title: Exercise blood pressure correlates with the maximum heart rate corrected QT interval in hypertension.
abstract: Submaximal exercise systolic blood pressure (ExSBP) is a recognised predictor of cardiac mortality. This study examined the possibility that this might be related to increased QT dispersion or prolonged maximum QT(c) interval (QTcmax). Twenty-nine untreated hypertensive subjects were assessed. Each subject underwent an echocardiographic examination and a 24-h ambulatory blood 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 (R2 = 22.4%, P = 0.018) and QT(c) dispersion (R(2) = 25.3%, P = 0.012). However, with respect to QTcmax, ExSBP (R2 = 21.6%, P = 0.02) emerged as the sole significant predictor of this index. Five (17.2%) out of the 29 subjects had prolonged QTcmax > or = 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 blood pressure measured during exercise correlated with QT(c) max in hypertension. This finding may partly explain the prognostic value of exercise blood pressure.
authors.affiliation: Department of Cardiology, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK. limpo@cf.ac.uk
authors.forename: P O
authors.initials: PO
authors.lastname: Lim
authors.forename: B S
authors.initials: BS
authors.lastname: Rana
authors.forename: A D
authors.initials: AD
authors.lastname: Struthers
authors.forename: T M
authors.initials: TM
authors.lastname: MacDonald
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis