NT-ProBNP and hsTnI: A Multistate Survival Analysis in Outpatients with Reduced Left-Ventricular Ejection Fraction

Heart failure (HF) with reduced ejection fraction (HFrEF) has a well-known epidemic relevance in western countries. It affects up to 1-2% of patients > 60 years and reaches a prevalence of 12% in octogenarian patients. The role of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitive troponin I (hsTnI) in risk stratifying HFrEF patients has been established; at present, evidence is exclusively based on one-time assessments, and the prognostic usefulness of serial biochemical assessments in this population still remains to be determined. We prospectively recruited 226 patients with chronic HFrEF, who were all referred to the Outpatient Clinic of our institution from November 2011 through September 2014. Recruited patients underwent full clinical evaluation with complete history taking and physical examination as well as ECG, biochemical assessment, and standard 2D and Doppler flow echocardiography at the first visit, and then again at each visit during the follow-up, repeated every 6 months. During the follow-up period, cardiovascular (CV) death, which occurred in 16 patients, was not statistically correlated with gender (p = 0.088) or age (p = 0.1636); however, baseline serum levels of NT-proBNP, which were 3 times higher in deceased patients, were significantly related to this clinical event (p = 0.001). We found that NT-proBNP represents a strong and independent predictor of CV outcome; serum levels of hsTnI, which are significantly related to an increased risk of hospitalization, cannot properly predict the relative risk of CV mortality. Our study validates, eventually, the multimarker strategy, which reflects the complexity of the HF pathophysiology.