title: Calcitriol regresses cardiac hypertrophy and QT dispersion in secondary hyperparathyroidism on hemodialysis.
abstract: BACKGROUND
  Sudden cardiac death is common in patients on hemodialysis (HD), and its rate is as high as 25% of all cardiac deaths associated with left ventricular hypertrophy (LVH) and secondary hyperparathyroidism. A prolonged QT interval on standard electrocardiography is related to an increase in sudden death in various patient groups. It is also well known that LVH has been noted in uremic patients with high parathyroid hormone levels.
  
  
  METHODS
  To evaluate the response of intravenous calcitriol treatment on the QT interval and LVH in HD patients with secondary hyperparathyroidism (intact parathyroid hormone, iPTH, > 450 ng/ml), echocardiographic, electrocardiographic (ECG), and biochemical assessments were performed over a 15-week period in 25 HD patients before and after intravenous calcitriol treatment. We also evaluated 25 age-, sex-, HD duration-, and BMI-matched HD control patients with secondary hyperparathyroidism.
  
  
  RESULTS
  In patients receiving intravenous calcitriol, a significant reduction in iPTH levels (p < 0.05) and alkaline phosphatase levels (p < 0.01) was found without changes in values of serum calcium and ionized Ca2+, phosphorus, Na+, K+, Mg2+, hematocrit, blood pressure, or other hemodynamic changes. Echocardiograms showed significant decreases in the thickness of the interventricular septum (p < 0.05), left posterior wall thickness (p < 0.05), and left ventricle mass index (LVMi, p < 0.01). In addition, sequential ECG measurement in patients with calcitriol treatment showed significant reductions in QTcmax (QTmax interval corrected for heart rates, p < 0.01) and QTc dispersion (QT dispersion corrected for heart rates, p < 0.01). However, in the control patients, biochemical, hemodynamic, and ECG changes, as well as myocardial structural and functional changes were not seen. Multiple regression analysis in all patients indicated that iPTH and LVMi levels were independent predictors of QTcmax while the LVMi level was the only independent predictor of QTc dispersion (p < 0.05).
  
  
  CONCLUSIONS
  Our study showed a significant correlation between LVMi and QT dispersion in HD patients with secondary hyperparathyroidism. Intravenous calcitriol treatment, to be used for the control of secondary hyperparathyroidism, was found to cause regression of myocardial hypertrophy and a reduction in the QTc interval and dispersion, without biochemical and hemodynamic changes. These findings suggest that an active vitamin D metabolite has a cardioprotective action in HD patients.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, Korea.
authors.forename: Hyung Wook
authors.initials: HW
authors.lastname: Kim
authors.forename: Cheol Whee
authors.initials: CW
authors.lastname: Park
authors.forename: Young Shin
authors.initials: YS
authors.lastname: Shin
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Seok Jun
authors.initials: SJ
authors.lastname: Shin
authors.forename: Yong-Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Euy Jin
authors.initials: EJ
authors.lastname: Choi
authors.forename: Yoon Sik
authors.initials: YS
authors.lastname: Chang
authors.forename: Byung Kee
authors.initials: BK
authors.lastname: Bang
mesh_terms: D000328:Adult; D002117:Calcitriol / Q000008:administration & dosage / Q000494:pharmacology*; D002120:Calcium Channel Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D015897:Comorbidity; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000453:epidemiology / Q000503:physiopathology*; D017379:Hypertrophy, Left Ventricular / Q000188:drug therapy*; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis
chemical_list: D002120:Calcium Channel Agonists; D002117:Calcitriol