Few data are available on the association between the prolonged heart rate-adjusted QT (QTc) interval and high blood pressure in elderly individuals, particularly in subjects over 80 years old. The aim of the present study was to determine the association between the QTc interval and blood pressure in 80-year-old subjects. This study was part of the 8020 Data Bank Survey, which was designed to collect the baseline data of systemic and dental health conditions in 80-year-old subjects. We studied the cross-sectional association of the QTc interval with blood pressure in 642 Japanese (257 men and 385 women), all 80 years old. Mean systolic blood pressure (SBP) rose from 146.0 mmHg in the first quartile of QTc: interval to 149.1 mmHg in the second, 154.6 mmHg in the third, and 152.3 mmHg in the fourth quartile (test for trend, p=0.008). Mean diastolic blood pressure (DBP) also rose from 76.9 mmHg in the first quartile of QTc: interval to 77.7 mmHg in the second, 81.8 mmHg in the third, and 79.0 mmHg in the fourth quartile (test for trend, p=0.003). We performed multiple regression analysis, controlling for factors known to influence the QTc intervals - e.g., SBP, heart rate, sex, and left ventricular hypertrophy assessed by the voltage amplitudes recorded in the precordial leads of the electrocardiogram. The association between the QTc interval and SBP was highly statistically significant in all analyses. These results show that SBP by itself may influence the QTc: interval in very old subjects.
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