Rheumatoid arthritis with a prosthetic mitral valve

Correct answer: C. Increased susceptibility to infection from bone marrow suppression

• A. Osteonecrosis of the jaw is associated with antiresorptives — bisphosphonates and denosumab — and with antiangiogenics, not with methotrexate.
• B. Xerostomia is caused by anticholinergics, tricyclic antidepressants, antihistamines, diuretics and many antihypertensives. It is not a leading methotrexate effect.
• C. CORRECT. Methotrexate is a folate antagonist that suppresses the bone marrow. The consequences that matter dentally are LEUKOPENIA, raising infection risk and impairing healing after surgery; THROMBOCYTOPENIA, adding to bleeding risk on top of the warfarin; and ORAL ULCERATION and MUCOSITIS from the antifolate effect on rapidly dividing mucosal cells. A recent complete blood count with differential should be reviewed before extraction.
• D. Gingival enlargement is caused by phenytoin, cyclosporine and dihydropyridine calcium channel blockers such as nifedipine and amlodipine — not methotrexate.

Note: Do not give this patient an NSAID: NSAIDs reduce renal clearance of methotrexate and can precipitate methotrexate toxicity. Folate supplementation is standard alongside weekly dosing.

Correct answer: B. The heart and the joints

• A. Liver and spleen are not affected by rheumatic fever.
• B. CORRECT. Acute rheumatic fever is an immune sequela of Group A streptococcal pharyngitis, in which antibodies cross-react with host tissue. CARDITIS is the consequence that matters long-term — valvulitis scars the mitral valve above all, then the aortic — and migratory POLYARTHRITIS of the large joints is the most common acute feature. The Jones criteria capture both, alongside chorea, erythema marginatum and subcutaneous nodules.
• C. Renal involvement follows a DIFFERENT streptococcal complication, post-streptococcal glomerulonephritis. The lungs are not a rheumatic fever target.
• D. Erythema marginatum is a skin sign, but the skin is not a damaged organ system, and peripheral nerves are not involved. Sydenham chorea reflects central, not peripheral, involvement.

Note: Mnemonic for the major Jones criteria — J♦NES: Joints, ♦ carditis, Nodules, Erythema marginatum, Sydenham chorea.

Correct answer: C. Some dental procedures will require antibiotic prophylaxis

• A. Progression of her rheumatoid disease is a real medical issue but it is not the governing consideration for this dental appointment.
• B. Hospital care is not required for a routine extraction in a stable outpatient. Her INR should be checked within 24 to 72 hours and, if therapeutic, warfarin is CONTINUED with local haemostatic measures.
• C. CORRECT. A PROSTHETIC HEART VALVE is one of the four AHA categories that still require antibiotic prophylaxis, alongside previous infective endocarditis, unrepaired or recently repaired cyanotic congenital heart disease, and cardiac transplant with valvulopathy. Prophylaxis is indicated for procedures involving gingival manipulation, the periapical region, or perforation of oral mucosa — an extraction qualifies. Amoxicillin 2 g orally, one hour before.
• D. Vasoconstrictors are not contraindicated. A limited dose of epinephrine is safe and desirable in stable cardiac patients, because good anaesthesia reduces endogenous catecholamine release.

Note: Note the deliberate contrast with a SUCCESSFULLY REPAIRED tetralogy of Fallot with no residual defect, which needs NO prophylaxis after the first six months. Prosthetic material in the valve position is a different category.