Cardiopulmonary exercise test link with analytical markers, right ventricular dysfunction and first year hospitalization in patients with dilated cardiomyopathy

Abstract

Purpose: To study in ambulatory pts with chronic heart failure (CHF) with left ventricular (LV) systolic dysfunction the association between parameters of cardiopul-monary exercise test (CPET) with analytical markers, right ventricular dysfunction and hospitalization in the first year. Methods: Prospective analysis of 53 pts followed in CHF outpatient clinic, 83% male, age 58.0±13.0 years, LV ejection fraction 27,7±10.6%, LV diastolic volume 202.3±75.2mL, hemoglobinemia (Hb) 14.4±1.5 g/dL, creatinine 1.2±0.4 mg/dL and Nt-ProBNP 2204±3823pg/mL (median 682pg/mL). A complete echocar-diographic study was performed including pulmonary artery systolic pressure (PASP), the tricuspid annulus plane systolic excursion (TAPSE), systolic tricuspid annulus DTI (STRIC). Pts were submitted to CPET aiming exercise duration of 8-12 minutes where maximal oxygen consumption (VO2max), ventilatory anaerobic threshold (VAT) were obtained. Clinical follow-up: overall hospitalization in 12 months. Relationship between parameters performed according to the Pearson correlation coefficient and linear regression model (backward method). Assessment of VO2max hospitalization prognostic potential by ROC curve, Kaplan Meier survival curve analysis and Cox regression. Results: The average VO2max was 22.8±6.3mL/kg/min. Hb correlated with VO2max (r=0.351, p=0.005), METS (r=0.376, p=0.003) and VAT (r=0.515, p=<0.001). RDW inversely correlated with METS (r=-0.324, p=0.011), and VO2max (r=-0.307, p=0.015). NT-proBNP correlated with METS (r=-0.296, p=0.027) and VO2max (r=-0.338, p=0.010). By linear regression model, Hb (p=0.025) and NT-proBNP (p=0.050) were independent predictors of VO2max. PSAP inversely correlated with VO2max (r=-0.507, p=0.004), percentage of the predicted VO2max (pVO2max) (r=- 0.534, p=0.003) and METS (r=-0.643, p=<0.001). The pVO2max also correlated with TAPSE (r=0.511, p=0.013) and STRIC (r=0.433, p=0.019). The hospitalization rate was 15.1%. The ROC curve for hospitalization was associated with VO2max (AUC 0.798, 95% CI: 0.622-0.974, p=0.030). Pts with VO2max <20 mL/kg/min had a higher risk of hospitalization (p=0.050, OR=8.80). Survival analysis with Kaplan Meier - rate of hospitalization was significantly lower in pts with VO2max <20mL/kg/min (Log rank p=0.036). By Cox regression, VO2max was associated with hospitalization at 365 days (p=0.038, HR=0.841, 95% CI 0,714-0, 991). Conclusions: The exercise functional capacity in systolic CHF pts was influenced by the severity of anemia and Nt-proBNP, is associated with the degree of pulmonary hypertension and provides information about first year hospitalization risk.