Underutilization of Exercise-Based Cardiac Rehabilitation

Disclosure: Drs. Franklin and Goel have no disclosures relative to this commentary.
Pub Date: Dec. 16, 2011
Author: Barry A. Franklin, Ph.D.
Affiliation: William Beaumont Hospital

Balady GJ, Ades PA, Bittner VA, Franklin BA, Gordon NF, Thomas RJ, Tomaselli GF, Yancy CW. Referral, enrollment, and delivery of cardiac rehabilitation/secondary prevention programs at clinical centers and beyond: a presidential advisory from the American Heart Association. Circulation. 2011: published online before print November 14, 2011, 10.1161/CIR.0b013e31823b21e2.

An estimated 80 million Americans (nearly 1 in 3) have cardiovascular disease (CVD); in fact, coronary heart disease (CHD) and stroke are currently the #1 and #4 causes of mortality, respectively.  In 2010, an estimated 785,000 Americans experienced a new cardiac event, and approximately 470,000 had a repeat acute myocardial infarction (AMI).  For literally millions of previously affected adults in the United States, interventions that have been shown to reduce the risk of recurrent cardiovascular events, collectively referred to as secondary prevention, may include exercise-based cardiac rehabilitation (CR) programs.

The objectives of contemporary CR are to increase functional capacity, decrease anginal symptoms, facilitate cardiovascular risk reduction, and improve psychosocial well-being.  Interventions designed to retard the progression, promote plaque stability, or induce regression of the underlying atherosclerotic process, and to restore and maintain optimal physical, psychological, emotional, social and vocational functioning, are paramount.  Accordingly, comprehensive or multidisciplinary CR programs should include 5 core components: baseline patient assessment; nutritional counseling; risk factor management (lipids, blood pressure, weight, diabetes mellitus, and smoking); psychosocial interventions; and, physical activity counseling/exercise training.¹

The just-published presidential advisory from American Heart Association (AHA) highlights the importance of outpatient CR in patients with CVD,² with specific reference to referral patterns, participation gap, models of delivery and recommendations to improve utilization at the patient, medical community, public policy, and third-party payer level.

Table 1 - Benefits of Exercise-Based Cardiac Rehabilitation

Patient category	Participation Rate	% Change in Outcomes
Myocardial Infarction	13.9% (overall); up to 55%	12% ARR in all-cause mortality in elderly3; 56% RRR in all-cause mortality and 28% RRR in recurrent MI
Coronary Artery Bypass Graft Surgery	31%	5.3% ARR in all-cause mortality in elderly3; 39% RRR in all-cause mortality and 26% RRR in recurrent MI (36 sessions vs. 1 session)
Percutaneous Coronary Intervention	20.9% (overall); 40%	6.3% absolute risk reduction in elderly3; 45-47% RRR in all-cause mortality, trend towards reduced cardiac mortality (HR, 0.69; 95 % CI, 0.44–1.07), no reduction in recurrent MI, PCI or CABG
Coronary Heart Disease	18.7%	8.3% ARR in all-cause mortality3; 13% RRR in all-cause mortality, 26% RRR in cardiovascular mortality and no reduction in recurrent MI, PCI or CABG
ARR= Absolute risk reduction; RRR= Relative risk reduction; HR = Hazard ratio; CI = Confidence intervals

Table 1 outlines the participation rates and/or impact of CR on long-term outcomes in patients with CHD.^3-8 CR participation is associated with reduced all-cause and cardiovascular mortality in patients who have experienced myocardial infarction (MI), percutaneous coronary intervention (PCI), or coronary artery bypass graft surgery (CABG).^3,4,7,8 However, inconsistent effects have been reported on the incidence of recurrent MI and the need for subsequent coronary revascularization. In the most recent meta-analysis and systematic review of 47 studies that randomized 10,794 patients (who had MI, PCI, CABG, angina pectoris or angiographically documented coronary disease) to exercise-based CR or usual care, a 13% reduction in all-cause mortality, 26% reduction in cardiovascular mortality and 31% reduction in hospital admissions was reported in the treatment cohort, with no difference between groups in the risk of recurrent MI, CABG or PCI.

Hammill et al.⁸ examined the relationship between the number of electrocardiographically (ECG)-monitored outpatient rehabilitation sessions attended and subsequent cardiovascular events in 30,161 Medicare beneficiaries who had MI, CABG, stable angina pectoris, heart failure, or combinations thereof.  After correcting for baseline differences, patients who attended more exercise sessions, up to a total of 36, demonstrated a dose-dependent reduction in mortality and recurrent myocardial infarction.  Following the early ECG-monitored phase of CR, commonly referred to as phase II, patients may continue in a home-based or medically-supervised group maintenance program (phase III) which involves long-term exercise and lifestyle intervention. Recently, a significant reduction in the incidence of major adverse cardiovascular events was reported in a small case-control study of 111 male patients with stable coronary disease (74 controls) attending phase III CR for 6 months.⁹

Numerous factors may be responsible for the improved outcomes associated with CR, as summarized in Table 2.  Recent studies in persons with and without CHD have expressed exercise capacity in the context of survival benefit per metabolic equivalent (MET; 1 MET = 3.5 mL O2/kg/min) achieved during peak or symptom-limited exercise testing.  Each 1-MET increase in exercise capacity was associated with large (8% to 35%) improvements in survival,¹⁰ presumably from multiple mechanisms, including antiatherosclerotic,¹¹ anti-ischemic, antiarrhythmic, antithrombotic, and psychologic effects (Figure 1).  Because > 40% of the risk reduction associated with exercise cannot be explained by changes in traditional risk factors, Green et al.¹² proposed a cardioprotective “vascular conditioning” effect, including enhanced nitric oxide vasodilator function, improved vascular reactivity, and altered vascular structure.  Decreased vulnerability to arrhythmias and increased resistance to ventricular fibrillation have also been postulated to reflect exercise-related adaptation in autonomic control (e.g., increased vagal tone, decreased adrenergic activity).  Thus, contemporary secondary prevention guidelines now list exercise-based CR as a class I indication for clinically stable angina or post-MI patients or those who have undergone coronary revascularization (post-CABGS or post-PCI), and a class IIa indication for outpatients with a history of congestive heart failure.^13-15

Benefits of Exercise-Based Cardiac Rehabilitation: Potential Mechanisms

• Improved coronary risk factor profile
• Increased cardiorespiratory fitness (peak METs)
• Vascular conditioning effect
• Enhanced psychosocial well-being - Combats depression, stress, social isolation
• Provides ongoing medical surveillance
• Healthy adherer effect (?)*

*The Coronary Drug Project showed that individuals who adhere to placebo therapy generally have better health outcomes. Accordingly, patients who adhere to exercise-based cardiac rehabilitation programs often demonstrate better health outcomes, but it remains unclear whether this is due solely to the intervention per se, or whether these individuals are more likely to adhere to healthy lifestyle practices, prescribed cardioprotective medications, regular follow-up with their physician, or combinations thereof.

Figure 1

Suboptimal Referral Rate

Despite the apparent survival advantage and related beneficial outcomes associated with CR, during the past decade, the patient-based characteristics of referral to CR have remained largely unchanged.¹⁶  Most contemporary reports indicate referral rates of approximately 20%,¹⁷ highlighting the vast underutilization of these services, especially in women ¹⁸ and older adults.^19-21  Other groups who are underserved include those who have lower levels of education and/or socioeconomic status, those who do not have English as their primary language, members of minority populations, and African Americans.² These data are especially troubling, since the latter cohort are more likely to die of an AMI than any other racial group.²²  African Americans also have higher rates of sudden cardiac death, depression symptoms, more stress and fewer stress resilience factors;²³ moreover, as compared with whites, the deaths are likely to occur at a younger age.²²

In addition to traditional patient subsets (e.g., post-MI, CABG, PCI), other patient cohorts who may benefit from CR include individuals with symptomatic or asymptomatic myocardial ischemia, compensated heart failure, cardiomyopathies, threatening ventricular arrhythmias, nonischemic heart disease, concomitant pulmonary disease, pacemaker or cardioverter-defibrillator implantation, heart valve repair or replacement, and cardiac transplantation.²⁴

Perhaps the most critical factor in patient participation and adherence to CR is the primary care physicians’ or cardiologists’ strong recommendation on the value of this treatment option.^21,24   Limited access to a medically-supervised CR program has been associated with a decreased likelihood of referral and attendance, particularly among women, who may be faced with several unique barriers to program participation (e.g., role of caregiver, transportation problems, concomitant family demands).¹⁸  Another survey also emphasized geographic accessibility as the primary physician barrier to CR referral; 30.4% of the physicians surveyed (60% of responding physicians were family practitioners) identified access to a program as an important consideration.²⁵  Equally concerning are the suboptimal participation rates of referred coronary patients; some studies report a drop-off from referral to enrollment of > 50%.^26-28

Participation Rates

Despite the known benefits of CR, participation rates remain low nationally, averaging between 10% and 30%.⁶  In an analysis of more than 250,000 fee-for-service Medicare beneficiaries, wide fluctuations in the use of exercise-based CR was noted across different states, averaging 6.6%, 7.4% and 53% in Idaho, Maryland and Nebraska, respectively.⁶  Several variables are negatively associated with these utilization patterns,² including older age, female gender, non-white race and distance from a CR program.⁶  In PCI patients, co-morbid conditions like diabetes, chronic obstructive pulmonary disease, current smoker, and history of previous PCI were associated with reduced CR participation.⁵  Similar associations were also reported for the cumulative number of sessions attended in CR participants.⁸  Because a high prevalence of musculoskeletal and neurological problems has been reported in CR participants,²⁹ addressing these issues during the exercise intervention may be helpful in maximizing adherence and reducing the drop out rate.

Insurance coverage and excessive co-pays are also important determinants of CR utilization. In 2006, the Center for Medicare and Medicaid services (CMS) included PCI, heart valve repair/replacement, and heart or heart-lung transplants as covered indications for reimbursement.³⁰ Although no direct evidence is available regarding the impact of insurance coverage on CR participation, the study in Olmsted County patients undergoing elective PCI’s revealed a significant increase in CR participation after 2006.⁵ The AHA advisory lists varied opportunities at the national level involving CMS and the Department of Health and Human Services which may be helpful in reducing access disparities to increase the referral and participation rates in CR.²

Delivery Models: Site-Supervised Versus Home-Based Exercise Rehabilitation Programs

Although traditional supervised group CR programs are associated with increased cost, extended travel time,³¹ and accessibility challenges, considerable data are available regarding the safety, efficacy, and cost-effectiveness of this model.¹⁹  Site-supervised programs are also more appropriate for the growing medical complexity of patients who may be at high risk for future cardiac events.  Moreover, such programs facilitate patient education and counseling in regard to exercise and lifestyle modification for coronary risk reduction, provide equipment variety and recreational opportunities, and offer staff assistance and the potential for enhanced adherence, safety, and serial surveillance.²⁴

The advantages of a home-based exercise training program as part of comprehensive CR include its lesser cost, increased practicability, convenience, and potential to promote independence and self-responsibility.²⁴  For low-to-moderate risk patients, medically directed, home-based exercise rehabilitation and supervised group programs have shown comparable safety and efficacy.  Cardiovascular risk reduction can also be successfully achieved in a home-based rehabilitation setting.^32,33  A variety of newer methods of monitoring and surveillance may be used between patients managed at home and CR staff, including regular telephone contact, e-mail, completion of activity logs, use of pedometers and/or ambulatory tracking devices, video recording, Internet, and transtelephonic ECG monitoring.^31,33

The growing consensus that moderate-to-vigorous exercise training following a cardiac event or revascularization procedure is safe, provided there has been appropriate medical evaluation and an individualized exercise prescription, lends support to a role for home-based CR programs.  One controlled trial compared functional capacity and quality-of-life (QOL) rehabilitation outcomes in the home setting using ECG and voice transtelephonic monitoring versus site-supervised exercise training.³⁴  At baseline, the two groups were comparable in terms of age, gender, cardiorespiratory fitness, and QOL measures.  Rehabilitation resulted in improved cardiac efficiency and QOL indices in both study groups; no cardiac events occurred in either group.  The investigators concluded that home-based rehabilitation, using novel technologies to provide simultaneous communication to rehab staff, can serve as a model in extending secondary prevention services to other settings.

The Internet has the potential to mitigate common barriers to CR/secondary prevention program participation, that is, cost and accessibility, while simultaneously delivering cardiovascular risk reduction interventions.²  Others have demonstrated that more convenient, lower cost, modified³⁵ or hybrid³⁶ programs that emphasize self-responsibility and independent exercise offer comparable outcomes to traditional site-supervised interventions.  Regardless of the model employed, strategies to motivate patients to participate and improve adherence may include ‘readiness to change’ assessments³⁷ and motivational interviewing,³⁸ providing services that minimize barriers to participation, setting short-term, attainable goals, designing an exercise program that minimizes the likelihood of musculoskeletal injury, providing positive reinforcement through periodic fitness and risk-factor assessments, recruiting spouse participation and support, and monitoring participation and goals achieved.

Conclusions

Perhaps Thomas16 summed it up best in his editorial accompanying a sobering report6 highlighting the continuing deficiencies in providing CR/secondary prevention programs.  “Their study (Suaya et al.6) is a wake up call to all providers of cardiovascular health care to find solutions to this problem to help our patients maneuver more safely through the whitewater rapids of the rehabilitative and preventive stages of post-CHD event care.  We have been missing this boat for too long.  It is time for all of us to find better ways to help our patients climb aboard.”  The challenge for physicians is to enroll increasing numbers of cardiac patients, especially those subsets that are currently underserved, in home-based or group CR programs that are designed to circumvent or attenuate barriers to participation and adherence, so that many more individuals may realize the benefits that secondary prevention can provide.

As the late Herman K. Hellerstein, MD, summarized it in 197239, “…a planned program featuring exercise training among other measures (i.e., aggressive modification of coronary risk factors) may tangibly reduce the risk of reinfarction and greater myocardial damage.”  Like all statements of wisdom, this hypothesis is both justifiable and unadorned, so clearly evident and acceptable today that we feel we should have known it all along.

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-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association