Weintraub et al
Acute Heart Failure Syndromes
presentation and treatment, large-scale clinical trials, utilizing prospective data collection, have not been designed to recruit patients in the ED setting. Factors contributing to this include a long-standing difficulty establishing consensus on reason- able end points4 as well as a desire to ensure accurate diagnosis before enrollment. More importantly, there has been a misperception by HF specialists that identification and enrollment of ED patients is problematic.3 The net result is a lingering uncertainty with regard to the impact of early intervention on outcomes and de facto inclusion of patients who have refractory symptoms.3,4 The latter, in particular, may be responsible for the predominantly neutral findings associated with the majority of AHFS investigations that have been conducted to date.
As highlighted in this Introduction, a paradigm shift in the clinical practice and investigative agenda surrounding AHFS is warranted. Sensing the urgency of this matter, the National Heart, Lung, and Blood Institute recently convened a multi- disciplinary working group of individuals with expertise in AHFS management and tasked them with development of the Institute’s future research focus for AHFS.13 Although the proceedings were published elsewhere, there was firm resolve among all participants regarding the need to improve the evidence base in AHFS by initiating study of these patients in the ED, and that a better understanding of AHFS could only be achieved through broad collaboration.
and decrease mortality and length of stay.15–19 This difficult task is further compounded by the organizational structure and operations of most EDs, which tend to be better suited for rapid stabilization, treatment, and disposition of acute emer- gencies such as shock, arrhythmias, or ST-segment myocar- dial infarction, as opposed to the timely recognition and treatment of more subtle or complicated forms of AHFS which most often are related to decompensation of underlying, chronic HF.20 It may be easier to judge how seriously ill patients are when their baseline has deviated from a previously healthy state, than when their condition represents deterioration of a chronic illness that is protean in nature, especially when the emergency physician is unfamiliar with the patient.
The ED phase of AHFS management concludes with a disposition decision (admit to ED observation unit, in-hospital telemetry unit, intensive care unit, or discharge to the outpatient environment).21 Because it is challenging to identify patients at risk for poor outcomes in the ED, including acute and 30-day adverse cardiac events,22 and because definitive resolution of symptoms is seldom achieved in the ED, 80% of patients who present to the ED with AHFS are hospitalized.23 At present, however, there is little evidence to guide disposition decisions, and imprecise risk stratification and uncertainty regarding the etiology of AHFS often prompts the decision to admit for further treatment and testing.21
Organization of Writing Group and Relationships With Industry Experts in the subject of AHFS were selected and charged with examining subject-specific data and writing this scien- tific statement. The writing group performed a formal litera- ture review and weighed the strength of evidence for or against existing treatments or procedures using established AHA statement and guideline methodology. Discussion of patient-specific modifiers, comorbidities, and issues of pa- tient preference that might influence the choice of particular tests or therapies were considered, as were frequency of follow-up and cost-effectiveness. When available, informa- tion from studies on cost was considered; however, review of data on efficacy and clinical outcomes constituted the pri- mary basis for any related recommendations. To ensure that any actual, potential, or perceived conflicts of interest were identified, all members of the writing group, as well as peer reviewers of the document, completed “Relationship with Industry” forms when the writing group was formed. Writing group members were also required to review and update their disclosure information before publication. The writing group used the “Methodology Manual for ACC/AHA Guideline Writing Committees”14 as a guide for developing this state- ment. Writing group and reviewer disclosures that are perti- nent to this scientific statement are provided at the end of this statement.
What Happens Currently in the ED:
Diagnosis, Treatment, and Disposition? Diagnosis and treatment of AHFS in the ED is a clinical challenge that requires complex decision-making skills to achieve hemodynamic balance, improve functional capacity,
Current Diagnostics The evaluation of the patient in the ED with possible AHFS includes history, physical examination, chest radiography, 12-lead ECG, cardiac troponin testing (I or T), electrolytes, and a complete blood cell count. The chest radiograph remains a cornerstone for diagnostic testing, but can lack signs of congestion in over 15% of patients, thus limiting its ability as a screening tool.24 In select cases, liver and thyroid function tests may be considered. The natriuretic peptides b-type natriuretic peptide (BNP) and N-terminal (NT)- proBNP have demonstrated diagnostic utility in this patient population when clinical uncertainty remains after initial history, physical examination, and chest radiography. These biomarkers are generated from a prohormone released from cardiac myocytes in response to ventricular dilatation and pressure overload.25–27 After release from the cardiac myo- cyte, the prohormone proBNP is cleaved into BNP, which is metabolically active, and NT-proBNP, which is metabolically inactive. Both BNP and NT-proBNP are elevated in AHFS and the magnitude of marker elevation is correlated with severity of illness.28 –32
A large study that investigated the diagnostic utility of natriuretic peptides was the Breathing Not Properly trial which enrolled 1586 patients, and evaluated BNP measure- ment in ED patients with possible AHFS.28 Using a cutoff of 100 pg/mL, BNP had a sensitivity, specificity, negative predictive, and positive predictive value of 90%, 76%, 79%, and 89%, respectively. In this capacity, BNP is highly useful to exclude AHFS. In a multiple logistic regression analysis including history, physical examination, and chest x-ray findings, an elevated BNP was the strongest independent predictor of AHFS, with an odds ratio of 29.6 (95% confi- dence interval [CI] 17.75 to 49.37). In a secondary analysis
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