Key result
Non-cardiac QT-prolonging meds show no link to ventricular arrhythmia or arrest in LBBB or RBBB ICU patients.
Why the study?
Conventional QTc formulae overestimate repolarization in wide QRS complexes, leading clinicians to withhold symptom-management therapies in patients with bundle branch block based on inaccurate measurements.
Does exposure to common non-cardiac QT-prolonging medications increase the risk of ventricular arrhythmia and cardiac arrest in adult ICU patients with bundle branch block?
Cohort (n=1,722)
Does exposure to common non-cardiac QT-prolonging medications increase the risk of ventricular arrhythmia and cardiac arrest in adult ICU patients with bundle branch block?
Common non-cardiac QT-prolonging medications were not associated with increased arrhythmic risk in ICU patients with bundle branch block, suggesting QTc-based alerts may overestimate risk in this population.
Answers are grounded in this paper and cite their sources.
May inform cautious drug selection in ICU patients with BBB; leaves open need for prospective validation of arrhythmogenic risks by phenotype.
BACKGROUND: Bundle branch block (BBB) affects 11-17% of adults over 80 and is associated with mortality and heart failure. Conventional QTc formulae overestimate repolarization in wide QRS complexes, with clinicians holding symptom-management therapies based on inaccurate measurements. OBJECTIVES: This retrospective study utilized the MIMIC-IV database to examine arrhythmogenic risk by drug class and BBB phenotype. METHODS: Adult ICU admissions with BBB were stratified by drug exposure: amiodarone, high-risk anti-arrhythmics (sotalol, dofetilide, procainamide, ibutilide, quinidine, disopyramide), and common non-cardiac QT-prolonging agents (haloperidol, ondansetron, quetiapine, methadone, levofloxacin, azithromycin). The primary outcome was a composite of ventricular arrhythmia and cardiac arrest; a sensitivity analysis restricted to ventricular arrhythmia was performed. Propensity score matching (1:1) with time-varying Cox regression addressed confounding and immortal time bias. RESULTS: The matched cohort included 1722 admissions (LBBB =1252; RBBB =470). Common non-cardiac agents were not associated with the composite outcome in LBBB (HR 0.96, p = 0.83) or RBBB (HR 0.61, p = 0.24; 28 events, hypothesis-generating). Amiodarone was associated with the composite (LBBB: HR 3.63, p < 0.01; RBBB HR: 3.90, p < 0.01), but not the LBBB sensitivity analysis (HR 1.61, p = 0.19), suggesting confounding by indication. Among patients with QTc >500 ms, common agents remained non-significant. CONCLUSION: Common non-cardiac QT-prolonging medications were not associated with increased risk in patients with BBB, even with prolonged QTc. The divergence between composite and sensitivity results for amiodarone highlights the influence of confounding by indication. Medication alerts should incorporate stratification by drug class rather than QTc alone.
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Derector et al. (2026) conducted a cohort in Bundle branch block (n=1,722). Common non-cardiac QT-prolonging medications was evaluated on Composite of ventricular arrhythmia and cardiac arrest (HR 0.96, p=0.83). Common non-cardiac QT-prolonging medications were not associated with ventricular arrhythmia or cardiac arrest in ICU patients with LBBB (HR 0.96, p=0.83) or RBBB (HR 0.61, p=0.24).
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