Didn’t know that was possible with Omega 3. The pills I have are 660mg and recommends 1 per day, seems you took about 3.5x that dose

By the way, how can you detect arrhythmia? Blood pressure monitor or Apple Watch? General feeling?

You can use an Apple Watch and it might eventually catch it or if you have pulse oximeter you can watch the pulse wave or you can just feel for it at your wrist, carotid neck, or left peck. You want a steady beat, you can tell if there is a pause.

Probably the best way, other than a medical Holter monitor that you wear and a cardiologist reviews, would be to buy a chest strap that can independently record and you can review the rhythm. Look up PVC, PAC EKG.

Some premature contractions are normal. Nothing to go off on a tangent if you catch one in blue moon.

All that said, you will probably just feel a small kick in the chest and the above is unnecessary. Some people tend to anxiously get into these things without reason but the above can help with gathering evidence for your doctor if you suspect a problem that doesn’t go away with stopping supplements or coffee or booze etc. as sometimes heart things can be transient and hard to catch out of the moment. Palpitations can be caused by A LOT of things, I’ve noticed them from coq10, but there are so many other possibilities that it’s not necessarily something you want to self hack if you really do have a problem.

People can often feel arrhythmia. It can feel like heart fluttering, or skipping a beat, like when you get startled. Depends on the type of arrhythmia too.

That's exactly how "palpitations" were so named, because they can be unmistakably felt by the patient.

Some people can’t, I don’t understand how but they do exist.

General feeling. At night I could definitely feel it going to sleep, and it went away after decreasing the dose. It could be a coincidence, but regardless of my personal experience, there's actual science behind it. Too much o3 can affect the blood vessels.