ASA (acetylsalicylic acid, often sold as Aspirin) is often used by people to reduce their risk of stroke or heart disease. It works by being what is called an anti-platelet agent. Platelets are one of the components required to make blood clot. They are approximately one-quarter the size of red blood cells and are not whole cells.
ASA used as an anti-platelet agent has been a cornerstone therapy for patients who have blockages called atherosclerotic vascular disease in the coronary (or heart) vessels, cerebral (or brain) vessels, and peripheral beds, such as in our legs. This is known as secondary prevention.
For years, many people have used ASA as primary prevention to prevent the risk of a first heart attack or reduce the risk of a first stroke. To help better understand who should use ASA, the Canadian Cardiovascular Society created an anti-platelet guideline. Its goal is to provide a comprehensive, evidence based, treatment centred statement on managing anti-platelet therapy in Canadian outpatients who have existing, or are at risk of developing vascular disease.
It is important to remember that ASA can have a series of side effects, such as bleeding and heartburn. Other side effects include:
Bruising more easily
Nausea or Vomiting
Pain, Buzzing or Ringing in ears
Severe or continuing abdominal or stomach pain, cramping, or burning
Unusual tiredness or Weakness
What’s new in the guideline:
For men and women who do NOT have a vascular disease — your average healthy individual — ASA at any dose in not recommended for routine use to prevent what are called ischemic vascular events such as a heart attack or stroke. The guidelines do allow for some latitude and discretion for a prescribing doctor. In special circumstances, in men and women who don’t have evidence of present vascular disease but in whom the risk is considered high and a risk for bleeding is considered low, ASA 75 mg-162 mg can be considered for use, but the evidence to support this statement is not as strong as the statement against routine non-use.
Another group of people considered at high risk for cardiovascular disease are diabetics. The guidelines say that there is currently no evidence to recommend routine use of ASA at any dose for the primary prevention of vascular ischemic events in these patients. For patients with diabetes who are older than 40 and don’t have a high risk for bleeding, then ASA 75-162 mg daily can be considered for use for primary prevention if they have other cardiovascular risk factors. Those diabetics who have shown vascular disease can use low dose ASA for what would now be secondary prevention.
The guidelines as well have very specific recommendations for patients who have established disease and speaks to the use and combination of both ASA and other anti-platelet agents such as clopidogrel ( commonly known as Plavix). For example, patients who have already had a TIA (transient ischemic attack) or ischemic stroke should be treated with an anti-platelet agent. The choices can include ASA or other agents and the choice should take into account cost, ability to tolerate and other side effects.
The guidelines also point out that if you are on a low dose ASA, then use of anti inflammatory medications should be undertaken with caution. It is recommended that only specific kinds of anti inflammatory medication be used. The different kind of non-steroidal anti inflammatory (NSAID) increase cardiovascular risk and if possible, should be avoided in patients who are considered at risk if ischemic vascular events. If you are wondering about your use of ASA, speak to your doctor.
The key points:
· For men and women without evidence of manifest vascular disease, the use of ASA at any dose is not recommended for routine use to prevent ischemic vascular events.
· There is currently no evidence to recommend routine use of ASA at any dose for the primary prevention of vascular ischemic events in patients with diabetes.
· Antiplatelet therapy should be continued for life in all patients with manifest ischemic vascular disease unless specifically contraindicated.
· Long term dosing of ASA > 162 mg/day should be avoided due increased bleeding risk and the lack of greater anti ischemic benefit over lower doses.
· Antiplatelet therapy should not be discontinued for minor or nuisance bleeding.