Wonderful question. Mine is only a month old and I am constantly looking for signs that something has changed; even check my pulse occasionally and it's always near 60 except when I'm on the treadmill. Pre-pacer, I could always feel my pulse but with the device it seems to me my heart is not beating as strongly. Wondering if the Metoprolol has reduced the strength of the contractions. At times I can imagine a micro-spark and don't know if my brain is creating things to worry about. Any input on the subject would be welcome.