To provide information on the use of acetylsalicylic acid in the prevention of vascular thromboembolic events.Acetylsalicylic acid (ASA) is well-established in the management of acute myocardial infarction and in the secondary prevention of cardiovascular disease among both men and women, based on large randomized trials. ASA may also be considered in selected patients for prevention of recurrent venous thromboembolism (VTE) and for prevention of VTE following joint arthroplasty. In addition, in select patients, ASA may be considered for primary prevention of cardiovascular events. The net benefit of ASA use depends on weighing the anticipated reduction in cardiovascular events against the increased risk of gastrointestinal and intracranial bleeding.ASA irreversibly inhibits platelet aggregation by inhibiting thromboxane A2 (TxA2) synthesis.# 
myocardial infarction and cardiovascular death, and for the prevention of acute limb ischemia and mortality [see Clinical Guide: Rivaroxaban (Xarelto) iv. Prosthetic heart valves:
a. ASA 81 mg daily is recommended in addition to vitamin K antagonist (VKA) in selected high-risk patients with a mechanical valve prosthesis  b. ASA 81 mg daily is reasonable in all patients with a bioprosthetic aortic or mitral valve who are not taking an oral anticoagulant  i. For patients not at high risk of VTE, consideration can be given to rivaroxaban 10 mg orally per day until post-operative day 5, followed by ASA 81 mg daily for an additional 9 days following total knee arthroplasty or for 30 days after total hip arthroplasty.  7) Prevention of Preeclampsia in Pregnancy i. For patients at moderate to high risk of preeclampsia DOSING OF ASA:
- The usual antiplatelet dose of ASA is 81 mg daily. Higher doses are not associated with any evidence of increased efficacy or bleeding risk, but with lower treatment adherence. - A single initial dose of 162 mg chewed or crushed is recommended in patients suffering an ACS event, and then indefinite therapy with 81 mg daily.
- A single initial dose of 325 mg chewed or crushed is recommended in patients prior to angioplasty (if not already receiving chronic daily ASA). - An initial dose of 81 mg once daily should be utilized in patients suffering a TIA or ischemic stroke of noncardiac origin.
Note: For patients with a history of, or at high risk of, gastrointestinal bleeding, consider coadministration of a gastroprotective agent (i.e. proton pump inhibitor , H2 antagonist) or using an alternate antiplatelet agent such as clopidogrel.

# ADVERSE EFFECTS OF ASA:
- Bruising and other minor bleeding is very common with use of ASA - Dyspepsia - The most common serious adverse effect of ASA is bleeding into the gastrointestinal tract (which is dose-related) - Allergic reactions, aspirin-induced asthma (may be severe)

# PERI-PROCEDURAL MANAGEMENT FOR PATIENTS TAKING ASA:
Patients receiving ASA and: 1) Undergoing an invasive diagnostic test, i. associated with a low risk of bleeding, should continue ASA without interruption.
ii. associated with a high risk of bleeding, should discontinue ASA 7 to 10 days prior to the procedure. iii. Patients with coronary stents deserve special consideration, and consultation with a specialist is advised. 2) Undergoing arthrocentesis, continue ASA through the time of the procedure.
3) Undergoing a minor surgery, dental, eye, or skin procedure, generally continue ASA around the time of the procedure. 4) Undergoing elective major non-cardiac surgery, should discontinue ASA 7 to 10 days prior to the procedure except in those undergoing carotid endarterectomy, or with recent coronary artery stenting (consultation with a specialist is advised). When ASA is interrupted, it should be resumed when the risk of bleeding related to surgery has passed, between 8 to 10 days after major noncardiac surgery (See Clinical Guide: Perioperative Management of Antiplatelet Therapy). 5) Undergoing coronary artery bypass grafting (CABG), should continue ASA (See Clinical Guide:
Perioperative Management of Antiplatelet Therapy).

# SPECIAL CONSIDERATIONS:
1) Concomitant use of therapeutic doses of anticoagulants and ASA is discouraged and should only be considered in patients with an indication for anticoagulation who are at relatively low bleeding risk AND have one of the following indications:
i. Very recent ACS and/or PCI +/-coronary artery stent (short duration of ASA in combination with clopidogrel and an anticoagulant, after which dual pathway with clopidogrel and an anticoagulant alone is preferred) ii. High risk prosthetic heart valve (e.g. older generation valve or mitral valve replacement with atrial fibrillation, left ventricle (LV) dysfunction or previous systemic embolus on therapeutic anticoagulation) iii. Proven TIA/ischemic stroke while on therapeutic doses of anticoagulation alone
In most other patients taking ASA, if anticoagulation is started, the ASA should be stopped.
2) Patients taking ASA for vascular protection should avoid the concomitant use of NSAIDs. If a patient taking low-dose ASA for vascular protection requires an anti-inflammatory agent, specific cyclooxygenase-2 inhibitors should be chosen over traditional NSAIDs.
3) ASA should be avoided or used with caution in patients with asthma or nasal polyps, in those at high risk of bleeding or with recent major bleeding, and in patients with severe thrombocytopenia or with familial or acquired bleeding disorders.

# PEDIATRICS:
When possible, pediatricians with expertise in thromboembolism should be involved when ASA is being considered for antiplatelet therapy. When this is not possible, a combination of a neonatologist/pediatrician and an adult hematologist, supported by consultation with an experienced pediatric hematologist, is recommended. 

# Date of Version: 12July2021
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.