[The mechanism of giant negative T wave in electrocardiogram in patients with apical hypertrophic cardiomyopathy: evaluation with thallium-201 and iodine-123 metaiodobenzylguanidine myocardial scintigraphy].

The aims of this study were to clarify the mechanism of giant negative T waves (GNT) in patients with apical hypertrophic cardiomyopathy (AHCM), using myocardial SPECT with thallium-201 (201TI) and iodine-123 metaiodobenzylguanidine (123I-MIBG). Myocardial SPECT in 8 patients with AHCM, diagnosed with GNT in EKG and apical hypertrophy in echocardiogram, were compared with those in 7 normal subjects. The EKG in patients with AHCM showed tall R waves, GNT and ST segment depression in the left precordial leads. With the SPECT, the ratio of radioisotope activities apical ROI vs. other ROI (anterior, septal and lateral segments) were calculated. The ratio of 201TI was high in AHCM, compared with that of normal subjects, suggested the increase in apical myocardial blood flow. The ratio of 123I-MIBG tended to be low in AHCM. The 201TI/123I-MIBG ratio was high in the apical myocardium in AHCM, indicated low sympathetic nerve activities, though there was myocardial hypertrophy. We concluded that giant negative T waves in apical hypertrophic cardiomyopathy might be due to relatively low cardiac sympathetic nerve activities in apical myocardium with idiopathic hypertrophy.