Measuring brain natriuretic peptide in suspected left ventricular systolic dysfunction in general practice: cross-sectional study

Abstract

The prevalence of heart failure is increasing.1 Patients usually present to their general practitioner but a definitive diagnosis of left ventricular systolic dysfunction can only be achieved by cardiac imaging. Measuring plasma concentrations of brain natriuretic peptide has been advocated as a screening test that might reduce demands on cardiological services. 2 We report the results of a community based study designed to investigate the effectiveness of measuring brain natriuretic peptide to diagnose left ventricular systolic dysfunction. The study was approved by the local research ethics committee. Participants, methods, and resultsGeneral practitioners were invited to refer patients with suspected heart failure to our clinic. The results of transthoracic echocardiography were reported by a single, experienced observer (IA). Ischaemia was diagnosed if Q waves, bundle branch block, T wave inversions, or left ventricular hypertrophy were present on an electrocardiogram. Evidence of heart failure on a chest radiograph was defined as the presence of pulmonary oedema or cardiomegaly. Concentrations of brain natriuretic peptide were measured by immunoradiometric assay (Shionoria assay, Shionogi, Osaka, Japan) of plasma stored at − 70°C. A concentration > 17.9 pg/ml was considered abnormal based on the results of a large study of left ventricular systolic dysfunction. 3 Altogether, 126 patients (68 men) with a mean age of 74.4 (SD 8.9) years were included in the study. Concentrations of the peptide were raised in the 40 patients with left ventricular systolic dysfunction (median concentration 79.4 pg/ml, interquartile range 35.9-151.0) compared with those with normal ventricular systolic function (26.7 pg/ml, 12.2-54.3; P < 0.001). A concentration > 17.9 pg/ml had a sensitivity of 88% and specificity of 34%. Choosing different cut points did not improve the predictive characteristics: at 10 pg/ml sensitivity was 92% but specificity was 18%, and at 76 pg/ml sensitivity was 66% and specificity 87%.The prior probability that a disease exists (its prevalence) and the extent to which a test result alters the chance of the disease existing determine whether further investigation is needed; this is the likelihood ratio of positive and negative tests. In the case of heart failure it is unlikely that a single positive test result will remove the need for further cardiac imaging before treatment is started. In contrast, a negative result may give a low posterior probability of disease so that further investigations are unnecessary.The prevalence (or prior probability) of left ventricular systolic dysfunction in this study was 32%; this is consistent with that reported in other studies. 4 The likelihood ratio for a patient without a history of myocardial infarction, with negative results on chest radiography and electrocardiography, and with concentrations of brain natriuretic peptide below the cut off, individually and in combination, are shown in the table. Measuring the concentration of brain natriuretic peptide ...

The Diagnostic Value of Physical Examination and Additional Testing in Primary Care Patients With Suspected Heart Failure

“…The prevalence of heart failure was 28.7%, which is similar to comparable previous studies. 25,26,31,32 The use of a loop diuretic was a predictor of the presence of heart failure in our study, which seems somewhat surprising as its prescription is often related to heart failure, but is understandable from a clinical point of view. Patients presenting with symptoms of volume overload will often be treated with loop diuretics to alleviate symptoms, usually before tests to confirm heart failure are performed.…”

“…Three other studies of similar patients comparing BNP with other readily available diagnostic tests concluded that BNP is the most powerful diagnostic test. 25,26,32 The vast majority of other studies assessing the diagnostic value of NT-proBNP were, however, performed in hospital emergency rooms and not in an outpatient or primary care setting. It should be emphasized that univariable diagnostic characteristics, such as sensitivity and specificity, cannot be routinely generalized from 1 setting to another.…”

Natriuretic Peptides as Markers of Mild Forms of Left Ventricular Dysfunction: Effects of Assays on Diagnostic Performance of Markers

“…A consistent finding of all reports is the excellent negative predictive value of BNP. Furthermore, BNP has a good negative likelihood ratio for diagnosis of LVD compared with standard clinical indices, such as clinical history, electrocardiogram, and chest x-ray (17 ). These clinical results led to the development of numerous commercially available assays to determine different natriuretic peptide hormones (18 ).…”

Plasma B-Type Natriuretic Peptide as a Marker of Myocardial Asynchrony

“…The absence of statistically significant differences in BNP levels in these groups may be accounted for by the well-known stimulating effect of low EF on BNP release [14, 15, 18, 19]. This mechanism outweighs the impact of asynchrony on the increase in BNP, which is already high in the presence of reduced EF.…”