Not all heart attacks start with chest pain and shortness of breath. Sometimes, the clearest signs of a cardiac event come too late, says Dr. Steven Kunkes, of Bridgeport Hospital.

Former Marine Peter Macrae had a twinge in his left side. A home blood pressure device linked to an iPhone app told him he had an irregular heartbeat. He thought it might be broken.

“I wasn’t sure,” he says. “So I bought another one."

He went to see Dr. Kunkes, who, during an exercise stress test, found severe blockages in the arteries to Macrae’s heart. Macrae went into what he says was a lifesaving surgery.

"The last four men on my paternal tree have died of heart disease," he says.