Determinants of anti-fibrotic response to mineralocorticoid receptor antagonist therapy: insights from the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS) and Early Eplerenone Treatment in Patients with Acute ST-elevation Myocardial Infarction without Heart Failure (REMINDER) trials

Introduction: After myocardial infarction complicated by heart failure or diabetes, eplerenone (compared to placebo) significantly decreases amino-terminal propeptide of type III procollagen (PIIINP). Determining the subset of patients who are more prone to have a decrease in PIIINP and those who may respond better to the anti-fibrotic effects of mineralocorticoid receptor antagonists (MRA) therapy may be relevant for a personalized treatment approach. The aim of this study is to identify predictors of a PIIINP decrease and assess potential subgroups of "responders" to eplerenone. Methods: Clinical factors and biomarkers were evaluated as predictors of a PIIINP decrease from randomization to month 9 in 323 patients from the biomarker substudy of Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS). Additionally, the association between PIIINP decrease and the composite of cardiovascular (CV) death or CV hospitalization were also explored. External validation was performed in the REMINDER trial. Results: Female sex, eplerenone, reperfusion therapy, potassium < 4 mmol/L, circulating levels of PIIINP ≥ 3.6 ng/mL and PINP ≥ 27 ng/mL predicted a PIIINP decrease (AUC = 0.75). Randomization PIIINP showed a significant interaction with the treatment allocation: patients with PIIINP ≥ 3.6 ng/mL had a better response (decrease in PIIINP) to eplerenone (OR for PIIINP ≥ 3.6 = 2.9, 95% CI 1.46–5.89, p = 0.003) and OR for PIIINP < 3.6 = 1.09, 95% CI 0.55–2.2, p = 0.8; interaction_p = 0.026). These findings were internally robust using another statistical approach (LOESS). External validation showed good discrimination (AUC = 0.70). There was a tendency toward a lower rate of CV death/CV hospitalizations in patients with decreased PIIINP (adjusted HR = 0.52, 95% CI 0.26–1.02, p = 0.058). Conclusion: In patients who had a myocardial infarction, clinical factors used in combination and treatment with eplerenone were associated with a PIIINP decrease. Interestingly, higher randomization PIIINP levels might help in identifying patients more prone to have an "anti-fibrotic response" when treated with MRAs. Predictors of an antifibrotic response after MI complicated by HF. Several clinical factors and biomarkers predicted a PIIINP decrease after an MI complicated by HF. There was a significant interaction between baseline PIIINP levels and eplerenone treatment: patients with baseline PIIINP ≥ 3.6 mmol/L treated with eplerenone had the best response (PIIINP decrease). [ABSTRACT FROM AUTHOR]