Which statement correctly describes the Sokolow-Lyon criterion for LVH on the ECG?

• A. R in V1 plus S in V5/V6 ≥ 35 mm
• B. S in V2 plus R in V5/V6 ≥ 35 mm
• C. S in V1 plus R in V4 ≥ 30 mm
• D. S in V2 plus R in V4 ≥ 40 mm

Answer: (B)

Sokolow-Lyon LVH is a voltage-based ECG criterion that relies on how the left ventricle’s enlarged mass shifts electrical forces toward the left chest leads. When the LV is enlarged, the R wave tends to be larger in the left lateral leads (V5 or V6) and the S wave in the right chest lead (V1) tends to be deeper. The criterion specifically states that LVH is present if the sum of the depth of the S wave in V1 and the height of the R wave in V5 or V6 (whichever is larger) reaches or exceeds 35 mm on the standard ECG tracing. This threshold helps identify a level of voltages consistent with significant LV mass.

If the combination uses different leads or a different threshold, it no longer reflects the Sokolow-Lyon standard. For example, using S in V2 or R in V4, or applying a threshold other than 35 mm, does not align with this widely taught criterion. The essential idea is pairing S in V1 with the higher R in V5/V6 and comparing to 35 mm.