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 cardiology department in a large referral hospital. Thirty patients (18 men, 12 women, mean age 56 ± 12 years) with systemic amyloidosis verified by biopsy and strong indications of cardiac amyloidosis comprised the study group, with 30 healthy age- and sex-matched individuals serving as controls. Complete M-mode and two-dimensional echocardiographic 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 amyloidosis was significantly greater than that of the control group, as was the ratio LVmass/body surface area (p < 0.001). There was no significant difference in the max QT interval or in QT_c dispersion between the two groups, although the max QT_c was greater in the patients with cardiac amyloidosis. Patients with cardiac amyloidosis did not have a higher incidence of arrhythmias than the controls. Although patients with thickened cardiac walls due to cardiac amyloidosis have a prolonged QT_c in comparison with controls, they do not show an increase in interlead QT_c dispersion which might suggest the possibility of regional disturbances of the uniformity of repolarization. Patients with cardiac amyloidosis do not have a higher incidence of arrhythmias than controls.