Globally the prevalence of cardiovascular disease continues to rise with an increase in the aged population.^1,2 This in turn increases the percentage of patients seen in physiatric practices with underlying cardiovascular conditions that affect patient function, participation with therapy, and recovery. Studies have demonstrated that cardiac rehabilitation is associated with substantial physiologic benefits in cardiovascular atherogenesis, inflammation, and function (Table 49–1).

Research has clearly demonstrated decreased mortality rates in patients who have undergone cardiac rehabilitation when compared to those that who not.³ Cardiac rehabilitation is a class I indication for most patients with stable angina, acute MI within the last year, percutaneous coronary intervention, congestive heart failure, cardiac transplant or coronary artery bypass surgery.⁴

A meta-analysis of 63 trials of 14,486 cardiac patients with a history of myocardial infarction or revascularization demonstrated that exercise decreased CV mortality (relative risk [RR], 0.74; 95% confidence interval [CI], 0.64–0.86), decreased the risk of hospital admission (RR, 0.82; 95% CI, 0.70–0.96), and did not significantly increase the death.⁵ Other studies have indicated that cardiac rehabilitation improves heart rate recovery by 41%, as well as left ventricular remodeling.^6,7

Interestingly, another study identified a dose dependent relationship, Medicare MI patients that attended 36 sessions over a period of 5 years decreased their likelihood of death by 14% (HR, 0.86; 95% CI, 0.77–0.97) when compared to those that only completed 24 sessions in the same time period.³

Despite clear evidence of efficacy, studies have estimated that only a minority of patients actually received such therapy.⁸ Poor socioeconomic status, lack of physician referral, and logistics have been cited as possible reasons for the underutilization of cardiac rehabilitation.⁹

It is critical that the practicing physiatrist have a basic understanding of cardiovascular conditions prior to prescribing a cardiac rehabilitation program to maximize its efficacy and minimize adverse events.

Common indications for cardiac rehabilitation are described in Table 49–2. Patients who have had revascularization procedures are also candidates for cardiac rehabilitation and may have slightly higher referral rates.^6,10,11

This chapter will provide an overview of the most common cardiovascular conditions and outline the principles of cardiac rehabilitation in order to provide a clinical framework in which to understand the rehabilitation of all patients with underlying cardiovascular disease.

Prior to the initiation of cardiac rehabilitation, it is critical that a comprehensive physiatric history and physical examination be performed. This includes an assessment of modifiable (inactivity, smoking, obesity, diabetes, 12-lead electrocardiogram [ECG], hypertension) and nonmodifiable (age, male gender, family history, prior cardiac history, and socioeconomic status) risk factors.

Identification of contraindication for a cardiac rehabilitation program is important during the initial assessment. These contraindications include greater than 2 mm ST displacement on an ECG, severe hypertension (systolic blood pressure greater than 200 mm Hg or diastolic blood pressure greater than 110 mm Hg), uncontrolled cardiac arrhythmia, third-degree heart block, unstable heart failure, orthostatic hypotension, unstable angina, or medical instability (see Table 49–2).

Prior to the initiation of cardiac rehabilitation, patients are assessed for risk with the use of the guidelines published by the American Heart Association (AHA).¹² According to these guidelines, Class A patients are healthy and have no apparent increased cardiovascular risk with exercise. Class B patients have stable heart disease and are at low risk with exercise (see Table 49–3).

Class C patients have either a moderate or high risk of cardiac complications (Table 49–4). Class C patients often have had a history of multiple MIs, severe angina, or restricted exercise capacity (fewer than six METS). Additionally these patients typically have had ischemic changes found on the stress test. Class D patients have unstable cardiac disease and exercise is contraindicated.

Typically, cardiac rehabilitation is divided into four phases. Heart rate and intensity are typically calculated at the beginning of the cardiac rehabilitation program. For the healthy adult, the American Heart Association recommends the maximum heart rate (HR_max) to be (HR_max = 220 – Age); the maximal exercise target HR_max ranges between 70% and 85% of HR_max. In contrast, the cardiac rehabilitation patient typically will be initiated at 50% of the HR_max. Great care should be taken when rehabilitating patients on beta blockers; their target maximal and submaximal rates should be reduced by 20 to 40 beats.

Oxygen saturation and consumption are typically monitored during the cardiac rehabilitation program. Clinically, the Borg Rating of Perceived Exertion is used during cardiac rehabilitation and correlates directly with exertion and oxygen utilization during exercise. Cardiac rehabilitation patients should exercise at a Borg rating ranging between 11 and 15, and should always be able to have a conversation.

The first phase of cardiac rehabilitation is generally the first 14 days after a cardiac event and begins in the hospital. The main focus of this phase is to initiate early mobilization and range of motion and mitigate the effects of inactivity. Maximum metabolic equivalents (METs) in this phase range between 5 and 7 with a goal of between 2 and 4 METs and Borg RPE Scale of between 11 and 12. To qualify for phase 1, patients generally need to (1) be free of any angina for the preceding 8 hours, (2) have no cardiac enzyme increase, (3) have no clinical signs of heart failure, and (4) have no new signs of any changes in the ECG in the preceding 8 hours.¹³ The first phase may last up to 6 weeks, and an exercise stress test is often utilized to assure improvement. As a general rule, patients should not be stressed to a point that they are not able to converse during cardiac rehabilitation (above a Borg perceived exertional scale rating of 13); if this occurs, the rehabilitation session should be paused (Table 49–5).

A relative perceived exertion (RPE) of 13 corresponds roughly to 60% VO₂ max, whereas an RPE of 16 corresponds to a VO₂ max of 85%. An understanding of the correlation of the RP with VO₂ max during exercise is critical in cardiac rehabilitation¹² (Fig. 49–1).

The second phase generally starts after 6 weeks of the adverse event and is usually in the ambulatory setting. A goal of this phase is to educate the patient about how to exercise safely in a structured environment. Typically, an exercise stress test is obtained prior to beginning phase 2 of cardiac rehabilitation. The exertion of activities may be increased to 7 to 8 METs, if results of the stress test are reassuring.

Cardiac stress testing is a low-risk diagnostic test to determine potential for ischemia, electrical abnormalities, and effect of exercise on blood pressure control simultaneously. Absolute and relative endpoints have been developed in stress testing (Table 49–7). These tests play an important role in the different phases of cardiac rehabilitation described earlier.

The Bruce protocol is frequently utilized in cardiac rehabilitation but is limited by the fact that it starts at 4.6 METs. In contrast, the modified Bruce protocol initiates at 2.3 METs and increases at the same rate as the standard Bruce protocol. Patients intolerant of the modified Bruce protocol may benefit from the Naughton-Balke protocol, which starts at 2 mph, with an elevation increasing by 3.5% every 3 minutes.

Patients intolerant of the exercise stress test (e.g., conduction abnormality, left ventricular hypertrophy, positive inotrope utilization/requirement, ischemic ECG changes during the test) are candidates for pharmacologic stress testing (Fig. 49–2).

The numerous types of stress tests can be divided into exercise and chemically induced stress testing. Standard testing involves the patient actively exercising, whereas the chemical testing utilizes infusion of a chemical to raise the heart rate or cause cardiac ischemia when direct physical exercise is not practical. All tests will conclude with a comment on potential for ischemia. Stress tests are often repeated in order to determine interval change over time. It is not uncommon to see improvement in function after a course of cardiac rehabilitation combined with aggressive medical optimization.¹⁴ Absolute and relative endpoints are identified in stress tests (Table 49–6).

Results of the stress test are critical in planning future cardiac rehabilitation, as it predicts risk (Table 49–7). Of note, tolerance of each additional MET conveys an additional 12% increase in the likelihood of survival.¹⁵

The third phase of cardiac rehabilitation consists of an independent cardiac rehabilitation program often under the supervision of a physical therapist. Phase 3 generally occurs two to three times a week. Phase 4 is completely independent exercise in a gym or health club venue.