Cardiac magnetic resonance in transfusion dependent thalassaemia: assessment of iron load and relationship to left ventricular ejection fraction.

Cardiac Magnetic Resonance (CMR) has replaced all other surrogate measurements in the determination of transfusional cardiac iron overload in patients with thalassaemia major. We aimed to determine the diagnostic value of CMR T2* with respect to cardiac dysfunction (CD) as determined by CMR-derived left ventricular ejection fraction (LVEF). Cardiac T2* values and LVEF measured by CMR were recorded in 303 patients with thalassaemia major, at the time of their first CMR. T2* was correlated with LVEF (regression coefficient: 0·57, P<0·001). The prevalence of CD was 32·9% in patients with T2*≤8 ms, 12·5% in patients with T2*>8 ms and ≤14 ms and reduced to 9·1% in patients with T2* between 14-20 ms. As the probability of CD is progressively, and not suddenly, reduced with increasing values of T2*, CMR has a limited diagnostic value for CD (Receiver operating characteristic analysis, area under the curve = 0·68). Patients with cardiac T2*≤8 ms require careful and intensive management. This risk decreases with increasing values of T2* but even in mildly loaded patients the probability of impaired LVEF is not negligible.

Comparison of echocardiographic (US) volumetry with cardiac magnetic resonance (CMR) imaging in transfusion dependent thalassemia major (TM).

BACKGROUND: Despite advances in survival in patients with thalassemia major (TM) the most common cause of death is cardiac disease. Regular cardiac follow-up is imperative in order to identify and reverse pathology. Cardiac Magnetic Resonance (CMR) and Echocardiography (US) are applied in parallel to TM patients for cardiac evaluation and ongoing monitoring. A comparison between mutual features would be useful in order to assess the accuracy and reliability of the two methods, with a particular focus on routine US application. TM's special attributes offer an excellent opportunity for cardiac imaging research that has universal general purpose applications. METHODS: 135 TM patients underwent US (Teichholz's M-mode formula - rapidly accessible means of measuring volumes and ejection fraction) and CMR volumetry. Paired-samples t-test, Passing & Badlock regression and Bland & Altman plot were used while comparing the common parameters between the CMR and the US. RESULTS: We found that the US volumes were underestimated, especially the end-diastolic volume (p < 0.001). The end-systolic volume showed a borderline two-tailed probability (p approximately 0.05). The correlation for the ejection fraction was acceptable (r = 0.60) without a statistically significant difference (p = 0.37) and the Bland Altman plot range was narrow (25.8%). There was a satisfactory correlation of the US' shortening fraction with CMR's ejection fraction (r = 0.58). CONCLUSION: In cases where cardiac wall movement abnormalities are absent, the US Teichholz's M-mode formula for volume measurements, though less sophisticated in comparison to the high resolution CMR technique, offers an adequate ejection fraction estimation for routine use, especially when monitoring gross alterations in cardiac function over time, and is easy to perform.

Cardiac magnetic resonance imaging R2* assessments and analysis of historical parameters in patients with transfusion-dependent thalassemia.

Recent advances in magnetic resonance imaging (MRI) techniques allow the assessment of iron overload in tissues 1 especially the heart, 2 in transfusion-dependent thalassemia patients. The R2* value (1/T2*) recorded in the intraventricular septum of the heart indirectly measures the degree of cardiac iron load. Applying this new technology we looked at a number of historical and biochemical parameters in order to determine their relationship to cardiac iron overload and the effect of cardiac iron on functional and structural changes of the heart in transfusion-dependent thalassemics.

Correlation of echocardiography parameters with cardiac magnetic resonance imaging in transfusion-dependent thalassaemia major.

BACKGROUND AND OBJECTIVE: Heart iron load (cardiac Fe) can be indirectly quantified by cardiac magnetic resonance (CMR) T2*. CMR accessibility is limited, whereas echocardiography (Echo) is relatively inexpensive and readily available. The objective was to find Echo parameters that may be useful for predicting cardiac Fe. DESIGN AND METHODS: We compared a number of parameters derived from Echo to cardiac Fe in 142 thalassaemia major patients who had undergone a CMR study. RESULTS: All patients with decreased left ventricular (LV) function had cardiac Fe. After removing those patients from the analysis, the total diameter index (Tdi) >5.57 cms/m2, left atrial diameter index >2.41 cm/m2, and the diastolic parameter E/A > 1.96 were highly specific (91.4%, 97.1% and 96.9% respectively) but had low sensitivity (31.8%, 20.45% and 21.8%) in predicting iron load. A right ventricular index >1.47 cm/m2, LV systolic index >2.26 cm/m2 or Tdi >6.26 cm/m2 discriminated between patients with no, or mild to moderate cardiac Fe from those with heavy load, with specificity of 91%, 98.5%, and 98.5%, respectively, but with low sensitivity. INTERPRETATION AND CONCLUSIONS: Echo parameters for cardiac Fe prediction have restricted value, whereas CMR is essential to assess cardiac Fe. However, patients with decreased LV systolic function should be considered a priori as having cardiac Fe, and chelation therapy should be intensified. This also applies to patients who have the above-described Echo criterion values, even if CMR is not available. Once a patient is found by CMR to have cardiac Fe, then the above Echo criterion values may be useful for ongoing monitoring.