Reassess the citalopram risk-benefit given the prolonged QTc, review for additional QTc-prolonging factors, and consider switching to a lower-risk antidepressant.

Citalopram's QTc prolongation risk led to the FDA's 2012 dose limitation (20 mg maximum in patients >60 years). A QTc of 485 ms exceeds the female threshold of concern (>460 ms). The PMHNP should assess for additional QTc-prolonging factors (other medications, hypokalemia, hypomagnesemia), address correctable contributors, and consider switching to an antidepressant with lower QTc risk (sertraline, bupropion, mirtazapine have more favorable QTc profiles). QTc >500 ms is high risk for torsades de pointes.

Continue citalopram at the current dose since the patient is asymptomatic and the QTc is below the high-risk threshold of 500 ms.

A QTc of 485 ms in a patient on a QTc-prolonging medication requires action regardless of symptoms. QTc prolongation is asymptomatic until a fatal arrhythmia occurs.

Increase citalopram to 40 mg since the current dose may be subtherapeutic and the QTc prolongation is likely unrelated to the medication.

Increasing to 40 mg in a patient over 60 with an already prolonged QTc directly violates the FDA recommendation and increases arrhythmia risk.

Repeat the EKG in 6 months to monitor for further QTc changes while maintaining the current treatment regimen unchanged.

Passive monitoring of a prolonged QTc in a patient on a known QTc-prolonging agent is inappropriate. Active reassessment and intervention are required.