The Critical Importance of Recognizing De Winter's T-wave Pattern: A Case of Acute Proximal LAD Occlusion by In-Stent Restenosis.

De Winter's T-wave pattern is a high-risk ST-elevation myocardial infarction (STEMI) equivalent signifying acute proximal left anterior descending (LAD) occlusion, characterized by precordial upsloping ST-depression and tall, peaked T-waves. We present a 69-year-old man with chest pain whose electrocardiogram (ECG) showed a classic De Winter's pattern. He rapidly developed acute respiratory failure, and his high-sensitivity troponin I peaked at >27,027 pg/mL. Urgent angiography identified severe in-stent restenosis (ISR) in the proximal-mid LAD as the culprit lesion. This was successfully treated with a drug-coating balloon. This case highlights that De Winter's pattern is a critical finding that must be immediately recognized to prevent delays in emergent reperfusion therapy.