Below is a comprehensive article on diet, supplements and Afib. It is easy to understand and for those interested it is contains abundant amount of information.
"Dietary interventions in the management of atrial fibrillation
https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2024.1418059/full
As for taking nut oils as a supplement I know of no nut oils that are used as a supplement like in a pill. Using health oils in dietary cooking and preparing foods is different than taking oils as a supplement. The only oil that is known to be used for cardiovascular health is flax seed oil. Note that flax seed oil and some other nut oils are high in alpha-linolenic acid, an omega-3 fatty acid. Fish such as salmon, mackerel, and sardines provide the other forms of omega-3s (eicosapentaenoic acid and docosahexaenoic acid).
As a prostate cancer survivor x 24 years I have learned to carefully limit consuming high amounts of α-linolenic acid because it is associated with a significant increase in risk of prostate cancer.
"A 24-year prospective study of dietary α-linolenic acid and lethal prostate cancer"
https://pubmed.ncbi.nlm.nih.gov/29315549/
FYI "11 Best and Worst Oils for Your Health"
https://www.everydayhealth.com/news/best-worst-oils-health/