What baseline assessment is recommended prior to starting antipsychotics with potential QT prolongation risk?

• A. Baseline QTc measurement
• B. Baseline liver enzymes only
• C. Baseline kidney function only
• D. No baseline assessment needed

Answer: (A)

Understanding the risk of QT prolongation is essential when starting antipsychotics that can affect cardiac repolarization. The QT interval on an ECG represents the time for the heart’s ventricles to depolarize and then repolarize, and the QTc adjusts this value for heart rate. Prolonged QTc increases the risk of torsades de pointes, a potentially life-threatening rhythm disturbance, especially in people with electrolyte imbalances, slow heart rates, congenital long QT, or those taking other QT-prolonging drugs. Getting a baseline QTc provides a crucial reference before exposure to these medications, helping you identify preexisting prolongation and plan monitoring, dosing, and corrective steps if needed. If the baseline QTc is normal, you can proceed with caution and monitor after starting or adjusting the dose; if it’s prolonged or risk factors are present, you may choose alternatives or take measures to optimize electrolytes and recheck QTc. While evaluating liver and kidney function is important for how the drug is processed, it doesn’t specifically screen for QT prolongation risk.