Abstract 1963: Influence of the Level of Right Ventricular Function on Functional Capacity: Comparison Between Patients with Dilated Cardiomyopathy and Normal (normally or highly trained) Subjects
Despite similar levels of LV function, functional capacity (FC) strongly differs among the population, lower in heart failure pts and higher in highly trained athletes.
Aim of the study: to evaluate the echocardiographic factors affecting cardiopulmonary exercise (CP Ex) parameters among pts with a wide range of LVEFand FC. We studied 84 pts (63M, 40±16 [17–75] yrs, LVEF 45±16 % [10–74], peak VO2 37±17 ml/kg/min [10 –76]), including 37 pts with idiopathic dilated cardiomyopathy (DCM) (gr1, 49±15 yrs, 24M), 22 normal pts (gr 2, 43±14 yrs, 16M) and 25 athletes (gr 3, 25±4 yrs, 23M). All pts had measurements of 1) LV and RV myocardial performance index (MPI), 2) tricuspid annular plane systolic excursion (TAPSE), 3) pulsed DTI recording of systolic longitudinal myocardial velocities (Sm) in the basal portion of the RV free wall (RV), the septum (sep) and the LV free wall (LV) from apical 4C view. Peak VO2 (ml/kg/min), anaerobic threshold (AT, ml/kg/min) and VE/VCO2 slope were calculated during CP ex. Coefficients of correlations between echo and functional parameters were calculated.
Results: Among the whole population, FC correlated significantly well with LV function (Simpson LVEF, LV MPI), RV function (RV MPI, TAPSE) and with Sm of RV, sep, and LV walls. Among subgroups, LVEF, LV MPI and TAPSE no longer correlated with FC. RV MPI still significantly correlated with VO2 (r=−0.36, p=0.03), AT (r=−0.32, p=0.05) and VE/VCO2 (r=0.35, p=0.03) in gr1, but did not show any significant correlation in other groups. In gr1, RV Sm also correlated with VE/VCO2 (r=0.37, p=0.02), and Sep Sm with VO2 (r= 0.43, p=0.008), but LV Sm did not show any significant correlation. Among gr1, RV MPI was higher than 0.36 (nl value + 2SD) in 18 pts. When comparing VO2, AT, and VE/VCO2 according to the level of RV MPI (< or > than 0.36), VO2 (23,1±6,0 vs 18,6±4,9, p=0.02), AT (16,9±5,2 vs 12,7±4,5, p=0.01) were significantly higher and VE/VCO2 (33,3±6,4 vs 37,9±4,3, p=0.01) significantly lower in the subgroups of pts with nl values of RV MPI. Thus, these findings confirm that both LV and RV function play a role in FC of pts with a wide range of LVEF. RV, but not LV function, is the most important factor in pts with DCM: at the same level of LV dysfunction, an additional RV dysfunction impairs functional capacity in DCM pts.