I think you hear the majority of people are on Metoprolol, followed by Atenolol, Propanolol, then Sotalol all
beta blockers. Then comes Verapamil, which is a calcium channel
blocker like Diltiazem. Perhaps is has something to do with the nature of how a Class IV anti-arrhythmic affects the cardiovascular system. It decreases or slows conduction through theĀ AV node, and reduces the contractility of the heart, so it could be inappropriate in cases of heart failure.