Long-term continuation to pharmacological treatment for secondary prevention after a myocardial infarction: a register study

Abstract Background Pharmacological treatment for secondary prevention after acute myocardial infarction (MI) is crucial to prevent new events. Several studies report inconsistence and need for improvement of pharmacological treatment. Study follow-up is often less than 10 years and showing that continuation to drug treatment decreases with time. Objective To study long-term follow-up of nationally guideline recommended medical therapy (GDMT) for secondary prevention after a myocardial infarction. Method The study population consisted of individuals aged 18-84 years, who were hospitalized for a MI between January 2006 and December 2022 and were followed up to 16 years. The study subjects were identified through the National Inpatient Register and linked to the Prescribed Drug Register. Four classes of drugs were analyzed: antiplatelet/anticoagulant therapy, lowering therapy, betablockers and angiotensin converting enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARB). Time-updated survival analyses were used to investigate the relationship between continuation of preventive pharmacological treatment and mortality and recurrent MI after an acute MI. Results A total number of 139 413 individuals (mean age 69.1±10.6) were included and 33.3% were female. At baseline 51.2% had hypertension, 21.5% diabetes mellitus and 15.2% heart failure. All prescriptions of GDMT were decreased significantly after hospitalization after MI and during first years and remained plateau (figure 1). During follow-up 55487 persons died (39.8%, event rate 5.81 per 100 person years [95% CI 5.76-5.86]). Medication with antiplatelets/anticoagulantia, ACEi/ARB and statins decreased risk of all cause-mortality and myocardial infarction [HR 0.83 [95% CI 0.79-0.86], p-value <0.001, HR 0,79 [95% CI 0.77-0.83], p-value <0.001, HR 0.70 [95% CI 0.67-0.73], p-value <0.001) respectively. Conclusion Pharmacological treatment as a part of secondary prevention remained greatly underutilized both shortly and during long-term after MI. Usage of antiplatelets or antigulantia, ACEi or ARB and statins decreased the risk of all-cause mortality and recurrent myocardial infarction.