That's interesting ...!
I have had a history of fainting when under stress, such as having teeth pulled or painful injections, and I always just put it down to being a wimp. My RHR when I was fit was 34 bpm and even now after illness and losing a lot of fitness, it is only about 55 bpm.
I had never heard of heart block. When I had my pulmonary embolism last year, the doctors did tell me that something didn't look quite right on the ECG, and I have had some rhythm problems since then but they told me that they thought it was caused by the large clots pressing against the side of the heart. They did an ultrasound scan of my heart to take a look at what was going on and I have had a couple of CT scans as well.
If things stop improving, I will have to get them to check my heart again.