Tissue Doppler echocardiography can accurately diagnose acute heart failure in emergency departments, according to research published online in Heart.
"The TD imaging may be a good diagnostic tool for acute dyspneic patients and especially helpful for those patients with inconclusive plasma BNP (B-type natriuretic peptide) results," wrote Dr. Chien-Hua Huang and colleagues from National Taiwan University Medical College and National Taiwan University Hospital in Taipei (Heart, June 27, 2006).
While acute heart failure carries high mortality and morbidity rates, symptoms of acute dyspnea are nonspecific, according to the researchers. Using conventional echocardiography, left ventricle (LV) ejection fraction, LV size, and transmitral flow have limitations and can't satisfactorily estimate the real hemodynamic and fluid status correctly.
To investigate the role of the tissue Doppler echocardiography technique, the Taiwanese study team prospectively evaluated 92 acute dyspneic patients from a tertiary medical center between January and August 2005, performing TD echocardiography and recording the ratios of peak early diastolic transmitral blood flow velocity (E) to the peak early diastolic tissue velocity over mitral annulus (Ea).
The echocardiography studies, including TD imaging, were performed by a cardiologist in the emergency ultrasonography laboratory within the emergency department using a System V ultrasound scanner (GE Healthcare, Chalfont St. Giles, U.K.) and a 3.5-MHz multiphase-array probe. The data were then digitized and stored.
The studies were then analyzed by an echocardiologist blinded to all clinical, hemodynamic, and BNP data. Of the 92 patients, 51 had final diagnoses of acute heart failure, and 41 were diagnosed as non-HF.
To evaluate the correlation of E/Ea with the diagnosis of acute HF, the researchers performed ROC curves for patients with preserved systolic function and impaired LV systolic function. From the ROC curves, the study team determined the best cutoff value of E/Ea for diagnosing acute HF was 11.0, producing a sensitivity of 88.9%, specificity of 82.9%, and accuracy of 85.5% for patients with preserved systolic function.
For patients with LV systolic dysfunction, the best cutoff value of E/Ea for diagnosing acute HF was 16.0, yielding a sensitivity of 70.8%, specificity of 100%, and accuracy of 76.7%.
To evaluate the overall accuracy of the E/Ea index for diagnosing acute HF in dyspnea patients, the researchers used the cutoff values for patients with preserved and impaired LV systolic function, and checked the prediction accuracy for all patients. The result was a combined sensitivity of 80.4%, specificity of 85.4%, and accuracy of 82.6%.
"The TD echocardiography can help to differentiate the acute HF from non-HF etiology for acute dyspneic patients," the authors concluded. "The E/Ea higher than 16 for patients with LV systolic dysfunction and E/Ea higher than 11 for those with preserved LV systolic function, which may implicate elevated LVEDP, suggested acute HP for dyspneic patients in the emergency department."
The researchers acknowledged a number of limitations in their study, including a limited number of cases, the difficulty of obtaining an adequate echocardiographic window in 11.5% of patients, the lack of a plasma BNP assay for every patient, and different underlying diseases of the dyspneic patients.
By Erik L. Ridley
AuntMinnie.com staff writer
July 12, 2006
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