Anesthetic management of patients with coronary stents Dr. S. Parthasarathy MD, DA, DNB, Dip Diab.MD,DCA, Dip software based statistics, PhD (physiology) FICA

What is this ?? In the 1980s the primary management of ACS was thrombolysis Switched over to primary PCI and stents in this decade !!

Types of stents In 1986, French researchers implanted the first stent into a human coronary artery. In 1994, the FDA approved the first heart stent for use in the U.S. First-generation stents were made of bare metal. Bare- metal stents almost eliminated the risk of the artery collapsing. About 25% of all coronary arteries treated with bare- metal stents would close up again, usually within about six months.

Three types now Bare metal – cobalt chromium alloy wire mesh DES - cobalt chromium alloy wire mesh + polymer with sirolimus or paclitaxel (Antiproliferative) Bio absorbable special polymer + drug

Why do we want DES and ?? Bare metal stents are associated with restenosis in 30 % within 3 months We add sirolimus to prevent intimal hyperplasia and restenosis What’s the price ?? Damaged vessel is still exposed – antiplatelet necessary for more time !!

BMS

DES Re stenosis is less Anticoagulation is a must. Dual antiplatelet therapy – must Restenosis 30 % to 5- 8 % after DES ELUTE - - to wash out or extract; specifically : to remove (adsorbed material) from an adsorbent by means of a solvent.

Bioabsorbable – months to a few years Magnesium alloy Polycarbonate Polyopronate Igaki-Tamai bioabsorbable stent. Heparin coated stent don’t elute !!

Bms Bms DESDES

Coronary artery stenting and noncardiac surgery Better to avoid PCI and stenting before elective surgery BMS – minimum 4 weeks DES – one year

2 weeks, 6 weeks, 1 year

Surgery !! ?? Competition stopping DAPT and stent thrombosis And bleeding episodes 5 % patients come for surgery within one year Going on increasing !!

Urgent surgery after stenting Cardiology, anes and surgeon as a team DAPT may continue The plan to stop clopidogrel means – atleast five days Ticagrelor, is reported to have a shorter half-life may offer a slight advantage in the future over clopidogrel when more rapid reversal of antiplatelet effect is required Heparin ?? ( antiplatelet ?? )

Tirofiban and eptifibatide are administered parenterally, have half lives < 2 h, and are eliminated by renal clearance. Platelet function returns to 60% - 90% of normal after the infusion is stopped for 6 – 8 h. Cangrelor – newer antiplatelet drug as bridging therapy

The most serious complication is acute stent thrombosis. This is often due to under deployment of stents with a lack of stent strut apposition to the vessel wall interruption of dual antiplatelet therapy May be 40 % mortality

The rates of coronary stent-related complications in patients undergoing non- cardiac surgery range from 0.6% to 45%, with a mortality rate of 2.6–4.9%. Stents with atrial fibrillation Warfarin to keep INR around 2

Three strategies Continue dual antiplatelet Stop clopidogrel,bridge with other drugs continue aspirin Stop clopidogrel, continue aspirin— Restart with clopidogrel 600 mg as soon as the surgeon permits

On clopidogrel ( not stopped for atleast 5 days ) No neuraxial blocks No catheters Peripheral blocks USG guided acceptable Deep blocks – no Stress reduction !!

On anticoagulants

NO NO ? OK ? OK

In stent restenosis is insidious Stent thrombosis is acute and catastrophic

Risk factors for thrombosis Diabetes ( insulin treated ) Lesion more than 28 mm Left main Smoker Multiple stents Renal impairment Advanced age Primary PCI is the treatment

What does Surgery do ?? Surgery Sympathetic response Inflammatory mediators Platelet aggregation Vasospasm Decreased fibrinolysis Prothrombotic Pain and anxiety – tachy and hypertension Withheld DAPT !!

Anesthetic goals Anxiolysis Minimal stress response Good analgesia Myocardial balance

Myocardial oxygen balance DECREASE O2 SUPPLY Decreased CBF tachycardia hypotension increased preload hypocapnia ↓ Oxygen content anemia Hypoxemia decreased release – ODC - Lt INCREASED O2 DEMAND Tachycardia Increased wall tension ↑ preload ↑ afterload Increased contractility

In the OT Ready for stent thrombosis and urgent PCI Then we may need extra antiplatelets (Problem of RA) Or ready for transfusions Two IV lines, blood ready Platelet transfusions four hours prior may help in critical cases– stents can adsorb newer platelets – dangerous

Neuro surgery and spine Prostate Eye Middle ear Bleeding is a danger

Monitoring ECG leads properly fixed Elevated troponin levels But TEE is the monitor of choice to detect early RWMAs Coagulation status

Control Diabetes Hypertension COPD Parkinson Other anti ischemic drugs

Minor bleeding after surgery Continue antiplatelet therapy. Perform coagulation tests. Check platelet function Major – communicate with cardio, surgeon Possible only aspirin, after monitoring

Aspirin and clopidogrel resistance 10 – 20 % Impedance aggregometry, platelet function analysis and thrombo-elastography But platelet function analysis and bleeding don’t go together

Five components

Summary Balloon angioplasty alone or BMS or DES Urgent or elective Risk of thrombosis or not Risk for bleeding or not Continue DAPT or bridge or stop Ready for PCI and blood transfusion – monitor ECG, TEE Consider co morbidities and optimize Anxiolysis, myocardial oxygen balance, analgesia, stress reduction, superficial nerve blocks post op follow up