Dose-response effect of physical prehabilitation on major cardiac and cerebrovascular events and disability levels after cardiac surgery in frail patients

Abstract

BACKGROUND: Prehabilitation enhances patients’ resilience to surgical stress and may improve postoperative outcomes. However, the dose-response of prehabilitation on outcomes remains unknown. RESEARCH QUESTION: Does a twice-weekly supervised outpatient exercise program before elective cardiac surgery in frail patients have dose-response effects on 90-day postoperative major cardiac and cerebrovascular events (MACCE) and disability levels? STUDY DESIGN AND METHODS: A post-hoc analysis of the PREhabilitation for improving QUality of recovery after ELective cardiac surgery trial that compared physical prehabilitation (up to 19 sessions over 10 weeks) with usual care in very mild to moderately frail participants. Primary outcomes included the 90-day risk of MACCE and changes in disability levels measured by the World Health Organization Disability Assessment Schedule 2.0 score. Secondary outcomes were preoperative changes in the 6-minute walk test (6MWT) distance, submaximal metabolic equivalents of tasks (METs), and frailty measures. We used a generalized estimating equation model to examine the association between the dose of prehabilitation and the risk of MACCE. Causal inference was assessed by dose-response function models while allowing non-linearity. RESULTS: Of the 143 participants, 135 underwent cardiac surgery. No exercise-induced adverse events occurred in 64 participants during 551 sessions. The dose of prehabilitation was not associated with the risk of MACCE (16 participants with 24 episodes; adjusted odds ratio/session: 0.98, 95% CI, 0.88–1.09). However, improvements in disability levels, 6MWT distance, and METs were directly related to the number of consecutive doses of prehabilitation before surgery. Improvements in clinical frailty after exercise training were observed in a few patients after seven weeks of training. INTERPRETATION: In frail cardiac patients, a greater number of consecutive doses of physical prehabilitation had favorable effects on improving preoperative exercise capacity and lowering disability levels at 90 days after surgery.