Exercise blood pressure correlates with the maximum heart rate corrected QT interval in hypertension

Submaximal exercise systolic blood pressure (ExSBP) is a recognised predict or of cardiac mortality. This study examined the possibility that this migh t be related to increased QT dispersion or prolonged maximum QT, interval ( QT,max). Twenty-nine untreated hypertensive subjects were assessed. Each su bject underwent an echocardiographic examination and a 24-h ambulatory bloo d pressure (ABP). ExSBP was measured during a 3-min lightweight submaximal Dundee step test. In multiple regressional analyses, only left ventricular mass index significantly predicted QT dispersion (R-2 = 22.4%, P = 0.018) a nd QT, dispersion (R-2 = 25.3%, P = 0.012). However, with respect to QT,max , ExSBP (R-2 = 21.6%, P = 0.02) emerged as the sole significant predictor o f this index. Five (17.2%) out of the 29 subjects had prolonged QT(c)max gr eater than or equal to 430 ms and these subjects were not differentiated by 24-h ABP (146 (s.d. 21)/83 (16) vs 140 (14)/88 (11) mm Hg, P = Ns) but by ExSBP (226 (15) vs 188 (24) mm Hg, P = 0.002). In conclusion, systolic bloo d pressure measured during exercise correlated with QT, max in hypertension . This finding may partly explain the prognostic value of exercise blood pr essure.