Abstract
Acetylsalicylic acid (aspirin, ASA) reduces mortality and major adverse cardiovascular events by 22% when used in coronary and peripheral artery disease secondary prevention. Laboratory assessed aspirin antiplatelet therapy effectiveness showed an inadequate response to the ASA treatment in about one third of patients.
This phenomenon is often called "aspirin resistance". Most of the studies and metaanalyses regarding the aspirin resistance proved a certain correlation between the ASA resistance assessed by various laboratory methods and the worst clinical outcomes.
In the metaanalysis with nearly 3,000 patients the pooled odds ratio of cardiovascular events in ASA resistant patients was 3.8. The ASA resistance frequency shown in various clinical studies varies from almost zero values to as much as 70% of resistant patients.
The distinct differences in the ASA resistance frequency are caused by variability in used laboratory methods, different clinical situations in particular studies (stable or acute cardiovascular disease or healthy volunteers) and other aspects as drug interactions etc. In the text as follows, we describe the clinical and laboratory aspects influencing the ASA resistance incidence and the influence of the ASA resistance on patient prognosis.
Nowadays, there is no solid proof available which would confirm the fact that the ASA resistance guided treatment modification is associated with better clinical outcomes. Nevertheless, herein we describe various methods of therapy modification used in clinical studies for improving the laboratory ASA treatment response.