I’ve been on it close to a decade now. I would have to say very effective in my condition. I take it with a beta blocker. It is hard to opine on just this medication without considering the beta blocker. I would also have to qualify any assessment based on dosage. All that said this type of medication does slow me down. I also have to be careful of taking meds with some food. But it does result in far fewer PVCs and I don’t have any non sustained VT anymore. There may be other Meds that do the same that you could tolerate better.