title: Methadone Therapy in Underserved Urban Community: QTc Prolongation and Life-Threatening Ventricular Arrhythmias.
abstract: OBJECTIVE
  Methadone has been associated with QTc prolongation and ventricular arrhythmias but the prevalence of QTc prolongation and association with ventricular arrhythmias remains unclear. We investigated this in our inner city urban community (Bronx, New York) that has a large number of patients on methadone.
  
  
  METHODS
  Telemetry records, nursing documentation and electronic charts of 291 patients spanning856 encounters were evaluated. QT was manually measured from ECG utilizing standardized QT measurement guidelines and was corrected for heart rate using Hodges formula. QTc >470 ms in males and >480 ms in females was considered to be prolonged.
  
  
  RESULTS
  Patients had prolonged QTc, QTc >500 ms and ventricular arrhythmias during 25.6%, 14.1% and 3.4% of encounters, respectively. There was a very weak dose dependent relationship between methadone dose and QTc (Spearman's rho = 0.09).In addition to methadone, patients were on at least one QT prolonging drugs during 39% of the encounters. Patients who were receiving two interacting drugs in addition to methadone had the highest prevalence (29%) of QTc prolongation.
  
  
  CONCLUSIONS
  Although the prevalence of QTc prolongation among patients on methadone therapy is high, the prevalence of ventricular arrhythmia is relatively low. Hospitalized patients on sustained methadone therapy are frequently on multiple additional QTc prolonging drugs. There is no significant dose dependent relationship between methadone dose and QTc. However, the concurrent use of methadone and interacting drugs lead to an increased prevalence of QTc prolongation.
authors.affiliation: Department of Internal Medicine, Yale School of Medicine/Yale-New Haven Hospital, New Haven, CT, USA.
authors.forename: Mohsin
authors.initials: M
authors.lastname: Chowdhury
authors.affiliation: Department of Pharmacy, Yale-New Haven Hospital, New Haven, CT, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Wong
authors.affiliation: Department of Pharmacy, Montefiore Medical Center, Bronx, NY, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Cheng
authors.affiliation: Department of Critical Care Medicine, Montefiore Medical Center, Bronx, NY, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Khilkin
authors.affiliation: Department of Cardiovascular Medicine, Montefiore Medical Center, Bronx, NY, USA.
authors.forename: Eugen
authors.initials: E
authors.lastname: Palma
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced; D008297:Male; D008507:Medically Underserved Area; D008691:Methadone / Q000009:adverse effects*; D008875:Middle Aged; D009519:New York City; D058850:Opiate Substitution Treatment / Q000009:adverse effects*; D015995:Prevalence; D012189:Retrospective Studies; D014505:Urban Population
chemical_list: D008691:Methadone
keywords: Methadone maintenance therapy; Polypharmacy; Prolonged QTc; Torsade; Ventricular arrhythmia