Anesthetic implication in a patient with coronary heart disease.pptx

coronary stent and anaesthesia

1. Anaesthetic Management Of Patient With Coronary Stent In Situ Presenter : Dr. Mohit Jagga Moderator : Dr. Naresh Dr. Priya

2. INTRODUCTION Percutaneous coronary intervention (PCI) has developed rapidly. TECHNIQUE: It involves the passage of a small (3 F) catheter into the involved coronary artery and through the stenosis. With the balloon portion of the catheter straddling the stenosis, inflations are performed. That results in enlargement of the stenotic lumen. The luminal widening is achieved by the controlled injury Plaque compression, intimal fissures and medial stretching.

3. Stand-alone balloon angioplasties have high complication rates ranging between 15% and 60%, resulting in substantial morbidity. They are associated with a risk of early vessel closure due to elastic recoil and late inflammatory restenosis ; hence the use of angioplasty alone without stenting is limited Coronary stents are introduced to maintain long term patency.

4. BARE METAL STENT(BMS) Introduced in the 1980s to help avoid the shortcomings of balloon dilatations. These devices function as vascular scaffolds and are regarded as a major advance in the nonsurgical management of coronary artery disease. Advantage: BMS reduced the rates of restenosis, coronary artery recoil, and dissection Disadvantage: Stent implantation, which induces trauma to the vessel wall, initiates complex interactions between the vessel wall, stent surface, and blood components, leading to thrombogenesis and neointimal hyperplasia, much like the formation of scar tissue.

5. Neointimal hyperplasia , which in turn resulted in in-stent restenosis (ISR ), affects 10% to 30% of these patients over the course of 3-6 months. In coronary arteries, even a small amount of hyperplastic tissue can significantly reduce the luminal diameter, resulting in gradual stent occlusion and ischemia. Currently only about 25% of all stents implanted during PCIs are BMS.

6. Drug-eluting Stents (DESs) Introduced as a potential solution for the prevention of ISR. The metallic scaffold was coated with a drug delivery polymer embedded with a pharmacologic agent to discourage scar tissue formation. Advantage: The antiproliferative drugs (taxus and limus families) used to coat the stents were successful in preventing the proliferation of smooth muscle and markedly reduced the rates of restenosis to a range of 5% to 8%. Disadvantage: Whereas re- endothelialization after a BMS occurs within the first 6 to 7 months of implantation, the first-generation DESs were not fully endothelialized even after 3 years.

7. Immunosuppressive and antiproliferative pharmacologic agents on DESs interferes with and delays the disrupted endothelium from healing. Subendothelial substrate exposed to the circulating platelets and inflammatory mediators for prolonged periods of time. Collagen in the exposed subendothelium is the most potent stimulus for platelet activation.

8. As a result, late stent thrombosis(ST) is a problem in these patients. While ISR is a pathology that evolves gradually over a period of 6 to 9 months ST is an abrupt thrombotic vessel occlusion that can lead to an acute myocardial infarction with a mortality of 10% to 30%

9. First-Generation DESs It consists of a stainless steel metallic stent platform coated with a polymer that elutes the antiproliferative pharmacologic agent. Sirolimus is an immunosuppressive compound that reduces neointimal hyperplasia. Elution off the sirolimus platform is complete in about 6 weeks. Paclitaxel is an agent that has antiproliferative and cytotoxic properties; 10% of the drug is released in the first 10 days, and the remainder elutes indefinitely

10. Second-Generation DESs Second-generation DESs comprise thinner, more radiopaque alloy and flexible cobalt-chromium or platinum-chromium alloy struts coated with a biocompatible polymer with superior re- endothelialization kinetics. Zotarolimus inhibits smooth-muscle cell proliferation and completely disapppears after full elution. Everolimus , simlar to sirolimus in anti-proliferative and immunosuppressive properties, is more lipophilic , allowing rapid absorption into the arterial wall

11. Next-Generation Stents The development of antibody-coated stents , which attract circulating endothelial progenitor cells to enhance the repair of endothelial cells, is now being explored. Novel techniques aimed at developing bioabsorbable polymers are under way to speed healing delayed by the polymers. The development of hollow, drug-filled BMS is being explored as a way to eliminate the need for the polymer.

12. Antiplatelet Therapy(APT) Activation of platelets is recognized as the primary source of ST. Multiple pathways must be blocked in order to achieve effective APT. It is well known that there is significant crosstalk between the various receptors on the surface of the platelets. Hence, dual antiplatelet therapy (DAPT) is currently recommended as the cornerstone of anti-thrombotic prophylaxis.

13. The currently available antiplatelet drugs fall into three main categories : Thromboxane inhibitors (including aspirin). Aspirin is recommended as a lifelong therapy that should never be interrupted for patients with coronary stents unless the bleeding risk far exceeds the risk for ST. GPIIb / IIIa inhibitors (including tirofiban , eptifibatide , and abciximab ). These drugs can be used to bridge the gap between discontinuation of DAPT and surgery in selected high-risk patients.

14. P2Y12 or Adenosine Diphosphate receptor blockers (including clopidogrel, prasugrel, ticlopidine, ticagrelor and cangrelor ). Prasugrel : A third-generation thienopyridine , was approved by the FDA in 2000. It is more potent than clopidogrel and has a lower rate of drug resistance with a more predictable antiplatelet response. These effects come at the cost of a higher risk for bleeding and greater expense. Ticagrelor : An orally active reversible P2Y12 receptor antagonist that was approved by the FDA in 2011. It does not require metabolic activation for its clinical effect. The new short-acting, reversible platelet inhibitor. Cangrelor : currently being evaluated as a bridging antiplatelet therapy in the perioperative setting.

15. The antiplatelet agents most frequently used consist of aspirin and clopidogrel Irreversible platelet inhibitors They have been extensively studied and have the most favorable risk–benefit profile.

16. ASPIRIN : Exerts its action through irreversible blockade of COX-1, the enzyme that catalyzes the synthesis of thromboxane A2(TXA2) from arachidonic acid(AA). Efficacy of low dose aspirin is supported in various studies, The dose dependent risk for upper GI bleed with no increase in efficacy was observed.

17. CLOPIDOGREL : It is a prodrug that requires metabolism in the liver through a double oxidation process mediated by cytochrome P450 isoforms Converted finally into its active metabolite, which irreversibly blocks the ADP P2Y12 platelet receptors. After its approval in 1997, clopidogrel soon replaced ticlopidine due to its more favorable safety profile and it achieves a faster onset of action.

18. Genetic variability and interaction with other drugs metabolized by this mechanism may interfere with the effectiveness of clopidogrel. Genetic testing for drug resistance is routine in some institutions in high-risk patients Both aspirin and clopidogrel may be partially ineffective in as many as 30% of patients

19. PRE-OPERATIVE EVALUATION History and physical examination Cardiac risk stratification Timing of Elective Non-cardiac Surgery in Patients With Previous PCI Perioperative Drug Therapy Perioperative antiplatelet agents

20. PRE-OPERATIVE EVALUATION History: Indication for stenting, date of implantation, types of stents and current oral antiplatelets therapy Physical examination: Assessment of exercise and functional capacity The duke activity status index(DASI) Metabolic equivalents(METs) Evaluation of the presence or absence of any coronary syndrome/symptoms after coronary revascularization

21. Functional status is a reliable predictor of perioperative and long-term cardiac events. It can be assessed more formally by activity scales, such as the DASI (Duke Activity Status Index)

22. Metabolic equivalents ( mets ) 1 MET is the resting or basal oxygen consumption of a 40 year-old, 70-kg man. It represents an oxygen consumption of 3.5 ml/kg/min. Functional capacity is classified as Excellent (>10 mets ), Good (7 mets to 10 mets ), Moderate (4 mets to 6 mets ), Poor (<4 mets ), or unknown

23. Cardiac risk stratification An overall assessment of perioperative cardiac risk requires consideration of The type of surgery planned Presence and type of specific indicators of CADs Fuctional status of the patients

24. REVISED CARDIAC RISK INDEX (RCRI) Simple, validated, and accepted tool to assess perioperative risk of major cardiac complications (MI, pulmonary edema , ventricular fibrillation or primary cardiac arrest, and complete heart block) It has 6 predictors of risk for major cardiac complications, only 1 of which is based on the procedure—namely, “Undergoing suprainguinal vascular, intraperitoneal, or intrathoracic surgery.” Patient with 0 or 1 predictor(s) of risk would have a low risk of MACE. Patients with ≥2 predictors of risk would have elevated risk.

25. Perioperative Drug Therapy Beta blockers should be continued in patients undergoing surgery who have been on beta blockers chronically. Statins should be continued in patients currently taking statins and scheduled for noncardiac surgery. Alpha-2 agonists for prevention of cardiac events are not recommended in patients who are undergoing noncardiac surgery. Continuation of angiotensin-converting enzyme inhibitors is reasonable and if held before surgery, restart as soon as clinically feasible postoperatively

26. Perioperative antiplatelet agents Management of the perioperative antiplatelet therapy Determined by a consensus of the surgeon, anesthesiologist , cardiologist, and patient, who should weigh the relative risk of bleeding with those of prevention of stent thrombosis. In patients undergoing urgent noncardiac surgery during the first 4 to 6 weeks after BMS and DES implantation requiring surgery within 12 months of stent placement Dual antiplatelet therapy should be continued unless the relative risk of bleeding outweighs the benefit of the prevention of stent thrombosis.

27. Perioperative management of patients receiving aspirin and/or clopidogrel Continue aspirin throughout perioperative period for all patients. Manage clopidogrel as per surgical procedure For noncardiac surgery, stop clopidogrel 7 days before surgery unless recent stent insertion. Discussion with cardiologist is recommended.

28. Bridge Therapy There is an unmet need for drugs that can be used as ‘bridge therapy’ to prevent stent thrombosis after interruption of dual antiplatelet therapy This is analogous to discontinuing warfarin before surgery and instituting a heparin infusion to prevent thrombo -embolic events. Unfortunately, heparins possess minimal antiplatelet effect Theoretically unsuitable as ‘bridge’ treatment when dual antiplatelet therapy is discontinued.

29. The pharmacologic profile of cangrelor and ticagrelor (reversible, rapid onset, and short half-life) might also be attractive for perioperative use. But these drugs are in various phases of pre-market testing

30. TIROFIBAN It has a short half-life (2 h) and has been suggested to meet the ‘bridge therapy’ requirement. Four hours after tirofiban infusion is stopped, bleeding time returns to normal and platelet aggregation increases to 50% of normal function However, bleeding risks with these agents are higher than with oral drugs and their effects cannot be reversed with platelet transfusions

31. Goals Intraoperative Management Perioperative myocardial injury Perioperative coronary stent thrombosis INTRAOPERATIVE MANAGEMENT

32. GOALS The primary goal of anesthetic management is the avoidance of myocardial ischemia and myocardial infarction. Improve the myocardial oxygen supply-demand balance primarily by controlling the patient’s hemodynamics. By detecting and treating myocardial ischemia, if it occurs.

33. Use of hemodynamic assist devices may be considered when urgent or emergency noncardiac surgery is required in the setting of acute severe cardiac dysfunction (i.e., acute MI, cardiogenic shock) that cannot be corrected before surgery. Routine use of pulmonary artery catheterization in patients, even those with elevated risk, is not recommended Prophylactic intravenous nitroglycerin is not effective in reducing myocardial ischemia in this patients. Maintenance of normothermia may be reasonable to reduce perioperative cardiac events in this patients.

34. Noncardiac surgery and stent thrombosis Interruption of OAA therapy, As often happens for noncardiac surgery It has been shown to be an important factor in stent thrombosis.  The consequences of stent thrombosis are severe 64% rate of death or myocardial infarction Mortality rate of between 9% and 45%.  When a patient with previous coronary stenting requires noncardiac surgery Indication for stenting Date of implantation, Type(s) of stent(s) used, Patient’s current OAA therapy and proposed duration.

35. Perioperative management issues for patients with a coronary stent Management of anticoagulation Appropriate duration from percutaneous coronary intervention to surgical procedure Choice of anaesthetic technique Perioperative monitoring Immediate access to a cardiac catheterization laboratory

36. Management of anticoagulation The goals of percutaneous coronary intervention consist of restoring coronary blood flow and minimizing iatrogenic tissue (vessel) damage. Percutaneous coronary interventions by nature produce severe coronary endothelial injury and an increased risk of thrombosis. Dual antiplatelet therapy is critical for preventing thrombosis. Of the risks posed to the coronary stent patient, the most dominant concerns The management of anticoagulation, in particular interruption of dual antiplatelet therapy

37. Electrocardiography is the most cost-effective means of detecting myocardial ischaemia . Elevated biomarkers ( troponins ) should be used to confirm the diagnosis of a perioperative myocardial infarction, But the clinician should not wait for laboratory results if stent thrombosis is the probable diagnosis The presence of angina plus objective signs of myocardial ischaemia or infarction mandates immediate triage to the cardiac catheterization laboratory to rule out and/or manage stent thrombosis. Transoesophageal echocardiography is currently considered the de facto standard for early recognition of intraoperative myocardial ischaemia

38. Immediate Availability Of The Interventional Cardiac Catheterization Laboratory Once the diagnosis of an acute myocardial infarction due to possible stent thrombosis is made (or considered), triage to the interventional cardiology suite within 90 min is critical. Mortality increases by nearly 50% with delayed re-perfusion (3% at 30 min to 4.3% at 90 min). Prompt transfer to a cardiac catheterization laboratory can be lifesaving.

39. To conclude , the dominant risk factor for stent thrombosis and poor outcome is the interruption of dual antiplatelet therapy for the operative procedure. If continuing clopidogrel is contraindicated, then continuation of aspirin is essential unless contraindicated by the site of the surgical procedure. The next major risk factor is the interval between stent placement and the operation.

40. POSTOPERATIVE MANAGEMENT Predictors of perioperative cardiac morbidity Highest risk- postoperative period During this period, upto 67% of the ischaemic events occur Postoperative hypothermia Hypercoagulability Postoperative pain Postoperative anemia

41. Thank you

42. 4-quadrant approach Suggested by Metzler et al The risk for thrombosis plotted against the risk of bleeding DAPT should be stopped in this subset with the institution of a pharmacologic bridge therapy Procedures with a high risk for bleeding include intracranial, intramedullary spinal, prostate, middle ear, ophthalmologic and aortic surgeries