Abstract 14453: Ventilatory Inefficiency Associated With Stage a Heart Failure

Abstract

Introduction: Peak oxygen utilisation (VO 2 ) and ventilatory efficiency (VE/VCO 2 slope) provide strong prognostic information in symptomatic heart failure (HF). Transition from subclinical to symptomatic HF is poorly understood. Cardiopulmonary exercise testing (CPET) in subclinical HF may advance risk profiling. Hypothesis: HF risk factors are associated with metabolic and ventilatory abnormalities that may serve as risk markers. Methods: Sedentary subjects (n=81; 67 (66-72) years; 65% female; BMI 29.9[26.6-33.9] kg/m 2 ) with ≥1 HF risk factors (Stage A HF, SAHF) without pulmonary disease and healthy sedentary subjects (controls, n=21; 70 (67-73) years; 52% female; BMI 25.1 [24-25.9] kg/m 2 ) underwent treadmill CPET to determine peak VO 2 , ventilatory threshold (VT, V-slope method) and VE/VCO 2 slope (linear regression). Global longitudinal strain≤16%, diastolic dysfunction or left ventricular hypertrophy defined subclinical left ventricular dysfunction (LVD). Results: LVD was present in 41 (51%) with SAHF. CPET parameters did not differ by presence of LVD. There were no differences in peak RER or VT (% peak VO2) between controls and SAHF. VO 2 peak was higher in controls vs. SAHF (22.1±4.6 vs. 19.9±4.6ml/kg/min, p=0.047). VE/VCO 2 slope was markedly steeper in SAHF vs. controls (40.2±6.2 vs. 29.3±6.1, p<0.001) (Figure). VE/VCO 2 slope was >34 (prognostic in symptomatic HF) in 83% vs. 19% for SAHF vs. controls (p<0.001). BMI was the only independent predictor (β 0.45 (0.19-0.72, p=0.001) (r 2 0.16) of VE/VCO 2 slope (SBP and heart rate reserve were not). BMI was not associated with increment in respiratory rate or tidal volume (β0.18(-0.07-0.42) and β3.9 (-10.8-18.7)). Conclusions: Cardiorespiratory exercise parameters do not differ in SAHF by presence of LVD. Ventilatory inefficiency is pronounced in SAHF compared with healthy controls suggesting it may be a risk marker, but prognostic significance is unknown.