Passive Prescription of Secondary Prevention Medical Therapy During Index Hospitalization for Acute Myocardial Infarction is Prevalent and Associated with Adverse Clinical Outcomes

Background: Secondary prevention therapy reduces death and re-infarction after acute myocardial infarction (AMI) but is under-utilized in clinical practice. Mechanisms for this therapeutic gap are not well established. We aimed to evaluate the impact of passive continuation compared to active initiation of secondary prevention therapy for AMI patients during index hospitalization. Methods: We analyzed 1083 consecutive patients with AMI to a tertiary referral hospital in Hong Kong and assessed discharge prescription rates of secondary prevention therapies (aspirin, clopidogrel, beta-blockers, statins, angiotensin-converting enzyme inhibitor or angiotensin II receptor blockers (ACEI/ARBs)). Multivariate analysis was used to identify independent predictors of discharge and 6-month medication, Kaplan-Meier survival curve was used to evaluate 12-month survival. Results: Overall prescription rates of aspirin, clopidogrel, beta-blockers, statins, ACEI/ARBs on discharge was 94.8%, 54.2%, 64.5%, 83.5% and 61.4%, respectively. Multivariate analysis showed that prior use of each therapy, except clopidogrel, was an independent predictor of prescription of the same therapy on discharge: aspirin [Odds ratio (OR) =4.8, 95% CI =1.9-12.3, P<0.01]; beta-blockers (OR=2.5, 95%CI =1.8-3.4, P<0.01); statins (OR=8.3, 95%CI =0.4-15.7, P<0.01) and ACEI/ARBs (OR=2.9, 95%CI =2.0-4.3, P<0.01). Passive continuation of prior medication was associated with higher 1-year mortality rates than active initiation in treatment naïve patient [aspirin (13.7% vs. 5.7%), beta-blockers (12.9% vs. 5.6%), statins (11.0% vs. 4.6%), all P<0.01].Active prescription was more common in lower risk patients (who were younger, with less co-morbidity, and with higher left ventricular ejection fraction) who were treated more aggressively with secondary prevention medication on discharge. Also patients who were not on a given medication before admission were less likely to be prescribed it on discharge. Conclusions: Overall use of secondary prevention medication for AMI was suboptimal compared to guideline recommendations. Our findings suggested the practice of passive continuation of prior medication was prevalent and associated with adverse clinical outcomes compared to those who received secondary preventive medication for the first time during index hospitalization. Failure to start additional medication and possible inadequate dose titration in the passive continuation group may be in part the reason for the poorer clinical outcome in this group.