High-Intensity Interval Versus Aerobic Training for Patient-Reported Outcomes in Women With Heart Failure. (HIIT-WHEF)

Patients assigned to HIIT

A 12-week supervised cardiac rehabilitation programme consisting of three individual sessions per week. Aerobic exercise will be performed on a treadmill or cycle ergometer, with intensity individually prescribed according to cardiopulmonary exercise testing and ventilatory thresholds. Sessions will include a 5-minute warm-up below the first ventilatory threshold, at least four high-intensity intervals above the second ventilatory threshold interspersed with active recovery intervals of equal duration below the first ventilatory threshold, and a 5-minute cool-down. Exercise duration and intensity will be progressed according to individual tolerance and clinical response. Both groups will also undertake individualised resistance training targeting the major muscle groups. Total session duration will be approximately 60 minutes. All sessions will be supervised by a physiotherapist, with clinical monitoring and exercise modification or interruption when indicated for safety.

Patients assigned to MICT

A 12-week supervised cardiac rehabilitation programme consisting of three individual sessions per week. Aerobic exercise will be performed on a treadmill or cycle ergometer at an individually prescribed moderate intensity between the first and second ventilatory thresholds, avoiding significant dyspnoea. Sessions will include a 5-minute warm-up below the first ventilatory threshold and a 5-minute cool-down. Exercise duration will progress according to individual tolerance and clinical response, towards approximately 30 minutes of continuous aerobic exercise. Both groups will also undertake individualised resistance training targeting the major muscle groups, progressing towards approximately 40-60% of one-repetition maximum, with 8-15 repetitions and at least two sets per muscle group when tolerated. Total session duration will be approximately 60 minutes. All sessions will be supervised by a physiotherapist, with clinical monitoring and exercise modification or interruption when indic

Number of participants randomised per month during the first nine months of recruitment. Feasibility will be classified as green if at least 2 participants per month are randomised, amber if 1 to less than 2 participants per month are randomised, and red if fewer than 1 participant per month is randomised.

Proportion of eligible women referred for cardiac rehabilitation who agree to randomisation. Green: at least 50%; amber: 30% to less than 50%; red: less than 30%.

Proportion of randomised participants with a post-intervention assessment. Green: at least 85%; amber: 70% to less than 85%; red: less than 70%.

Proportion of prescribed exercise sessions attended by participants who complete the programme. Green: at least 80%; amber: 65% to less than 80%; red: less than 65%.

Proportion of HIIT sessions in which at least four intervals are completed above the second ventilatory threshold. Green: at least 75%; amber: 60% to less than 75%; red: less than 60%.

Proportion of randomised participants with a completed Minnesota Living with Heart Failure Questionnaire (MLHFQ) at post-intervention assessment. Green: at least 90%; amber: 75% to less than 90%; red: less than 75%.

Frequency and nature of adverse events related to exercise, including serious adverse events and events requiring modification of exercise prescription. Feasibility criteria are green if no serious exercise-related adverse event occurs; amber if non-serious events require modification of the prescription in more than 20% of cases; and red if any serious adverse event attributable to exercise occurs.

Between-group difference in the post-intervention MLHFQ total score, adjusted for baseline score using analysis of covariance (ANCOVA). The MLHFQ ranges from 0 to 105, with higher scores indicating worse health-related quality of life. The baseline-to-post-intervention change will also be reported. This is an exploratory clinical outcome in the pilot trial and will not be used to establish confirmatory superiority.

Between-group difference in peak oxygen uptake measured during cardiopulmonary exercise testing, adjusted for baseline VO2peak. VO2peak will be expressed in mL/kg/min and defined as the highest oxygen uptake achieved during the final 30 seconds of exercise.

Between-group difference in left ventricular ejection fraction measured by echocardiography, adjusted for baseline LVEF. Results will be expressed as percentage points.

Changes in circulating NT-proBNP, high-sensitivity C-reactive protein (hs-CRP) and CA125 concentrations from baseline to post-intervention. Between-group comparisons will be exploratory and adjusted for baseline values where appropriate.