By Casey RossJune 24, 2026
Chief Investigative Reporter, Data & Technology
It is one of the oldest mysteries in medicine: Why do fundamentally healthy people drop dead? Sudden cardiac arrest kills upward of 350,000 people a year in the U.S., a fate that is particularly tragic because it’s preventable with an implantable defibrillator.
The challenge is figuring out who needs one.
A study published in Nature Wednesday uses artificial intelligence to identify those people, and pinpoints a possible reason why they so often evade detection. It reports that a culprit once considered relatively benign — cardiac fibrosis, or scar tissue scattered throughout the heart — is commonly present in people with the highest risk of sudden death.
