Atypical de winter pattern preceding anterior STEMI: clinical judgement beyond rigid ECG criteria

Background The de Winter ECG pattern should raise strong suspicion for an unstable thrombotic culprit lesion associated with high-risk anterior ischemia requiring urgent expert evaluation — classically involving the proximal left anterior descending artery (LAD) — that frequently does not fulfil conventional ST-segment elevation criteria and is therefore regarded as a STEMI equivalent. Case presentation We report the case of an 85-year-old woman with sudden-onset chest pain radiating to both shoulders. The prehospital 12-lead ECG showed atypical de Winter pattern, prompting direct transport to a PCI-capable centre and administration of antiplatelet and anticoagulant therapy. On arrival, symptoms partially improved; however, repeat ECG evolved into typical anterior ST-segment elevation. Urgent coronary angiography demonstrated an 80% ostial LAD stenosis with thrombus, successfully treated with direct PCI and drug-eluting stent implantation. Conclusion This case illustrates the dynamic nature of the de Winter-like pattern and underscores that early recognition of STEMI equivalents is crucial to minimise reperfusion delays. On the other hand, it should be emphasized that causality between this precise ECG phenotype and specific angiographic anatomy cannot be generalized from a single case report, atypical de Winter-like morphologies remain incompletely standardized, and broader prospective validation of atypical STEMI-equivalent phenotypes remains limited.