What Is it and Who Benefits?

Cardiovascular disease (CVD) leading to acute coronary syndrome (ACS) and sudden cardiac death is the leading cause of morbidity and mortality in the world, with an estimated cost of over $200 billion per year in the United States alone.^1,2 Recent estimates attribute over 1 in every 3 deaths to CVD and over 90% of CVD morbidity and mortality to preventable risk factors.³ Potential reversible factors such as poor diet leading to diabetes, smoking cigarettes, and lack of physical activity continue to account for an overwhelming majority of CVD and death.⁴ Moreover, previous experimental studies5 and an increasing body of evidence suggest an increase in incidence of recurrent ACS in the first year following the initial event, with nearly one million people in the United States suffering an ACS, and roughly half of these are a repeat event.⁵

Cardiac rehabilitation (CR) is typically an outpatient-based, supervised exercise training and lifestyle reformation for patients following myocardial infarction, coronary revascularization (percutaneously or surgically), valvular heart disease, cardiac transplantation, or heart failure with reduced systolic function. There are multiple components of post-acute care in CR delivered by a team of physicians, nurses, exercise scientists, nutritionist, and psychologists. This team engages the patients, usually 3 times weekly for a 3-month period but sometimes longer, and attempts to steer them toward healthier lifestyles focused on improved physical activity, exercise training, dietary counseling, weight loss, medication adherence, smoking cessation, diabetes management, and psychosocial support via behavior-change theories and methods. The overarching goal of CR is to empower patients to provide self-care to facilitate the management of chronic, stable coronary artery disease (CAD).

Extensive data have shown that CR improves outcomes; reduces the risk of CVD events over the ensuing year; improves exercise performance; enhances medication compliance; reduces symptoms such as angina, dyspnea, and fatigue; and reduces all-cause mortality by 25%.⁶ In fact, the number needed to treat for all-cause mortality in one sample of patients after coronary artery bypass graft surgery (CABG) was only eight.⁷ Large randomized trials have provided data that CR is superior to counseling alone in reducing cardiovascular risk profiles of patients at high risk for CVD,⁸ yet referral and utilization rates remain low. Studies show that automatic referral increases enrollment and adherence to CR programs.⁹ Despite the cost savings noted among those who use CR, particularly with higher frequency,¹⁰ there remains a significant increase in adherence to vital cardiovascular medications at 3 years in patients who attend CR.¹¹ Thus, the overwhelming benefits of CR are well-established, and efforts to continue conferring these benefits beyond the 3-month timeframe of usual CR should be sought to reduce the burden of repeat CVD. However, compliance within the programs is difficult due to logistical and monitoring capabilities such as age, gender, lower socioeconomic status, travel distance, and other comorbidities.¹²

Approaching Various Populations

The incidence of CVD increases with age, lower socioeconomic status, and various racial/ethnic backgrounds.¹ A study from Mayo Clinic found that CR after an ACS is underused, particularly in women,¹³ those of different racial minorities, and the elderly.¹⁴ Poor adherence to these programs typically leads to worse outcomes in these underrepresented groups.^15,16 A recent analysis of Medicare claims data revealed that only 13.9% of Medicare beneficiaries enroll in CR after ACS, and only 31% enroll after CABG. Older persons, women, nonwhites, and individuals with comorbidities were less likely to enroll in CR programs. But when these patients do attend even minimal CR, their outcomes are greatly improved.^15,16

Interestingly, when referral and adherence are monitored and reported, there is an increase in each of these metrics.¹⁷ Despite no specific trials focused on the elderly, large observational studies have continually shown improvements in outcomes and CVD intermediates in patients over the age of 65.^18,19 Data have also shown improved outcomes in those of different racial backgrounds if adherent to CR.^20,21 Efforts are ongoing to improve referral and adherence to CR in these populations; however, large gaps still exist in outcomes among various populations, and large-scale interventions aimed at creating a form of CR that is deliverable to these populations are desperately needed.

Indications and Outcomes

The most common indication for CR remains CAD, typically in a post-revascularization fashion either after percutaneous coronary intervention or CABG. Participation and referrals for CR have been largely stable over the past decade, with barriers including geography, age, physical limitations, and socioeconomic status playing a role. Typically, CABG patients are more compliant and derive more benefit; however, the mechanism of this is unclear and could be related to "complete revascularization," the hospital-based referrals, or the mentality of the patient after such a serious operation.

CR is also tested, approved, and recommended in patients with heart failure with reduced ejection fraction (HFrEF) based on the results of HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training).²² There remains, however, a gap in the CR referrals for patients with heart failure and preserved ejection fraction (HFpEF). Along these lines, there are data demonstrating improvements in symptoms in patients after receiving implantable cardiac defibrillators²³ and left ventricular assist devices.²⁴ Other indications for CR include valvular heart disease because meta-analytic data support CR for the improvement in symptoms (but not outcomes) in patients after valvular procedures.²⁵ That CR improves outcomes in patients with CAD, HFrEF, and valvular heart disease leads to the question: Can CR benefit patients after transcatheter aortic valve implantation? Thus far, there are no large data sets supporting this; however, there are also not large-scale projects currently published. Other patient populations that CR will hopefully soon encompass include patients with peripheral artery disease, HFpEF, atrial fibrillation, non-cardiac transplants, and cancer and pediatric patients.

Making the Lifestyle Changes Beyond 3 Months

CR following ACS is included in the American Heart Association and American College of Cardiology guidelines as a proven secondary prevention measure²⁶ and is a Class 1A recommendation, yet patients vastly underuse CR, with lifestyle adherence afterward being quite poor. Despite the fact that the majority of the risk factors and causes of CVD are attributable to preventable lifestyle-related choices, data regarding the efficacy and adherence to CR beyond the prescribed 3 months of usual CR show, overwhelmingly, that compliance and documented changes in positive lifestyle behaviors decrease in the unsupervised months following CR.²⁷ Although there are no hard CVD endpoints reported, most post-CR studies estimate that adherence to lifestyle changes such as physical activity, diet, and medication adherence initially soar during 3 months of outpatient CR and then return to near pre-event levels in the 9-12 months following usual CR. Data from Mayo Clinic estimate that in patients who have undergone 3 months of usual CR following ACS medication, adherence to statins and beta-blockers at 1 year hovers near the 70% mark, falling to 50% at 3 years.²⁸ Moreover, the functional gains achieved during 3 months of usual CR regress substantially, irrespective of the dose of physical activity prescribed during the initial 3 months of usual CR.²⁹ Interestingly, new data regarding the psychology of post-CR care seem to indicate that having patients become more responsible for the scheduling and execution of their own post-CR plan appears to have the most impact in terms of adherence,³⁰ and recent data have shown that mHealth and digital health interventions improve outcomes in CR populations.^31,32 Thus, novel methods that shift some responsibility to the patients should be sought. Further work in expanding the reach and applicability of CR to cardiac patients with multiple indications and comorbidities should be a paramount goal for the immediate future.

References

1. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics--2015 update: a report from the American Heart Association. Circulation 2015;131:e29-322.
2. Pfuntner A, Wier LM, Steiner C. "Costs for Hospital Stays in the United States, 2010." HCUP Statistical Brief #146. Rockville, MD:Agency for Healthcare Research and Quality; 2013.
3. Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet 2004;364:937-52.
4. Go AS, Mozaffarian D, Roger VL, et al. Executive summary: heart disease and stroke statistics--2013 update: a report from the American Heart Association. Circulation 2013;127:143-52.
5. Dutta P, Courties G, Wei Y, et al. Myocardial infarction accelerates atherosclerosis. Nature 2012;487:325-9.
6. Anderson L, Thompson DR, Oldridge N, et al. Exercise-based cardiac rehabilitation for coronary heart disease. Cochrane Database Syst Rev 2016;5:CD001800.
7. Pack QR, Goel K, Lahr BD, et al. Participation in cardiac rehabilitation and survival after coronary artery bypass graft surgery: a community-based study. Circulation 2013;128:590-7.
8. Balducci S, Zanuso S, Nicolucci A, et al. Effect of an intensive exercise intervention strategy on modifiable cardiovascular risk factors in subjects with type 2 diabetes mellitus: a randomized controlled trial: the Italian Diabetes and Exercise Study (IDES). Arch Intern Med 2010;170:1794-803.
9. Grace SL, Russell KL, Reid RD, et al. Effect of cardiac rehabilitation referral strategies on utilization rates: a prospective, controlled study. Arch Intern Med 2011;171:235-41.
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11. Shah ND, Dunlay SM, Ting HH, et al. Long-term medication adherence after myocardial infarction: experience of a community. Am J Med 2009;122:e7-13.
12. European Association of Cardiovascular Prevention and Rehabilitation Committee for Science Guidelines; EACPR, Corrà U, et al. Secondary prevention through cardiac rehabilitation: physical activity counselling and exercise training: key components of the position paper from the Cardiac Rehabilitation Section of the European Association of Cardiovascular Prevention and Rehabilitation. Eur Heart J 2010;31:1967-74.
13. Beckie TM, Beckstead JW. Predicting cardiac rehabilitation attendance in a gender-tailored randomized clinical trial. J Cardiopulm Rehabil Prev 2010;30:147-56.
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15. Hess CN, Kaltenbach LA, Doll JA, Cohen DJ, Peterson ED, Wang TY. Race and Sex Differences in Post-Myocardial Infarction Angina Frequency and Risk of 1-Year Unplanned Rehospitalization. Circulation 2017;135:532-43.
16. Prince DZ, Sobolev M, Gao J, Taub CC. Racial disparities in cardiac rehabilitation initiation and the effect on survival. PM R 2014;6:486-92.
17. Pack QR, Squires RW, Lopez-Jimenez F, et al. Participation Rates, Process Monitoring, and Quality Improvement Among Cardiac Rehabilitation Programs in the United States: A NATIONAL SURVEY. J Cardiopulm Rehabil Prev 2015;35:173-80.
18. Suaya JA, Stason WB, Ades PA, Normand SL, Shepard DS. Cardiac rehabilitation and survival in older coronary patients. J Am Coll Cardiol 2009;54:25-33.
19. de Vries H, Kemps HM, van Engen-Verheul MM, Kraaijenhagen RA, Peek N. Cardiac rehabilitation and survival in a large representative community cohort of Dutch patients. Eur Heart J 2015;36:1519-28.
20. Allen JK, Scott LB, Stewart KJ, Young DR. Disparities in women's referral to and enrollment in outpatient cardiac rehabilitation. J Gen Intern Med 2004;19:747-53.
21. Weingarten MN, Salz KA, Thomas RJ, Squires RW. Rates of enrollment for men and women referred to outpatient cardiac rehabilitation. J Cardiopulm Rehabil Prev 2011;31:217-22.
22. O'Connor CM, Whellan DJ, Lee KL, et al. Efficacy and safety of exercise training in patients with chronic heart failure: HF-ACTION randomized controlled trial. JAMA 2009;301:1439-50.
23. Zeitler EP, Piccini JP, Hellkamp AS, et al. Exercise training and pacing status in patients with heart failure: results from HF-ACTION. J Card Fail 2015;21:60-7.
24. Marko C, Danzinger G, Käferbäck M, et al. Safety and efficacy of cardiac rehabilitation for patients with continuous flow left ventricular assist devices. Eur J Prev Cardiol 2015;22:1378-84.
25. Sibilitz KL, Berg SK, Tang LH, et al. Exercise-based cardiac rehabilitation for adults after heart valve surgery. Cochrane Database Syst Rev 2016;3:CD010876.
26. Smith SJ Jr, Benjamin EJ, Bonow RO, et al. AHA/ACCF Secondary Prevention and Risk Reduction Therapy for Patients with Coronary and other Atherosclerotic Vascular Disease: 2011 update: a guideline from the American Heart Association and American College of Cardiology Foundation. Circulation 2011;124:2458-73.
27. Arrigo I, Brunner-LaRocca H, Lefkovits M, Pfisterer M, Hoffmann A. Comparative outcome one year after formal cardiac rehabilitation: the effects of a randomized intervention to improve exercise adherence. Eur J Cardiovasc Prev Rehabil 2008;15:306-11.
28. Shah ND, Dunlay SM, Ting HH, et al. Long-term medication adherence after myocardial infarction: experience of a community. Am J Med 2009;122:e7-13.
29. Hansen D, Dendale P, Raskin A, et al. Long-term effect of rehabilitation in coronary artery disease patients: randomized clinical trial of the impact of exercise volume. Clin Rehabil 2010;24:319-27.
30. Rodgers WM, Murray TC, Selzler AM, Norman P. Development and impact of exercise self-efficacy types during and after cardiac rehabilitation. Rehabil Psychol 2013;58:178-84.
31. Widmer RJ, Collins NM, Collins CS, West CP, Lerman LO, Lerman A. Digital health interventions for the prevention of cardiovascular disease: a systematic review and meta-analysis. Mayo Clin Proc 2015;90:469-80.
32. Widmer RJ, Allison TG, Lennon R, Lopez-Jimenez F, Lerman LO, Lerman A. Digital health intervention during cardiac rehabilitation: A randomized controlled trial. Am Heart J 2017;188:65-72.

Keywords: Angina, Stable, Cardiac Rehabilitation, Cardiovascular Diseases, Acute Coronary Syndrome, Heart Failure

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