Patterns of 12-Month Post-Myocardial Infarction Medication Use According to Revascularisation Strategy: Analysis of 15,339 Admissions in Victoria, Australia

Abstract

Clinical guidelines recommend secondary prevention medications following myocardial infarction (MI) regardless of revascularisation strategy. Studies suggest that there is variation in post-MI medication use following percutaneous coronary intervention (PCI) and coronary artery bypass grafts (CABG). We investigated initial dispensing and 12-month patterns of medication use according to revascularisation strategy following non-ST-elevation MI (NSTEMI). We included all public and private hospital admissions for NSTEMI for patients aged ≥30 years in Victoria, Australia, between July 2012 and June 2017. We investigated initial dispensing of P2Y12 inhibitors (P2Y12i), statins (total and high intensity), angiotensin-converting-enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARB), and beta blockers within 60 days after discharge. Twelve-month post-MI medication use was estimated as the proportion of days covered (PDC) over a 12-month period from the date of hospital discharge. Analyses were performed using adjusted regression models, stratified by revascularisation strategy. There were 15,399 admissions for NSTEMI: 11,754 with PCI and 3,645 with CABG. Following adjustments, predicted probability of initial dispensing in the PCI and CABG groups, respectively, was 0.94 (95% confidence interval 0.93-0.95) vs 0.17 (0.13-0.21) for P2Y12i; 0.69 (0.66-0.71) vs 0.42 (0.37-0.48) for ACEi/ARB; 0.59 (0.57-0.62) vs 0.69 (0.64-0.74) for beta blockers; 0.89 (0.87-0.91) vs 0.89 (0.85-0.92) for statins; and 0.60 (0.57-0.62) vs 0.69 (0.63-0.73) for high intensity statins. The 12-month PDC in the PCI and CABG groups, respectively, was 0.82 (0.80-0.83) vs 0.12 (0.09-0.15) for P2Y12i; 0.62 (0.60-0.65) vs 0.43 (0.39-0.48) for ACEi/ARB; 0.53 (0.51-0.55) vs 0.632 (0.58-0.66) for beta blockers; 0.79 (0.78-0.81) vs 0.78 (0.74-0.81) for statins; and 0.49 (0.47-0.51) vs 0.55 (0.50-0.59) for high intensity statins. Post-discharge dispensing of secondary prevention medications differed with respect to revascularisation strategy from 2012 to 2017, despite clear evidence of benefit during this period. Interventions may be needed to address possible clinician and patient uncertainty about the benefits of secondary prevention medications, regardless of revascularisation strategy.