Table 3.
Risk Factors for QTc Prolongation in Twenty-Eight Patients with Prolonged QTc at Baseline Prior to Initiation of Methadone
| Number of patients (%) | |
|---|---|
| Medicationsa | 21 (75) |
| 1. Generally accepted to carry a risk of torsades de pointes | 3 (11) |
| 2. Prolong the QT interval and/or in some reports have been associated with torsades de pointes | 7 (25) |
| 3. Carry a risk of torsades de pointes and/or QT prolongation under certain conditions | 11 (39) |
| Structural cardiac diseases | 7 (25) |
| Coronary artery disease | 5 (18) |
| Congestive heart failure | 2 (7) |
| Valvular heart disease | 1 (4) |
| Female sex | 5 (18) |
| Electrolyte abnormalities | 3 (11) |
| Hypokalemia | 2 (7) |
| Hypocalcemia | 2 (7) |
| No identifiable risk factors | 6 (21) |
a
Medications associated with QT prolongation were classified based on criteria set forth by the Arizona Center for Education and Research on Therapeutics.23