This ECG of a 75-year-old man has been recorded in the Emergency Department. No clinical information has been supplied and no previous ECGs are available for comparison:

• Sinus rhythm, 85/min with frequent premature ventricular complexes in a pattern of bigeminy
• Left ventricular hypertrophy with repolarization abnormality
• Septal infarction, probably acute

The wide QRS complexes with RBBB pattern are preceded by P waves with shorter P-R interval. They are PVCs that occur relatively late, when the atrial activation is completed but has not yet reached the ventricles. If they were aberrantly conducted sinus complexes, the PR interval would be the same or longer than that of the narrow QRS.

Because of the lack of clinical information and the lack of previous ECGs for comparison, the statement “septal infarction probably acute” was made. ST elevation may persist after the acute stage of a myocardial infarction. ST elevation in V1-V3 may also be reciprocal to the ST depression in V5-V6 (“strain pattern”) due to left ventricular hypertrophy.