Medical toxicologists' practice patterns regarding drug-induced QT prolongation in overdose patients: a survey in the United States of America, Europe, and Asia Pacific region.
Level 4 - case-series / case-control
Cross-sectional survey of physician practice patterns
PubMed 25706450 · doi:10.3109/15563650.2015.1013547
What was done
An electronic survey evaluated clinical practice patterns for drug-induced QT prolongation and torsades de pointes (TdP) in overdose among physician members of toxicology societies across the USA (ACMT), Europe (EAPCCT), and the Asia Pacific region (APAMT). Responses were compared against AHA, ACC, and ESC guidelines.
What was found
The response rate was 37% (229/617). Twelve toxicologists used QT nomograms or uncorrected QT and were excluded from subsequent QTc-specific questions, leaving 217 respondents. Approximately 52% relied on automated ECG machine QTc measurements, while Bazett's formula was the most common manual method (40%). Thresholds for prolonged QTc varied widely: 28% used >450 ms in men, 25% used >460 ms in women, and approximately 15% required >500 ms for both sexes. In a hypothetical scenario of an overdose with QTc 560 ms and heart rate 90 beats/minute, 59% would not recommend IV magnesium sulfate, although 45% believed magnesium shortens QTc and 36% believed it prevents TdP. Nearly 90% believed 1-2 IV magnesium boluses were safe without known serum levels. For cardiac pacing, 38% of responses matched AHA/ACC/ESC recommendations, and 21% reported they would not pace a patient with TdP regardless of scenario.
Why it matters
Practice patterns among medical toxicologists vary widely regarding the assessment and management of drug-induced QT prolongation and TdP, indicating a lack of standardized approaches and divergence from published cardiology recommendations.
Limits
The study is limited by a low response rate (37%), introducing potential non-response bias. Practice patterns were assessed via self-reported responses to hypothetical scenarios rather than direct observation of clinical care. Respondents who used QT nomograms were excluded from the majority of questions, and patient outcomes were not evaluated.
Cited by
- context Intravenous magnesium is recommended by American Heart Association guidelines as the treatment for torsades de pointes.