ABSTRACT
OBJETIVO - Avaliar a medida da dispersäo do QT (DQT) em portadores de hipertensäo arterial sistêmica, com e sem hipertrofia ventricular esquerda (HVE) e comparar com indivíduos normais. MÉTODOS - Foram submetidos a ecocardiograma e eletrocardiograma (ECG) de 12 derivaçöes simultâneas, alinhadas, na velocidade de 50mm/s, 38 pacientes (21 homens e 17 mulheres, com idade média 55ñ15 anos). Nenhum deles estava em uso de antiarrítmicos. Dezenove eram näo hipertensos constituindo o grupo controle (G-I); 19 hipertensos (GII), sendo 9 sem HVE (índice de massa 96ñ33g/m²=GIIa) e 10 portadores de HVE (índice de massa 163ñ33 g/m²=GIIb). A DQT foi obtida pela subtraçäo entre o mior e o menor QT medidos nas 12 derivaçöes, obtendo-se a média de 3 batimentos consecutivos. RESULTADOS - A DQT foi maior nos indivíduos hipertensos com ou sem HVE, quando comparada com indivíduos controles (G-I31ñ9ms, G-II52ñ15ms, P<0,001; G-IIa 46ñ10ms e G-IIb 56ñ18ms X G-I, p<0,0005). Entretanto, quando comparamos entre si os indivíduos hipertensos com e sem hipertrofia ventricular esquerda, apesar de ter havido diferença em valores absolutos quando testado estatisticamente, essa diferença näo foi identificada. CONCLUSÄO - A DQT é significativamente maior nos indivíduos hipertensos e estas modificaçöes ocorrem antes do aparecimento de HVE, sugerindo que alteraçöes elétricas do miocárdio podem preceder alteraçöes morfológicas e estruturais. Estes achados podem servir como subsídios para a compreensäo dos mecanismos relacionados à maior mortalidade dos hipertensos
Purpose - To evaluate QT dispersion in hypertensive patients, with and without left ventricular hypertrophy, and compare with normal persons. Methods - Thirty eight patients (21 male and 17 female, age 55±15 years) underwent echocardiography and simultaneous 12 lead, vertically aligned, electrocardiogram at 50mm/s speed. No patient was on antiarrythmic therapy. There were 19 non-hypertensive patients that constituted the control group (G-I). Group II was constituted by the other 19 patients, who were hypertensives. This group was further divided in group II-A (9 patients without left ventricular hypertrophy) and group II-B (10 patients with left ventricular hypertrophy). QT dispersion was obtained by the difference between the longest and the shortest QT registered. Results - QT dispersion was significantly increased on hypertensive patients, both with and without left ventricular hypertrophy, when compared to controls (G-I 31±9 ms, G-II 52±15ms, P<0.0001; G-IIa 46±10ms and GIIb 56±18ms X G-I, p<0.0005). In hypertensive patients, there was no statistically significant difference between group II-A and group II-B. Conclusion - We conclude that QT dispersion is significantly increased on hypertensive patients when compared to non-hypertensive individuals and that such increase, occurs before left ventricular hypertrophy develops. These findings suggest that, in hypertensive patients, electrical changes in left ventricular myocardium can precede structural and morphological abnormalities. Such findings offer new insights into the mechanisms related to enhanced mortality among hypertensive patients