Aspirin for primary cardiovascular prevention: Why the wonder drug should not be precipitously dismissed

Primary cardiovascular prevention is the combined set of actions aimed at reducing the likelihood of symptomatic atherosclerotic disease or major adverse cardiovascular events (MACEs) in currently asymptomatic individuals. Older studies on aspirin for primary prevention were positive or neutral as to the primary ischemic endpoint (often represented by MACE), but the reduction in nonfatal ischemic events seemed largely counterbalanced by an increase in bleeding events. The 3 latest large randomized controlled trials on aspirin in primary prevention, all published in 2018, reached basically similar conclusions, leading to an intense debate on whether aspirin therapy is warranted in asymptomatic patients and whether there are subgroups that may benefit. In the present review, we provide an overview of the available evidence on aspirin for primary cardiovascular prevention, focusing on the results of meta-analyses and on strengths and pitfalls of meta-analytic assessments. Based on a meta-regression of the benefits and harm of aspirin therapy in primary prevention as a function of the 10-year risk of MACE, which is an alternative type of pooled analysis of available evidence, we propose a treatment algorithm acknowledging differences among patients and emphasizing the need for an individualized assessment of benefits and risks. Following general preventive measures (physical exercise, smoking cessation, treatment of hypertension and hypercholesterolemia, etc), a tailored approach to aspirin prescription is warranted. When patients are younger than 70 years of age, clinicians should assess the 10-year cardiovascular risk: when such risk is high and bleeding risk is low, aspirin treatment should still be considered, also taking patients' preferences into account.