(CNN) -- If Douglas Mogle hadn't collapsed exactly where he did in the Notre Dame parking lot on October 22, 2011, he might not be alive today.
He landed in front of the tailgate party of a pediatrician, who immediately began CPR. A medic in a golf cart driving by rushed over. Then a cardiologist arrived on the scene.
Not that Mogle remembers any of this. He had gone into sudden cardiac arrest. He was down for 52 minutes and shocked nine times on the way to the hospital. After being airlifted to Northwestern Memorial Hospital in Chicago, he spent two weeks in the cardiac ICU.
"If only I knew that those days in intensive care would prove to be much easier (for me at least) than the days and months ahead," Mogle wrote on iReport.com.
Mogle developed post-traumatic stress disorder, or PTSD, after he was released from the hospital, something new research shows may be common for survivors of a traumatic medical event.
Nearly one in four stroke patients experience PTSD in the year following their stroke, according to a study published Thursday in the scientific journal PLOS ONE. Lead author Dr. Donald Edmondson and his colleagues analyzed nine previous studies with a total of 1,138 participants to arrive at this conclusion. Although the sample size was relatively small for a study of this kind, Edmondson has done previous research on PTSD after traumatic medical events with similar results.
Last year Edmondson published a study looking at PTSD caused by cardiovascular events, similar to Mogle's. Analyzing data from more than 2,300 patients, he found one in every eight heart attack survivors develop PTSD, and that those who do are twice as likely to have another heart attack or die in the three years following their first.
"This is the same disorder most people think about (associated) with combat survivors or sexual assault," says Edmondson, an assistant professor of behavioral medicine at Columbia University Medical Center in New York. "The symptoms are similar. It's diagnosed the same way."
At 31, Mogle was younger than most heart attack patients, although we know they can happen at any age. He was also in good health at the time -- he had recently lost some weight; he worked out five to six times a week; he never smoked.
The fact that he had a heart attack anyway frustrated him.
His girlfriend noticed the PTSD symptoms first. Mogle was irritable. Impatient. He got bored quickly and once even slammed a door at work -- totally out of character for the usually mild-mannered fourth-grade teacher.
"I would think about it all the time," he said. "I was somewhat embarrassed that it happened because it's related so much to health and eating and exercising. A lot of it for me was genetic."
People asked him about the incident all the time, adding to his embarrassment. He hated scheduling rehab appointments because they had to happen early in the morning. He often ignored his doctors' orders to avoid eating certain foods.
"I guess I was being defiant to a degree," he said. "I was adamant about trying to get back to a normal life."
But when he closed his eyes at night, all he could think about was having another heart attack.
Many doctors aren't familiar with PTSD following a traumatic medical event, Edmondson said. More research is needed to confirm his findings and make clinicians aware of screening and treatment plans.
Scientists aren't sure exactly how traumatic a medical event has to be for patients to develop PTSD. Researchers at Oregon Health & Science University found 20% of people who underwent low-back fusion surgery suffered from the disorder.
We also don't know why one patient is more likely to develop PTSD than another. Age may be a factor, Edmonson said. Younger patients haven't seen peers deal with similar events, and a heart attack or stroke may have more of an impact on their day-to-day life.
One of the things Edmondson hopes to study in the future is the distinction between PTSD caused by external traumatic events -- such as combat or sexual assault -- and internal medical events. A combat survivor, he says, can usually remove reminders of his or her traumatic event, but for medical patients it's not that simple.
"For someone who has a heart attack or stroke, we actually prescribe that they pay attention to the very reminders of their heart attack or stroke -- increased heart rate, blood pressure," he said. "They're constantly having to think about it."
In a previous study Edmondson found that heart attack survivors with PTSD were less likely to take their medication, which is strange considering their fear of having another one. But Edmondson believes the daily pills simply remind survivors of what they experienced.
"What if the immediate psychological need to not feel anxious and in danger or threatened in the moment is more pressing than the long-term future need of not having to have another stroke," he asks.
Mogle went to see a psychiatrist after his girlfriend confronted him about his behavior. He was put on antidepressants, and the therapist helped him work through his anger. In October he went back to Notre Dame and met with some of the EMTs and firefighters who worked on him that day.
In January he joined the CNN Fit Nation team, which has helped him channel his energy into training for a triathlon. He wears a heart-rate monitor during every workout to ensure he doesn't trigger his ICD or implantable cardioverter-defibrillator.
"Life is never going to be like it was when I was 30," he said. "So I just have to get used to that."