Multi-Parametric Cardiac Magnetic Resonance for Prediction of Cardiac Complications in Thalassemia Intermedia: A Prospective Multicenter Study

Introduction: Cardiovascular Magnetic Resonance (CMR) has an established role in managing and predicting prognosis of patients with Thalassemia Major (TM). Thalassemia Intermedia (TI) is a milder variant of beta-thalassemia showing a different clinical and prognostic profile; pulmonary hypertension (PH) is a more common complication in TI patients. We prospectively determined the predictive value of CMR parameters, including measurement of right ventricular mass, for cardiac complications in TI.

Methods: We considered 342 TI patients enrolled in the Myocardial Iron Overload in Thalassemia network; about half of them (178/302, 58.9%) were transfusion-dependent. Myocardial and liver iron overload were measured by T2* multiecho technique. Atrial dimensions, left and right ventricular mass and systolic function were quantified by cine images. Late gadolinium enhancement (LGE) images were acquired to detect myocardial fibrosis.

Results: Twenty-three patients were excluded because a cardiac complication was present at the time of first CMR, so we prospectively followed 319 patients.

All 319 patients were white, with a mean age at time of their first scan of 38.02±11.69 years and 165 (51.7%) of them were females.

Mean follow-up time was 52.24±24.87 months (median 54.64 months).

Cardiac events were recorded in 22 patients (6.9%): heart failure (HF) in 1 patient, arrhythmias in 12 patients, pulmonary hypertension (PH) in 7 patients and myocardial infarction (MI) in 2 patients.

Due to the low number of events, only arrhythmias, PH and cardiac complications globally considered were taken as cardiac outcomes for univariate and multivariate analysis.

In the multivariate analysis RV hypertrophy was the only independent predictive factor for arrhythmias (HR=33.83, 95% CI=6.07-188.74, P<0.0001) and PH (HR=73.33, 95% CI=10.00-537.57, P<0.0001). When cardiac complications were considered all together, RV hypertrophy (HR=24.12, 95% CI=5.09-114.12, P<0.0001) and myocardial fibrosis by LGE (HR=6.59, 95% CI=1.33-32.67, P=0.021) were independent prognostic factors in the multivariate analysis.

The Figures display the Kaplan-Meier curves showing the impact of the independent predictive factors on each outcome.

Conclusions: For the first time we studied the prognostic value of right ventricular mass as part of multiparametric CMR imaging in a population of TI patients. RV hypertrophy identified patients at high risk for arrhythmias and PH. Both RV hypertrophy and fibrosis detected by LGE were independent predictive factor for cardiac complications. Measurement of RV mass should be part of the multi-parametric CMR study of patient with thalassemia intermedia.

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