High rates of discontinuation and reinitiation of secondary preventive medications after a first myocardial infarction

Abstract Introduction Following a myocardial infarction (MI), many patients are prescribed secondary preventive medications including statins, renin-angiotensin-aldosterone system (RAAS) inhibitors, beta-blockers, and low dose aspirin. Previous studies indicate that the utilization of these medications after an MI is low. However, these studies have been limited by small or selected cohorts, dated data and short follow-up times. Thus, more information is needed to assess the use of these drugs in large contemporary MI cohorts from clinical practice. Purpose To evaluate the initiation, discontinuation, reinitiation, and proportions of patients with ongoing secondary preventive therapy after MI. Methods Using data from nationwide registers in Sweden, we included all adult patients who had a first-time MI (January 1st, 2006–December 1st, 2021) received a first-time prescription of a statin, RAAS inhibitor, beta-blocker, and aspirin, and survived 30 days after discharge. Separate study cohorts were created for each study drug and allowing patients to be included in several cohorts. Initiation was defined as being discharged with the drug and filling a prescription of the study drug within 30 days of discharge. Discontinuation was defined as a ≥90-day gap after the estimated end date of the last filled prescription of the drug class. Reinitiation was defined as the first filled prescription following discontinuation. The proportion of patients with ongoing treatment was assessed with the proportion of patients covered method in all patients who were alive with ongoing treatment based on filled prescriptions, regardless of previous discontinuation. Patients were followed from discharge until death, 12 years of follow-up, emigration or end of the study period (December 31st, 2021). Results We identified 128,288 patients discharged with a first-time prescription of a statin, 79,968 a RAAS inhibitor, 105,095 a beta-blocker, and 127,463 with aspirin. Across all drug classes, 95-97% of patients initiated therapy. The range of discontinuation was 12-14% at 1 year, 28-46% at 5 years, and 36-51% at 12 years (Figure 1a). Among patients who had discontinued therapy, 28-46% had reinitiated after 1 year, 42-62% after 5 years, and 47-67% after 12 years (Figure 1b). The proportions of patients covered ranged from 91-92% at 1 year, 79-82% at 5 years, and 74-79% at 12 years (Figure 1c). Conclusions In a nationwide cohort of patients after a first-time MI, almost all patients initiated therapy with statins, RAAS-inhibitors, beta-blockers, and aspirin. While discontinuation of the drugs were common, many patients reinitiated treatment, such that the proportion with ongoing long-term use rates remained high.Figure 1