Do you restrict the dose rate during treatment delivery to a pacemaker in addition to limiting the Dmax?  

Delivering a high dose rate implies that the pacemaker would be exposed to the machine's direct output. High-dose-rate exposure to a pacemaker could lead to an instantaneous malfunction and, even if temporary, should be avoided. Please err on the safe side.

AAPM has very detailed guidelines for the Management of radiotherapy patients with implanted cardiac pacemakers and defibrillators: A Report of the AAPM TG-203. Miften et al., PMID 31571229Also from Practical Rad Onc: Fagerstrom and Marotta, PMID 37578411.

Avoid heroics; call the patient's electrophysiologist and request that he move the pacemaker/CIED to the patient's right side, far away from the target. It is a same-day surgery and requires light anesthesia. If the patient's device is intracardiac and immovable, then defer radiation therapy. No dev...