CLINICAL INVESTIGATION
Diagnostic Accuracy of Emergency Doppler Echocardiography for Identification of Acute Left Ventricular Heart Failure in Patients with Acute Dyspnea: Comparison with Boston Criteria and N-terminal Prohormone Brain Natriuretic Peptide Peiman Nazerian, MD, Simone Vanni, MD, PhD, Maurizio Zanobetti, MD, Gianluca Polidori, MD, Giuseppe Pepe, MD, Roberto Federico, MD, Elisabetta Cangioli MD, and Stefano Grifoni, MD
Abstract Objectives: Echocardiography is a fundamental tool in the diagnosis of acute left ventricular heart failure (aLVHF). However, a consultative exam is not routinely available in every emergency department (ED). The authors investigated the diagnostic performance of emergency Doppler echocardiography (EDecho) performed by emergency physicians (EPs) for the diagnosis of aLVHF in patients with acute dyspnea. Methods: A convenience sample of acute dyspneic patients was evaluated. For each patient, the Boston criteria score for heart failure was calculated, and N-terminal prohormone brain natriuretic peptide (NT-proBNP) and EDecho were contemporaneously performed. Four investigators, after a limited echocardiography course, performed EDechos and evaluated for a ‘‘restrictive’’ pattern on pulsed Doppler analysis of mitral inflow and reduced left ventricular (LV) ejection fraction. The final diagnosis, established after reviewing all patient clinical data except NT-proBNP and EDecho results, served as the criterion standard. Results: Among 145 patients, 64 (44%) were diagnosed with aLVHF. The median time needed to perform EDecho was 4 minutes. Pulsed Doppler analysis was feasible in 125 patients (84%). The restrictive pattern was more sensitive (82%) and specific (90%) than reduced LV ejection fraction and more specific than the Boston criteria and NT-proBNP for the diagnosis of aLVHF. Considering noninterpretable values of the restrictive pattern and uncertain values (‘‘gray areas’’) of Boston criteria (4 < Boston criteria score < 7) and of NT-proBNP (300 < NT-proBNP < 2,200 pg ⁄ mL) as false results, the accuracy of the restrictive pattern in the overall population was 75%, compared with accuracy of 49% for both NT-proBNP and Boston criteria. Conclusions: EDecho, particularly pulsed Doppler analysis of mitral inflow, is a rapid and accurate diagnostic tool in the evaluation of patients with acute dyspnea. ACADEMIC EMERGENCY MEDICINE 2010; 17:18–26 ª 2010 by the Society for Academic Emergency Medicine Keywords: dyspnea, echocardiography, natriuretic peptide, heart failure
A
cute dyspnea is one of the most common reasons for presentation to the emergency department (ED). The rapid and accurate identification
From the Department of Emergency Medicine, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. Received May 15, 2009; revision received July 23, 2009; accepted July 29, 2009. Address for reprints and correspondence: Peiman Nazerian, MD; e-mail:
[email protected].
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ISSN 1069-6563 PII ISSN 1069-6563583
of the cause, especially acute left ventricular heart failure (aLVHF; whether new onset or decompensated chronic heart failure) can be difficult in the acute setting. Accurate and timely diagnosis is important to decrease morbidity and mortality and to provide cost-effective treatment.1,2 Brain natriuretic peptide (BNP) and its amino-terminal fragment N-terminal proBNP (NT-proBNP) have been described as powerful diagnostic tests to exclude aLVHF.3–5 However, their diagnostic accuracy is not
ª 2009 by the Society for Academic Emergency Medicine doi: 10.1111/j.1553-2712.2009.00630.x
ACAD EMERG MED • January 2010, Vol. 17, No. 1
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satisfactory, especially for the large proportion of patients with intermediate values.3–5 Moreover, the tests lack specificity, with high levels of natriuretic peptides found in sepsis, ischemic heart disease, anemia, pulmonary embolism, atrial fibrillation, and chronic obstructive pulmonary disease with cor pulmonale.6–10 Echocardiography is a fundamental tool in the diagnosis of aLVHF.11 Unfortunately, a formal exam is not routinely available in the ED. The role of ultrasound in emergency medicine as a diagnostic tool and as a guide to therapy is expanding rapidly, but the value of bedside emergency Doppler echocardiography (EDecho) performed by emergency physicians (EPs) to determine the cause of dyspnea has not been adequately studied. The goal of this study was to investigate the accuracy of EDecho in patients presenting to the ED with acute dyspnea for the diagnosis of aLVHF. METHODS Study Design This was a prospective cohort study of a convenience sample of patients presenting to the ED with acute dyspnea. Informed consent was obtained; if a patient could not give consent, it was obtained from a family member. The study was approved by the institutional review board. Study Setting and Population The study was performed in the ED of an adult tertiary referral university hospital with an annual census of 120,000 visits. The patients were recruited during 3 months, from January 2007 to March 2007. EDechos were performed and interpreted by four investigators (two resident and two assistant physicians) who had already completed an emergency medicine ultrasound workshop consisting of didactic and practical sessions, with a minimum of 150 proctored examinations (trauma, abdominal, and venous). An investigator was present to enroll patients for an average of 14 hours per day, inclusive of nights and weekends. All adult patients presenting to the ED for dyspnea as their main symptom while an investigator was present were considered for the study. Dyspnea, including acute-onset dyspnea or worsening of chronic dyspnea, had to be present at the time of the treating physician evaluation. Patients with trauma, ST-elevation myocardial infarctions, or dyspnea clearly caused by something other than heart failure, such as pneumothorax, were excluded. Patients were also excluded if they had received intravenous (IV) therapy in the ED before EDecho and NT-proBNP were performed. Patients who met the inclusion criteria were invited to participate in the study. EDecho was performed in all patients who met the inclusion criteria. However, if the investigator judged that both left ventricular (LV) ejection fraction and pulsed Doppler analysis of mitral inflow were not interpretable due to a very poor acoustic window, the patient was excluded from the study because EDecho was not feasible.
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Table 1 Boston Criteria for Diagnosis of Heart Failure12 Criterion Category I: history Rest dyspnea Orthopnea Paroxysmal nocturnal dyspnea Dyspnea while walking on level area Dyspnea while climbing Category II: physical examination Heart rate abnormality (1 point if 91 to 110 beats ⁄ min; 2 points if more than 110 beats ⁄ min) Jugular venous elevation (2 points if greater than 6 cm H2O; 3 points if greater than 6 cm H2O plus hepatomegaly or edema) Lung crackles (1 point if basilar; 2 points if more than basilar) Wheezing Third heart sound Category III: chest radiography Alveolar pulmonary edema Interstitial pulmonary edema Bilateral pleural effusion Cardiothoracic ratio greater than 0.50 Upper zone flow redistribution
Point Value* 4 4 3 2 1 1 or 2 2 or 3
1 or 2 3 3 4 3 3 3 2
Study Protocol Initial patient assessment included a clinical history, physical examination, chest x-ray, 12-lead electrocardiogram (ECG), arterial blood gas analysis, and routine blood tests. Treating physicians were asked to complete a Boston criteria form for congestive heart failure. Heart failure was classified as ‘‘definitive,’’ ‘‘possible,’’ and ‘‘unlikely’’ based on clinical score12 (Table 1). Within 30 minutes of inclusion in the study and before initiation of therapy, blood samples for NT-proBNP assay were collected and at the same time EDecho was performed. The treating physician was blinded to NT-proBNP and EDecho results. NT-proBNP analysis. Blood samples (ethylenediaminetetraacetic acid) were centrifuged immediately and stored at )80C. NT-proBNP analysis was performed with a commercially available immunoassay (Elecsys pro-BNP, Roche Diagnostics, Indianapolis, IN) on an Elecsys 1010 analyzer. According to the manufacturer’s data, the coefficient of variation for inter- and intraassay precision was
