(NPR) In 2008, Army Reserve Capt. LeRoy Torres returned home to Robstown, Texas, after a tour in Iraq. He went back to work as a state trooper with the Texas Highway Patrol.

Torres was a longtime runner. So when a suspect took off on foot one morning, Torres sprinted after him. But something was wrong. A burning sensation in his chest hurt so bad, it almost knocked him down.

“I was able to catch up, but afterwards, my goodness, I remember just — I laid on the ground, I was so exhausted,” Torres says. “One of my buddies said, ‘Man, what’s wrong?’ I said, ‘Man, I don’t know. I just feel really, really tired — my chest feels really tight. I don’t know.’ I couldn’t catch my breath.”

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