You are correct that just skipping your metoprolol has a strong probability of both raising your bo to dangerous levels.. Even to the point where you suffer a hemmorhagic stroke and die pretty much instantly.
So yeah.. Definately ask for advice before you do that.
That said toprolol is actually one of the drugs that can be used to treat pvcs.. I dont think its making your problem worse..
Whats more likely here is that your problem has gotten worse to the point where the toprolol is insufficient. You might need to actually up the dose of metoprolol or add an additional medication as opposed to dialing the dose you have down.
Lowering dose from 50 to 25 carries a 80% -90% chance of making everything worse to at least some degree.
The Toprol XL (Metoprolol Succinate) tablet should not be cut in half. Doing so defeats it's time release properties. If you want to mess with dosages (and I don't think you should), the generic Metoprolol Tartrate (referred to as just Metoprolol) can be cut in half without a problem. I take an odd, 75mg. Per day; 50mg at dinner, and 25mg (half a pill) upon rising. Think of your dose level as a "starting dose level". I've been as high as 200mg, and my cardiologist has prescribed 400mg to a few patients. I was at 100mg of a few years until my cardiac ablation in 2010 when it was reduced to 75mg for mild hypertension control. So you have plenty of room to experiment with your physician's advice.
Now, all that said, I found Metoprolol to be totally ineffective in PVC control, and I've had my share of PVC clusters over the years. Right now, I'm in a quiet spell for the past 9 months or so with hardly any any all. If you find that Motoprolol isn't working, there are plenty of other antiarrhythmics to experiment with. Metoprolol is easily tolerated my most, and I refer to it as the Tic-Tac of beta blockers. By the way, switching to Metoprolol Tartrate will save you any lot of money or co-pays. It's literally pennies per dose compared to the Toprol XL brand.
Curious, how did they cardiovert you?