I'm not surprised that your medical team has "outlawed" Diltiazem and Metoprolol at the same time -- I think they amount to a double-barreled attack on arrhythmia. According to <drugs.com> "Diltiazem is a calcium channel blocker. It is used to treat hypertension (high blood pressure), angina (chest pain), and certain heart rhythm disorders." It also is one of the first-option medication treatments for hypertension. Metoprolol is a common beta blocker used for hypertension and easing of heart beats.

In my case, A-fib is my problem along with hypertension. I'm taking Coreg (like Metoprolol a beta blocker). I was prescribed another calcium channel blockers (Amlodipine) a few years ago, but my nephrologist cancelled that and listed it as an allergen when she started me on Coreg (Carvedilol). Because of A-fib, I also am on a Coumadin (Warfarin anticoagulant) regimen to prevent clots from forming in my heart.

Mysteriously, the Coumadin failed me 20 months ago, and I suffered a "small stroke" that caused me some minor imbalance and uncoordination problems that have been overcome with physical therapy -- teaching my brain to pay attention, stop assuming what I want to do, and behave. It turns out that this brain behavior -- issuing subconscious signals and directives to certain nerves, muscles, and glands -- has a far broader effect on me than I ever imagined. Frequent urination, for example, is necessary -- not because my bladder is full to overflowing, but because my assumptive brain believes that's what I want to do when I draw a glass of cold water from the refrigerator or turn on the kitchen faucet or roll over in bed ! ! ! ! My nephrologist has me exercising my brain to break its tendencies to initiate urination on the basis of false signals from my environment . . . and I think I'm making progress! I also think my nephrologist is a miracle worker.
Martin