I agree with everything said. In addition, is your father seeing a regular cardio or is he seeing an ep who specializes in rhythm problems? My ep told me he's done ablations for people in their 90's.
And @Tom. I'd suppose a pacemaker would be more invasive and difficult than ablation. (just me guessing - if you'd like to check my medical credentials - they're the same as my cat - and she's stupid)
But I like Tom's call here: how old a 73-year old we have here? My inlaws are getting there and they're the biking-hiking-est people you'd meet... and what is insurance going to say. Both procedures are going to cost a ton. (even in co-pay)
In my opinion, I guess it would depend on a lot of things. You didn't say what this procedure would be for? Does he have any underlying conditions. How "old" of a 73 is he? I know 73 year old men who run, ski, and do other active hobbies where a pacemaker might be troublesome. Another factor is cost of the procedures. Would they be covered under his Medicare and any supplemental insurance? I have an 84 year old friend who just had an ablation for A-Fib., and she's doing great. Ablation therapy is not a dangerous life threatening procedure for most people. Depending on his problem, ablation therapy might be something certainly worth looking at.