I have always thought we all have a similar problem happening within our bodies that is causing our afib problems. After 17 years of watching my afib come and go, and logging everything I eat, I am pretty sure our hearts are fine but we have a problem with a gland(s) or an organ(s). For example:
1). The Sympathetic Nerve INCREASES the heart rate.
2). The Vagus Nerve DECREASES the heart rate.
3). The Adrenal Gland INCREASES the heart rate (with adrenaline).
4). The Thyroid Gland both DECREASES and INCREASES the heart rate.
5). The Hypothalamus Gland produces hormones directing other glands to do stuff.
6). The Pancreas processes sugar, which cause other glands to do different things.
7). To further complicate the situation, when one gland stops working, sometimes another gland will try to pick up the slack.
Plus - there are lots more glands in the body - and don't forget the organs, which (some) also influence the heart rate.
Medications, chemicals, foods etc. can all cause our glands and organs to mis-fire. For me, sugar (and dehydration) are causing some gland(s) or organ(s) in my body to mis-fire, sending mixed signals to the heart - for example, telling the heart to beat fast and slow at the same time. This would explain why a healthy heart sometimes beats abnormally. It also explains why my heart afibs when I eat too much sugar, because the heart does NOT use sugar to contract (uses fatty acids) so obviously sugar/dehydration is causing something to misfire which in turn is directing the heart to afib. In our old age, I suspect a gland or organ is not working as it used to, causing afib or other heart palpitations. Unfortunately doctors and researchers don't know what it is (yet). In the meantime we will have to listen to our bodies VERY closely to see what is causing our problems and reduce or eliminate our afib by reducing what triggers it.
FYI - If you have a gland(s) that is not working correctly due to a nutritional deficiency, you can identify that with a Nutritional Response Tester and get it corrected, or partly corrected – which will greatly decrease your afib episodes and reduce the severity of afib episodes that do happen. I have done that myself and have been able to add years of living without medications, and a big improvement to the quality of life (for example can run up stairs with my mild afib and not have an oxygen problem – i.e. getting lightheaded and dizzy).
Hope this helps some of you.