Prognostic relevance of magnesium alterations in patients with a myocardial infarction and left ventricular dysfunction: insights from the EPHESUS trial.

AIMS: Magnesium changes are common in myocardial infarction (MI) complicated with left ventricular systolic dysfunction (LVSD) and/or heart failure (HF). The relation between serum magnesium and clinical outcomes is insufficiently elucidated in this population. METHODS AND RESULTS: The EPHESUS trial randomized 6632 patients to either eplerenone or placebo. Hypomagnesemia and hypermagnesemia were defined as a serum magnesium <0.66 and >1.10 mmol/L, respectively. Linear mixed models and time-dependent Cox regression analysis were used to determine the effect of eplerenone on magnesium changes and the prognostic importance of magnesium. The co-primary outcomes were all-cause mortality and a composite of cardiovascular (CV) mortality and CV hospitalization. A total of 5371 patients had a post-baseline magnesium measurement. At baseline, 231 (4.3%) patients had hypomagnesemia and 271 (5.0%) patients had hypermagnesemia. During a median follow-up of 16 months, 682 (13%) developed hypomagnesemia and 512 (9.5%) hypermagnesemia. Eplerenone treatment did not result in a different magnesium level during follow-up (P = 0.14). After covariate adjustment hypo- and hypermagnesemia were not associated with a higher risk of CV events. Magnesium levels did not modulate the effect of a high potassium (>5 mmol/L) or low potassium (<4 mmol/L) on the clinical outcome. Baseline magnesium levels did not influence the treatment effect of eplerenone (P-interaction > 0.1 for all primary and secondary endpoints). CONCLUSION: In patients with MI complicated by LVSD or HF, magnesium alterations were not associated with clinical outcomes nor did they influence the effect of eplerenone. Serum magnesium did not modulate the effect of potassium changes on clinical outcome or the treatment effect of eplerenone. CLINICALTRIALS.GOV IDENTIFIER: NCT00232180.

Serum sodium and eplerenone use in patients with a myocardial infarction and left ventricular dysfunction or heart failure: insights from the EPHESUS trial.

BACKGROUND: Sodium changes are common in myocardial infarction (MI) complicated with left ventricular systolic dysfunction (LVSD) and/or heart failure (HF). Sodium handling is fine-tuned in the distal nephron, were eplerenone exhibits some of its pleotropic effects. Little is known about the effect of eplerenone on serum sodium and the prognostic relevance of sodium alterations in patients with MI complicated with LVSD and/or HF. METHODS: The EPHESUS trial randomized 6632 patients to either eplerenone or placebo. Hyponatremia and hypernatremia were defined as sodium < 135 mmol/L or > 145 mmol/L, respectively. Linear mixed models and time updated Cox regression analysis were used to determine the effect of eplerenone on sodium changes and the prognostic importance of sodium changes, respectively. The primary outcomes were all-cause mortality and a composite of cardiovascular (CV) mortality and CV-hospitalization. RESULTS: A total of 6221 patients had a post-baseline sodium measurement, 797 patients developed hyponatremia (mean of 0.2 events/per patient) and 1476 developed hypernatremia (mean of 0.4 events/per patient). Patients assigned to eplerenone had a lower mean serum sodium over the follow-up (140 vs 141 mmol/L; p < 0.0001) and more often developed hyponatremia episodes (15 vs 11% p = 0.0001) and less often hypernatremia episodes (22 vs. 26% p = 0.0003). Hyponatremia, but not hypernatremia was associated with adverse outcome for all outcome endpoints in the placebo group but not in the eplerenone group (interaction p value < 0.05 for all). Baseline sodium values did not influence the treatment effect of eplerenone in reducing the various endpoints (interaction p value > 0.05 for all). Development of new-onset hyponatremia following eplerenone initiation did not diminish the beneficial eplerenone treatment effect. CONCLUSION: Eplerenone induces minor reductions in serum sodium. The beneficial effect of eplerenone was maintained regardless of the baseline serum sodium or the development of hyponatremia. Sodium alterations should not refrain clinicians from prescribing eplerenone to patients who had an MI complicated with LVSD and/or HF. TRAIL REGISTRY: ClinicalTrials.gov identifier: NCT00232180. Serum sodium and eplerenone use in patients with a myocardial infarction and left ventricular dysfunction or heart failure: insights from the EPHESUS trial.