This 23 year old presented to the Emergency Department with pharyngitis, but also complained of dyspnea on exertion. This ECG was recorded:
The wide complex (QRS 155 ms) may distract your attention from the rhythm, which is simply sinus. There are massive S-waves in lateral leads, with an extreme right axis deviation (180 or -180, same thing). There are massive R' waves of RBBB in the right precordial leads. The combination of wide S-wave in V5 and V6, and large R' wave in lead V1 is diagnostic of RBBB. The precordial voltage is extreme, approximately 60 mm (6.0 mV) in V1.
So this is diagnostic of massive Right ventricular hypertrophy. One might be concerned for ischemia because of the large amount of ST depression and T wave inversion in V1-V3. Some discordant (in the opposite direction of a high voltage or bundle branch block QRS) ST depression and T inversion is usually found at baseline in RBBB, but this is more than usual. However, the voltage is also more than usual. The ratio of the ST depression to QRS voltage is about 4mm to 60 mm, or 0.067, which is normal. The troponin was mildly elevated due to demand ischemia of the RV.
Further history revealed congenital pulmonic stenosis which was dilated at age 7 days. The patient did not have further followup. Echocardiogram revealed an estimated peak systolic pulmonary pressure of 127 mmHg with RV enlargement and severe hypertrophy.