14-Cardiac Rehabilitation

Background:

cardiac rehabilitation has been provided to somewhat lower-risk patients who could exercise without getting into trouble. However, astonishingly rapid evolution in the management of CAD has now changed the demographics of the patients who can be candidates for rehabilitative training. Currently, about 400,000 patients who undergo coronary angioplasty each year comprise a subgroup that could benefit from cardiac rehabilitation. Furthermore, approximately 4.7 million patients with CHF are also eligible for a slightly modified program of rehabilitation, as are the ever-increasing number of patients receiving heart transplantation.
This review addresses the objectives, indications, program components, exercise training, monitoring, benefits, risks, safety issues, outcome measures, and cost effectiveness of cardiac rehabilitation.

Objectives:
Cardiac rehabilitation aims to reverse the limitations that have developed following adverse pathophysiologic and psychological consequences of cardiac events. Identification of the patients at risk for recurrence of such events (ie, risk stratification) is central to formulating an appropriate medical, rehabilitative, and surgical strategy to prevent such recurrences. Patients who are at low or moderate risk typically undergo early rehabilitation.

The major goals of cardiac rehabilitative programs are:

• Curtail the pathophysiologic and psychosocial effects of heart disease.
• Limit the risk for reinfarction or sudden death.
• Relieve cardiac symptoms,
• Retard or reverse the atherosclerosis by instituting programs for exercise training, education, counseling, and risk factors alteration
• Reintegrate heart disease patients into successful functional status in their families and the society.

Cardiac rehabilitation programs have been consistently shown to improve objective measures of exercise tolerance and psychosocial well being, without increasing the risk of significant complications.

Utilization:
The Agency for Health Care Policy and Research (AHCPR); National Heart, Lung and Blood Institute (NHLBI); and the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) have recognized the wide variation in awareness and understanding of the role of cardiac rehabilitation among physicians, ancillary health care providers, third-party payers, and patients with heart disease. Only 11% of patients participate in rehabilitation programs following acute coronary events. In the past few years, fortunately, the participation in these programs has increased. Approximately 38% of US patients and 32% of Canadian patients with acute MI who were involved in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) trial were enrolled in cardiac rehabilitation programs.

Outcome measures:
Current cardiac care has already reduced early acute coronary mortality so much so that further exercise training, as an "isolated" intervention, may not be able to cause significant reduction in the morbidity and mortality. Nonetheless, exercise training has the potential to act as a catalyst for promoting other aspects of rehabilitation, including risk factor modification through therapeutic lifestyle changes (TLC) and optimization of psychosocial support. Therefore, the outcome measures of cardiac rehabilitation now include improvement in quality of life (QOL), such as the patient's perception of physical improvement, satisfaction with risk factor alteration, psychosocial adjustments in interpersonal roles, and potential for advancement at work commensurate with the patient's skills (rather than simply return to work).
Similarly, among patients who are elderly, such outcome measures may include achievement of functional independence, prevention of premature disability, and reduction in the need for custodial care. Despite limited data, older patients of both sexes in observational studies have been shown to improve their exercise tolerance comparable to younger patients participating in equivalent exercise programs. In addition, the safety of exercise within cardiac rehabilitation programs, as studied in over 4,500 patients, is well accepted and established.
Cardiac rehabilitation services are, therefore, an effective and safe intervention. These services are, undoubtedly, an essential component of the contemporary treatment of patients with multiple presentations of coronary heart disease and heart failure.

History:
In the 1930s, patients with MI were advised to observe 6 weeks of bedrest. Chair therapy was introduced in the 1940s. By the early 1950s, 3-5 minutes of daily walking was advocated, beginning at 4 weeks. Clinicians gradually began to recognize that early ambulation avoided many of the complications of bedrest, including pulmonary embolism (PE), and it did not increase the risk. However, concerns about safety of unsupervised exercise remained strong, which led to the development of structured physician-supervised rehabilitation programs that included clinical supervision, as well as electrocardiographic monitoring.
In the 1950s, Hellerstein set out his thoughts for the comprehensive rehabilitation of patients recovering from acute cardiac events. He advocated a multi-disciplinary approach to the rehabilitation program. His approach has been adopted by the so-called "cardiac rehabilitation programs" throughout the world. Despite multiple advances, Hellerstein's original ideas have not been improved upon significantly. However, due to changing patient demographics, many more patients now have the opportunity to receive the benefits offered by cardiac rehabilitation. Multifactorial intervention, including aggressive risk factor modification, has become an integral part of present day cardiac rehabilitation.

Definition:
According to the US Public Health Service (USPHS), cardiac rehabilitation is defined as a rehabilitative program that involves the following:

• Medical evaluation.
• Prescribed exercise
• Education.
• Counseling of patients with cardiac disease .

Cardiac rehabilitation has to be both comprehensive and individualized at the same time. The main goals of a cardiac rehabilitation program should include the following:
Short-term goals :

1. "Reconditioning" sufficient enough for resumption of customary activities.
2. Limiting the physiologic and psychological effects of heart disease.
3. Decreasing the risk of sudden cardiac arrest or reinfarction.
4. Controlling the symptoms of cardiac disease.

Long-term goals:

1. Identification and treatment of risk factors.
2. Stabilizing or even reversing the atherosclerotic process.
3. Enhancing the psychological status of the patients.

Physiology of exercise and cardiovascular benefit:

Coronary vasodilatation is mainly driven by bioavailability of nitric oxide (NO), which is produced by the activities of endothelial-derived enzyme, NO synthase, and metabolized by reactive oxygen species. This fine-tuned balance is disturbed in person with CAD. This form of impairment of NO production, along with excessive oxidative stress, results in loss of endothelial cells via apoptosis. Further aggravation of endothelial dysfunction, in turn, ensues, which triggers myocardial ischemia in persons with CAD. In healthy individuals, increased release of NO from the vascular endothelium in response to exercise training results from changes in endothelial NO synthase expression, phosphorylation, and conformation.
By the same token, exercise training has assumed a role in cardiac rehabilitation of patients with CAD because it reduces mortality and increases myocardial perfusion. This has been largely attributed to exercise training?mediated correction of coronary endothelial dysfunction in persons with CAD. Regular physical activity leads to restoration of the balance between NO production by NO synthase and NO inactivation by reactive oxygen species in persons with CAD, thereby enhancing the vasodilatory capacity in various vascular beds.
Because endothelial dysfunction has been identified as a predictor of cardiovascular events, the partial reversal of endothelial dysfunction achieved by regular physical exercise appears to be the most likely mechanism responsible for the exercise training?induced reduction in cardiovascular morbidity and mortality in patients with CAD.

Patient selection:
Cardiac rehabilitation encompasses both short-term and long-term goals that are to be achieved through exercise, education, and counseling. The patients generally fall into following categories:

• Lower-risk patients following an acute cardiac event.
• Patients who have undergone coronary bypass surgery .
• Patients with chronic stable angina pectoris.
• Patients who have undergone heart transplantation.
• Patients following percutaneous coronary angioplasty .
• Patients without prior events but at risk because of remarkably unfavorable risk factor profile.
• Patients with stable heart failure.
• Patients following non-coronary cardiac surgery.
• Patients with previously stable heart disease now seriously deconditioned by intercurrent comorbid illnesses.

The short-term goals of cardiac rehabilitation include restoration of the physical, psychological, and social condition, while the long-term goals involve promotion of heart-healthy behaviors that enable the individual to return to productive and/or joyful vocational and avocational activities.
The cardiac rehabilitation programs benefit women and men equally. Elderly patients also can derive significant benefit from rehabilitation programs.

Risk stratification:
The risk stratification process is very valuable for cardiac patients; it serves as the basis for individualizing prescription of exercise training and assessing the need and extent of supervision required. The risk stratification process is based upon the assessment of the following patient attributes:

(A) Functional capacity

• Functional capacity is defined as the maximum ability of the heart and lungs to deliver oxygen and the ability of the muscles to extract it. Functional capacity is measured by determining the maximal oxygen uptake (VO 2 max) during incremental exercise.
• In most patients, a rough calculation of functional capacity can be performed by using multiples of 1 MET (metabolic equivalent, 3.5 mL O 2 uptake/kg/min). In complicated patients, such as those with severe left ventricular (LV) dysfunction and CHF, the functional capacity can be ascertained with greater accuracy by using cardiopulmonary exercise (CPX) testing. Most cardiac rehabilitation facilities, however, are not currently equipped for CPX.
• Factors that influence functional capacity include the following:
  -Age.
  -Precardiac event physical capacity.
  -Treatments and bed rest during the event.
  -Fluid volume, such as relative dehydration or volume overload in patients with CHF.
  -LV dysfunction.
  -Residual myocardial ischemia.
  -Skeletal muscle performance, such as deconditioning or in presence of concurrent non-cardiac illness.
  -Autonomic function, such as diabetic neuropathy.
  -Peripheral vascular status.
  -Pulmonary status.
  -Other systemic illnesses, especially orthopedic problems limitingflexibility and locomotion.

Every attempt should be made to recognize the potential effects of these factors on functional capacity in order to minimize risk of the individualized reconditioning program that is being formulated.

(B) Myocardial ischemia
Symptomatic or asymptomatic (silent) myocardial ischemia may limit the patient's exertional capacity by causing limiting angina, dyspnea, or fatigue.

(C) Ventricular dysfunction

• Fixed LV dysfunction or damage may be present in the absence of angina. Patients with LV dysfunction develop early dyspnea and become fatigued easily.
• Cardiopulmonary exercise testing preferably should be performed to determine the functional capacity in an objective manner.
• Exercise intolerance in patients with LV dysfunction is due to skeletal muscle hypoperfusion resulting from inadequate cardiac output that can be better quantified by measuring VO 2 max.

(D) Arrhythmias

• Ventricular irritability and complex ventricular arrhythmias require assessment through use of signal averaged electrocardiogram (ECG) or electrophysiologic studies.
• Appropriate medical or device treatments should be undertaken whenever feasible prior to beginning phase II of the cardiac rehabilitation program.
• Very close surveillance is necessary in patients with significant cardiac arrhythmias during their exercise training routines. Concomitant rhythm monitoring with telemetry, Holter or event monitoring should be considered. In many cases of serious arrhythmias, therapy remains controversial and the safety of exercise unclear, which complicates the decision-making process.
• Patients with severe ventricular arrhythmias and uncontrolled supraventricular arrhythmias should be excluded from exercise training unless proper evaluation and effective therapy has been instituted. Patients with devices, such as pacemakers and defibrillators, should be carefully monitored during exercise. Rate-responsive pacemakers are quite helpful even for those patients who are completely pacemaker-dependent. In case of implantable cardioverter defibrillators (ICDs), exercise training can be provided as long as underlying arrhythmias are controlled with pharmacotherapy. Heart rate should be kept well below the threshold at which the antitachycardia algorithm of the ICD begins.

(E) Educational and psychosocial status

• Approximately 20-25% of acute MI patients demonstrate severe psychological stress or major depression and show higher morbidity and mortality. Clinically significant depressive symptoms are found in 40-65% of patients after an MI.
• Exercise does provide some benefit, but severe cases may require specific therapy that has been shown to enhance the benefits derived from subsequent cardiac rehabilitation.
• Promotion of self-efficacy and control over one's activities is of paramount importance for boosting self-confidence.
• Coronary prone behavior (CPB) is known as a cardiac risk factor, but its effect on prognosis is unclear. Some data suggest that modification of CPB can improve the coronary disease prognosis.

Initial continuous ECG monitoring is recommended in most patients during cardiac rehabilitation exercise training; however, clinicians may decide whether to use continuous or intermittent ECG monitoring. After the initial period, use of ECG depends on the clinical judgment of the supervising physician.

(F) Alternative approaches to cardiac rehabilitation
In carefully selected patients, alternatives to the traditional supervised (group or individual) cardiac rehabilitation program have been examined. These alternatives are applicable primarily to very low-risk patients and include the following options:

• Home-based cardiac rehabilitation (effective and safe)
• Exercise with transtelephonic monitoring/surveillance

Cardiac rehabilitation in patients with heart failure:
Heart rate recovery (HRR) after maximal exercise is a predictor of all-cause mortality. In a 2006 study, Streuber et al hypothesized that aerobic exercise training could increase HRR in patients with heart failure because it has been shown to be accelerated in athletes and improved in patients with CAD after cardiac rehabilitation. They conducted a retrospective study of 46 patients with heart failure who had completed a phase 2 aerobic cardiac rehabilitation program with entry and exit maximal stress tests. The results indicated that even short-term aerobic training can favorably modify HRR in patients with heart failure who have low exercise capacity.

Indications:
Cardiac rehabilitation initially was designed for low-risk cardiac patients. Now that the efficacy and safety of exercise have been documented in patients previously stratified to the high-risk category, such as those with CHF, the indications have been expanded to include such patients. Exercise training benefits persons with the following cardiac conditions:

• Recent myocardial infarction.
• Coronary bypass.
• Valve surgery.
• Coronary angioplasty.
• Cardiac transplantation.
• Angina.
• Compensated CHF.
  Exercise prescription depends on the results of exercise testing, which often includes cardiopulmonary exercise (CPX) testing.

Modifications of exercise:
Patients with limitations due to chronic obstructive pulmonary disease (COPD), peripheral vascular disease (PVD), stroke, and orthopedic conditions still can be trained in the exercises through special techniques and adaptive equipment (eg, use of arm-crank ergometer).

Contraindications:
Cardiac rehabilitation services are contraindicated in patients with the following conditions:

• Severe residual angina.
• Uncompensated heart failure.
• Uncontrolled arrhythmias.
• Severe ischemia, LV dysfunction, or arrhythmia during exercise testing.
• Poorly controlled hypertension.
• Hypertensive or any hypotensive systolic blood pressure response to exercise.
• Unstable concomitant medical problems (eg, poorly controlled or "brittle" diabetes, diabetes prone to hypoglycemia, ongoing febrile illness, active transplant rejection)
  In such patients, every effort should be made to correct these abnormalities through optimization of medical therapy, revascularization by angioplasty or bypass surgery, or electrophysiologic testing and subsequent antiarrhythmic drug or device therapy. Patients should then undergo retesting for exercise prescription.

Exercise testing:
Two forms of exercise tests are performed in patients following an acute cardiac event: submaximal exercise testing and symptom-limited exercise testing. Furthermore, CPX also may be performed, particularly in patients with cardiomyopathy or CHF, to determine objectively the patient's exercise capacity.

• Submaximal exercise testing:
  -In this strategy, the patients exercise enough to achieve 70% of maximum predicted heart rate for their ages (ie, 70% of 220 minus age in years).
  -This test is performed commonly prior to discharge and is followed by maximal exercise testing 6-8 weeks later (when patients aim to achieve 90% of maximum predicted heart rate).
• Symptom-limited exercise testing
  -The patients exercise soon after a cardiac event.
  -A representative schedule might begin exercise at intervals such as 7-21 days following uncomplicated acute MI, 3-10 days following angioplasty, or 14-28 days after bypass surgery.
  Submaximal exercise testing is not necessarily safer than the symptom-limited testing. In fact, submaximal strategy may have certain disadvantages including (1) failure to elicit important factors in prognosis, such as ischemia, cardiac dysfunction, or arrhythmia, (2) inappropriate limitation in patient's routine activities and exercise training, and (3) significant delay in the patient's returning to work.
• CPX testing
  -Incremental exercise is employed, using modified Naughton protocol for treadmill or modified protocols on a bicycle ergometer.
  -Concomitant minute-to-minute breath analysis and measurement of oxygen consumption and elimination of carbon dioxide are performed to determine VO 2 max, which is the most objective method of determining functional capacity in patients with cardiac dysfunction, valvular disease, or recent acute cardiac event.
  -Modified Bruce or Naughton protocols typically are used during the testing phase, as the standard Bruce protocol has been modified to avoid too abrupt an increase of METs (by 2-3 METs per stage).
  -The modified Naughton protocol starts at a lower MET workload and increases by 1-MET per stage, thus allowing better-tolerated gradual progression in exercise and a more accurate assessment of exertional capacity.
  -The usual symptomatic endpoints are fatigue and breathlessness.
  -Severe abnormalities found on stress testing may contraindicate exercise training until they have been corrected. Less severe abnormalities, such as development of above symptoms at high workloads, may not necessarily contraindicate exercise training; however, certain modifications and closer surveillance may be required, including ECG monitoring.
  -Some reports have questioned early exercise training following acute anterior MI, suggesting that it may lead to abnormal scar formation. Nonetheless, evidence is strong that moderate exercise training is not associated with worsening LV function in patients following acute anterior MI.

Exercise prescription and surveillance:
Phase 2 of a cardiac rehabilitation program is initiated based on the result of the exercise testing, and the exercise prescription is individualized. Three main components of an exercise training program are as follows:

• Frequency: The minimum frequency for exercising to improve cardiovascular fitness is 3 times weekly
• Time: Patients usually need to allow 30-60 minutes for each session, which includes a warm-up of at least 10 minutes
• Intensity: The intensity prescribed is in relation to one's target heart rate. Aerobic conditioning is emphasized in the first few weeks of exercise. Strength training is introduced later. The Borg scale of Rate of Perceived Exertion (RPE) is used. Patients usually should exercise at an RPE of 13-15.
• Borg scale of perceived exertion
  * 6
  * 7 - Very, very light
  * 8
  * 9 - Very light
  * 10
  * 11 - Light
  * 12
  * 13 - Somewhat hard
  * 14
  * 15 - Hard
  * 16
  * 17 - Very hard
  * 18
  * 19 - Very, very hard
  * 20 - Exhaustion

Exercise initiation:
Exercise sessions should begin with 10 minutes of warm-up, during which light calisthenics and muscular stretching are performed to avoid muscle injury and bring about a graded increase in heart rate. This warm-up period is followed by 40 minutes of aerobic exercise (eg, walking, jogging, bicycling) and a final 10 minutes of cool-down period involving muscular stretching. The cool-down period is very important. Gradual cool-down prevents ventricular arrhythmias, which may occur in patients with coronary disease on abrupt cessation of exercise.

Progression:
The patient's peak heart rate is noted. The target is, subsequently, increased by 5-10% of the peak heart rate until the patient is able to exercise at 85% of the peak heart rate. Most patients are able to do so by 2-3 months. A follow-up treadmill test should be performed at 4-8 weeks after the patient starts the program, and the result should be used to fine tune the exercise training.

Special considerations:
In patients with myocardial ischemia, exercise training still can be performed safely. The maximal heart rate should be kept 10 beats per minute (bpm) lower than the heart rate at which ischemia occurred. Closer surveillance and ECG monitoring are recommended in patients following myocardial ischemia. Patients with arrhythmias also need ECG monitoring. Patients with CHF require a much more modified exercise program.

Cardiac rehabilitation services are divided into 3 phases beginning with phase 1 that is initiated while the patient is still in the hospital, followed by phase 2 that is a supervised ambulatory outpatient program spanning 3-6 months, and subsequently continuing into phase 3, a lifetime maintenance phase, in which physical fitness, as well as additional risk factor reduction, are emphasized.

Cardiac rehabilitation: Phase 1 (in-hospital phase):

• This program begins while patients are still in the hospital.
• Phase 1 includes a visit by a member of the cardiac rehabilitation team, education regarding the disease and its recovery process, personal encouragement, and inclusion of family members in classroom group meetings.
• Some of the older patients may serve as volunteers and share their experiences about learning to live with heart disease.
• Team members include cardiac nurses, exercise specialists, physical therapists, occupational therapists, dietitians, and social workers.
• In the coronary care unit, assisted range of motion exercises can be initiated within the first 24-48 hours.
• Low-risk patients should be encouraged to sit in a bedside chair and begin to perform self-care activities (eg, shaving, oral hygiene, sponge bathing).
• On transfer to the step-down unit, patients should try to sit up, stand, and walk in their rooms in the beginning. Subsequently, they should start to walk in the hallway at least twice daily either for certain specific distances or as tolerated without unduly pushing them or holding them back. Standing heart rate and blood pressure should be obtained followed by 5 minutes of warm-up or stretching. Walking, often with assistance, is resumed with target heart rate of <20>
• Team members including the nurse educator, dietitian, exercise rehabilitation trainer, and physician should incorporate in the discharge planning an appropriate emphasis on secondary prevention through risk factor modification and therapeutic lifestyle changes (TLC), such as aspirin and beta blocker use in all patients, angiotensin converting enzyme (ACE) inhibitor use in patients with left ventricular ejection fraction of less than 40%, smoking cessation, lipid management, weight management, and stress management. They must also ensure that phase 1 patients get referred to appropriate local, convenient, and comprehensive phase 2 programs.

Cardiac rehabilitation: Phase 1.5 (Postdischarge phase):

• This phase begins after the patient returns home from the hospital.
• Better understanding of how to keep the heart healthy and strong is emphasized. Team members work with patients and family members.
• Team members check the patient's medical status and continuing recovery and should offer reassurance as the patient regains health and strength.
• This phase of recovery includes low-level exercise and physical activity and instruction about changes for resumption of an active and satisfying lifestyle.
• Risk reduction strategies are emphasized again.
• After 2-6 weeks of recovery at home, the patient is ready to start cardiac rehabilitation phase 2.

Cardiac rehabilitation: Phase 2 (supervised exercise):

• The patients who have completed hospitalization and 2-6 weeks of recovery at home can begin phase 2 of their cardiac rehabilitation program.
• Physician and cardiac rehabilitation staff members formulate the level of exercise to meet an individual patient's needs.
• Exercise treatments usually are scheduled 3 times a week at the rehabilitation facility.
• Constant medical supervision is provided, including exercise electrocardiograms (ECGs), as well as supervision by a nurse and exercise specialist.
• In addition to exercise, counseling, and education about stress management, smoking cessation, nutrition, and weight loss also are incorporated.
• This phase of rehabilitation may last 3-6 months.

Cardiac rehabilitation: Phase 3 (maintenance phase):

• Phase 3 of cardiac rehabilitation is a maintenance program designed to continue for the patient's lifetime. The exercise sessions usually are scheduled 3 times a week.
• Activities consist of the type of exercises the patient enjoys, such as walking, bicycling, or jogging. A registered nurse supervises these classes.
• ECG monitoring usually is not necessary.
• The main goal of phase 3 is to promote habits that lead to a healthy and satisfying lifestyle.
• Phase 3 programs do not usually require medical or nursing supervision. In fact, most patients participate in "phase 3" equivalent exercises at the exercise facilities in the community (eg, YMCA, YWCA, Gold's gym, Life-style fitness).

Sexual activity:

• Common sexual problems encountered by cardiac patients include impotence and premature or delayed ejaculation in men and reduced libido in both men and women. These difficulties may be due to medications (eg, beta blockers, diuretics), depression, and fear in both the patient and his or her partner of precipitating a cardiac event.
• Maximum heart rate during sexual intercourse averages 120 bpm, which is similar to heart rates associated with other routine activities in and around the house.
• The hemodynamic response is greater with an unfamiliar partner or surroundings and after eating or consuming alcohol.
• Adapting less strenuous positions, such as side-to-side rather than missionary positions, can reduce cardiac stress.
• Patients may start sexual activity 2-3 weeks following an uncomplicated MI. They must be instructed to report any untoward symptoms to the physician or member of the rehabilitation team.

Cardiac rehabilitation provides many benefits for patients. The most important benefits are discussed below.

Improved exercise tolerance:
Cardiac rehabilitation exercise training for patients with coronary heart disease or CHF leads to objectively verifiable improvement in exercise capacity in men and women, regardless of age. Adverse outcomes or complications of exercise are exceedingly rare. The nonfatal infarction rate is 1 patient per 294,000 patient-hours; the cardiac mortality rate is 1 patient per 784,000 patient-hours. The benefits are even greater in patients with diminished exercise tolerance. This beneficial effect does not persist long-term after completion of cardiac rehabilitation without a long-term maintenance program. Therefore, exercise training must be maintained long term to sustain the improvement in exercise capacity.

Control of symptoms:
In patients with coronary heart disease, angina significantly improves during the cardiac rehabilitation exercise program. Objective evidence of improvement in ischemia has been seen by performing interval stress ECG or radionuclide testing. Similarly, patients with LV failure or dysfunction show improvement in the symptoms of heart failure. Use of gas analysis (CPX) has shown that patients' exertional tolerance improves significantly with exercise training.

Improvement in the blood levels of lipids:
Improvements in lipid and lipoprotein levels are observed in patients undergoing cardiac rehabilitation exercise training and education. Exercise must be combined with dietary and medical interventions for required lipid control.

Effect on body weight:
Exercise training as a sole intervention has an inconsistent effect on controlling excess weight. Optimal management of obesity requires multifactorial rehabilitation, including nutritional education and counseling, behavioral modification, and exercise training.

Effect on blood pressure:
Rehabilitative exercise training as a sole intervention has minimal effect; however, multifactorial intervention has been shown to have beneficial effects. Inconsistencies with this theory remain unresolved.

Reduction in smoking:
Cardiac rehabilitation services with well-designed educational, counseling, and behavioral modification programs result in cessation of smoking in a significant number of patients. Cessation of smoking can be expected in 16-26% of patients. This reduction is combined with the spontaneously high smoking cessation rates following acute coronary events.

Improved psychosocial well being :
Cardiac rehabilitation exercise and education services enhance measures of psychological and social functioning.

Reduction of stress:
In multifactorial cardiac rehabilitation programs, improvement in the measures of emotional stress occurs, as well as reduction of Type A behavior patterns. This reduction of stress is consistent with improvement in psychosocial outcomes that occurs in nonrehabilitation settings.

Enhanced social adjustment and functioning:
Cardiac rehabilitation exercise training improves social adjustment and functioning. Exercise training is recommended to improve these social outcomes.

Return to work:
Cardiac rehabilitation exercise training exerts less influence on rates of return to work than on other aspects of life. Many nonexercise variables also affect this outcome (eg, prior employment status, employer attitude, economic incentives).

Reduced mortality:
Scientific data suggest a survival benefit for patients who participate in cardiac rehabilitation exercise training, but it is not attributable to exercise alone. This survival benefit is due to multifactorial interventions. A meta-analysis of the post-MI randomized controlled trials of exercise has shown a 25% reduction in mortality at 3-year follow-up. This magnitude of benefit is as large as the benefit seen with the use of beta-blockers post-MI or with the use of ACE inhibitors in LV dysfunction along with MI. Trials that involve exercise alone still show a 15% mortality reduction.

Pathophysiologic measures:
Extent of coronary atherosclerosis: When combined with intensive dietary intervention, with and without lipid-lowering drugs, exercise training may result in limitation of progression or regression of angiographically documented coronary atherosclerosis.
Hemodynamic measurements: Exercise training in patients with heart failure and compromised LV ejection fraction produces favorable hemodynamic changes in the skeletal musculature. Cardiac rehabilitation exercise training is recommended to improve skeletal muscle functioning, but it does not seem to improve hemodynamic function or collateral circulation significantly.
Patients following cardiac transplantation
Rehabilitative exercise training in patients following orthotropic cardiac transplantation is recommended to improve measures of exercise tolerance.

Elderly patients and women:
Coronary patients who are elderly have exercise trainability comparable to that of younger patients participating in similar rehabilitative programs. Elderly patients, both male and female, show comparable improvements. Unfortunately, referral to and participation in cardiac rehabilitation are less frequent in elderly patients, particularly elderly women. No complications or adverse outcomes for elderly patients were described in any study. Elderly patients of both sexes should be encouraged to participate in cardiac rehabilitation.

Patients on dialysis and following coronary artery bypass grafting surgery:
Patients who are on renal dialysis are at high risk for cardiac death and have a large burden of cardiovascular disease and cardiovascular disease risk factors. Cardiac rehabilitation can promote improved survival of nondialysis patients after coronary artery bypass grafting (CABG) surgery and is covered by Medicare, but no previous studies have investigated whether dialysis patients' survival after CABG may be improved as a function of cardiac rehabilitation.
In a 2006 study by Kutner et al, dialysis patients who received cardiac rehabilitation after CABG had a 35% reduced risk for all-cause mortality and a 36% reduced risk for cardiac death compared with dialysis patients who did not receive cardiac rehabilitation, independent of sociodemographic and clinical risk factors, including recent hospitalization. Only 10% of patients received cardiac rehabilitation after CABG, compared with an estimated 23.4% of patients in the general population, and lower-income patients of all ages as well as women and black patients aged 65 or older were significantly less likely to receive cardiac rehabilitation services. This observational study suggests a survival benefit of cardiac rehabilitation for dialysis patients after CABG.


Exercise training involves certain risks, especially in patients with undiagnosed or undertreated myocardial ischemia, ventricular arrhythmias, or LV dysfunction. The intensity of exercise must be kept below the level of exercise at which the abnormalities were elicited during the risk stratification and testing phase.

Selection of patients:
Proper selection of patients is of paramount importance before beginning phase 2 or phase 3 exercise programs. Patients with certain characteristics are at a higher risk, and therefore, require all attempts at correction of the high-risk condition prior to exercise training. Patients also must be monitored with continuous ECG and supervised closely. These high-risk features include the following:

• Severe LV dysfunction, LV ejection fraction (EF) less than 30%, congestive heart failure (CHF), and history of cardiogenic shock
• Severe exercise-induced ischemia, such as angina at a workload less than 5 METs, ST-segment depression greater than 0.2 mV on the ECG, multiple perfusion defects on exercise nuclear stress testing, or multiple dyskinetic LV segments on stress echocardiography
• Complex ventricular arrhythmias, such as nonsustained ventricular tachycardia (less than 30-second run of ventricular tachycardia [VT]) at rest or with exercise or history of previous sudden cardiac arrest (SCA)
• Hypotensive response to exercise (ie, drop in systolic pressure of more than 20 mm Hg at incremental exertion)
• Low functional capacity (ie, peak workload less than 5 METs, functional capacity determined by cardiopulmonary exercise [CPX] testing with reduced peak oxygen [VO 2 max] consumption)
• Patient's inability to self-monitor his or her heart rate
  For some patients, the risks of exercise may outweigh the benefits. In these instances, patients should be counseled against exercise training, and their medical management must first be optimized with thorough supervision.

Surveillance:
(A) High-risk patients, constituting approximately 15-25% of all patients referred for cardiac rehabilitation, require the maximum level of supervision and surveillance involving continual ECG monitoring. The group of high-risk patients described above constitutes the bulk of such patients.
(B) Intermediate-risk patients need somewhat less intense surveillance. The level of supervision needed includes unmonitored exercise training in groups in the presence of health professionals who are certified in advanced cardiac life support (ACLS).

(C) Very low-risk patients can exercise safely and independently, once they have learned how to monitor their pulse rates and are able to recognize warning signs. Such patients have greater than 8 METs of exercise capacity without symptoms or signs of angina, heart failure, or arrhythmias.

(D) Alternative approaches to the traditional supervised cardiac rehabilitation programs have been evaluated and found to be reasonably safe. These off-site self-monitored or telemetry-monitored programs are applicable primarily to very low-risk patients and include (1) home-based cardiac rehabilitation (effective and safe) and (2) exercise with trans-telephonic surveillance.

Safety:
Supervised exercise training programs have extremely good safety records, despite the inherent potential for cardiovascular complications during exercise. None of the more than 3 dozen randomized controlled trials of cardiac rehabilitation exercise testing and training in patients with coronary heart disease, involving over 4,500 patients, showed any increase in morbidity or mortality in rehabilitation compared with control patient groups. A 1980-1984 survey of 142 US cardiac rehabilitation programs reported a low rate of nonfatal myocardial infarction (1 case per 294,000 patient-hours) and cardiac mortality (1 case per 784,000 patient-hours). A total of 21 episodes of cardiac arrest occurred, out of which, 17 were successfully resuscitated. Therefore, the safety of exercise within cardiac rehabilitation programs is well accepted and established.

Analysis of cost effectiveness:
Cardiac rehabilitation is a clinically effective intervention for coronary heart disease that has been subjected to preliminary cost analyses. A randomized US 8-week trial of rehabilitation beginning 6 weeks following MI showed cost/effectiveness (C/E) of $9,200 per quality adjusted life year. A similar more recent analysis shows a C/E of only $4,950 per year of life saved. In contrast, cholesterol lowering for secondary prevention has a C/E of $9,630 per year of life saved, thrombolytic therapy of acute MI has a C/E of $32,700 per year of life saved, and bypass surgery has a C/E of $18,700 for a year of life saved.
A comprehensive cost analysis of cardiac rehabilitation performed in Sweden in patients following MI or bypass surgery with 5-year follow-up showed rehospitalizations decreased from 16 to 11 days, and higher rate of return to work (53% versus 38%). Overall, cardiac rehabilitation programs resulted in cost savings to the Swedish system of $12,000 per patient.
Therefore, cardiac rehabilitation is not only clinically effective, but it is cost effective as well. Cardiac rehabilitation compares favorably with other medical interventions performed commonly in patients with coronary heart disease.

Cardiac rehabilitation is an important component of current multidisciplinary approach for management of the patients with various presentations of coronary heart disease. Cardiac rehabilitation involves exercise training, education, counseling regarding risk reduction and lifestyle modification, and, frequently, behavior interventions.
The goals of cardiac rehabilitation services are to improve both the physiologic and psychosocial condition of the patients. Physiologic benefits include improvement of exercise capacity and reduction of risk factors (eg, cessation of smoking, lowering of lipid levels, body weight, blood pressure, blood glucose), where the exercise component provided through rehabilitation may cause reduction in the progression of atherosclerosis. Psychological improvements include reduction of depression, anxiety, and stress. All these improvements enable acquisition and maintenance of functional independence and return to satisfactory and appropriate activity that benefits both the patient and society.