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Marked Q-T prolongation due to encainide therapy
W Davies1, M Jazayeri, P Tchou
1University of Wisconsin-Milwaukee Clinical Campus, Sinai Samaritan Medical Center.
Cardiovascular Drugs and Therapy
|September 1, 1988
Summary
Encainide therapy can cause Q-T interval prolongation. This case report details a patient with marked Q-T prolongation and normal Q-R-S intervals, linked to abnormal encainide metabolism.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Electrophysiology
Background:
- Encainide is a Class Ic antiarrhythmic drug used for tachycardia.
- Typical side effects include mild Q-T and Q-R-S interval prolongation.
- Atrioventricular nodal reentrant tachycardia is a common supraventricular arrhythmia.
Observation:
- A case report of a patient experiencing unusual and marked Q-T interval prolongation.
- The patient presented with no concurrent Q-R-S interval prolongation during encainide treatment.
- Serum analysis revealed elevated levels of the 3-methoxy-O-demethyl encainide metabolite.
Findings:
- The 3-methoxy-O-demethyl encainide metabolite appears to significantly prolong cardiac repolarization.
- Elevated levels of this specific metabolite correlate with pronounced Q-T interval prolongation.
- This suggests a potential link between abnormal encainide metabolism and severe Q-T prolongation.
Implications:
- Abnormal encainide metabolism may predispose certain patients to significant Q-T interval prolongation.
- Understanding metabolite profiles is crucial for managing antiarrhythmic drug therapy.
- This finding warrants further investigation into the pharmacokinetics and pharmacodynamics of encainide metabolites.