[Differential diagnosis of dyspnea - significance of clinic aspects, imaging and biomarkers for the diagnosis of heart failure].
Dyspnea is a frequent reason for emergency consultations in hospitals or community medical facilities. Besides heart failure, a wide variety of other disorders may cause this symptom. Thus, early and accurate differential diagnosis is mandatory in order to facilitate rapid institution of appropriate therapy. This CME article elaborates on the specific usefulness of traditional diagnostic tools as history, symptomatology and physical signs along with chest X-ray and ECG and the more recently introduced natriuretic peptides to discriminate heart failure from other causes of dyspnea in the emergency setting. According to a systematic search and meta-analysis of the respective literature, several features from history and physical examination as well as pulmonary congestion on chest X-ray, atrial fibrillation and a high level of confidence of the initial clinical judgment indicate a cardiac cause of dyspnea with high specificity, but less sensitivity. Thus, in patients presenting with one or several of these characteristic features, little further diagnostic yield is to be expected from natriuretic peptides. If, however, the suspicion of heart failure remains unsettled by these means, determination of biomarkers may be helpful, although it needs to be considered that moderately elevated levels have only a limited specificity in particular in elderly patients with comorbidities. As also recognized by the European Guidelines for diagnosis and treatment of chronic heart failure, a BNP level of <100 pg/ml has proven particularly useful for excluding heart failure. Thus, a directed history, symptoms, physical findings, chest-X-ray and ECG remain the diagnostic mainstay. If the diagnosis cannot be established by these traditional tools, BNP or NT-proBNP testing may be very helpful, especially for ruling out heart failure.