Table 3: Characteristics of Exercise Trials (Functional Electrical Stimulation) in HFpEF Patients.

Study	Intervention/Control (n)	EF/NYHA Class	Major Exclusion Criteria	Session Time/Frequency/Duration	Control	Outcomes (Cardiac Structure/Function)	Outcomes (Exercise Capacity)
Karavidas et al. 2013[39]	15/15	>50% II or III	Recent (≤4 weeks) HF decompensation, ACS	30 min/ 5 days a week/ 6 weeks	Sham stimulation	E/A, E/e’, LA volume	Peak VO2, 6MWD
TRAINING-HF 2019[36]	15/13	>50% ≥ II	Recent (<3 months) ACS or cardiac surgery, COPD	45 min/ 2 days a week/ 12 weeks	Usual care	E/e’, LA volume	Peak VO2

6MWD = 6-minute walk distance; ACS = acute coronary syndrome; COPD = chronic obstructive pulmonary disease; E/A; the ratio of peak early to late diastolic mitral inflow velocities; E/e’ = the ratio of early diastolic mitral inflow to annular velocities; e’ = early diastolic mitral annular velocity; EDV = end-diastolic volume; EF = ejection fraction; HFpEF = heart failure with preserved EF; LA = left atrial; LV = left ventricular; NYHA = New York Heart Association; peak VO₂ = peak exercise oxygen uptake.