Maybe this is a dumb question, but is there any chance that a beta blocker (metoprolol ER, the generic form of toprol XL) could actually increase the frequency of PACs? I was put on toprol almost a year ago after an episode of a-fib. After taking it for several weeks, I began to have PACs more and more often. My cardiologist kept increasing the dose to reduce the PACs, but every time they just kept increasing. Now I am having extended periods every day where every 3rd or 4th beat is a PAC. I am wondering if this could be a paradoxical effect of the toprol, since before I started taking it I only had occasional isolated PACs, never long strings of them. They almost always start around the same time of day (10am-noon), which is about 4 hours after I take my morning dose of toprol. My doctor's solution always seems to be to keep ramping up the dosage, but I am reluctant to continue doing this since it doesn't seem to be working and I am concerned about side effects. I would appreciate any insight anyone might have about this.