Lack of prognostic value of normalized integrated backscatter analysis of myocardium in patients with thalassemia major: a long-term follow-up study.

ABSTRACT

BACKGROUND: Patients with beta-thalassemia major often present with severe anemia and must undergo continuous transfusion therapy, consequently developing iron overload leading to hemochromatosis. Because of these the iron deposits and/or secondary structural changes, patients develop an increase in myocardial integrated backscatter (IB). AIM: To investigate the prognostic value of analyzing acoustic quantitative properties of the myocardium in patients with beta-thalassemia major. PATIENTS AND METHODS: Between 1989 and 1990, 38 patients (mean age 18 years, range 7-26, 21 males) with beta-thalassemia major and without clinical signs of cardiac failure were enrolled prospectively. All patients were on chelation therapy (desferroxiamine). To obtain quantitative operator-independent measurement of the IB signal of the left ventricular septum and posterior wall, the ultrasonic radiofrequency signal integrated values were normalized to the pericardial interface and expressed in percentage (IB%). RESULTS: Follow-up was 122 +/- 36 months, during which 15 events (7 cardiac deaths and 8 heart failures) occurred. The event-free survival was comparable in patients with normal and abnormal IB%. Septal IB% was 33 +/- 14 in the 15 patients with events, and 33 +/- 12 in the 25 patients without events (P = ns). The %IB had no prognostic value in this population. A prognostic value was found in multivariate analysis for patient refusal/noncompliance of chelation therapy (P = 0.02, OR 4.37, 95% CI 1.72-16.9) and also body mass index (P = 0.04, OR 1.2, 95% CI 1.0-1.4). CONCLUSION: Analysis of end-diastolic IB% of myocardium in patients with beta-thalassemia and iron overload was not predictive of adverse cardiac events during long-term follow-up in this study.