title: Prognostic value of ventricular repolarization prolongation in resistant hypertension: a prospective cohort study.
abstract: OBJECTIVE
  The prognostic value of prolonged ventricular repolarization in patients with resistant hypertension is unknown. The aim of this prospective study was to investigate the usefulness of electrocardiographic QT-interval parameters as predictors of cardiovascular morbidity and mortality.
  
  
  METHODS
  At baseline, 538 resistant hypertensive patients had five QT-interval components measured in standard 12-lead ECGs: maximum QRS, QTpeak, QTend, JT and Tpeak-to-end-interval durations. Primary endpoints were a composite of fatal and nonfatal cardiovascular events, all-cause and cardiovascular mortalities. Multiple Cox regression assessed the associations between QT-interval parameters and subsequent endpoints.
  
  
  RESULTS
  After a median follow-up of 4.8 years, 69 (12.8%) patients died, 46 from cardiovascular causes, and 107 (19.9%) fatal or nonfatal cardiovascular events occurred. After adjustment for several traditional risk factors, including 24-h ambulatory systolic blood pressure, an increment of 1 SD (35 ms) in QTcend-interval was associated with hazard ratios of 1.38 (1.15-1.67), 1.51 (1.16-1.98) and 1.30 (1.03-1.64), respectively, for the composite endpoint, cardiovascular mortality and all-cause mortality. Further adjustment for left ventricular hypertrophy attenuated the relative risks, but they remained significant for cardiovascular mortality (1.45, 1.07-1.97) and for the composite endpoint (1.35, 1.11-1.66). After full adjustment, a prolonged QTcend-interval (> or =460 ms) conferred a 1.7-fold (1.1-2.6) higher risk of having a future fatal or nonfatal cardiovascular event. No other QT-interval component added further prognostic information to QTcend-interval duration.
  
  
  CONCLUSIONS
  Prolonged ventricular repolarization is a risk marker for cardiovascular morbidity and mortality in patients with resistant hypertension, over and beyond traditional cardiovascular risk factors, including ambulatory blood pressure and left ventricular hypertrophy.
authors.affiliation: Department of Internal Medicine, University Hospital Clementino Fraga Filho, Medical School, Federal University of Rio de Janeiro, Brazil. gilsalles@hucff.ufrj.br
authors.forename: Gil F
authors.initials: GF
authors.lastname: Salles
authors.forename: Claudia R L
authors.initials: CR
authors.lastname: Cardoso
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Muxfeldt
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality; D015331:Cohort Studies; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000175:diagnosis* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012044:Regression Analysis; D016019:Survival Analysis