Canadian antiplatelet guidelines update: changes include no ASA for routine primary prevention of cardiac disease

An update to the Canadian antiplatelet guidelines brings changes to clinical practice for cardiologists and primary care physicians. The update to the guidelines from the Canadian Cardiovascular Society and Canadian Association of Interventional Cardiology was released in late October. Changes to the guidelines include: not recommending acetylsalicylic acid (ASA) for the routine use in primary prevention providing dual antiplatelet therapy for all patients after a coronary artery bypass graft (CABG) procedure de-escalating antiplatelet therapy for certain patient populations giving patients with atrial fibrillation oral anticoagulant and P2Y12 inhibitor (but no ASA) after percutaneous coronary intervention The last update was in 2018. Since then, numerous randomized clinical trials have provided more evidence about how to best prevent primary and secondary heart disease. “We are very proud with this document in that every single section we have done a systematic review and meta-analysis of the most contemporary evidence that is out there to make our recommendations,” said Dr. Kevin Bainey, lead author of the update, associate professor of medicine at the University of Alberta and interventional cardiologist at Mazankowski Alberta Heart Institute in Edmonton. The update to the guidelines is meant to be easy to use. Each section includes an illustration and the document contains a number of decision-making tools. The update touches on four major areas: 1. Using acetylsalicylic acid (ASA) in primary prevention of atherosclerotic cardiovascular disease Guidelines around the world differ in how they approach ASA for primary prevention of atherosclerosis cardiovascular disease. In the U.S., it’s recommended for patients over 50 years old, yet in Europe it isn’t recommended. In this Canadian update, the routine use of ASA for the primary prevention of atherosclerotic cardiovascular disease is not recommended. This holds true for most people, even those at an older age. Because of the meta-analysis and systematic reviews conducted by the guideline authors, “we are confident with the recommendation about aspirin for primary prevention that it is not routinely recommended for use in primary prevention,” Dr. Bainey said. Read: CPAP use may reduce secondary CVD events The update gives a nod to findings that preventative ASA could reduce the risk of a first-time myocardial infarction by 10%, although this good outcome is countered by bleeding risk. The recommendation comes with a "best practice statement," saying that ASA may have a role in primary prevention of atherosclerosis cardiovascular disease in patients who are at high risk of an ischemic event and have a low risk of bleeding. This includes some patients who are diabetic, have high cholesterol levels, smoke, have high blood pressure or have a positive family history; and they have no bleeding abnormalities or have never had a bleeding event. Any decision to use ASA for primary prevention must be patient-centred, Dr. Bainey said. There’s a decision tool in the update’s supplementary material that doctors can use when discussing this with their patients. 2. Length of dual antiplatelet therapy as secondary prevention in patients with high risk of bleeding New for this update are recommendations for patients with higher risk of bleeding who may benefit from a shorter duration of dual antiplatelet therapy. “This is very new in the Canadian guidelines and separate us from the rest of the world as well,” he said. “The standard of care still, once you’ve had a heart attack, is one year of dual antiplatelet therapy. We’ve just identified specialty populations or patients who have bleeding risk where you can modify that regimen,” Dr. Bainey explained. The update includes a decision-making tool to help physicians estimate bleeding risk. There’s also a nudge to remind interventional cardiologists to provide the treating physicians with information on how long to give the patient dual antiplatelet therapy. De-escalation of dual antiplatelet therapy can be done by switching to single antiplatelet therapy, or by giving less potent dual antiplatelet therapy. Since the last update, trial results have provided more information on what dual antiplatelet therapy to use in what patients, and when. The guideline authors still don’t differentiate between ticagrelor vs. prasugrel in patients with acute coronary syndromes who receive percutaneous coronary intervention (PCI), although the ongoing SWITCH-SWEDEHEART study might provide more answers on which agent is more effective. Read: Guidelines propose new way to define ‘death’ How long to use dual antiplatelet therapy after PCI in patients with a high risk of bleeding There’s a decision tree on whether to extend, give the standard, or de-escalate antiplatelet therapy following acute coronary syndrome or elective PCI in patients with high risk of bleeding. In contrast to the 2018 update, the recommendation is now that patients with high bleeding risk receive dual antiplatelet therapy for only one to three months, instead of six to 12 months following PCI. If they don’t have further bleeding events in the first month, they can be on maintenance therapy with a single antiplatelet agent. A practice tip states that a P2Y12 inhibitor should be considered over ASA for this maintenance therapy. The guidelines note that extra care should be given to patients who undergo complex PCI, as defined in the guidelines. These patients, and those with a history of stent thrombosis, may not be suitable for dual antiplatelet therapy. Read: CPAP use may reduce secondary CVD events Treatment with dual antiplatelet therapy before coronary angiography The pre-treatment recommendations in this patient population depend on what brings them to the cath lab. For example, routine pre-treatment with a P2Y12 inhibitor is recommended for patients receiving PCI for ST-elevation myocardial infarction. Again, a decision tree is included in the update. 3. Antiplatelet therapy management before and after coronary artery bypass graft (CABG) surgery The update recommends discontinuing ticagrelor two to three days before CABG surgery, where previously it was five to seven days before surgery. The update also provides a best practice statement that clopidogrel should be discontinued two to seven days before surgery. ASA can be given until surgery and resumed early after the surgery. Some patients aren’t prescribed the appropriate antiplatelet therapy following CABG surgery, Dr. Bainey said. The update recommends the use of dual antiplatelet therapy over single antiplatelet therapy after CABG surgery, regardless if the patient has acute coronary syndrome or not. Therapy can start when the surgical team decides the bleeding risk is acceptable. “We’ve combed the literature again to recommend that it doesn’t matter what kind of bypass surgery you had, it doesn’t matter if it’s in the setting of a heart attack or an elective bypass surgery, we strongly do believe that dual antiplatelet therapy is required to improve the patency of the bypass graft.” “So this is a big change in that all patients who’ve had bypass surgery should be on dual antiplatelet therapy,” he said. The recommendation of what type of dual antiplatelet therapy (e.g, ticagrelor, prasugrel or clopidogrel and ASA) depends on whether the patient has acute coronary syndrome or not. Dual antiplatelet therapy should be prescribed for up to one year after CABG surgery. Read: An app to saves precious time during heart attack? 4. Antiplatelet therapy in patients with atrial fibrillation requiring oral anticoagulation after PCI or medically managed acute coronary syndrome (ACS) In the past, patients with atrial fibrillation (AF) who had a PCI would be given oral anticoagulation and dual antiplatelet therapy (known as triple therapy) for at least a short time after PCI. This update recommends a “dual pathway strategy,” which is oral anticoagulant with a P2Y12 inhibitor, and no ASA. Clopidogrel is preferred due to its lower bleeding risk, the recommendation state. One year after the PCI or acute coronary syndrome, patients with AF can go back to oral anticoagulant on it’s own. The guidelines were also presented at the Vascular 2023 conference, held in Montreal in late October. They’re published in the Canadian Journal of Cardiology. Read: Updated Canadian guidelines on pharmacotherapy of stable COPD

Canadian antiplatelet guidelines update: changes include no ASA for routine primary prevention of cardiac disease

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