Pocket Blockers for Atrial Fibrillation

This week during rounds, a question was raised about whether or not "pocket blockers" as recommended by the CCS for symptomatic paroxysmal atrial fibrillation will actually work or if they take too long to work. Cardiology is NOT my strongest area of practice.

The patient was an elderly man who was having occasional, upsetting episodes of palpitations that were caused by paroxysmal atrial fibrillation that lasted for several hours, especially at night. During the day, his heart rate was often too low to consider a beta blocker. I don't want to be the cause of a fall in one of my elderly patients. I decided, on the advice of another doc, to give him a beta blocker (bisoprolol) at bedtime only. I still worry though that his heart rate may drop when he doesn't need it and cause a fall on the way to the washroom at night. Would it be worth considering a pocket blocker for this guy?

"The choice of rhythmcontrol relates to AF characteristics. For patients with a lowburden of infrequent paroxysmal AF, pill-in-pocket antiarrhythmictherapy might be reasonable. For more frequentparoxysmal AF, daily maintenance antiarrhythmic therapymight be tried, followed by consideration of catheter ablationif the response is not adequate."

It seems unlikely to me that the CCS would make this recommendation, and a pretty graphic to go with it, if it wasn't going to work.

Now, to determine which beta blocker to choose, because, damn, there are a lot of beta blockers.
Let's go alphabetically. I've taken my info from Up To Date because it's the easiest for me to search through the blockers. I'm just looking at the Canadian types and oral delivery because that's all I care about for the patient we were discussing.
acebutalol: onset 1-2 hours, 1/2 life 12-24 hours
atenolol: onset 2-4 hours, 1/2 life 12-24 hours
bisoprolol: onset 1-2 hours, 1/2 life 9-12 hours
carvedilol: onset 30 min - 1 hour, 1/2 life 7- 10 hours
labetalol: onset 20 min - 1 hour, peak effectiveness in 1-4 hours, 1/2 life 6-8 hours
metoprolol: onset 1-2 hours, 1/2 life 3-4 hours
nadolol: no onset info given, 1/2 life 20-24 hours
nevibolobol: peak onset 1.5 hours, 1/2 life 12 hours
penbutolol: peak onset 1.5 hours, 1/2 life 5 hours
pindolol: peak onset 1 hour, 1/2 life 3-4 hours (up to 15 hours in the elderly)
propranolol: onset 1-2 hours, 1/2 life 3-6 hours
sotalol: onset 1-2 hours (or sooner), 1/2 life 12 hours
timolol: onset 15-60 minutes, 1/2 life 2-2.7 hours

OK, so 3 of these are appealing based on onset less than an hour - carvedilol, timolol and labetalol. They also have half lives less than 12 hours with timolol definitely winning. Most of these though are active by 1 hour. For most patients that are symptomatic during the day, any of these might be great. But I worry about this elderly man with low blood pressure, low heart rate during the day, and multiple medications.

 I think finding a cardio selective drug might be most helpful and decrease the risk of side effects. Those are metoprolol, acebutalol, atenolol and bisoprolol.

Of these, metoprolol has the shortest half life. I have a winner, and since my patient has side effects on the bisoprolol, it's worth changing.