A 74-year-old man is admitted to the intensive care unit due to progressive shortness of breath for the last several days. He has a past medical history of coronary artery bypass grafting at age 50, mitral valve repair at age 64, ischemic cardiomyopathy with left ventricular ejection fraction of 20%, atrial fibrillation, type 2 diabetes mellitus, peripheral vascular disease, and stage III chronic kidney disease. The patient has had several hospital admissions for decompensated congestive heart failure over the past 2 years.
His temperature is 37.2 C (99 F) , blood pressure is 90/60 mm Hg, pulse is 96/min, and respirations are 22/min. The patient's pulse oximetry is 88% on room air. He is in mild respiratory distress. Jugular venous pressure is elevated at 15 cm H₂O. Lung examination reveals decreased breath sounds at the bases with bibasilar crackles up to the middle of the chest. Cardiac examination reveals irregular heart tones and a II/VI holosystolic murmur heard over the cardiac apex. There is 3+ lower extremity edema up to the mid thighs.
ECG shows atrial fibrillation at a rate of 94/min and low-voltage QRS complexes in the precordial leads. Chest x-ray reveals cardiomegaly and significant pulmonary vascular congestion in addition to small bilateral pleural effusions.
Which of the following best describes the benefits of milrinone infusion in this patient?

Question

Quizplus · Accepted Answer

Milrinone is a phosphodiesterase inhibitor that decreases cyclic AMP (cAMP) degradation, increases cellular cAMP, and is both an arterial and venous vasodilator. Increased cellular cAMP leads to increased cellular calcium influx, intracellular calcium concentration, and myocardial contractility (inotropic effect). Intravenous milrinone can acutely improve hemodynamics and decrease dyspnea in patients with symptomatic advanced congestive heart failure (New York Heart Association [NYHA] class III or IV) with low output state, marginal systolic blood pressure, and/or inadequate response to standard therapy (eg, vasodilators, diuretics). This patient with marginal blood pressure and NYHA class IV symptoms unresponsive to intravenous diuretics may attain symptomatic relief with intravenous milrinone. (Choices B, C, D, and E) A multicenter, randomized, placebo-controlled trial found that intravenous milrinone resulted in a significantly increased number of hypotensive episodes that required discontinuation or further intervention, an increased incidence of atrial and ventricular arrhythmias, and a non-statistically significant increase in in-hospital and 60-day mortality. Ischemic cardiomyopathy patients did significantly worse, possibly due to milrinone-provoked ischemia from increased myocardial oxygen demand and consumption. Chronic use of oral milrinone has been associated with significantly increased mortality. Educational objective: Intravenous milrinone (inotrope) can provide symptomatic relief in patients with severe decompensated heart failure with evidence of low output state, marginal systolic blood pressure, or inadequate response to vasodilator and diuretic therapy. Its use is associated with a significant increase in hypotensive episodes and atrial or ventricular arrhythmias, and a non-statistically significant increase in in-hospital and 60-day mortality. __________ References: Symptomatic improvement in patients treated with intermittent infusion of inotropes: a double-blind placebo controlled pilot study. (http://www.ncbi.nlm.nih.gov/pubmed/12939113) Short-term intravenous milrinone for acute exacerbation of chronic heart failure: a randomized controlled trial. (http://www.ncbi.nlm.nih.gov/pubmed/11911756)

A 74-Year-Old Man Is Admitted to the Intensive Care Unit