title: Assessment of the relationship between nondipping phenomenon and microvolt T-wave alternans.
abstract: OBJECTIVE
  The aim of this cross-sectional study was to evaluate microvolt T-wave alternans (MTWA) as a marker of myocardial electrical instability in normotensive and hypertensive individuals with either nondipper or dipper-type circadian rhythm of blood pressure.
  
  
  METHODS
  The study group included a total of 181 patients: 118 hypertensive patients and 63 normotensive healthy volunteers [mean age 46 ± 8; 34 men (54%)]. The patients with hypertension were divided into two groups on the basis of their results of 24-h ambulatory blood pressure monitoring: 61 patients with dipper hypertension [mean age 46 ± 6; 32 men (52.5%)] and 57 patients with nondipper hypertension [mean age 48 ± 10; 36 men (63.2%)]. The MTWAs of all patients were analyzed using the time-domain modified moving average method by means of a treadmill exercise stress test.
  
  
  RESULTS
  MTWA positivity was statistically significantly different between all groups. Left ventricular mass index, E/E', interventricular septum, posterior wall, 24-h systolic blood pressure and diastolic blood pressure, and night-time systolic blood pressure and diastolic blood pressure were correlated positively with MTWA. Left ventricular mass index and the presence of nondipper hypertension were determined to be independent predictors of MTWA positivity.
  
  
  CONCLUSIONS
  The blunting of the nocturnal decrease in blood pressure was associated with MTWA positivity in hypertensive patients.
authors.affiliation: aCardiology Department, Mehmet Akif Ersoy Thoracic and Cardiovascular Surgery Training and Research Hospital bCardiology Department, Acibadem University Hospital, Istanbul cCardiology Department, Regional Training and Research Hospital, Erzurum, Turkey.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Surgit
authors.forename: Mehmet
authors.initials: M
authors.lastname: Erturk
authors.forename: Ozgur
authors.initials: O
authors.lastname: Akgul
authors.forename: Hamdi
authors.initials: H
authors.lastname: Pusuroglu
authors.forename: Ali Fuat
authors.initials: AF
authors.lastname: Korkmaz
authors.forename: Yalcn
authors.initials: Y
authors.lastname: Avci
authors.forename: Ender
authors.initials: E
authors.lastname: Ozal
authors.forename: Fatih
authors.initials: F
authors.lastname: Uzun
authors.forename: Ali
authors.initials: A
authors.lastname: Buturak
authors.forename: Abdurrahman
authors.initials: A
authors.lastname: Eksik
mesh_terms: D000328:Adult; D062186:Arterial Pressure / Q000502:physiology*; D015415:Biomarkers; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography
chemical_list: D015415:Biomarkers