Preclinical thalassemic cardiopathy: a study by acoustic densitometry

The cardiac function in thalassemia major has never been studied at ultrasonic backscatter techniques. We assessed the utility of acoustic densitometry in thalassemic patients without clinical or echocardiographic signs of heart failure.

Three groups of subjects with comparable age, sex and body surface area were analyzed: 25 with beta-thalassemia major (group A), 14 with thalassemia intermedia (group B) and 10 healthy subjects (group C). All patients were asymptomatic and without conventional echocardiographic signs of systo-diastolic dysfunction. The left ventricular mass and volumes were echocardiographically evaluated. The ultrasonic myocardial integrated backscatter signal (IBS) was recorded and analyzed by means of acoustic densitometry in the parasternal long-axis view at the septum and posterior wall, both at the basal and intermediate levels. Both the average image intensity and the systo-diastolic variations of the IBS (cyclic variation index-CVIibs and peak-to-peak intensity-PPI), respectively related to the structure and contractility of the myocardium, were calculated. The serum ferritin and liver iron concentrations were also measured, as markers of tissue iron storage.

The CVIibs was significantly lower in groups A and B than in group C at basal (22.7 +/- 8.4 vs 22.1 +/- 7.8 vs 31.8 +/- 10.2%; p = 0.001) and intermediate septum (24.4 +/- 7.6 vs 25.3 +/- 8.1 vs 30 +/- 9.8%; p = 0.03) and at basal (25.9 +/- 7.6 vs 24.5 +/- 6.1 vs 31.1 +/- 10.6%; p = 0.02) and intermediate posterior wall (25.1 +/- 5.1 vs 24.3 +/- 6.2 vs 30.2 +/- 6.6%; p = 0.02). The PPI was also significantly lower in groups A and B than in group C. Both CVIibs and PPI were comparable in groups A and B. The average image intensity and left ventricular mass and volumes were not significantly different in the three groups. No correlation was found between the densitometric findings and markers of tissue iron storage.

In asymptomatic patients with thalassemia major with normal conventional indexes of systo-diastolic cardiac function, acoustic densitometry may show a reduced cyclic variation of the IBS as a possible marker of initial myocardial contractile deficiency. On the contrary, neither structural alterations nor the extent of myocardial iron stores are detectable by this technique in this type of patients.