Dear, How accurate is the heart monitor of the Apple Watch 4? I live in the Netherlands and have no possibility to use the ECG function. I am a patient to Tietze Syndrome, that mimics heart pain issues. So far, nothing serious has happened. However, I do have more of these Tietze issues than normal. So far, I have always ignored this pain and linked it to Tietze. The reason to start worrying, is because my Apple Watch gives abnormal rates. Yesterday I had a huge pain, took some paracetamol and went to sleep. My heart rate was 144 when I went to sleep, was 46 when I woke up. In my perfect world my Apple Watch is not accurate and it is a software issue. So I want to know, how accurate is the heart rate really? I do realize you're not a doctor, but based on your experiences I'd like to know if it is just the Watch or not.