Clinical Utility of plasma NT-proBNP in diagnosing acute Dyspnea
Objectives: To evaluate the clinical utility of NT-ProBNP assay in patients, admitted in Intensive care unit, with acute dyspnea.
Material & Methods: This Observational cross-sectional study was conducted at Combined Military Hospital Malir Cantt Karachi From Jan 2019 to Dec 2019. In this study, total 632 patients were selected with purposive non-probability sampling who were admitted in the intensive care unit (ICU) with acute dyspnea. ECGs, CXRs, Echos and plasma NT-ProBNP levels were analyzed along with other lab tests. Using the discharge diagnosis as the gold standard, clinical findings, provisional diagnoses and NT-ProBNP levels were cross tabulated with the final diagnosis. The Chi-square test for categorical data and student’s t test for numerical data were applied and p value < 0.05 for significance level was applied to compare cardiac vs non-cardiac dyspnea. Further comparative analysis between the age groups was done by one-way ANOVA test.
Results: Of the total 632 cases studied of acute dyspnea, NT-proBNP levels were acutely raised in 73% of cases to a mean level of 19760pg/ml which were alarming numbers. These patients were categorized and treated as ‘cardiac dyspnea with heart failure’, as compared to the remaining 27% cases in which the NT-proBNP levels were either normal or marginally elevated with a mean value of 119 pg/ml. They were diagnosed and treated as ‘non-cardiac dyspnea without heart failure’ (p=0.001). The diagnostic accuracy of NT-proBNP at a cutoff of 400 pg/ml for age <45 years was 100% sensitivity but 34% specificity. An optimal strategy to identify acute Heart Failure (HF) was to use age-related cut-points, 800 pg/ml for ages> 45 years having 98% sensitivity and 87% specificity.
Conclusions: NT-proBNP is a rapid and reliable cardiac biomarker which can revolutionize the clinician’s approach towards diagnosing and treating the underlying cause of acute dyspnea. In addition, its serial essays can predict the prognosis and outcome of admitted patients.
Key Words: Dyspnea, Heart failure, Plasma NT-ProBNP.