A Method to His Madness

ANSWER

The correct interpretation includes sinus tachycardia with biatrial enlargement and ST- and T-wave abnormalities consistent with inferolateral ischemia.

Sinus tachycardia is evident from an atrial rate > 100 beats/min, with a consistent PR interval for each P and R wave.

Criteria for right atrial enlargement include tall P waves in leads II, III, and aVF, and for left atrial enlargement, P waves in lead I ≥ 110 ms with terminal negativity of the P wave in lead V₁ ≥ 1 mm². When both criteria are met, the diagnosis is biatrial enlargement.

The presence of ST elevation in lead V₄ and T-wave inversions in leads V₅ and V₆ and limb leads II, III, and aVF suggest inferolateral ischemia.