Sounds like you are in great shape. I must admit, you also seem incredibly skilled in cardiology.
It's interesting to know what you wrote about ST-dep, my mother is exactly at your age and she has more or less (probably less, though) the same problem, with sudden flare-ups of 10-12.000 PVCs/day, also with great exercise tolerance, but she has also got the ST-depression, resting EKG reveals mild ST depression, nonspecific ST-T changes and wide complex premature beats. Her PVCs disappear at heart rate >110, she maxed at heart rate 180, 12 MET. PVCs returned at heart rate 110.
It's normal for PVCs to occur with slow heart rate, but I understand your bigeminy is getting bothersome (I assume your experienced heart rate is 20-30, so your real heart rate is 40-60) and causing low blood pressure. Cardizem lower blood pressure, so you could try asking your doctor if you really need a calcium channel blocker, I'm not a doctor, so I can't say if you need certain medications or not.
The question is if your PVCs are multifocal or unifocal. Unifocal PVCs can be ablated. A holter test will reveal how many locations your PVCs origin from, but I assume this is already evaluated, with 2 EP studies they can't have missed anything. I assume your potassium (and other electrolytes) is normal. Low or low-normal potassium can cause ST-T changes and PVCs.
Hard to say why this happened, you may have suffered some subclinical heart inflammation causing irritable spots in your heart, but if you did, your problems would usually have increased with exercise. A history of heavy aerobic exercise can also cause your symptoms, but if so, I would assume you would have more supraventricular arrhythmias (such as A-fib) as well.
Sorry for a fairly nonconclusive answer, but with all your tests, it's hard to add anything useful :-)
It sounds like you have tried a ton of different med combos. Good for you and your cardiologist for being persistent. The only thing I can think of is whether or not a pacemaker device would help in your situation. Im not really up to date on recent treatments for symptomatic bradycardia, and if your cardio doc hasnt mentioned it yet then Im sure he has a good reason why. But it cant hurt to ask about it to hear his thoughts on the matter.
Best wishes to you, it sounds like youre dealing with a lot right now.
Thanks guys for your insight & help! Yes unifocal (monomorphic) focus that they couldn't ablate from inside heart because right on top of major artery (LAD). Approach from outside heart might be possible but I hate the thought of open surgery or digging around out there when technology will probably provide an internal solution sooner rather than later. Maybe that's too stubborn, but w 70% maybe success... Hmmm. If I could just get a life in the meanwhile. This is bad or it feels that way to me as I lay here w symptomatic bigeminy.
Midijane: great ep guy indeed & he has mentioned pacer set at 70(?) a few times in passing for the bradycardia/sinus pauses if no resolution & then meds for the pvcs & tachycardia. Do u have one? Are they limiting? When the pvcs go, brady is less! Good thought about the cardizem- it's being used only at bedtime to slow AV node as I have collapsed w tachycardia (couldn't induce avnrt that they expected but found ectopic atrial pacemaker) a few times since July but even flecainide alone couldn't stop collapse but the combo seems to work better for some reason. Think I'll ask if it might be worth a try to d/c it when (if) things settle down on rythmol.
Is_something_wrong: your mom & I must be sisters from another mother! My pvcs disappear w exertion, return on recovery as do hers, max hr 180, 13.4 mets. Same EKG except have lvh voltage criteria (mild.)
Maybe this has something to do w athlete's heart? I'm far from an elite athlete now but have been a lifelong jock- the stress echo did show mild asymmetric LV hypertrophy but nl wall motion.