Evaluation of point‐of‐care thoracic ultrasound and NT‐proBNP for the diagnosis of congestive heart failure in cats with respiratory distress

Abstract

BackgroundThe diagnosis of congestive heart failure (CHF) in cats is challenging. Point‐of‐care (POC) thoracic ultrasound and NT‐proBNP testing are emerging tools that may aid in diagnosis.Hypothesis/ObjectivesTo assess the diagnostic accuracy of POC lung ultrasound (LUS), focused cardiac ultrasound (FCU), and NT‐proBNP in predicting a final diagnosis of CHF.AnimalsFifty‐one cats in respiratory distress.MethodsBlood NT‐proBNP, LUS, and FCU evaluating left atrial (LA) size and presence of pericardial effusion (PCEFF) were performed in all cats. Lung ultrasound findings including pleural effusion (PLEFF), number of B‐lines, and sub‐pleural abnormalities were noted. Medical records were evaluated for final diagnosis.ResultsThirty‐three of 51 (65%) cats were diagnosed with CHF. Lung ultrasound and blood NT‐proBNP were significant predictors of CHF in a multivariate model. The LUS criterion that maximized accuracy for CHF diagnosis was presence of >1 site strongly positive for B‐lines (>3 B‐lines per site), resulting in sensitivity of 78.8%, specificity of 83.3%, and area under the curve (AUC) of 0.833. Subjective LA enlargement was 97.0% sensitive and 100% specific for CHF (AUC 0.985). Presence of PCEFF also was 100% specific, but only 60.6% sensitive, for CHF (AUC 0.803). A positive blood NT‐proBNP test was 93.9% sensitive and 72.2% specific for the diagnosis of CHF (AUC 0.831).Conclusions and Clinical ImportancePoint‐of‐care diagnostic techniques of LUS, FCU, and NT‐proBNP are useful to diagnose CHF in cats with respiratory distress.

ACVIM consensus statement guidelines for the classification, diagnosis, and management of cardiomyopathies in cats

“…In contrast to dogs, the radiographic pattern associated with cardiogenic pulmonary edema in cats is highly variable . A combination of physical examination, point‐of‐care ultrasound examination and point‐of‐care NT‐proBNP often can be helpful when deciding if CHF is the cause of respiratory distress (LOE high) …”

“…The quantitative feline‐specific NT‐proBNP assay using plasma or pleural fluid has good diagnostic accuracy for discriminating between cats with cardiac and noncardiac causes of respiratory distress (LOE high), but it is not recommended for guiding therapeutic decision‐making in cats with respiratory distress because of the delay in receiving test results from an external laboratory. Instead, a point‐of‐care NT‐proBNP assay provides rapid results while maintaining reasonable diagnostic accuracy in discriminating between cardiac and noncardiac causes of respiratory distress, and should be considered when point‐of‐care ultrasound examination is not available (LOE medium) . The point‐of‐care assay can be used on plasma or pleural fluid, the latter diluted 1:1 with saline for greater specificity …”

“…If radiographs cannot be obtained safely, point‐of‐care thoracic ultrasound examination or a point‐of‐care NT‐proBNP test should be considered (LOE high). With point‐of‐care ultrasound examination, the presence of effusions or B‐lines in association with severe LA enlargement is highly suggestive of CHF . A negative result on a point‐of‐care NT‐proBNP test suggests that respiratory disease is more likely to be the cause of respiratory distress than is cardiac disease.…”

The use of focused cardiac ultrasound to screen for occult heart disease in asymptomatic cats

“…In both human patients and in veterinary species in the emergency room setting, focused assessment with sonography for trauma, triage, and tracking protocols help diagnose certain conditions, including cavitary effusions, pleural space disease, and pulmonary disease . Focused cardiac ultrasound is useful for differentiating congestive heart failure from non‐cardiac causes of dyspnea in cats . The FCU in the present study is distinct from previously described sonographic protocols due to its use in nonemergent clinical scenarios and its concentration on specific heart structures visualized from a limited number of acquired images …”

Retrospective evaluation of the safety and tolerability of pimobendan in cats with obstructive vs nonobstructive cardiomyopathy

“…It is well recognized that cats with structural heart disease that is predominately phenotypically left-sided can develop either pulmonary edema, pleural effusion, or both. A number of studies have reported the relative frequency of different manifestations of CHF in cats,[30][31][32] reporting incidence of pleural effusion between 51% and 79% and…”