To provide guidance to clinicians, based on the Canadian Cardiovascular Society recommendations, for the perioperative management of patients on antiplatelet therapy who require non-cardiac or cardiac surgery.Antiplatelet drugs are commonly used in the primary and secondary prevention of cardiovascular disease. Patients receiving antiplatelet therapy have a broad range of cardiovascular risk depending on the clinical indication for treatment.# 
With over 200 million noncardiac surgical procedures performed worldwide each year, clinicians face unique challenges regarding the perioperative management of patients with coronary artery disease who are receiving acetylsalicylic acid (ASA) alone; clopidogrel alone; or any combination of ASA and a P2Y12 inhibitor (clopidogrel, prasugrel, ticagrelor). Clinicians must balance the risks of major adverse cardiovascular events associated with interrupting these therapies against the risk of bleeding from continuing these therapies in the perioperative period. Additionally, other factors including the pharmacokinetic actions of antiplatelet drugs and the optimal timing of surgery in patients with coronary stenting must be considered. The latter group of patients requires special consideration due to the increased risks and significant mortality of stent thrombosis.

# RISK STRATIFICATION FOR PERIOPERATIVE THROMBOSIS AND BLEEDING
Risk stratification for thrombosis and bleeding is largely empiric in patients who are receiving antiplatelet therapy. Patients considered at highest risk for cardiovascular events in the perioperative period include those with recently (i.e. within one year) implanted bare metal stents (BMS) or drugeluting stents (DES), recent myocardial infarction (MI), those with carotid ulcerating plaque and stroke or aortic ulcerating plaque and systemic embolism. Patients at low risk for perioperative cardiovascular events are those taking antiplatelet therapy for primary prevention of MI, limb ischemia or stroke (although this is rarely indicated). Clinicians must balance these risks against the associated risks of perioperative bleeding (listed in Table 1).
In patients with high thromboembolic risk (e.g. antiphospholipid syndrome), a consultation with a thrombosis expert is recommended.

# DIAGNOSTIC TESTING, ARTHROCENTESIS, AND MINOR DENTAL, SKIN AND EYE PROCEDURES
Patients undergoing arthrocentesis, minor dental (extraction, root canal), eye (cataract) or skin (biopsy, skin cancer excision) procedures, as well as low bleeding risk diagnostic procedures, can continue ASA without interruption. Less is known about the safety of continuing P2Y12 inhibitors (clopidogrel, ticagrelor, prasugrel) around minor procedures when taken as monotherapy. It is reasonable to discontinue them for a short period (3-4 days) before the procedure. If patients are also taking ASA (dual antiplatelet therapy), the P2Y12 should be discontinued prior to surgery (clopidogrel and ticagrelor for 5-7 days, prasugrel for 7-10 days) while ASA is continued.
Patients having a diagnostic test associated with a higher risk for bleeding should be managed like higher risk surgeries, as outlined below.

# MANAGEMENT OF PATIENTS WITHOUT CORONARY STENTS UNDERGOING ELECTIVE OR NON-URGENT NONCARDIAC SURGERY
The Perioperative Ischemic Evaluation (POISE) 2 trial is the only randomized trial in noncardiac surgery to assess perioperative antiplatelet drug management. It demonstrated that continuing ASA did not have an effect on the incidence of major adverse cardiovascular events or mortality but increased the risk of major bleeding. Only 4% of patients in this study had a coronary stent and it excluded patients who underwent carotid endarterectomy, received a BMS in the 6 weeks before surgery, or a DES in the 12 months before surgery.
Initiating ASA before surgery to reduce perioperative cardiovascular events is not recommended.
ASA should be discontinued 5-7 days prior to elective or non-urgent non-cardiac surgery except in patients undergoing carotid endarterectomy or with recent coronary artery stenting (see below for approach). Perioperative ASA continuation might also be reasonable for some surgical interventions to prevent local thrombosis (e.g. lower extremity bypass or arterial aneurysm repair).
In patients with an indication for chronic ASA, this medication should be resumed when the risk of bleeding related to surgery has passed, usually between 8-10 days after major noncardiac surgery or after venous thromboembolism prophylaxis has stopped.

# MANAGEMENT OF PATIENTS WITH CORONARY STENTS UNDERGOING ELECTIVE OR NON-URGENT NONCARDIAC SURGERY
A sub-study of the POISE-2 trial involving 470 patients with previous percutaneous coronary intervention (PCI) and cardiac stents revealed that for every 1000 patients with prior PCI, perioperative ASA will prevent 59 myocardial infarctions but cause 8 major bleeds. It is, therefore, viewed that in patients with prior PCI undergoing noncardiac surgery, perioperative ASA may be more likely to benefit than harm patients.
Clinicians must consider the timing of surgery and perioperative dual antiplatelet (DAPT) management in patients being treated with DAPT after PCI with a BMS or DES. Recommended to be discontinued ideally 5 days prior to surgery.

# Clopidogrel
Suggested to discontinue a minimum of 48-72 hours prior to surgery to minimize the risk of bleeding.
Recommended to be discontinued ideally 5 days prior to surgery.

# Prasugrel
Suggested to discontinue a minimum of 5 days prior to surgery to minimize the risk of bleeding.
Recommended to be discontinued ideally 7 days prior to surgery. 

# OTHER RELEVANT THROMBOSIS CANADA CLINICAL GUIDES

# Date of Version: 04July2021
Please note that the information contained herein is not to be interpreted as an alternative to medical advice from your doctor or other professional healthcare provider. If you have any specific questions about any medical matter, you should consult your doctor or other professional healthcare providers, and as such you should never delay seeking medical advice, disregard medical advice or discontinue medical treatment because of the information contained herein.