Canadian Stroke Best Practice Recommendations, seventh edition: acetylsalicylic acid for prevention of vascular events

Abstract

I n 2016, 270 204 people in Canada (excluding Quebec) were admitted to hospital for heart conditions, stroke and vascular cognitive impairment, including 107 391 women and 162 813 men, of whom 91 524 died. 1 This equates to 1 out of every 3 deaths in Canada and outpaces other diseases; 13% more people die of heart conditions, stroke or vascular cognitive impairment than die from all cancers combined. 1 The benefits of acetylsalicylic acid (ASA) for secondary prevention of atherosclerotic cardiovascular disease are well established. In contrast, although low-dose ASA therapy for primary prevention of atherosclerotic cardiovascular disease was once commonly recommended, this practice is now being reconsidered in light of recent evidence. Three large randomized controlled trials on primary prevention found no net benefit of ASA for prevention of cardiovascular events or mortality in healthy older adults (defined in the ASPREE [Aspirin in Reducing Events in the Elderly] trial as > 65 yr) or persons with diabetes or other risk factors. 2-4 Moreover, 2 recent systematic reviews incorporating the evidence from these trials provided somewhat conflicting results. 5,6 Both found that the risk of major bleeding events was significantly increased in participants receiving ASA. However, 1 systematic review found that the use of ASA did not reduce the risk of all-cause mortality or ischemic stroke, 6 while the other reported that ASA did reduce the risk of a composite of cardiovascular mortality, nonfatal myocardial infarction, nonfatal stroke and ischemic stroke. 5 With greater awareness of the risks and benefits of ASA, overall lower rates of cardiovascular events in contemporary populations compared with those in older studies, and conflicting recommendations in guidelines and systematic reviews, clinicians are increasingly uncertain about the role of ASA for primary prevention. 2 The actual number of people in Canada who are taking ASA prophylactically (either as prescribed by a health professional or of their own volition) is not known, although it is likely substantial. A US study reported results from a public poll that found 29 million people were taking ASA in that country, with 23% doing so without a physician's recommendation. 7

Rationales and uncertainties for aspirin use in COVID-19: a narrative review

“…The Heart and Stroke Foundation of Canada in collaboration with the Canadian Stroke Consortium does not recommend the use of aspirin for primary prevention in individuals without a history of symptomatic CVD as the harms of daily aspirin use could potentially outweigh the benefits. 18 …”

“…Low-dose aspirin has a putative role for secondary prevention of arterial thrombosis in patients with COVID-19 with established CVD, 14 but its role in the primary prevention of atherosclerotic cardiovascular disease (ASCVD) with chronic endothelial dysfunction is controversial. [15][16][17][18][19] Aspirin has pleiotropic effects on endothelial function and assessing these effects during COVID-19 era in further research will be very helpful for proper understanding and management of COVID-19 infection.…”

“…44 Primary prevention of arterial thrombosis during COVID-19 pandemic The COVID-19 Treatment Guidelines and European Society for Cardiology (ESC) Guidance for the Diagnosis and Management of CVD during the COVID-19 pandemic do not include any recommendations regarding aspirin for the primary prevention of arterial atherothrombosis during this pandemic. 1 14 This role is controversial in literature before the COVID-19 era [15][16][17][18][19] (table 1).…”

Canadian Consensus Conference on Diagnosis and Treatment of Dementia (CCCDTD)5: Guidelines for management of vascular cognitive impairment

“…Contemporary randomized controlled trials in older persons without a history of stroke confirm the excess bleeding risks with ASA, and fail to consistently show that ASA prevents first-ever cardiovascular events. 50 Consequently, a recent guideline from the Heart and Stroke Foundation of Canada recommends against using ASA for primary prevention of first-ever stroke while finding that "the net benefit of ASA in individuals with asymptomatic atherosclerosis is uncertain." 50 Therefore, at this time there is insufficient evidence to determine whether ASA is effective at preventing cognitive decline in patients with VCI and brain infarcts.…”

New Canadian guideline is wrong to say acetylsalicylic acid is only for patients with symptomatic vascular disease

“…There are important problems with a recent Canadian guideline, published in CMAJ, 1 that recommended prescribing acetylsalicylic acid (ASA) only to patients with symptomatic vascular disease. In excluding ASA for patients with asymptomatic carotid stenosis, the guideline panel relied on 2 studies.…”