Urgent Extraction in a Patient on Dual Antiplatelet Therapy Three Months After Coronary Stenting
A 68-year-old man presents as an emergency with a three-day history of increasing pain and swelling of the left lower jaw. Eleven weeks ago he had a non-ST-elevation myocardial infarction treated by percutaneous coronary intervention with a drug-eluting stent to the left anterior descending artery. His medication is aspirin 100 mg daily, ticagrelor 90 mg twice daily, bisoprolol 5 mg, atorvastatin 40 mg and metformin 1 g twice daily; his HbA1c is 7.6%. He is apyrexial apart from 37.9 degrees Celsius, blood pressure 152/90 mmHg, pulse 88 and regular. There is a 2 cm buccal swelling with trismus limiting opening to 28 mm, no dysphagia, no elevation of the floor of the mouth and no stridor. The lower left second molar (37) is grossly carious, non-vital and tender to percussion, with a 6 mm buccal pocket. He has not slept for two nights.
1. What is the immediate priority, and what antibiotic, if any, would you prescribe given his medical history?
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Priority: remove the source. This is a localised, non-spreading odontogenic infection - no dysphagia, no floor-of-mouth swelling, no airway compromise, no systemic toxicity. It is urgent but not an airway emergency. Definitive treatment is drainage: extraction of 37 (or pulpectomy if it were restorable) plus incision and drainage of the buccal collection, under local anaesthesia. Antibiotics are an adjunct, never a substitute.
Antibiotic choice
- First line: amoxicillin 500 mg three times daily for 3-5 days, or amoxicillin-clavulanate 625 mg three times daily if there has been prior treatment failure.
- Add metronidazole 400 mg three times daily where anaerobic spread is suspected.
- Avoid clarithromycin. It is a strong CYP3A4 inhibitor and raises ticagrelor exposure, increasing bleeding risk. If a penicillin allergy is genuine, azithromycin is the safer macrolide.
- Review renal function before continuing metformin through an acute infection, and advise holding it if he becomes dehydrated.
Antibiotic prophylaxis is not indicated for his coronary stent - stents are not an indication under any current guideline.
Do not prescribe tablets and send him home. Without drainage, a diabetic patient with a buccal swelling can progress to a submandibular or fascial space infection within days. Give clear return instructions and an out-of-hours contact.
2. How do you manage his antiplatelet therapy and the bleeding risk of extraction, and what analgesic do you choose?
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Do not stop aspirin or ticagrelor. He is eleven weeks post-stent with a recent NSTEMI. Interrupting dual antiplatelet therapy in the first six months carries a risk of stent thrombosis and myocardial infarction that far outweighs the bleeding risk of a single extraction. Current cardiology and dental consensus is that extractions can be performed while he continues dual antiplatelet therapy; if in doubt, telephone the cardiologist and document the conversation and the name of the person spoken to.
Local haemostasis
- Atraumatic extraction with careful curettage.
- Pressure with a gauze pack for at least 20 minutes.
- Sutures, and a haemostatic agent (oxidised cellulose or collagen sponge) in the socket.
- Tranexamic acid 4.8% mouthwash, 10 mL four times daily for two days; no vigorous rinsing for the first 24 hours.
- Written advice about oozing for 24-48 hours and when to seek help.
Analgesia Avoid NSAIDs: they add to bleeding risk on dual antiplatelet therapy and are best avoided after recent myocardial infarction. Prescribe paracetamol 1 g four times daily to a maximum of 4 g per day, with codeine if needed.
Also note that he is diabetic and post-MI: keep the appointment short, check his glucose if he is symptomatic, and confirm he has taken his bisoprolol, since unrelieved pain and anxiety drive catecholamine release in a recently stented heart.
3. Which local anaesthetic would you use, what dose limits apply, and what would you do if he developed chest pain in the chair?
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Agent. 2% lidocaine with 1:100,000 epinephrine, with aspiration before every injection. Each 1.8 mL cartridge contains 36 mg lidocaine and 18 micrograms epinephrine. Lidocaine maximum is 4.4-7 mg/kg - about 350-500 mg for an 80 kg man, roughly 10-13 cartridges - but in a patient with recent myocardial infarction the epinephrine dose binds first: a commonly cited conservative limit is 0.04 mg, that is about two cartridges. Use the minimum number of injections that achieves anaesthesia, and consider an infiltrative technique where feasible.
If epinephrine must be minimised, plain 3% mepivacaine is an alternative, but a mandibular block with a plain solution is less effective; bupivacaine with epinephrine is not appropriate here because of its long duration and greater cardiotoxicity. Note that his bisoprolol is cardioselective, so an exaggerated pressor response is less likely, but his tachycardia may be blunted.
If he develops chest pain
- Stop treatment, remove instruments, sit him upright.
- Oxygen, monitoring of pulse, blood pressure and consciousness.
- Sublingual glyceryl trinitrate 0.4 mg, provided systolic pressure is above 90 mmHg.
- If pain persists beyond five minutes, is severe, or radiates, treat as suspected MI: call emergency services, give aspirin 300 mg chewed unless allergic, and arrange transfer with a escort and a written summary.
- Bring the emergency kit and be ready to manage collapse; document the episode fully afterwards.