QT INTERVAL IN CARDIAC AMYLOIDOSIS

The aim of the study was to investigate whether cardiac amyloidosis is associated with QT interval abnormalities and ventricular arrhythmias . A controlled study of 30 patients was undertaken at a university car diology department in a large referral hospital. Thirty patients (18 m en, 12 women, mean age 56 +/- 12 years) with systemic amyloidosis veri fied by biopsy and strong indications of cardiac amyloidosis comprised the study group, with 30 healthy age- and sex-matched individuals ser ving as controls. Complete M-mode and two-dimensional echocardiographi c study was undertaken and QT interval and QT(c) were calculated. All patients and controls underwent 24-h Holter monitoring for arrhythmias . Left ventricular (LV) wall thickening was found in all patients with cardiac amyloidosis. The LV mass in the patients with cardiac amyloid osis was significantly greater than that of the control group, as was the ratio LVmass/body surface area (p < 0.001). There was no significa nt difference in the max QT interval or in QT(c) dispersion between th e two groups, although the max QT, was greater in the patients with ca rdiac amyloidosis. Patients with cardiac amyloidosis did not have a hi gher incidence of arrhythmias than the controls. Although patients wit h thickened cardiac walls due to cardiac amyloidosis have a prolonged QT(c) in comparison with controls, they do not show an increase in int erlead QT(c) dispersion which might suggest the possibility of regiona l disturbances of the uniformity of repolarization. Patients with card iac amyloidosis do not have a higher incidence of arrhythmias than con trols.