MINERALOCORTICOID RECEPTOR ANTAGONIST UTILIZATION IN ELIGIBLE PATIENTS POST ST-ELEVATION MYOCARDIAL INFARCTION

Abstract

Mineralocorticoid receptor antagonists (MRAs) have been demonstrated to reduce the morbidity and mortality when used in patients with reduced left ventricular ejection fraction (LVEF) post myocardial infarction (MI). Current Canadian guidelines ommend the initiation of an MRA in patients post MI with an LVEF of ≤40% and documented heart failure or diabetes before hospital discharge, in the absence of any contraindications. The objective of this study was to examine if discrepancies between guideline-based therapy and actual prescribing rates exists in the prescription of MRAs in acute ST-elevation myocardial infarction (STEMI) patients. We conducted a retrospective analysis of consecutive patients enrolled in the Vancouver Coastal Health Authority STEMI database between October 2007 and October 2014 to determine the utilization rates of MRAs in eligible patients. Inclusion criteria were based on those originally outlined in the EPHESUS trial, which included an LVEF <40% and documented heart failure or history of diabetes. Patients on dialysis or with a serum Cr >221 were excluded. A total of 2583 patients had a STEMI during the study period. Of these, 192 (7.4%) patients were determined to be eligible for MRA prescription at discharge, 32 of whom were excluded due missing discharge prescription information. Of the remaining 160 patients, the mean age was 67.9, 71.3% were male, 72.5% had an anterior MI and the mean LVEF was 30.4%. During the hospitalization, 51.6% had clinical evidence of HF and 21.3% were diagnosed with cardiogenic shock. PCI was performed in 75.6% of those eligible and 11.3% underwent CABG, 11.9% were medically managed and 1.25% underwent thrombolysis as a final revascularization strategy. On discharge >75% of patients were prescribed ASA, second anti-platelet agent, beta-blocker, ACEi and a statin. Only 22 (13.8%) of eligible patients were discharged on an MRA. There was no significant clinical difference amongst those that received an MRA when compared to those that did not. Despite the endorsement and Class IA recommendation for the use of MRAs in this patient population, our study demonstrates that the majority of patients are not prescribed an MRA after STEMI. This demonstrates a large care gap between evidence based guidelines and clinical practice. The reasons for this discrepancy in practice patterns are unclear and will be the focus of further study. Further strategies are urgently needed to address this care gap.