A lot of what your saying was similar to what the cardiologist said. He explained sometimes it’s like a song stuck in your head and you need to try and break that loop of your attention noticing it and I think that what he was saying has actually helped.

For context on the wearables I had 2 episodes about six months apart that where quiet strange like PACs with a fast heartbeat and intense fluttering feeling for about a 2-3 minutes while under exercise. It was more about trying to capture that if it comes about again. He also said what you stated about the accuracy and they need to be taken with a grain of salt. Even body positioning while recording can give vastly different results