The risk from a QT-prolonging antidepressant or antipsychotic is concentrated in people who already have a long QTc, low potassium or magnesium, bradycardia, or another QT-prolonging drug on board. The established step is to find those patients before prescribing, not after.
In anyone with cardiac disease, a family history of sudden death, or other QT-prolonging medication, take a baseline ECG and correct low potassium and magnesium before starting, then recheck after a dose increase. Most healthy younger patients need no routine ECG.
This is standard prescribing practice, and it is what lets you use an effective but mildly QT-prolonging drug safely rather than avoiding it.
- Take a baseline ECG before a QT-prolonging psychotropic in anyone with cardiac disease, a family history of sudden death, or another QT-prolonging drug.
- Correct low potassium and magnesium before starting and after a dose increase.
- Review the whole drug list for additive QT effects, including antiemetics and some antibiotics.
- A routine ECG is not needed for most healthy younger patients on a low-risk agent.
Why it matters
It lets you prescribe an effective antidepressant or antipsychotic safely instead of avoiding it over a theoretical cardiac risk.
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