Safety of Post-Infarction Dual Antiplatelet Therapy and Patient Adherence: EMIAS Data Analysis

INTRODUCTION. Actual effectiveness and safety of dual antiplatelet therapy (DAPT) can be evaluated only when patients genuinely adhere to prescribed therapy. Investigating the causes of non-adherence to DAPT inevitably involves a comprehensive analysis of adverse drug reactions (ADR), their clinical management, and the occurrence of clinically significant ischemic events in patients surviving acute myocardial infarction (AMI).
AIM. This study aimed to analyse the adherence dynamics to DAPT in the context of haemorrhagic complications, their pharmacological management, and clinically significant cardiac events in patients over the first year following AMI. The data were provided by Unified Medical Information Analysis System (EMIAS), Moscow, for the years 2021-2023. 
MATERIALS AND METHODS. A retrospective analysis was performed using EMIAS data on patients who were under outpatient follow-up by cardiologists at a Moscow polyclinic for one year following AMI. "Method based on assessment of all medical records" (WHO) was used to register ADRs. Patient medication adherence was evaluated by tracking prescripton claims for individual DAPT components and in total. Only patients who demonstrated adherence to DAPT during the first six months of therapy (n=168) were included in the analysis.
RESULTS. Upon hospital discharge, patients received acetylsalicylic acid 100 mg (97.6%) in combination with a P2Y12 platelet inhibitor, predominantly ticagrelor (76.2%). During the second six-month period, 73 (44.5%) patients lost adherence to DAPT (non-adherent). Haemorrhages of any severity were recorded in 24.4% of patients over the year (total ADRs — 57); and in 15.5% in the first six months. Within 6–12 months, compared to non-adherent patients, the severity of bleeding according to the BARC scale was higher among those who maintained adherence (p=0.035), with serious haemorrhagic ADRs observed only in this group. DAPT adjustment by cardiologists was performed in 29.3% of patients with bleeding, more often in the first half of the year than in the second (22% vs 7.3%; p=0.029). The number of hospitalisations for cardiac reasons in 6–12 months was higher in the non-adherent group (p=0.047), who mainly discontinued acetylsalicylic acid (PDC 52.9±26.9%) for an average of 111.7±37.7 days (“therapy interruption”).
CONCLUSIONS. Among patients initially adherent to DAPT in the first six months, only 56.5% maintained adherence in the second half of the year following AMI. The annual incidence of haemorrhagic ADRs was 24.4%. These ADRs were more severe among those who maintained adherence (p=0.035), however, more non-adherent patients were hospitalised for cardiac reasons (p=0.047). Benefit-risk balance of haemorrhages and thrombosis should be monitored for long-term DAPT; personalised approach is feasible in clinical practice, including risk stratification of haemorrhages using PRECISE-DAPT/BARC scales; high-risk patients require early switch to monotherapy (such as clopidogrel after 3–6 months) focusing on the balance between anti-ischaemic effectiveness and risk of haemorrhage.

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