The Relation Between Global Longitudinal Strain and Serum Natriuretic Peptide Is More Strict Than That Found Between the Latter and Left Ventricular Ejection Fraction: A Retrospective Study in Chronic Heart Failure

BACKGROUND: In chronic heart failure (CHF), the finding of elevated levels of the N-terminal fragment of the pro B-type natriuretic peptide (NT-proBNP) is a marker of pathological increase in myocardial ventricular wall stress and detrimental rise in ventricular filling pressures. However, the ensemble of data concerning the relationship between longitudinal deformation indices and NT-proBNP is still rather vague and approximate. METHODS: We carried out a retrospective study that involved 118 patients with CHF admitted to our clinic for CHF outpatients. For inclusion in the study, the CHF patients were required to have undergone at least a determination of global longitudinal strain (GLS) by means of speckle tracking echocardiography and to have practiced at least a determination of NT-proBNP. As regards the two determinations, the one echocardiographic and the other laboratory-based, the former should have been done not more than 24 hours before or after the latter. RESULTS: Correlation between log (NT-proBNP) and GLS was highly significant (r = 0.8386; P < 0.0001). The observed correlation between log (NT-proBNP) and left ventricular ejection fraction (LVEF) was also significant, but explained a smaller magnitude of the variance (r = -0.5465; P < 0.0001). In multiple linear regression analysis, GLS was shown to be the strongest independent predictor of log (NT-proBNP), within a parsimonious model including age, body mass index, estimated glomerular filtration rate, left atrial volume index, and LVEF (β (regression coefficient) = 305, rpartial = 0.7076; P < 0.0001). By using the median value of NT-proBNP (299.5 pg/mL) as a discriminating value for identifying relatively low (i.e., below the median) and relatively high (i.e., above the median) levels of NT-proBNP, GLS was associated with the upper quartiles, whereas LVEF was associated with lower quartiles of NT-proBNP. However, the C statistics for GLS were significantly higher than for LVEF (area under the curve (AUC): 0.949 (GLS) vs. 0.730 (LVEF); P = 0.0030). CONCLUSIONS: In CHF patients, GLS shows a stronger association with NT-proBNP levels with respect to LVEF. Thus, in both CHF with preserved and reduced LVEF, GLS is more accurate compared with LVEF in predicting increased levels of NT-proBNP.