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QRS Duration Risk in Repaired TOF — EECC MCQ

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ModerateCongenital Heart Disease (Adult)QRS Duration Risk in Repaired TOFEECC

A 30-year-old man with repaired tetralogy of Fallot presents with palpitations. His ECG shows a QRS duration of 180 ms (wide RBBB pattern). Holter reveals frequent PVCs and NSVT runs. His RVEF on CMR is 38%. What is the significance of QRS duration in repaired TOF?

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Correct answer: D — QRS duration ≥180 ms in repaired TOF is associated with increased risk of sustained VT and sudden cardiac death — it reflects RV dilatation and electrical dyssynchrony from the RVOT patch and severe pulmonary regurgitation; QRS prolongation is an independent risk marker alongside RV dysfunction

In repaired TOF, QRS duration is a well-established risk marker for ventricular arrhythmias and SCD. Key evidence: (1) QRS ≥180 ms is associated with a significantly increased risk of sustained VT and SCD (Gatzoulis et al., Lancet 2000); (2) progressive QRS prolongation over time reflects worsening RV dilatation from chronic severe PR (the RV stretch elongates the conduction pathway); (3) QRS prolongation is an independent predictor even after adjusting for RV size and function. The 2020 ESC ACHD and 2022 VA/SCD Guidelines use QRS duration alongside: (1) RV dysfunction (RVEF <47%); (2) RV dilatation (RVEDVi >160 mL/m²); (3) clinical arrhythmias (NSVT/sustained VT); (4) syncope. This patient's QRS 180 ms + RVEF 38% + NSVT represents a high-risk combination warranting: (1) PVR to address the haemodynamic substrate; (2) ICD consideration; (3) EP study for VT inducibility.

Reference: ESC (2020): ACHD; ESC (2022): VA/SCD; Gatzoulis et al. Lancet 2000