Mr. L. is a 62-year-old Native American with a past medical history significant for coronary artery disease status post-myocardial infarction and four-vessel coronary artery bypass grafting 2 years ago, as well as known heart failure with a left ventricular ejection fraction of 30%, type 2 diabetes, and hyperlipidemia. He presents to the emergency room complaining of shortness of breath with exertion, orthopnea, lower extremity edema, and dull chest pain. On initial evaluation he is hypotensive at 86/40 mm Hg, and lung exam reveals rales halfway up the posterior fields. A third heart sound is present. He is admitted to the inpatient cardiology service; the cardiology team notes that this is his third admission for similar symptoms in the past 7 months. What further information might help his clinicians maximize therapy for his chronic heart failure, and prevent future acute exacerbations?