Thanks to a suggestion from someone here, I have just completed a six hour course on ECG interpretation. futurelearn.com/courses/ecg...
I did not find it difficult. Some of the early material on how to do a full ECG was irrelevant to me, but the explanations of the physical heart and the electrical heart were super clear. In week two, you just get the basics: normal sinus rhythm, atrial problems, and ventricular problems. Once again the videos and pdf files were super clear. You can also download them and use them to explain to others what is happening.
Some of us have bought portable ECG machines, and use them to confirm/evaluate life events. I found the course helpful. My major frustration was that it stopped after the second week.
I am posting this because I think others on this forum would find the course interesting. It is free, and you work at your own speed.