RESTRICTIVE DIASTOLIC ABNORMALITIES IDENTIFIED BY DOPPLER ECHOCARDIOGRAPHY IN PATIENTS WITH THALASSEMIA MAJOR

The consequences of transfusional iron overload on left ventricular diastolic filling have never been investigated systematically in patients with thalassemia major. In the present study, the pattern of left ventricular filling was assessed by Doppler echocardiography in 32 patients with thalassemia major (age, 17 ± 5 years) who had not experienced symptoms of heart failure and had normal left ventricular systolic function. Data were compared with those obtained in 32 age-matched and sex-matched normal subjects. An abnormal Doppler pattern of left ventricular filling with increased flow velocity at mitral valve opening followed by an abrupt and premature decrease of flow velocity in early diastole was identified in the patients with thalassemia. Peak flow velocity in early diastole was increased in patients compared with controls (90 ± 10 vs. 81 ± 15 cm/sec; p < 0.01), and rate of deceleration of flow velocity after the early diastolic peak and the ratio between the early and late (atrial) peaks of flow velocity were also increased (1,050 ± 325 vs. 762 ± 193 cm/sec2 and 2.7 ± 0.7 vs. 2.2 ± 0.5, respectively; p < 0.001), whereas flow velocity deceleration time was reduced (97 ± 22 vs. 119 ± 19 msec; p < 0.001). This Doppler pattern of diastolic filling is usually described as 'restrictive' and reflects a decrease in left ventricular chamber compliance. A restrictive pattern of left ventricular filling was also identified in the subgroup of 16 study patients who had undergone optimal iron chelation therapy with deferoxamine. Rate of deceleration of flow velocity after the early diastolic peak was increased, and flow velocity deceleration time was reduced in these 16 patients (1,080 ± 356 cm/sec2 and 94 ± 19 msec) compared with controls (795 ± 214 cm/sec2 and 118 ± 19 msec, respectively; p < 0.01). The results of this investigation demonstrate that left ventricular filling is altered in patients with thalassemia major and that diastolic abnormalities develop in an early phase of cardiac involvement, when symptoms of heart failure are absent and systolic function is normal. The findings of this study also suggest that chelation therapy with deferoxamine does not completely protect patients with thalassemia from myocardial damage due to iron-related cardiac toxicity.