Adults in Denmark whose partner died had an increased risk of atrial fibrillation for up to a year after the death, according to a population-based, case-control study.

The odds ratio of developing atrial fibrillation was highest eight to 14 days after the partner died. Within 30 days after the death, the odds ratio of developing atrial fibrillation was 41 percent higher in people whose partners had died compared with those whose partners had not died.

Lead researcher Simon Graff, MD, of Aarhus University on Denmark, and colleagues published their findings online in Open Heart on April 5.

“The elevated risk was especially high for those who were young and those who lost a relatively healthy partner,” they wrote. “Our results call for further studies aiming at evaluating whether the association also applies to more common, but less severe, stressors and at identifying causal mechanisms and treatment possibilities.”

The researchers mentioned that the incidence of atrial fibrillation is increasing, and it is associated with an increased risk of death, stroke and heart failure. The estimated lifetime risk of atrial fibrillation is between 22 percent and 26 percent, according to previous research. They added that losing a partner often causes depression, anxiety, guilt, anger, hopelessness and other mental illness symptoms.

In this study, they prospectively collected information from four nationwide Danish registries and found 88,612 people with a first-time inpatient diagnosis of atrial fibrillation from 1995 through 2014. They then identified 886,120 age-matched and sex-matched controls based on risk-set sampling.

They also used the Danish Civil Registration System to identify cohabitant partner status, marital status, identification of corresponding spouse or partner and all spousal/partner deaths for cases and controls. In addition, they used to age-adjusted Charlson Comorbidity Index (ACCI) to predict the likelihood of death for all partners one month before their deaths.

During the study, 19.72 percent of the cases and 19.07 percent of the controls experienced partner bereavement.

The highest odds ratio was found in people who were younger than 60 years old. The odds ratio increased with decreasing ACCI scores.

There was no difference in the risk of atrial fibrillation when the researchers compared singles with cohabitating partners. There was also no difference when they excluded cases and matching controls who redeemed a prescription for an antithrombotic agent.

“We adjusted for several confounding factors, such as medication and comorbid conditions, and found only little change in the estimates,” the researchers wrote. “However, residual confounding cannot be ruled out because we had no information on potential confounding factors such as lifestyle factors, physical activities and family history of [atrial fibrillation]. We believe that the risk of residual confounding is likely to be small as we cannot think of any possible confounder that could cause a transiently increased risk of [atrial fibrillation] shortly after bereavement.”