Antiplatelet Therapy in Stent Patients - Friend or foe?

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PBLD 22 Antiplatelet therapy in stent patients – friend or foe? Kenichi Tanaka, M.D. Galina Dimitrova, M.D. Objectives: At the conclusion of this PBLD, the…
PBLD 22 Antiplatelet therapy in stent patients – friend or foe? Kenichi Tanaka, M.D. Galina Dimitrova, M.D. Objectives: At the conclusion of this PBLD, the participant will be able to: 1. Understand the pharmacology of antiplatelet medications used to treat patients with cardiovascular disease. 2. Discuss the different types of coronary artery stents and duration of antiplatelet therapy associated with them. 3. Develop a plan for the perioperative management of patients with coronary artery stents – timing of surgical procedure, preoperative evaluation, management of antiplatelet therapy, choice of anesthesia, and perioperative monitoring. Case Discussion: A 75 year-old female presents to the OR for exploratory laparotomy and bilateral salpingo- oophorectomy for ovarian mass. Her symptoms include mild, dull abdominal pain and abdominal distention. She is 60 inches tall, weighs 141 pounds with no recent weight loss. Past surgical history: back surgery and hysterectomy. Past medical history: coronary artery disease, hypertension, hyperlipidemia, osteoarthritis, chronic back pain, depression, and transient ischemic attack 3 years ago with no residual neurologic deficits. She was diagnosed with a NSTEMI 18 months ago. At that time she underwent a cardiac catheterization with balloon angioplasty and stenting of her proximal LAD and OM1 with drug eluting stents. 4 months after the stents were placed, she was diagnosed with a pelvic mass. She started to have again some chest discomfort for which she underwent another cardiac catheterization and was found to have 90% stenosis of both stents. Those were angioplastied successfully. 12 months after the initial stent placement (8 months after the angioplasty of the stents), patient underwent a stress test for new chest discomfort which showed mild inducible ischemia of the anterior and lateral walls. That led to a third catheterization which showed patent prox LAD stent, 60% distal LAD stenosis, minimal build up in the OM1 stent with less than 50% stenosis, and 80% stenosis of the RCA. Because the patient had a left dominant circulation and was awaiting surgery, it was decided that the patient would be managed medically. She is currently on metoprolol XL 50 mg, amlodipine 5mg, aspirin 81 mg, clopidogrel 75 mg, simvastatin 40 mg, ranitidine 300 mg, alprazolam 0.25mg, isosorbide 120 mg, multivitamins, and darvocet (acetaminophen/propoxyphene). As far as she had not had any chest discomfort for the last six months on that therapy it was decided to proceed with her surgery. Her medications were continued with exception of aspirin and clopidogrel, which were discontinued 10 days prior to patient’s surgery per her cardiologist recommendations. Social history: never smoked Physical exam: not in distress. CV: normal rate and rhythm, no murmurs Resp: bilateral, clear breath sounds Abdomen: mildly distended, non tender to palpation, no guarding, normal bowel sounds Vital signs: BP 142/66, HR 60, T 97.8 F, RR 18, SPO2 98%. Labs: WBC 5.7, Ht 31.2, Hb 10.8, Platelets 249, Na 139, K 3.9, Cl 107, bicarb 26, BUN 26, creat 0.76, Glu 102, PT 13.7, INR 1.0, PTT 28. CXR: mild cardiomegally, bi-apical pleural thickening, degenerative changes of the thoracic spine. ECG: sinus bradycardia Questions: 1. What are drug-eluting stents (DES)? What is the difference between DES and bare-metal stents (BMS)? Why is dual antiplatelet therapy important in patients with stents? 2. What antiplatelet agents are used in clinical practice? Indications, advantages and disadvantages. 3. Does the history of TIA influence the choice for antiplatelet therapy? What about patient’s age 4. How can you explain patient’s drug eluting stents restenosis within 2 months of the initial placement. 5. How long dual-antiplatelet therapy should be continued in patients with coronary artery stent 6. This patient’s dual antiplatelet therapy was discontinued prior to surgery. What other options for perioperative management of the antiplatelet therapy should be considered in patients with drug eluting stents. What are the current recommendations? 7. If the patient had a BMS instead, how would her antiplatelet therapy management change? 8. What is the bleeding risk of this patient? What would be the bleeding risk if the patient had continued her antiplatelet therapy? 9. Are invasive lines necessary to monitor her cardiac function during this procedure? 10. If this was an emergency procedure, and patient was still on aspirin and clopidogrel, how would you manage patient’s hemostasis? Would platelet transfusion be indicated in this patient in case of bleeding? Are there tests that can help guide the transfusion therapy? 11. What other hemostatic products should be considered in patients on dual antiplatelet therapy. 12. Can neuroaxial anesthesia be considered in this patient as a sole anesthetic or as a post operative pain management? Are there any alternatives to epidural for this patient for postoperative pain management? The patient was taken to the OR for exploratory laparotomy. She refused epidural for postoperative pain control because of concerns of worsening of her chronic back pain and good experience with i.v. PCA in the past. Standard ASA monitors were placed; general anesthesia was induced with propofol, fentanyl, and rocuronium. A second i.v. was placed in the OR. Despite of some difficulties because of adhesions, the salpingo-oophorectomy was carried uneventfully. The frozen pathology specimen revealed benign cyst. Patient’s abdomen was closed within 2 hours. Patient was hemodynamically stable throughout. She received about 1000ml of crystalloids. Urinary output was 250ml, and the total blood loss was 200 ml. The ECG remained unchanged throughout the case. Questions: 13. What is the cardiovascular risk for this surgery given the patient’s stenting history? How does this risk change in case of emergency surgery and continuation of the antiplatelet therapy? 30 min after arrival to PACU patient started complaining of chest pain and her blood pressure started to drop. Fluids and phenylephrine were unsuccessful in restoring patient’s blood pressure. ECG changes were noted on the monitor. Questions: 14. What steps should be taken in the management of this patient at this point? Stat cardiology consult was called, an arterial line was placed, and stat lab work was ordered which revealed Hb 10.8, Ht 31.2, WBC 5.7, platelets 249, chemistry - within normal limits. 12 lead ECG showed ST elevation in the posterior leads with deep ST depression and T wave inversion in V1 – V4. Within the next several min patient became unresponsive and was emergently intubated. She was transported to the cath lab where it was found that she had acutely occluded the stent in her OM1 with the thrombus extending into the proximal circumflex artery. Patient underwent successful PTCA.
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