"Death of a family member is so stressful that the resulting coping responses could lead to a heart attack," said Mikael Rostila, Ph.D., lead author of the study and associate professor at Stockholm University/Karolinska Institutet in Stockholm, Sweden. "But our results suggest that this association between the loss of a sibling and having a heart attack is more likely to occur some years after bereavement."

The study is the largest of its kind to show a link between death from heart attack and the death of an adult sibling. It included health information from a database of more than 1.6 million 40- to 69-year-olds in Sweden.

Researchers, looking at associations between loss of an adult sister or brother with heart attack and death in surviving siblings up to 18 years after their losses, found:

• Surviving women were 25 percent and men 15 percent more likely to die from heart attack after the death of a sibling, compared to people who had not lost a sibling.
• Increased risk of death from heart attack was four to six and a half years after the death of a sibling among women and two to six and a half years after among men.
• No notable increased risk of heart attack occurred immediately after their siblings died.
• If their sibling died of heart attack, the risk of heart attack death in the following years rose 62 percent among women and 98 percent among men.

Rostila said adverse coping responses, such as unhealthy lifestyles, underlie the association. Chronic mental stress following the death of a sibling could also lead to health consequences some years after the loss of a sibling. Similar genetics or shared risk factors during childhood may be the cause for both siblings dying from heart attack.

Healthcare providers should follow bereaved siblings to help recognize signs of acute or chronic psycho-social stress mechanisms that could lead to heart attack, Rostila said.

"We might be able to prevent heart attacks and other heart-related conditions by treating these siblings early on and recommending stress management," he said. "However, more detailed information from medical records, shared childhood social environment and family characteristics, and data on personal and relational characteristics is required to uncover the mechanisms causing the association between sibling death and heart attack."

Co-authors are Jan Saarela, Ph.D., and Ichiro Kawachi, Ph.D., M.D. Author disclosures are on the manuscript.

The Swedish Council for Working Life and Social Research and Swedish Research Council funded the study.