Sergey B. Fitilev, Alexander V. Vozzhaev, Irina I. Shkrebniova, Dmitry A. Klyuev, Anna O. Ovaeva, Darya K. Barsukova

Adherence to dual antiplatelet therapy among outpatients after acute myocardial infarction in primary care

Introduction

Adherence to dual antiplatelet therapy among outpatients after acute myocardial infarction in primary care. Investigate DAPT adherence among post-MI outpatients in primary care. Low, declining adherence significantly increases MACE risk. Enhancing medication adherence is crucial for better outcomes.

Abstract

Introduction: The efficacy outcomes of dual antiplatelet therapy (DAPT) observed in randomized controlled trials are often not replicated in real-world post-myocardial infarction (MI) patients due to suboptimal adherence to prescribed pharmacotherapy. This study aimed to assess DAPT adherence in outpatients after MI and evaluate its association with risk of major adverse cardiovascular events (MACE). Material and methods: This retrospective pharmacoepidemiologic study included 276 patients who experienced AMI between January 1, 2021, and December 31, 2023, based on electronic medical data. Adherence was measured using proportion of days covered (PDC) metric. Kaplan-Meier curves were constructed to evaluate the impact of DAPT adherence on the incidence of MACE over a 12-month period. Results: Patients primarily received ASA 100 mg (91.3%) in combination with P2Y12 inhibitor ticagrelor (68.5%). The proportion of patients fully adherent to DAPT (PDC≥80% for both components) over 12 months was only 46.4%, with a significant decline from 60.9% to 42.0% between first and second half-year periods (p<0.001). Adherence to P2Y12 inhibitors was significantly higher compared to ASA (87.8±18.9% vs. 73.6±27.5%; p<0.001), largely due to high adherence to ticagrelor (PDC=92.5±12.8%). Post-MI patients fully adherent to DAPT had a lower probability of MACE compared to non-adherent (p=0.047). The protective effect of optimal adherence, adjusted for patient comorbidity, was also assessed using Cox regression, which demonstrated a 2% reduction in MACE risk for every 1% increase in PDC (p<0.05). Conclusion: Higher adherence to DAPT following MI was associated with lower risk of MACE. However, adherence declined over time, underscoring the necessity of enhancing medication adherence in post-MI outpatients.

Review

This study effectively addresses a critical issue in cardiovascular secondary prevention: suboptimal adherence to dual antiplatelet therapy (DAPT) following acute myocardial infarction (AMI). Utilizing real-world electronic medical data from 276 outpatients, the authors aimed to quantify DAPT adherence and evaluate its impact on major adverse cardiovascular events (MACE). The findings underscore a significant gap between prescribed and actual medication usage, demonstrating that less than half of patients achieved optimal adherence over a 12-month period, which critically impacts patient outcomes. The research provides valuable insights into the real-world effectiveness of DAPT and the challenges faced in maintaining long-term adherence in a primary care setting. A key strength of this study lies in its pragmatic approach, measuring adherence using the Proportion of Days Covered (PDC) metric from electronic medical records, which offers an objective assessment of medication uptake. The results are compelling, revealing an overall low rate of full adherence (46.4%) and a concerning decline over time, particularly in the second half of the year. The differential adherence to DAPT components, with significantly higher adherence to P2Y12 inhibitors (especially ticagrelor) compared to ASA, is an interesting observation. Crucially, the study robustly demonstrates the clinical significance of adherence: fully adherent patients experienced a lower probability of MACE, and a 1% increase in PDC was associated with a 2% reduction in MACE risk, adjusted for comorbidities. This direct link between adherence and improved outcomes reinforces the importance of therapeutic continuity. While informative, the retrospective design inherently limits the ability to explore the underlying reasons for non-adherence, such as side effects, cost, or patient beliefs, which would be invaluable for targeted interventions. The reliance on dispensing data also doesn't definitively confirm actual pill ingestion. Future research could benefit from exploring qualitative factors contributing to adherence barriers and facilitators in this patient population. Nonetheless, the findings carry significant implications for clinical practice, emphasizing the urgent need for enhanced patient education, counseling, and adherence support strategies in post-MI care. Interventional studies testing various strategies (e.g., pharmacy counseling, simplified regimens, digital reminders) are warranted to improve DAPT adherence and, consequently, reduce the burden of recurrent cardiovascular events.

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