I have had left branch bundle block for at least 25 years. One doctor said I may had been born with it which I doubt but who knows. January of 2019 I had a devastating stock and was paralyzed on my right side which means the stroke was on the left side of my brain. My neurologist said it was from a blood clot but none of the test could find where it came from. Last December, 2024, I had a wild fall while I was preparing the cats food. I could see myself falling and was telling myself this was going to hurt and couldn't stop it. My heart doctor wired up up again for about the 5th time, to monitor my heart for two week. 2 days after I turned the monitor in I got a series of panic calls from the doctors nurse and the doctor himself. My heart was actually stopping for up to 20 seconds at a time. One week later I had a pacemaker. If there is a lesson to be learned don't be complacent about your tests. I went 2 years between mine. I had fallen 5 times in those two years and broke my foot one time my arm was dislocated and broken in two places the last time which led to the heart doctor and the pacemaker and probably saved my life.