Inclusion Criteria:

- Stage I-III breast cancer

- Scheduled to undergo treatment with doxorubicin-based chemotherapy regimen

- Able to provide informed consent

Exclusion Criteria:

- Use of anthracycline agents other than doxorubicin

- Baseline LVEF ≤50% by any modality (nuclear, echo, MRI)

- Atrial fibrillation or flutter

- Mitral valve disease (More than mild mitral stenosis or regurgitation, previous
mitral valve replacement or repair)

- Inability to obtain adequate echo images for required analysis

- Hyperkalemia (K+ >5.0)

- Glomerular filtration rate (GFR) <30 ml/min/1.73m2

- Uncontrolled hypertension, defined as having a systolic blood pressure > 180 mmHg
and/or a diastolic blood pressure >110 mmHg

- Symptomatic hypotension or systolic blood pressure <85 mmHg

- History of hypersensitivity to eplerenone or spironolactone

- Significant hepatic disease (e.g., previously documented positive serology for viral
hepatitis) or aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT)
>3 times the upper limits of normal

- Concomitant treatment with spironolactone, potassium-sparing diuretics, potassium
supplements, or strong inhibitors of CYP3A4 (i.e. ketoconazole, itraconazole,
nefazodone, troleandomycin, clarithromycin, ritonavir, nelfinavir)

- History of alcohol and/or any other drug abuse

- Women who are either pregnant, lactating or of childbearing potential and not using
an acceptable method of contraception

- Other severe acute or chronic medical or psychiatric condition or laboratory
abnormality that may increase the risk associated with trial participation or
investigational product administration or may interfere with the interpretation of
trial results and, in the judgment of the investigator, would make the subject
inappropriate for entry into this trial