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Tall R Wave in V1 Differential — EECC MCQ

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ModerateCardiac ImagingTall R Wave in V1 DifferentialEECC

A cardiology trainee asks about the interpretation of a 12-lead ECG showing tall R waves in V1-V2 (R/S ratio >1) with ST depression. The differential diagnosis includes RVH, posterior MI, WPW, RBBB variant, and HCM. Which investigation best differentiates these?

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Correct answer: B — Echocardiography can differentiate: RVH (RV hypertrophy/dilatation with TR), posterior MI (regional wall motion abnormality in posterior/lateral wall), HCM (asymmetric LVH), and WPW (delta waves on ECG with normal echo); posterior leads (V7-V9) can confirm posterior ST elevation MI

Tall R waves in V1 (R>S in V1) represent an important ECG pattern with multiple aetiologies: (1) RVH — associated with RAD, RV strain pattern (ST depression/T-wave inversion V1-V3), P-pulmonale; echo shows RVH/dilatation; (2) Posterior MI — actually ST elevation in posterior wall mirrored as tall R and ST depression anteriorly; confirmed by posterior leads (V7-V9) showing ST elevation >0.5 mm, and echo showing posterior wall motion abnormality; (3) WPW (left-sided pathway) — delta waves, short PR; echo typically normal; (4) RBBB — rsR' pattern (not pure tall R); (5) HCM (septal hypertrophy) — echo shows asymmetric LVH. Echocardiography is the single most useful differentiating investigation. In the acute setting, posterior MI must be rapidly excluded with posterior ECG leads and troponin.

Reference: ESC Guidelines; AHA/ACC ECG Interpretation