Background <p>Despite anxiety and coronary heart disease being associated, longitudinal research investigating the bidirectional relationship between the formal diagnosis of anxiety disorders and myocardial infarction (MI) remains scarce.</p> Objective <p>To investigate the bidirectional relationship between anxiety disorders and MI through a 15-year (2002–2016) longitudinal population-based retrospective cohort study using the National Health Insurance Research Database.</p> Methods <p>We selected 34,979 patients diagnosed with an anxiety disorder based on their claim records during 2002–2004 and 5,189 patients with a diagnosis of MI based on their claim records during 2002–2004. In both analyses, the size of the comparison group was four times larger than that of the exposed group. A Cox proportional hazards model was used to estimate adjusted hazard ratios for developing anxiety disorders or MI after adjusting for sociodemographic factors.</p> Results <p>In the first analysis, patients with anxiety disorders had a statistically significant 1.28-fold higher risk of MI than those without. Among the patients with anxiety, those with higher age, male sex, or lower comorbidity had a significantly higher risk of MI after adjusting for sociodemographic variables. In the second analysis, patients with MI had a statistically significantly 2.08-fold higher risk of anxiety disorders than those without MI. Among the patients with MI, women and patients with lower comorbidities had a significantly higher risk of anxiety disorders after adjusting for sociodemographic variables.</p> Conclusion <p>Our results demonstrate a meaningful connection between anxiety disorders and MI. By recognizing this relationship, healthcare providers can develop constructive strategies to effectively manage both conditions and improve patient outcomes.</p>