NT-proBNP levels, echocardiographic findings, and outcomes in breathless patients: Results from the ProBNP Investigation of Dyspnoea in the Emergency Department (PRIDE) echocardiographic substudy

Aims: The objective of this study was to determine the integrative utility of measuring plasma NT-proBNP levels with echocardiography in the evaluation of dyspnoeic patients. Methods and results: Of 599 emergency department patients enrolled in a clinical study of NT-proBNP at a tertiary-care hospital, 134 (22%) had echocardiographic results available for analysis. Echocardiographic parameters correlating with NT-proBNP levels were determined using multivariable linear-regression analysis. Independent predictors of 1-year mortality were determined using Cox-proportional hazard analysis. Independent relationships were found between NT-proBNP levels and ejection fraction (P = 0.012), tissue Doppler early and late mitral annular diastolic velocities (P = 0.007 and 0.018), right ventricular (RV) hypokinesis (P = 0.006), and tricuspid regurgitation severity (P < 0.001) and velocity (P = 0.007). An NT-proBNP level <300 pg/mL had a negative predictive value of 91% for significant left ventricular systolic and diastolic dysfunction. Overall 1-year mortality was 20.1% and was independently predicted by NT-proBNP level [HR 8.65, 95% confidence interval (CI) 2.7-27.8, P = 0.0003], ejection fraction (HR 0.95, 95% CI 0.91-0.99, P = 0.009), RV dilation (HR 2.98, 95% CI 1.05-12.8, P = 0.04), and systolic blood pressure (HR 0.97, 95% CI 0.96-0.99, P = 0.01). Conclusion: NT-proBNP levels correlate with, and provide important prognostic information beyond, echocardiographic parameters of cardiac structure and function. Routine NT-proBNP testing may thus be useful to triage patients to more timely or deferred echocardiographic evaluation.