American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the normal QTc interval in women?

1. 440 ms or less

2. 460 ms or less

3. 480 ms or less

4. 500 ms or less

The correct answer is: 460 ms or less

The normal QTc interval in women is considered to be 460 ms or less. The QT interval represents the time it takes for the heart's electrical system to recharge after each heartbeat, and the "c" in QTc stands for "corrected," which adjusts the QT interval based on heart rate. For women, an upper limit of 460 ms is established, differentiating from the slightly lower limits often cited for men. This understanding is critical in clinical practice because an elongated QTc interval can predispose individuals to serious arrhythmias and can be influenced by various factors such as medications, electrolyte imbalances, and underlying heart conditions. It's important to know these reference values to properly evaluate a patient's cardiac health and to assess the risk of potential complications due to QT prolongation. Thus, maintaining awareness of the upper limit for QTc in women being 460 ms supports better clinical assessments and interventions.