Tom Parker was 32 when his heart suddenly stopped. At home in Washington, D.C., his wife quickly started CPR with guidance from a 911 dispatcher. An emergency medical technician arrived on the scene minutes later. Using a portable defibrillator, he shocked Parker's heart to get it pumping again.

Parker was one of the more than 350,000 people in the U.S. who experience a outside of a hospital each year. Cardiac arrest occurs when the 's electrical system malfunctions, causing the heart to abruptly stop. Unless CPR is performed and an is used to shock the heart, death can occur within minutes. As a result, only 11 percent of those treated by survive, according to the American Heart Association's heart disease and stroke statistical update.

"Physicians spent decades making sure cardiac arrest patients could survive and live at all—making sure we could even get them to wake up," said Dr. Clifton Callaway, an emergency medicine physician at the University of Pittsburgh. "Now, anytime we can get them to that stage, we consider it a great success."

Yet, a study published Thursday in Circulation: Cardiovascular Quality and Outcomes suggests that returning to normal life may not be all that easy, especially if brain injuries occur when the heart stops.

The study, led by Dr. Gisela Lilja, an occupational therapist at Sweden's Lund University, assessed how 250 patients were doing six months after their cardiac arrest. Their experience was compared to that of 119 patients who, six months earlier, had a major heart attack. Both groups filled out a questionnaire about their societal participation and pre- and post-event work status. They were also evaluated for cognitive and emotional problems.

The research team found that less than half of cardiac arrest survivors had returned to their previous level of work, compared with 72 percent of heart attack survivors. In addition, nearly half of the cardiac arrest survivors reported more restricted participation in everyday life and society, such as difficulty with self-care, relationships and leisurely activities. Only 30 percent of heart attack survivors reported more restricted participation.

Those who had cognitive impairment from a cardiac arrest were three times more likely to be on sick leave six months later than cardiac arrest survivors with no impairment. Problems with mobility, memory, fatigue and depression were also tied to lower societal participation and community integration, such as fewer social contacts and participation in leisurely activities.

Lilja said the findings suggest more needs to be done to provide cardiac arrest survivors with rehabilitation services. For example, she said, referrals to specialists who can help with brain injury, fatigue, depression and other problems aren't routinely provided.

In Parker's case, four to five days after his cardiac arrest, he was seen by a neurologist and occupational and speech therapists at the George Washington University Hospital. He was diagnosed with anomic aphasia, or trouble retrieving words and expressing himself. Conversations left him exhausted.

After discharge, Parker began speech therapy, going three times a week for about two months before returning to work. He then continued with speech therapy for four more months. He also started running consistently.

Just seven months after his cardiac arrest, Parker completed a half-marathon. Today, two and a half years later, Parker, now 35, is a member of the board of directors for the Sudden Cardiac Arrest Foundation, a nonprofit based in Pittsburgh that raises awareness about prevention and treatment of cardiac arrest.

Callaway, who was not involved in the study, said it is important for cardiac arrest survivors who experience brain injuries to know that the problems they are experiencing can be addressed.

"For people having trouble with depression, we know that therapy or antidepressants can help," said Callaway, a past chair of the AHA's Emergency Cardiovascular Care committee. There are also therapists who can help survivors who have fatigue or mobility issues. "If we are able to relieve these issues for survivors," he said, "perhaps we can help people resume regular life more quickly."

Bottom line, he said, "Cardiologists need to be on the lookout for things that are not cardiological."

More information: Gisela Lilja et al. Return to Work and Participation in Society After Out-of-Hospital Cardiac Arrest, Circulation: Cardiovascular Quality and Outcomes (2018). DOI: 10.1161/CIRCOUTCOMES.117.003566

Journal information: Circulation: Cardiovascular Quality and Outcomes