Sudden cardiac death remains difficult to predict. The current clinical standard — reduced left ventricular ejection fraction (LVEF) — misses most at-risk patients and leads to many unnecessary defibrillator implants.

Researchers used deep learning on a large Swedish dataset of routine ECGs linked to death records and discovered a previously unknown ECG biomarker: a subtle slurred terminal R wave in lead aVL. This pattern is associated with higher risk of sudden cardiac death, likely linked to myocardial fibrosis.