Introduction: The MIOT (Myocardial Iron Overload in Thalassemia) Network was a network of thalassemia and CMR centers built in 2006 in order to assure homogeneous and standardized cardiac iron overload assessment for a significant number of patients.
Purpose: We describe the impact of this ten-year Network on cardiac iron, complications and deaths in patients with thalassemia major (TM).
Methods: 1746 TM patients (911 F; age 31.17±9.09 yrs) were enrolled in the MIOT Network. Myocardial iron overload (MIO) was quantified by the multislice multiecho T2* technique. Biventricular function was quantified by cine images.
Results: 1392 TM patients performed an end-of-study CMR. At the last CMR significantly higher global heart T2* values (35.44±10.69 ms vs 29.16±12.02 ms; P<0.0001) and a significant lower number of patients with global heart T2*<20 ms (26.3% vs 12.0%; P<0.0001) were detected. Four patterns of MIO were identified: no MIO (all segments with T2*≥20 ms), heterogeneous MIO and global heart T2*≥20 ms, heterogeneous MIO and global heart T2*<20 ms, and homogeneous MIO (all T2*<20 ms). At the last CMR a significant higher frequency of patients with no MIO and a significant lower frequency for the other three patterns indicating MIO were found (Figure 1).
In patients with global heart T2*<20 ms a significant increase in left ventricular ejection fraction (EF) (difference: 3.2±8.5%, P<0.0001) as well as in right ventricular EF (difference: 1.2±8.9%, P=0.002) were detected.
Based on CMR results the 75% of the patients changed the chelation therapy. At the last CMR the percentage of patients with an excellent/good compliance was significantly higher (94.8% vs 92.2%%; P<0.0001).
The complete history of cardiac complications-CC (heart failure, arrhythmias, pulmonary hypertension, myocardial infarction, angina, myo/pericarditis, peripheral vascular disease) was present for 1062 patients. Out of the 1001 patients with resolved CC or without CC before the enrolment in the project, the 6.6% had a CC before the enrolment in the project. During the study, the frequency of CC was 4.4%, significantly lower (P=0.023). In particular, the frequency of heart failure (HF) was significantly lower (3.5% vs 0.8%, P<0.0001).
Forty-six patients died during the study. HF continues to be the leading cause of death (30.4% of all causes), but there was a consistent decline in HF mortality rate, that was 60.2% in an Italian study dated 2004. No patients died for arrhythmias while cancer was the second leading cause of death.
Conclusion: Over a period of 10 years, the continuous monitoring of cardiac iron levels and a tailored chelation therapy allowed a reduction of MIO in the 70% of patients, with consequent improvement of cardiac function and reduction of cardiac complications and mortality from MIO-related HF. So, a national networking was effective in improving the care and reducing cardiac outcomes of TM patients.