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Diagnosis

Doppler echocardiography was more accurate than B-type natriuretic peptide assay for detecting CHF in acute dyspnea

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ACP J Club. 2003 Jul-Aug;139:22. doi:10.7326/ACPJC-2003-139-1-022


Clinical Impact Ratings

Emergency Med: 5 stars

Hospitalists: 5 stars

Cardiology: 5 stars


Source Citation

Logeart D, Saudubray C, Beyne P, et al. Comparative value of Doppler echocardiography and B-type natriuretic peptide assay in the etiologic diagnosis of acute dyspnea. J Am Coll Cardiol. 2002;40:1794-800. [PubMed ID: 12446063] (All 2003 articles were reviewed for relevancy, and abstracts were last revised in 2009.)


Abstract

Question

In patients with acute dyspnea, how does the accuracy of Doppler echocardiography compare with bedside B-type natriuretic peptide (BNP) assay for diagnosing decompensated congestive left-heart failure (CHF)?

Design

Blinded comparison of BNP levels and Doppler findings with a confirmatory clinical diagnosis.

Setting

Emergency department (ED) of a hospital in Clichy, France.

Patients

163 consecutive patients (mean age 67 y, 67% men) presenting to the ED with acute, severe dyspnea. Exclusion criteria were acute myocardial infarction, chest injury, recent surgery, receipt of treatments > 2 hours before arrival at the ED, or no available emergency echocardiography.

Description of tests and diagnostic standard

Blood for BNP levels was taken using the Triage BNP test (Biosite Diagnostics, San Diego, CA, USA), a point-of-care method based on fluorescence immunoassay. The BNP measurements were done on frozen plasma approximately 1 to 2 months after blood collection. Doppler echocardiography was done within 60 minutes of enrollment using a Hewlett-Packard Sonos 1500 (Andover, MA, USA) machine with a 2.5-MHz probe and included 2-dimensional and M-mode examination, pulsed Doppler analysis of mitral inflow, and continuous Doppler analysis of tricuspid regurgitation. 2 cardiologists and 1 pneumonologist, blinded to BNP assay and Doppler results, collaborated to determine the final diagnosis of CHF based on the Framingham criteria with corroborative information from other cardiac and pulmonary function tests.

Main outcome measures

Sensitivity, specificity, and accuracy of BNP assay and Doppler echocardiography.

Main results

115 of 163 patients (71%) had a final diagnosis of CHF. The highest accuracy (88%) for BNP was obtained with a cutpoint of 300 pg/mL (Table). The best diagnostic performance with Doppler echocardiography was with the “restrictive” mitral pattern (Table), which had an accuracy of 91%. Both BNP and Doppler added significant incremental predictive diagnostic values to the clinical variables, but BNP assay only predicted CHF when levels were > 300 pg/mL.

Conclusion

In patients with acute dyspnea, Doppler echocardiography was more accurate than B-type natriuretic peptide assay for diagnosing decompensated congestive left-heart failure.

Source of funding: French Federation of Cardiology.

For correspondence: Dr. D. Logeart, Hôpital Beaujon, Clichy, France. E-mail damien.logeart@bjn.ap-hop-paris.fr.


Table. Diagnostic characteristics of B-type natriuretic peptide (BNP) levels and Doppler echocardiography for diagnosing acute congestive left-heart failure*

Tests Sensitivity (95% CI) Specificity (CI) +LR −LR
BNP (pg/ml)
80 97% (93 to 99) 27% (15 to 42) 1.33 0.11
300 88% (81 to 94) 87% (75 to 95) 6.77 0.14
Doppler echocardiography
“Restrictive” mitral pattern 89% (82 to 95) 93% (82 to 97) 12.71 0.12

*Diagnostic terms defined in Glossary; LRs calculated from data in article, CIs provided by author.


Commentary

The diagnosis of CHF in an acutely ill patient with comorbid conditions remains a clinical challenge. The study by Logeart and colleagues evaluated the usefulness of Doppler echocardiography and the new assay for BNP in this setting.

BNP values were examined along with Doppler analysis of transmitral flow in patients presenting with severe dyspnea. In sinus rhythm, transmitral flow consists of an early, rapid phase and a second phase caused by atrial systole. Normally, the 2 components of flow are equal. In myocardial restriction, most blood flow into the left ventricle occurs early in diastole with very little supplied by the “atrial kick.” At times, a similar pattern, labeled “restrictive,” is seen in CHF and is clearly associated with a poor prognosis (1) regardless of the ejection fraction (2). In CHF, this early diastolic predominance of flow is attributed to elevated left atrial pressures.

The high likelihood ratio (LR) of a restrictive flow pattern for the diagnosis of CHF seen in this study is exciting, but should be taken with a grain of salt (or better still, a little furosemide!). Transmitral flow patterns can be greatly affected by volume status and loading conditions. In atrial fibrillation, the “atrial kick” is lost, and with rapid heart rates, the 2 phases of diastole merge into 1, making it difficult if not impossible to judge diastolic filling patterns in those settings. Clinically, restrictive Doppler flow patterns have been shown to predict prognosis but have not been correlated with actual filling pressures; Doppler analysis of tricuspid, pulmonary, and mitral insufficiency velocities are validated for that purpose. It is possible that the high LR for the restrictive pattern in this study was a result of the poor condition of the population being studied, who were admitted to an intensive care unit. These patients may therefore have been particularly ill, and as a group more likely to have restrictive patterns to their transmitral flows because of their poor prognosis.

Diagnosing CHF can be challenging. Good clinical assessment remains our first approach, and evidence supports the use of BNP levels to help clarify the diagnosis in challenging cases (3). Echocardiography is a powerful tool, but the use of Doppler flow patterns to help establish the diagnosis of CHF requires additional study.

Ellis W. Lader, MD
New York University School of Medicine
Kingston, New York, USA


References

1. Pinamonti B, Di Lenarda A, Sinagra G, Camerini F. Restrictive left ventricular filling pattern in dilated cardiomyopathy assessed by Doppler echocardiography: clinical, echocardiographic and hemodynamic correlations and prognostic implications. Heart Muscle Disease Study Group. J Am Coll Cardiol. 1993;22:808-15. [PubMed ID: 8354816]

2. Boccalandro F, Loghin C, Darwood S, Seung-Ho K, Barasch E. Restrictive left ventricular filling pattern with preserved systolic function assessed by Doppler echocardiography: clinical, echocardiographic and prognostic implications. Cardiology. 2002;98:148-53. [PubMed ID: 12417814]

3. Maisel AS, Krishnaswamy P, Nowak RM, et al. Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure. N Engl J Med. 2002;347:161-7. [PubMed ID: 12124404]