A recent history of myocardial infarction (MI) is an absolute contraindication for elective endodontic treatment because the patient is at high risk of cardiac complications during stress or invasive procedures. Elective dental care should be postponed for at least 6 months post-MI to ensure cardiac stability and reduce the risk of another infarction or sudden death. Proceeding before this period increases the likelihood of life-threatening events. Urgent care may be considered only with medical clearance. Other conditions listed are manageable risks but not absolute contraindications.

Reference: Cohen's Pathways of the Pulp, 12th Edition.