From the Research
The QTc cutoff to initiate SSRIs is generally 500 milliseconds. Patients with a QTc interval greater than 500 ms should be evaluated carefully before starting SSRI therapy due to the potential risk of further QT prolongation. For patients with borderline QTc intervals (470-500 ms for men, 480-500 ms for women), caution is advised, and alternative antidepressants with less QT-prolonging potential might be considered. Among the provided evidence, the most recent study 1 discusses the management of drug-induced QT prolongation in clinical practice, emphasizing the importance of considering patient-related risk factors, the potential risk of QT prolongation associated with the proposed drug, and co-prescribed medicines that could increase this risk. The study 2 from 2016, although not directly related to SSRIs, highlights that a QTc interval of at least 500 ms seems to be a major determinant of the risk of drug-induced proarrhythmias, supporting the cautious approach when the QTc interval exceeds this threshold. Given the potential for QT prolongation and the risk of torsades de pointes, a life-threatening ventricular arrhythmia, careful consideration and monitoring are necessary when initiating SSRI therapy, especially in patients with elevated baseline QTc intervals or other risk factors for QT prolongation. Before initiating SSRI therapy in high-risk patients, obtaining a baseline ECG is recommended, with follow-up ECGs after reaching steady-state concentrations, as suggested by the study 3. It's also important to note that among SSRIs, citalopram and escitalopram have the highest risk of QT prolongation, and other SSRIs like sertraline, fluoxetine, and paroxetine may be safer options for patients with elevated baseline QTc intervals, as discussed in the study 4. Therefore, initiating SSRIs with a QTc interval cutoff of 500 milliseconds is a prudent approach, balancing the need for effective treatment of depression with the risk of potentially life-threatening cardiac arrhythmias.