Its been my understanding that there are two different types of meds to treat rhythm and rate problems. Since I had both types of rhythm problems I took two meds- one for each problem. I took propafenone or rythmol for atrial fib and I took metoprolol (and other drugs over the years) for my SVT (supra ventricular tachycardia or rapid rate). Until my 50’s I only took rate drugs. My rapid rate was even and fast (up to 230 BPM) When I developed AFib I was put on rhythm drugs. My rate was still very fast but with the AFib it was also uneven or “all over the place”. Over the years I was prescribed a variety of cocktails as the ones I was on became ineffective over time and I had a lot of break through problems. Sometimes the drugs are interchangeable. I agree with vermontrob – your husband would benefit from seeing cardiologists who are trained in this area- electrophysiology. A reputable EP lab would be a good start. Let us know what you decide.