Cardiac prehabilitation: progress toward the who, what, when, where, and how

Every year, over one million cardiac operations are performed worldwide (1). Preoperative frailty, observed in 20–50% of cardiac surgery patients, is a risk factor for worse outcomes (2). A recent retrospective cohort study of 46,928 cardiac surgery patients from New Zealand and Australia showed that patients with a Clinical Frailty Score (CFS) of 5 to 8 had nearly three times the rate of in-hospital mortality (P<0.001), longer mechanical ventilation times, greater incidence of tracheostomy, greater need for renal replacement therapy, and longer intensive care and hospital length of stay (3). Another single-center prospective study from Japan showed lower survival rates, increased mortality, and rehospitalization from major adverse cardiovascular and cerebrovascular events (MACCE) as groups increased in frailty (from robust, to prefrail, to frail) (4). Cardiac prehabilitation has been shown to reduce postoperative complications (5-9). However, the efficacy of cardiac prehabilitation in the prefrail or frail populations remains understudied (Table 1).

Table 1. Recent studies of exercise-based cardiac prehabilitation.

Author [year]	Country	Study type	Number	Age (years)	Surgery type	Frailty?	Time before surgery (weeks)	Intervention duration (weeks)	Exercise intervention	Outcomes	Exercise-related adverse events	Feasibility
Yau [2025] (10)	China	RCT	164	≥18	CABG, valve	Frailty required	>5	5	Supervised exercise (aerobic) 2×/week	6MWD-improved, QoR15-ns, DAH30-ns, WHODAS-ns, MACCE-ns	None	Enrolled: 26.5%
												Completed: 82%
												Withdrew: 0%
Akowuah [2023] (9)	United States	RCT	180	≥18	Elective cardiac surgery	Frailty assessed	>2	2+	Supervised and home exercise (aerobic, respiratory) 2×/week	6MWD-ns, inspiratory pressure-improved, handgrip-ns, QOL-ns	6 minor (3 angina, 1 dyspnea, 2 muscle aches)	Enrolled: 23%
												Completed: 71%
												Withdrew: 16%
Steinmetz [2020] (11)	Germany	RCT	171	≥18	CABG	Frailty not specified	2.5–3	2	Supervised exercise (aerobic, respiratory) 3×/week	6MWD-improved, TUG-improved, QOL-ns	None	Enrolled: 28%
												Completed: 74%
												Withdrew: 26%
Waite [2017] (12)	United Kingdom	Cohort	22	≥65	CABG, valve, TAVR	Frailty assessed	6	6	Individualized home exercises (aerobic, strength) 3×/week, with weekly telephone calls	CFS-improved, 6MWD-improved, SPPB-improved, LOS-improved	None	Enrolled: 61%
												Completed: 91%
												Withdrew: 32%
Sawatzky [2014] (13)	Canada	RCT	17	≥18	CABG	Frailty not specified	4	4+ (max 26)	Supervised exercises (aerobic, strength) 2×/week	6MWD-improved, Gait-improved, QOL-improved, CR-improved	None	Enrolled: 29%
												Completed: 88%
												Withdrew: 12%

6MWD, 6-minute walk distance; CABG, coronary artery bypass grafting; CFS, Clinical Frailty Scale; CR, cardiac rehab enrollment; DAH30, days alive and at home at 30 days; Gait, 5 m gait speed; LOS, length of stay; MACCE, major adverse cardiac and cerebrovascular events; ns, no significant difference; QOL, quality of life; QoR15, Quality of Recovery-15; RCT, randomized controlled trial; SPPB, short physical performance battery protocol; TAVR, transcatheter aortic valve replacement; TUG, timed up and go; WHODAS, World Health Organization Disability Assessment Schedule.

To elucidate the effects of prehabilitation on the frail and vulnerable, Yau and colleagues performed a single-center, single-blinded, randomized controlled trial involving cardiac surgery patients with a CFS of 4–6 using a modified intention-to-treat analysis (10). Of the 164 randomized patients, 82 received standard of care, and 82 were enrolled in a 5-week prehabilitation intervention. The prehabilitation intervention consisted of a twice-weekly in-person exercise program as well as counseling for nutrition and smoking cessation, psychological support, and encouragement to participate in and document a home exercise program. The study’s primary outcome was the Quality of Recovery-15 (QoR-15) score on postoperative day 3. Secondary outcomes included days alive and at home at 30 days (DAH30), the World Health Organization Disability Assessment Schedule (WHODAS) 2.0, and MACCE.

Of the 620 patients screened, 164 (26.5%) met the inclusion criteria and agreed to participate. Though compliance with the in-person exercise program was 82%, only 25% of participants returned home exercise journals. Additional challenges for this study included a higher-than-expected dropout rate due to surgery cancellations (16% in prehabilitation vs. 10% accounted for in the study design). Median prehabilitation time was 5 weeks (interquartile range, 3 to 7 weeks). No difference was found between the standard care and prehabilitation groups for the primary outcome, DAH30, or MACCE. However, prehabilitation participants were able to increase their functional capacity before surgery and had less disability by postoperative day 90 (P=0.022) compared with controls.

Importantly, Yau et al. demonstrated that their individualized exercise-based prehabilitation intervention was safe in prefrail and frail patients awaiting cardiac surgery. Multiple trials have demonstrated at most minor adverse events (self-limited angina, dyspnea, muscle aches) during prehabilitation (Table 1). Safety has also been demonstrated with home-based exercise programs, as in Waite et al., who studied home exercise programs for frail patients initiated at least 6 weeks prior to cardiac surgery. In this study of 22 frail patients, a 6-week home prehabilitation program was safe, decreased the preoperative frailty score, improved distance and speed during the 6-minute walk test (6MWT), and short physical performance battery (12). The improvement in 6MWT distance was associated with a shorter hospital stay (P=0.03).

The focus on multiple patient-centered recovery outcomes in the frail population distinguishes Yau et al.’s trial from prior studies. Evaluating QoR-15 on postoperative day three may have been too early to see a difference, given a median postoperative length of stay in both arms of 8 days. However, the authors emphasize that a clinically meaningful difference in disability levels at postoperative 90 suggests that cardiac prehabilitation may support better recovery even if no difference in postoperative complications was identified. As postoperative complications and mortality after cardiac surgery continue to improve, the goals of prehabilitation reach beyond survival to optimizing recovery (14). Studies have examined the impact of preoperative cognitive impairment on postoperative ambulatory recovery after cardiac surgery, suggesting the importance of considering the interplay of multiple geriatric syndromes and their impact on recovery outcomes (15,16). Better characterization of baseline physical, cognitive, and emotional function may elucidate not only potential targets for prehabilitation interventions but also biological mechanisms related to optimizing recovery (17,18).

Though prehabilitation has been shown to be safe and beneficial, significant barriers limit widespread adoption and dissemination (14). In Yau et al., 17% of patients screened were either unavailable for prehabilitation or declined to participate. Programs modeled after cardiac rehabilitation with supervised exercise and multiple appointments each week require resources and infrastructure to administer. Patient transportation is often a barrier to participation, particularly for longer distances or patients without social support. Even in controlled research settings, prehabilitation studies are plagued by low enrollment and high levels of non-adherence (Table 1). These same barriers continue in the postoperative period where fewer than 50% of cardiac surgery patients participate in cardiac rehabilitation. Future approaches to cardiac prehabilitation will need to adapt home-based strategies and leverage mobile-health technologies (12,14). It is our hope that the work of Yau’s group will inspire others to continue researching prehabilitation for patients needing cardiac surgery and better define the who, what, when, and how of cardiac rehabilitation to best reduce postoperative complications and optimize recovery.

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