Background: Early diagnosis of nonacute heart failure is crucial because prompt initiation of evidence-based treatment can prevent or slow down further progression. To diagnose new-onset heart failure in primary care is challenging.
Methods and results: This is a cross-sectional diagnostic accuracy study with external validation. Seven hundred twenty-one consecutive patients suspected of new-onset heart failure underwent standardized diagnostic work-up including chest x-ray, spirometry, ECG, N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurement, and echocardiography in specially equipped outpatient diagnostic heart failure clinics. The presence of heart failure was determined by an outcome panel using the initial clinical data and 6-month follow-up data, blinded to biomarker data. Of the 721 patients, 207 (28.7%) had heart failure. The combination of 3 items from history (age, coronary artery disease, and loop diuretic use) plus 6 from physical examination (pulse rate and regularity, displaced apex beat, rales, heart murmur, and increased jugular vein pressure) showed independent diagnostic value (c-statistic 0.83). NT-proBNP was the most powerful supplementary diagnostic test, increasing the c-statistic to 0.86 and resulting in net reclassification improvement of 69% (P<0.0001). A simplified diagnostic rule was applied to 2 external validation datasets, resulting in c- statistics of 0.95 and 0.88, confirming the results.
Conclusions: In this study, we estimated the quantitative diagnostic contribution of elements of the history and physical examination in the diagnosis of heart failure in primary care outpatients, which may help to improve clinical decision making. The largest additional quantitative diagnostic contribution to those elements was provided by measurement of NT-proBNP. For daily practice, a diagnostic rule was derived that may be useful to quantify the probability of heart failure in patients with new symptoms suggestive of heart failure.