title: Sildenafil citrate does not alter ventricular repolarization properties: novel evidence from dynamic QT analysis.
abstract: BACKGROUND
  Sildenafil citrate may have direct cardiac electrophysiological effects, and is possibly responsible for some cardiac events. The aim of our study was to investigate the effects of sildenafil citrate on QT dynamicity properties with a new QT analysis program showing even small changes in ventricular repolarization.
  
  
  METHODS
  Twenty-four-hour Holter electrocardiographic recordings were used to obtain the data in the predrug phase (1-hour rest position before drug administration), and in the postdrug phase (1-hour rest position, which began 60 minutes after 50 mg oral sildenafil citrate administration). With the special QT analysis program (Verda, Reynolds Medical Ltd., UK); mean values of RR, QT, QTo (corrected QT), J (the exponent of correction formula) and S (QT/RR plots slope) parameters together with QT variability indexes (QTVI) were calculated for study phases.
  
  
  RESULTS
  Mean +/- SEM values for RR and QT were higher in postdrug phase than in predrug phase (RR: 845 +/- 42 ms vs 816 +/- 46 ms, P < 0.05; QT: 371 +/- 8 ms vs 361 +/- 9 ms, P < 0.05). However, sildenafil did not induce any significant change in mean +/- SEM values for QT(o), J, and S in postdrug phase compared with predrug phase (408 +/- 10 ms vs 406 +/- 8 ms, 0.474 +/- 0.030 vs 0.433 +/- 0.025, 0221 +/- 0.020 vs 0.198 +/- 0.017, respectively; P > 0.05). QTVIs were also not different in each phase (predrug: -0.874 +/- 0.071 vs postdrug: -0.997 +/- 0.067, P = 0.109).
  
  
  CONCLUSIONS
  Fifty milligrams sildenafil does not affect QT dynamicity properties. The cardiac events associated with sildenafil could not be explained with ventricular arrhythmias.
authors.affiliation: Department of Cardiology and Urology, School of Medicine, Afyon Kocatepe University, Afyon, Turkey.
authors.forename: Dayimi
authors.initials: D
authors.lastname: Kaya
authors.forename: Cem
authors.initials: C
authors.lastname: Guler
authors.forename: Ali Metin
authors.initials: AM
authors.lastname: Esen
authors.forename: Irfan
authors.initials: I
authors.lastname: Barutcu
authors.forename: Cetin
authors.initials: C
authors.lastname: Dincel
mesh_terms: D000284:Administration, Oral; D000368:Aged; D015716:Electrocardiography, Ambulatory; D007172:Erectile Dysfunction / Q000188:drug therapy; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines; D012307:Risk Factors; D000068677:Sildenafil Citrate; D018709:Statistics, Nonparametric; D013450:Sulfones
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate