The impact of left venticular filling pressure indexed to cardiac output on exercise capacity in heart failure subjects

Abstract

Abstract Background/Introduction Exercise intolerance is the most common symptom of patients with heart failure (HF), regardless of the phenotypes. We aim to investigate the determinants of exercise capacity in chronic stable HF with reduced, mildly reduced, preserved, and recovered ejection fraction (EF). Methods Ambulatory HF subjects were recruited for a combined cardiopulmonary exercise test and exercise stress echocardiography. Peak oxygen consumption (peak VO2) and minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) were obtained. Impaired exercise capacity was referred to a peak VO2 of <14 ml/kg/min, and a VE/VCO2 slope of >34 was defined as ventilatory inefficiency. Results Among a total of 66 participants, there were 16 HF with reduced EF, 18 HF with mildly reduced EF, 12 HF preserved EF, and 20 HF recovered EF. While both LVEF, global longitudinal strain (GLS), E/e’ ratio and diastolic dysfunction indices were crudely associated with peak VO2 and VE/VCO2 slope, only diastolic dysfunction indices were independently predictive of impaired exercise capacity (odds ratio and 95% confidence intervals: 3.847, 1.369-10.810). GLS at rest was independently correlated with ventilatory inefficiency (1.404, 1.050-1.877). Among the exercise indices, the peak medial E/e' to cardiac output ratio was independently associated with impaired exercise capacity (3.478, 1.313-9.214) and peak GLS was best related to ventilatory inefficiency (1.403, 1.076-1.828). Conclusions Among resting and exertional echocardiographic variables, the peak medial E/e' to cardiac output ratio, a non-invasive assessment of exertional left ventricular filling pressure indexed to cardiac output, was the major determinant of exercise capacity in patients with different HF phenotypes.