Antidepressants are not to blame for frequent atrial fibrillation among people with depression. This is the conclusion reached by researchers from Aarhus University in a major registry study, which also points towards the possibility of the actual cause of atrial fibrillation being insufficient treatment of depression.

2018.11.20 | Helle Horskjær Hansen

Over the last twelve months, more than 400,000 Danes have been prescribed antidepressant medicine – and this medicine has been linked with an increased risk of atrial fibrillation. A study of more than 785,000 Danes who began treatment with antidepressants during the period 2000-2013 now shows that the medicine is not the culprit.

"The study does in fact confirm that people undergoing antidepressant treatment are diagnosed with atrial fibrillation more than three times as frequently as others during the first few weeks of treatment. However, it also shows that their frequency is even higher before they begin treatment with antidepressant medicine. It’s therefore not reasonable to believe that the antidepressant medicine is what causes this frequent atrial fibrillation, which particularly affects the atria," says PhD student and senior statistician Morten Fenger-Grøn from the Department of Public Health at Aarhus University, who has headed the study.

The study ”Depression, antidepressants, and the risk of non-valvular atrial fibrillation: A nationwide Danish matched cohort study" is the latest result of a collaboration between researchers from Aarhus University and a research group in Seattle, USA. The study has been published in the cardiology journal European Journal of Preventive Cardiology.

Atrial fibrillation is already a frequent disorder that affects as many as one in three people in Denmark, and though the condition does not always have obvious symptoms, it is nevertheless associated with an increased risk of a number of serious complications, in particular blood clots in the brain.

"It’s not inconceivable that psychological problems can cause both atrial fibrillation and other cardiac disorders, meaning that the cause of the particularly high prevalence of atrial fibrillation in the period prior to treatment with antidepressants could be that depression in itself disrupts the heart rhythm. In which case, our results could be interpreted as showing that antidepressant treatment is not only harmless, but actually part of the solution to the problem," says Morten Fenger-Grøn.

Other reasons for contacting the healthcare system
However, he also points out that this is far from the only possible interpretation of the results:

"The fact that atrial fibrillation isn’t always discovered immediately makes the condition challenging both clinically and in a research context. We often see that people who contact the healthcare system for a completely different reason have an increased likelihood of being diagnosed with atrial fibrillation and that they have suffered from it for a period of time. In our study we show that this factor can be a significant part of the explanation of the high prevalence of atrial fibrillation among people who are prescribed antidepressive treatment."

The researchers behind the study emphasise that their results apply solely to the type of atrial fibrillation that affects the atria.

"It may still be relevant that certain types of antidepressant medicine are linked to an increased risk of other types of heart rhythm disorders, which may also be serious, but are fortunately much rarer than abnormal heart rhythm in the atrium," says Morten Fenger-Grøn.

Background for the results:

The study is a nationwide registry study by researchers from Aarhus University in collaboration with the research group in Seattle, in which they combined data from the following registries; The Danish civil registration number (CPR), the Danish National Prescription Registry, the National Patient Register and the National Health Insurance Service Register. In the study, 785,254 persons who began treatment with antidepressant medicine during the period 2000-2013 were compared to a 1:5 matched sample of non-treated Danes of corresponding gender and age.

The study is financed by the Lundbeck Foundation and the Health Science Research Foundation of the Central Denmark Region.

Read ”Depression, antidepressants, and the risk of non-valvular atrial fibrillation: A nationwide Danish matched cohort study”

Contact

PhD student and Senior Statistician Morten Fenger-Grøn
Aarhus University, Department of Public Health at Aarhus University

Email: mfgr@ph.au.dk
Mobile: (+45) 2745 6059