The greatest risk was for multiple myeloma, suggesting such patients may need additional monitoring.
Having cancer increases the risk of atrial fibrillation by almost 65%, according to a study of almost the entire population of South Korea.
The national study found that while all 19 cancers studied increased the risk of atrial fibrillation, haematological, intrathoracic (including lung and oesophageal cancer) and central nervous system cancers were the worst, increasing the risk more than two-fold.
Previous studies had found cancer was an independent risk factor for the heart problem, but the the effects of different cancers was unknown.
At the most severe end, atrial fibrillation was three times higher among those with multiple myeloma than the general population. In contrast, stomach cancer conferred the lowest risk, only 27% higher than normal.
âNotably, we found that the risk of incident atrial fibrillation varies depending on the type of cancer ⌠patients with multiple myeloma showed the highest risk of atrial fibrillation compared with the non-cancer control group, and patients with stomach cancer showed the lowest risk of atrial fibrillation,â the researchers said.
âHaematologic malignancies, including lymphoma, leukaemia and multiple myeloma, and intrathoracic malignancies, including lung cancer and oesophageal cancer, and central nervous system cancer were associated with a more than two-fold increased risk of atrial fibrillation.â
Given the high risk of atrial fibrillation, âphysicians might consider more intensive screening in these subgroupsâ but more research was needed to determine whether this would improve outcomes, they said.
Researchers used the database of the National Health Insurance Service of Korea, a compulsory health insurance program administered by the government and covering roughly 52 million people.
Almost 817,000 patients diagnosed with cancer between 2009 and 2016 cancer were matched with a control group of almost 1,634,000 patients without cancer.
After about five years, cancer diagnosis was associated with a 1.6-times higher risk of developing atrial fibrillation.
âIn line with previous studies, we found that patients diagnosed with cancer had a 63% higher risk of atrial fibrillation,â the authors wrote in JACC: CardioOncology.
The finding held even after adjusting for known atrial fibrillation risk factors such as hypertension, diabetes mellitus and dyslipidaemia.
The atrial fibrillation risk declined with time from cancer diagnosis but remained significant.
Overall, patients with cancer showed a 44% higher risk of atrial fibrillation development one year after cancer diagnosis and an 8% higher risk of atrial fibrillation five years after diagnosis â though tapering off of this risk also depended on what cancer those individuals had.
The elevated risk persisted for at least five years for people with multiple myeloma, leukaemia, lymphoma, lung, liver, renal and gynaecological cancers.
