Feasibility of early interval training in patients recovering from heart valve surgery due to infective endocarditis

BACKGROUND: Infective endocarditis is an infectious heart disease strongly associated with morbidity and mortality. Up to half of the patients with infective endocarditis require heart valve surgery. While early exercise-based rehabilitation is well documented for patients recovering from heart surgery for non-infective endocarditis, there is limited research on those who have undergone valve surgery due to this infection. This study aimed to explore the early aerobic training in this patient population. METHODS: A single-centre prospective feasibility study was conducted using the UK Medical Research Council's framework for complex interventions. The study investigated the feasibility (recruitment, retention, adherence), safety, acceptability, and preliminary functional outcomes of 4 × 4 interval training in this patient population. Training session data included the number, duration, and intensity, which were monitored via the Apple Watch S5 (Present Age-Predicted Maximum Heart Rate) and the Borg RPE scale. Functional outcomes were evaluated at baseline and 3 months post-surgery, including sub-maximal oxygen uptake (treadmill protocol), 6-min walk test, and quality of life (HeartQoL, EQ-5D-5L). RESULTS: Sixteen patients consented to participate, with 12 initiating the intervention and 11 completing it, yielding a retention rate of 91.7%. Training adherence averaged 73.1% of the minimum expected sessions, with high participant satisfaction and no serious adverse events reported. At the 12-week follow-up, participants demonstrated measurable change in functional capacity, including an increase in workload capacity (+ 95 W), METs (+ 3.4), and 6-min walk test distance (+ 219 m). Health-related quality of life also showed a noticeable increase, with HeartQoL physical and emotional scores increasing by 1.0 and 1.3, respectively, and EQ-5D-5L VAS scores rising by 17.2. The EQ-5D-5L index increased from 0.61 at baseline to 0.87 after 12 weeks. CONCLUSION: Interval training, when conducted with appropriate safeguards and tailored to individual needs, is a feasible and safe intervention for patients recovering from endocarditis and cardiac surgery. The observed improvements in functional capacity, quality of life, and patient satisfaction support the need for larger controlled studies. TRIAL REGISTRATION: Clinical Trials, ID NCT05703022. Registered on 25 November 2021, http://www. CLINICALTRIALS: gov.