I've had PVCs since childhood. Feels fluttery and makes me want to cough. Only thing that's ever stopped them is magnesium, though I haven't tried CoQ10. I use 300 mg, 1 - 2 times daily. I know they're considered to be from sympathetic overactivity, but they hit me at widely varying times, sometimes under stress, sometimes when I'm completely relaxed.
Do you have Hashimoto's disease or an overactive thyroid? Excess thyroid hormone, whether from destruction of thyroid tissue, as in Hashi's, or from outright hyperthyroidism, can cause this.