title: Drug-Induced QTc Interval Prolongation: A Multicenter Study to Detect Drugs and Clinical Factors Involved in Every Day Practice.
abstract: OBJECTIVE
  The actual prevalence of drug induced QTc prolongation in clinical practice is unknown. Our objective was to determine the occurrence and characteristics of drug-induced QT prolongation in several common clinical practices. Additionally, a subgroup of patients treated with dextropropoxyphene of particular interest for the regulatory authority was analysed.
  
  
  METHODS
  Medical history and comorbidities predisposing to QT interval prolongation were registered for 1270 patient requiring medical assistance that involved drug administration. Three ionograms and ECGs were performed: baseline, intra- and after treatment; QT interval was corrected with Bazzet formula.
  
  
  RESULTS
  Among patients, 9.9% presented QTc >450/470 ms, 3% QTc > 500 ms, 12.7% ΔQTc >30 ms and 5.2% ΔQTc >60 ms. QTc prolongation associated with congestive heart failure, ischemic cardiopathy, diabetes, renal failure, arrhythmias, hypothyroidism, and bradycardia. At univariate analysis, clarithromycin, haloperidol, tramadol, amiodarone, glyceryl trinitrate, amoxicillin + clavulanic acid, amoxicillin + sulbactam, ampicillin + sulbactam, fentanyl, piperacillin + tazobactam, and diazepam prolonged QTc. Prolongation remained significantly associated with furosemide, clarithromycin, glyceryl trinitrate and betalactamase inhibitors after multivariate analysis.
  
  
  CONCLUSIONS
  QT interval prolongation in everyday practice is frequent, in association to clinical factors and drugs that can be easily identified for monitoring and prevention strategies.
authors.forename: Guillermo A
authors.initials: GA
authors.lastname: Keller
authors.forename: Paulino A
authors.initials: PA
authors.lastname: Alvarez
authors.forename: Marcelo L
authors.initials: ML
authors.lastname: Ponte
authors.forename: Waldo H
authors.initials: WH
authors.lastname: Belloso
authors.forename: Claudia
authors.initials: C
authors.lastname: Bagnes
authors.forename: Cecilia
authors.initials: C
authors.lastname: Sparanochia
authors.forename: Claudio D
authors.initials: CD
authors.lastname: Gonzalez
authors.forename: M Cecilia
authors.initials: MC
authors.lastname: Villa Etchegoyen
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Diez
authors.affiliation: University of Buenos Aires, Argentina. gdigirolamo@fmed.uba.ar.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Di Girolamo
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects; D011431:Dextropropoxyphene / Q000009:adverse effects; D064420:Drug-Related Side Effects and Adverse Reactions / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D004562:Electrocardiography / Q000187:drug effects* / Q000379:methods; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000175:diagnosis* / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D000900:Anti-Bacterial Agents; D011431:Dextropropoxyphene