Cardiac Safety · Chapter 2
Antidepressants & QTc
Which antidepressants actually move the QT, which are safe when the heart is the constraint, and the dose rules that change with age, the liver, and interactions.
Bottom Line Up Front
The 30-second version
- When the heart is the constraint, sertraline is your default. It has the strongest cardiac safety evidence (SADHART) and fewer clinically significant interactions with cardiac drugs than other SSRIs.
- The antidepressants of greatest concern are citalopram and escitalopram — both classed by CredibleMeds as “known risk” of TdP (citalopram the larger effect) — and the TCAs (modest at therapeutic dose, lethal in overdose).
- Don't forget trazodone. Formally only a “conditional risk” agent, but its FDA label warns against use in known QT prolongation, with torsades reported at doses as low as 100 mg — and it hides on med lists as a sleep aid, so it rarely gets counted in the QT tally.
- The dose rules are the QT rules: citalopram and escitalopram ceilings drop with age, hepatic impairment, and CYP inhibition.
- The newest high-QT agent is gepirone (Exxua, 2024). It's contraindicated above a baseline QTc of 450 ms and is the only antidepressant that mandates an ECG before starting, during titration, and periodically — stricter than citalopram.
Why Antidepressants Affect QT
Almost all drug-induced QT prolongation works through the same final pathway: blockade of the rapid delayed-rectifier potassium current (IKr, the hERG channel), which slows ventricular repolarization. Antidepressants vary widely in how strongly they do this.
Most SSRIs are weak hERG blockers, which is why the class is generally low-risk — with citalopram and, to a lesser degree, escitalopram as the dose-dependent exceptions. TCAs are different animals: they block both sodium channels (widening QRS) and potassium channels (prolonging QT), which is why overdose produces a characteristic lethal cardiotoxicity. Trazodone blocks hERG directly. Because the effect tracks drug concentration, anything that raises the level — a higher dose, hepatic impairment, or a CYP inhibitor — raises the QT effect with it. That is the additive principle from Chapter 1, applied at the molecular level.
The Tiered Drug List
| Tier | Agents |
|---|---|
| Preferred / lower risk |
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| Use with caution |
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| Highest concern |
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Dosing & ECG Rules by Agent
| Agent | QT risk | Key dose / ECG rule | Notes |
|---|---|---|---|
| Sertraline | Low (conditional) |
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| Escitalopram | Known risk (lower magnitude) |
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| Citalopram | High (known risk) |
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| Gepirone (Exxua) |
Prolongs QTc; strictest rules |
|
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| Trazodone | Conditional risk + FDA warning |
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| Venlafaxine | Moderate at higher doses |
|
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| TCAs (amitriptyline, etc.) |
Overdose-lethal |
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| Mirtazapine | Possible (low magnitude) |
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| Fluoxetine / Paroxetine | Low (conditional) |
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| Duloxetine / Desvenlafaxine / Vortioxetine / Vilazodone | Low |
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| Auvelity (dextromethorphan/bupropion), Esketamine (Spravato), Zuranolone (Zurzuvae) | No relevant QT |
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Monitoring
Apply the baseline-ECG logic from Chapter 1: a young, healthy patient starting sertraline does not need a screening ECG, while a patient with stacked risk factors does — and the threshold drops further for citalopram, trazodone, or a TCA. When you do monitor: check a baseline ECG, correct potassium (> 4.0 mEq/L) and magnesium (> 2.0 mg/dL) first, and recheck after the drug reaches steady state or after a dose increase. Re-image any time you add a second QT-prolonging agent or the clinical picture shifts.
High-Risk Scenarios
- Elderly: escitalopram caps at 10 mg, citalopram at 20 mg
- Hepatic impairment: citalopram caps at 20 mg; duloxetine avoided
- Polypharmacy / CYP inhibition: fluvoxamine, fluoxetine, paroxetine raise other drugs' levels
- On methadone: a major QT load — favor sertraline, avoid stacking
- Overdose risk / suicidality: avoid TCAs — lethal in overdose
- Trazodone for sleep: count it as an active QT contributor
- Gepirone + strong CYP3A4 inhibitor: contraindicated (~5× exposure); severe hepatic impairment also contraindicated
Clinical Pearls
Pearls
- Sertraline is the default when cardiac risk drives the choice. Best evidence, no cardiac drug interactions, low QT.
- Trazodone is the silent contributor. Because it's prescribed for sleep, it rarely makes it onto the mental "QT drugs" list — but it belongs there, and TdP has occurred at low doses.
- Escitalopram is lower-risk than citalopram, not no-risk. Still cap it at 10 mg in older patients and respect QT risk factors.
- Some SSRIs endanger the QT indirectly. Fluvoxamine (potent CYP1A2, plus CYP3A4, CYP2C9, and CYP2C19 — the CYP3A4 inhibition can raise trazodone levels) and fluoxetine/paroxetine (CYP2D6) can raise the levels of co-prescribed QT-prolonging drugs without touching the QT themselves.
- For TCAs, think overdose lethality, not just steady-state QT. In a depressed, potentially suicidal patient, that distinction can decide the agent.
- Newer doesn't mean lower-risk — check the label. Most recent approvals (Auvelity, esketamine, zuranolone) are low-QT, but gepirone (2024) carries the strictest QT requirements of any antidepressant. A 2025 network meta-analysis found little QTc change for most agents in trial data (only nortriptyline and amitriptyline stood out) — but RCTs enroll younger, healthier patients, so real-world risk can run higher.
Red Flags — Stop and Escalate
Stop the agent and get help
- QTc > 500 ms, or a rise > 60 ms above baseline, on any antidepressant
- Syncope, presyncope, or palpitations after starting or up-titrating
- Starting a highest-concern agent (citalopram, trazodone, TCA) in a patient who already carries multiple QT risk factors
- Suspected TCA overdose — a medical emergency, not a QT recheck
Patient Counseling Script
Plain-language script
"This antidepressant is a good fit for you, and we've chosen it partly with your heart in mind. Some antidepressants can slightly affect the heart's electrical timing, so if you ever faint, feel dizzy, or notice your heart racing or skipping, call us or seek care right away. Please tell us before you start any new medicine — including anything for sleep, like trazodone, or antibiotics — because a few of them add to the same effect. And don't stop this medication on your own without talking to us first."
EMR / Documentation Template
References
- Glassman AH, O'Connor CM, Califf RM, et al. (SADHART Group). Sertraline treatment of major depression in patients with acute MI or unstable angina. JAMA. 2002;288(6):701–709.
- O'Connor CM, Jiang W, Kuchibhatla M, et al. (SADHART-CHF). Safety and efficacy of sertraline for depression in patients with heart failure. J Am Coll Cardiol. 2010;56(9):692–699.
- U.S. FDA. Drug Safety Communication: Abnormal heart rhythms associated with high doses of Celexa (citalopram). 2011 (rev. 2012); citalopram prescribing information (DailyMed).
- Trazodone hydrochloride prescribing information (FDA label) — QT/QTc prolongation and torsades warnings.
- Tisdale JE, Chung MK, Campbell KB, et al. Drug-Induced Arrhythmias: AHA Scientific Statement. Circulation. 2020;142(15):e214–e233.
- CredibleMeds (formerly AzCERT). QTdrugs lists. crediblemeds.org.
- EXXUA (gepirone) extended-release tablets, FDA prescribing information (DailyMed) — QT prolongation, contraindications, and ECG monitoring requirements.
- Network meta-analysis of antidepressant cardiometabolic effects (2025) — QTc findings across antidepressant classes.
Last reviewed June 2026. Part of the Psychiatry Education Forum Academy; for clinician education — it supports, and does not replace, individual clinical judgment and current local protocols.
Next: the antipsychotic tiers
Same framework, different class — including the IV-versus-oral haloperidol question and where ziprasidone really sits.
Educational use only. Refer to the sources cited above and current prescribing information for clinical decisions. Psychiatry Education Forum and authors assume no liability for use of this material.
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