Prognostic value of NT-proBNP and cardiac troponin levels in ambulatory patients with congestive heart failure - Insight from NHANES

Background Recently there has been increased interest in the utility of cardiac troponin and NT-proBNP to predict the prognosis in patients with CHF. The aim of this study was to investigate the prognostic significance of NT-proBNP and cardiac troponin in CHF patients in ambulatory settings. Methods The NHANES, conducted by the National Center for Health Statistics, collects nationally representative data on the health and nutritional status of the non-institutionalized US population. We included heart failure patients aged ≥ 40 years with valid entries for NT-proBNP and cardiac troponin. We used data collected during the period 1999 -2004. The primary endpoint was all-cause mortality. Vital status (dead or alive) was determined by linkage to a record match of the National Death Index, conducted by the National Center for Health Statistics through December 31, 2020. Follow up period was from the examination date to either the date of death or December 31, 2020, whichever came first. NT-proBNP and cardiac troponin levels were stratified into tertiles, and mortality was assessed using cox proportional hazard mortality multivariate logistic regression models. K-M survival curves were used to display mortality over time. All analyses were done using STATA version 17, with p-values less than 0.05 considered statistically significant. Results In all, there were 551 persons, corresponding to 4.4 million, with a diagnosis of CHF. Of this, 379, corresponding to 4.1 million persons, were retained for analyses. Hypertension (61.6%), diabetes (34.26%), CKD (32.7%), nicotine use (65.45%), and cardiovascular diseases (CVD) were the most prevalent comorbidities. On the multivariate analysis, compared to lower tertile for elevated NT-proBNP, being in the middle tertile increased the risk of all-cause mortality up to 54% (HR 1.54, CI 1.03 – 2.3, P = 0.035) and up to 2 fold for being in upper tertile (HR 1.95, CI 1.29 – 2.96, P = 0.002)(Figure 1). Similarly, compared to the lower tertile for elevated troponin, being in the upper tertile increased the risk of all-cause mortality up to threefold (HR 2.84, CI 1.82- 4.44, P = 0.000) while being in the middle tertile could not achieve statistical significance for predicting the outcome (HR 1.44, CI 0.95 - 2.17, P = 0.082)(Figure 2). Among other predictors included in the analysis, CKD and history of smoking were associated with overall worse survival (HR 1.68, CI 1.25- 2.23, P = 0.000) and (HR 1.5, CI 1.099-2.076, P = 0.011), respectively. Conclusion CHF patients in the middle and upper tertile for NT-proBNP and cardiac troponin compared to the lower tertile showed an overall poor prognosis on follow up in the ambulatory settings. Our findings suggest that monitoring NT-proBNP and cardiac troponin levels can be useful tools for predicting prognosis. Further studies are needed for the clinical implications of this strategy.