Benefits of Cardiac Rehabilitation (CR): Mechanisms to Restore Function and Clinical Impact: Circulation Research 🥸 Very proud of this work with my 2 mentors Daniel E. Forman, MD Dale Needham, MD, PhD published in Circulation Research & Parag Goyal MD MSc 😱Molecular to Clinical Mechanisms of CR 👇👇

🥸1️⃣ Cardiac rehabilitation (CR) reduces mortality, improves function, and enhances quality of life in cardiovascular disease. But <25% of eligible patients enroll, especially older adults, women, and those with frailty, disability, or limited access. 😱We need to do better.

🥸2️⃣ CR targets three core physiologic impairments that drive exercise intolerance in CVD: low cardiac output, impaired vascular function, and dysfunctional skeletal muscle metabolism. 😱These mechanisms are interrelated and highly prevalent in older adults. (See Figure 1)

🥸3️⃣ Stroke volume at peak exercise is often limited in CVD due to eccentric or concentric remodeling, ischemia, or impaired relaxation. All reduce cardiac reserve, impair contractility, and blunt VO₂ response; key contributors to frailty and poor outcomes. 😱(Look at Table)

🥸4️⃣ Chronotropic incompetence is common in older patients. Age-related β-receptor downregulation and altered autonomic reflexes prevent heart rate from rising adequately during exertion, severely limiting cardiac output and exercise capacity.

🥸5️⃣ In CVD, the peripheral oxygen extraction is reduced. Endothelial dysfunction, low capillary density, and anemia limit the widening of the arteriovenous O₂ gradient, another major factor in reduced VO₂ peak. CR directly improves these parameters.

🥸6️⃣ Skeletal muscle dysfunction, fewer oxidative fibers, lower mitochondrial density, and intermuscular fat, increases fatigue, reduces endurance, and worsens disability. These changes are reversible. 😱CR increases oxidative capacity and muscle quality.

🥸7️⃣ Chronic sympathetic activation in CVD causes vasoconstriction, impairs cardiac output, and raises vascular resistance. CR lowers sympathetic tone, improves baroreceptor sensitivity, and enhances autonomic regulation over time.

🥸8️⃣ VO₂ peak is a powerful prognostic marker. Lower values are associated with higher mortality in HF, ischemic heart disease, and older patients. CR improves VO₂ peak, which in turn improves survival, especially in those with low baseline fitness.

🥸9️⃣ Acute CVD events (MI, decompensated HF, arrhythmias) often occur on top of chronic multimorbidity. These events lead to deconditioning via reduced activity, poor sleep, malnutrition, and loss of reserve. CR breaks that cycle. 😱(See Figure 2)

🥸🔟 Every hospitalization carries risk. Functional decline accelerates with each event due to bedrest, polypharmacy, cognitive disruption, and sarcopenia. Without structured rehab, patients may never return to baseline function. 😱(Please see Figure 3)

🥸1️⃣1️⃣ In-hospital CR (Phase 1) is vastly underused. Studies show early mobilization improves strength, cognition, and reduces ICU stay, but fewer than 1 in 5 eligible patients receive it. This is a missed opportunity, especially for older adults.

🥸1️⃣2️⃣ ICU-based rehab using early mobilization, in-bed cycling, or neuromuscular electrical stimulation is safe and feasible, even in patients with temporary pacing, MCS, or post-CABG. Yet protocols remain under-implemented in cardiac units. 😱 Work led by Dale Needham, MD, PhD at JHU

🥸1️⃣3️⃣ Outpatient CR (Phase 2) includes supervised aerobic/resistance training, education, nutrition, medication review, and psychosocial support. It’s the critical for recovery and a Class I guideline recommendation, but access remains limited.

🥸1️⃣4️⃣ Home-based and hybrid CR models are expanding. A recent RCT showed home-hybrid CR matches site-based care in fitness gains, even in HF. Remote monitoring, wearables, and patient portals enhance adherence and safety, especially post-COVID.

🥸1️⃣5️⃣ Sarcopenia is a key barrier to recovery in older CR participants. Loss of muscle mass, strength, and function increases fall risk, impairs ADLs, and predicts hospitalization. CR helps reverse or slow down sarcopenia: Our work in Circulation 👇👇👇 ahajournals.org/doi/10.1161/CI…

🥸1️⃣6️⃣ Trials suggest exercise + protein supplementation improves muscle mass and function better than either alone. A pilot in HF showed gains in walk distance and leg strength. Larger studies in older, frail cardiac patients are underway. pubmed.ncbi.nlm.nih.gov/36600348/

🥸1️⃣7️⃣ Medications like ACE inhibitors and dietary nitrates may enhance muscle perfusion and metabolism in HF. Testosterone and selective androgen receptor modulators are under investigation for sarcopenia, but data are early and safety concerns remain.

Great summary as usual my friend Abdulla A. Damluji, MD, PhD . Agree with questions around not meeting PH assumptions. Would have been nice to see RMST analysis.

In collaboration with Dr. Michael Nanna Yale Cardiology, I am excited to launch the Cleveland Clinic Cardiovascular Center on Aging Grand Rounds & Distinguished Lecture Series Sept 25, 5–6 PM ET, for the inaugural lecture by Dr. Daniel E Forman on aging & CV care. Open to all.