Heart screening may not have prevented Hamlin's collapse

Quick on-the-field emergency care from well-rehearsed medical personnel is widely credited with helping save Damar Hamlin’s life. But whether his cardiac arrest could have been prevented is much less certain.

Doctors say they’re still evaluating what caused Hamlin’s heart to stop after a tackle during Monday night’s game in Cincinnati. One possibility — a fluke type of chest trauma called commotio cordis — is impossible to predict or prevent.

Existing heart conditions are the most common cause of sudden cardiac arrest in young athletes. Some of them can be detected through tests including EKGs, which measure the heart’s electrical activity, and echocardiograms, ultrasound imaging exams that show how the heart muscle and valves are working.

These tests can’t detect all heart conditions and sometimes overlook ones that can be deadly. They are routine in professional sports and used by about half of NCAA programs, said Dr. Andrew Peterson, a team physician for the University of Iowa.