heart T2* values were inversely correlated with serum ferritin levels (R=-0.272, p=0.003) and with MR liver iron concentration (LIC) values (R=-0.240, p=0.039). Global heart T2* values showed no association with the duration of the transfusion therapy and a positive association with the duration of the chelation therapy (R=0.239, p=0.031). To detect the predictors of global heart T2* values, a stepwise regression analysis was performed, including in the model age, duration of chelation therapy, serum ferritin levels, and MRI LIC. Age and serum ferritin levels were the strongest predictors of global heart T2* values (F=18.24; p<0.0001). No variable was excluded from the multivariable models due to excessive collinearity. Applying the conservative 20 ms cut-off, the prevalence of significant MIO was 2.6%. When a more sensitive, protocol-specific cut-off (32 ms) was used, early MIO was found in 15 (9.7%) patients. At receiver-operating characteristic (ROC) curve analysis, a serum ferritin level>786 ng/ml predicted the presence of a pathological global heart T2* with a sensitivity=69.2% and a specificity=72.9% (p=0.042). The area under the curve was 0.69 (95% confidence intervals=0.61-0.78). Summary/Conclusion: In TI, regular transfusions increase the risk of MIO. Global heart T2* values showed a significant inverse correlation with both serum ferritin and hepatic iron levels and, surprisingly, the association with serum ferritin levels emerged as the strongest one. The introduced cut-off of 786 ng/ml may help to identify the patients at high risk for cardiac iron accumulation, in whom it would be prudent to escalate or modify the iron chelation therapy. Keywords: Iron overload, beta thalassemia