My experience(s): Nov '18 - Treadmill stress test, no big deal. Excercise for me at that time was 1-hr. on the treadmill at 3.5 mph & slight incline followed by 2 mile walking track thingy, 5-6 times per week. EP replaced my 3 lead PM - due to low batt - on Nov 30 '18 with a 3 lead PM defib. The following month, I had 3 periods of excitement - diverticulitis followed by a C-Diff infection followed by a pneumonia. Mid Jan. '19 I was finally kinda normal except: exercise 45 min at 2.5 mph 4 times/week and NO walking track use. Daily fatigue set in. Currently, the EP wants to go in for a look 'cuz "that third lead isn't working." Could the new Medtronic PM w/cardiac resynchronization capability be not functioning as it should? I've had numerous device checks through 2019 along with a 48 hr. Holter monitor survey. Would any of this have caught a malfunctioning PM? My look at the Holter report reveals things like "Number of longest Ventricular beats: 9 - Number of Ventricular ectopics: 33,791 and so on. Nothing that points to how the third lead is involved. FWIW: The first Doc who suggested what my current issue is was my Dermatologist, Mary Evers, DO. I disrobed for a skin check and she took one look at my torso and muttered "Cardiac Cachexia" Not one cardio Doc had mentioned that condition earlier. Whatcha think?