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Weintraub et al

Acute Heart Failure Syndromes

1979

ics, achieve euvolemia, and avoid harm, such as myocardial and renal injury. Initial stabilization focuses on determining whether the patient requires ventilatory support, either via endotracheal intubation or noninvasive ventilation (NIV). NIV is used as an adjunct to acute pharmacological therapy in patients who present with respiratory distress. Although a large randomized trial suggests no mortality benefit associ- ated with NIV, it does improve dyspnea and reduce preload while other therapies are initiated.8 Diuretics are a central component of ED therapy, and their use is endorsed by guidelines from both the United States and Europe.5,64 – 66 Further studies are needed to resolve the conflicting results as to whether intermittent boluses or a constant infusion is more efficacious.67,68 Vasodilators, including intravenous angioten- sin-converting enzyme (ACE) inhibitors, are frequently used in the treatment of AHFS patients with congestion and normal or elevated blood pressure. In addition to the intrave- nous form, nitroglycerin is also available in sublingual and topical preparations. Topical nitroglycerin preparations are frequently used in the ED despite limited clinical trial data describing their utility. A highly selective study of patients with AHFS and low cardiac output and monitored by a pulmonary artery catheter suggests that 0.8 mg of sublingual nitroglycerin causes a clinically significant decrease in sys- temic vascular resistance and an increase in the cardiac index in less than 30 minutes.69 Similarly, clinically significant improvements in pulmonary capillary wedge pressure and cardiac index were also seen when nitroglycerin ointment (2.5 to 5 cm) was applied topically to patients with AHFS.70

ED patients with AHFS can be largely assigned into 2 groups based on presentation blood pressure: (1) hypertensive (140 mm Hg) and (2) normotensive (140 mm Hg). Hy- potension (90 mm Hg) and cardiogenic shock are rare and make up less than 5% of ED presentations.12,65 Those who present with hypertension may appear to be the most acutely ill, but aggressive blood pressure management often results in rapid resolution of symptoms. More importantly, once their acute symptoms are adequately managed, patients presenting with hypertension often have 60- to 90-day mortality rates that are much lower than those who present with normoten- sion.12,18,71,72 Although both of these subsets have signs and symptoms of pulmonary congestion, the actual mechanisms and volume status may differ. Traditional AHFS models describe fluid accumulation and acute symptoms as being almost synonymous. Recent data suggest that those patients who present with hypertension (ie, vascular crisis) may have congestion caused by a mismatch between rapidly increasing afterload and impaired systolic performance leading to vol- ume redistribution.7,73–75 Nevertheless, both groups of pa- tients present with similar symptoms and are often treated solely with intravenous diuretics despite differences in un- derlying pathophysiology and volume status.

Further subcategorization can be made based on underlying etiologies and reasons for decompensation such as AHFS related to dietary and medication nonadherence, ischemia, worsening renal function, arrhythmias, or a concomitant pulmonary pro- cess.76 In select cases this may help direct further therapy such as anitarrhythmics; however, regardless of the etiology, the major- ity of patients are admitted to the hospital for further therapy

targeting congestion reduction.12,77–79 Very few changes are made to medication regimens during hospitalization, and only a minority of patients receive a therapeutic procedure or device during their inpatient stay.80–82

According to the recently completed URGENT (Ularitide Global Evaluation in Acute Decompensated Heart Failure) dyspnea study, the ED approach does improve overt symptoms

of breathlessness in most patients by 6 hours.83

Yet, despite

improvement in symptoms by 6 hours, registry data also suggest that only 50% of patients have complete resolution of their congestive symptoms at hospital discharge.11 Furthermore, there is little randomized evidence of the benefit of diuretics beyond symptomatic improvement, because randomized trials are non- existent84 and signals increasingly point to the potential for induction of harm with both acute85,86 and chronic87 usage of diuretic medication. Previous studies of diuretics suggest not only an association with adverse outcomes, but also perhaps

direct causality.71,86,88–91

The development of in-hospital acute

renal injury has been associated with increased in-hospital mortality.92–94 Although, for some, diuresis is important and appropriate, could the nearly universal application of homoge- neous therapy to an inherently heterogeneous disorder nega-

tively impact the high rates of short-term recidivism95 mortality1 associated with AHFS?3,58

and

AHFS has historically been viewed as a transient event, characterized primarily by systolic dysfunction, low cardiac output, and fluid overload. This pathophysiologic model has been thought to be applicable across all patient groups,

varying only by degree of severity.96 –98

Consequently, short-

term treatment strategies such as intravenous diuretics, tar- geted at rapidly alleviating fluid congestion, were adopted without clinical trials evaluating long-term safety and effi- cacy. It is noteworthy that emerging data from several HF registries have largely challenged the traditional low cardiac output model exemplified by the prototypical male with ischemic heart disease, revealing a more complex and distinct group of pathophysiologic entities.77,78 Despite the heteroge- neous clinical profiles outlined above, suggesting that tar- geted treatment may be beneficial, the majority of patients with AHFS are treated with homogeneous therapy, namely intravenous diuretics. A next logical step would be to deter- mine whether select subsets of patients, classified via reliable objective measures after initial evaluation, would benefit from targeted therapy aimed at their risk profile, HF etiology, and reason for decompensation.

Emergency Department Disposition Decision Making The majority of patients who present to the ED with AHFS are admitted to the hospital.99,100 This approach is largely due to the challenge of identifying ED patients at low risk for poor outcomes. Risk stratification of patients with AHFS is tradi- tionally problematic, not only because of the patients’ under- lying HF, but also because of their multiple comorbidities. Further, even for patients who exhibit no objective markers of high risk, the subsequent inability to ensure close follow-up, provide bedside HF education, and address the importance of adherence to therapeutic recommendations makes direct ED discharge problematic.

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