Left ventricular ejection fraction and functional capacity: insights from cardiopulmonary exercise testing

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiac rehabilitation program (CRP) is a multidisciplinary intervention tailored to improve functional fitness in different cardiovascular conditions. Patients with reduced left ventricular ejection fraction (LVEF) are commonly unrepresented hence the impact of LVEF on functional fitness is uncertain. Purpose To evaluate changes on functional capacity in a cohort of patients referred to a CRP, according to baseline LVEF. Methods Tertiary-center retrospective analysis of patients referred to an exercise-based phase II CRP. To be enrolled patients had to complete a 12-weeks CRP and to perform a symptom-limiting cardiopulmonary exercise test (CPET), at the beginning and at the end of the program. Patients were stratified into a reduced (LVEF < 45%) or preserved (LVEF ≥ 45%) group. Four CPET parameters were evaluate: peak oxygen uptake (pVO2), predicted-pVO2 (ppVO2), O2 pulse and VE/VCO2 slope. Results 127 patients (mean age 57.8 ± 11.2 years; males 79.5%) were eligible for CRP, of which 86.6% were referred following an acute coronary event. Patients included in the reduced LVEF group (38.6%; mean LVEF 31% ± 8.1) had more dyslipidemia (48.8% vs 22.8%, p = 0.013), atrial fibrillation (24.5% vs 7.7%, p = 0.008) and implanted electronic devices with defibrillator (30.6% vs 2.6%, p<0.001). Regarding CPET parameters, reduced LVEF patients had a lower pVO2 (mean dif 2, p = 0.048), ppVO2 (mean dif 12.1%, p<0.001) and O2 pulse value (mean dif 2, p = 0.049) vs higher values of VE/VCO2 slope (mean dif 2.9, p = 0.036). The Weber and ARENA classifications analysis revealed similar distribution between groups: 24.4% of reduced vs 27.5% of preserved patients entering CRP had a low Weber class (C or D). Higher ARENA class (III-IV) included 28.5% of patients with reduced and 14.1% with preserved LVEF. At the end of the rehabilitation program, changes on CPET parameters were similar between reduced and preserved groups: ppVO2 increased by 4% vs 3.2% (p = 0.808), O2 pulse increased about 0.7 vs 0.5 mL/beat (p = 0.509) and VE/VCO2 slope reduces 1.7 vs 0.3 (p = 0.232). As a continuous variable, LVEF did not predict Weber´s (p = 0.546) or ARENA (p = 0.393) class changes. Yet, those with a reduced baseline LVEF derived a greater LVEF improvement after CRP (Δ 10.2 ± 9.8 vs Δ 2.2 ± 7.9; p<0.001) Conclusions All patients enrolled in CRP show improvement of exercise capacity irrespective of baseline LVEF. Thus, patients with reduced LVEF should not be denied for cardiac rehabilitation and a significant LVEF improvement is expected.