QTc prolongation
Pronunciation: Q-T-C prolongation
Extension of the corrected QT interval on electrocardiogram beyond normal limits, indicating delayed cardiac repolarization and potential arrhythmia risk.
Full Definition
QTc prolongation refers to an abnormally extended corrected QT interval, typically defined as >450ms in males and >470ms in females, though threshold values may vary by study protocol. The QT interval represents the time from the beginning of ventricular depolarization to the end of repolarization, and correction (QTc) accounts for heart rate variability using formulas like Bazett's or Fridericia's. In cardiovascular research, QTc prolongation is a critical safety parameter as it predisposes patients to potentially fatal arrhythmias such as torsades de pointes. Many cardiovascular medications require careful QTc monitoring, and significant prolongation often triggers dose adjustments or drug discontinuation.
Usage
Usage note: Use 'QTc' with lowercase 'c' to distinguish from 'QTC' (other medical abbreviations).
In Context
- "Patients with baseline QTc prolongation >500ms were excluded from the study." — Exclusion criteria
- "Serial ECGs were obtained to monitor for drug-induced QTc prolongation throughout the treatment period." — Safety monitoring protocol