Hi. What would NOT be done is to stop anticoagulation altogether.
here is a (free full text) study from 2007 on whether to: continue through with warfarin, or to stop the warfarin and bridge in between with enoxaparin or heparin (as snconorm had done).
http://www.circ.ahajournals.org/cgi/content/full/116/22/2531
So continuing through with warfarin seems to be the newer strategy.
What would NOT be done is to stop anticoagulation altogether. There is risk of bleeding, true, but on the opposite end is the risk of a clot - from the devices being poked around inside the vessels which might cause injury/inflammation and create a clot which travels to the brain or elsewhere.
(Btw, enoxaparin (aka Lovenox) is a "low molecular weight" heparin - which is something like a filtered version of heparin. They retain the active parts, and leave out the other parts which might have various unpredictable effects. It's more $$$, too. Heparin comes from pig intestines and cow lungs.)
If your father is taking Coumadin and his INR is high, the blood thinning can be reversed with intravenous medication, called Vitamin K, before the procedure. Even if his blood had already been thinned with Coumadin, he will receive intravenous Heparin blood thinner. Heparin works immediately, and the effects only last for a short time after the drug is stopped. The concern is bleeding at the catheter entry sites and in my case I waited a short time in the recovery room while the Haparin dissipated before the catheters were pulled.
My doctor (EP) provided a very specific schedule of when to stop Metoprol and Rythmol and your father should also have received this information. It may be worth checking with the doctor if there is any question.
They gave me the blood thinner injection after the His bundle ablation.
If the doctor doing the ablation is not concerned about bleeding due to coumadin, that's the answer.
To my understanding, ablation is done with radio-frequency energy burning... i.e., it may cauterize as it burns, seems to me it would, and thus little or no bleeding.