Exercise-Based Cardiac Rehabilitation Is Safe, Yet Underused in Japan

Cardiovascular disease (CVD) continues to be a very common cause of morbidity and mortality in Japan. Cardiac rehabilitation (CR) is the provision of comprehensive long-term services involving medical evaluation, prescriptive exercise, cardiac risk factor modification and education, counseling, and behavioral interventions.¹ Exercise-based CR has been shown to be beneficial in improving exercise capacity, lipid profile, obesity indices, inflammation, psychological distress, autonomic tone and quality of life, and reducing major morbidity and mortality in patients with CVD (Table).² Thus, exercise-based CR have an important role in both primary and secondary prevention of CVD.^3–5

Table. Benefits of Cardiac Rehabilitation and Exercise Training Programs

Improvement in exercise capacity

1. Estimated METS +35%

2. Peak V̇O2 +15%

3. Peak anaerobic threshold +11%

Improvement in lipid profiles

1. Total cholesterol –5%

2. Triglycerides –15%

3. HDL-C +6% (higher in patients with low baseline)

4. LDL-C –2%

5. LDL-C/HDL-C –5% (higher in certain subgroups)

Reduction in inflammation

hs-CRP –40%

Reduction in indices of obesity

1. BMI –1.5%

2. % fat –5%

3. Metabolic syndrome –37%

Improvements in behavioral characteristics

1. Depression

2. Anxiety

3. Hostility

4. Somatization

5. Overall psychological distress

Improvements in quality of life and components

Improvement in autonomic tone

1. Increased heart rate recovery

2. Increased heart rate variability

3. Reduced resting pulse

Improvements in blood rheology

Reduction in hospitalization costs

Reduction in major morbidity and mortality

BMI, body mass index; hs-CRP, high-sensitivity C-reactive protein; HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density lipoprotein-cholesterol.

Adapted with permission from Swift DL et al.²

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Exercise-based CR and exercise testing have been useful in practical cardiology.⁶ Cardiovascular complications related to exercise-based CR and exercise testing were reported before the 1990 s, the era of widespread use of revascularization.^7,8 The complication rates are not necessarily generalizable to contemporary cardiovascular patients who receive more aggressive therapies and are generally older with more coexisting illness. Moreover, there has not been a large-scale study in Japan regarding the safety of exercise-based CR and exercise testing. Therefore, it would be very useful to this in the present time.

In this issue of the Journal, Saito et al⁹ report on their questionnaire sent to 1,875 hospitals to investigate the safety of exercise-based CR and exercise testing for cardiac patients in modern Japanese cardiology practice. Of the 1,059 hospitals giving effective replies, only 136 (12.8%) were providing recovery-phase CR. The incidence of life-threatening adverse events (LAEs) and of all adverse events (AEs) related to exercise-based CR was very low. With regard to fatal events, there were no deaths related to exercise-based CR. CR programs were categorized into Formal and Non-formal, defined respectively as a program in which the exercise prescription of each patient was determined according to individual exercise testing or without individual exercise prescription. Consequently, the incidence of LAEs and AEs during exercise sessions was significantly lower in hospitals with Formal CR than in those with Non-formal CR. With regard to exercise testing, the incidence of LAEs and AEs was low. The amount of exercise testing was markedly lower in hospitals with Non-formal CR than in those with Formal CR, although there were no differences in the numbers of patients with acute myocardial infarction (AMI) and percutaneous coronary intervention (PCI) procedure. Thus, both exercise-based CR and exercise testing are generally safe in Japan.

The incidence of LEAs related to exercise-based CR in the previous studies conducted before the 1990 s was 1.71 to 2.88/100,000 patient-hours,^7,10 which is much higher than in the present study. In a 2003 French national survey, the incidence of LFAs was 0.13/100,000 patient-hours.¹¹ The incidence of LFAs related to exercise testing was 2.87 to 92.8/100,000 tests^8,12 in studies conducted before 1990 s and 2.4/100,000 tests in the recent French survey.¹¹ Comparing those data, exercise-based CR and exercise testing in Japan are much safer than before the 1990 s and comparable to the recent French report. The possible reasons for the safety of exercise-based CR may be recent advances in pharmacological treatments (eg, use of statins and β-blockers), in interventional treatments (eg, widespread of primary PCI with stent implantation), and surgical treatments (eg, development of off-pump coronary artery bypass graft surgery).

Saito et al⁹ emphasize the importance of individual exercise prescription determined by exercise testing for exercise-based CR. The patients who participate in exercise-based CR are heterogeneous because they have various pathologic states including persistent myocardial ischemia, impaired left ventricular function and fatal arrhythmia. In such patients, the exercise prescription should be strictly determined according to individual exercise testing. Accordingly, programs without individual exercise prescription may be unsafe for exercise-based CR. Exercise testing is used to determine the anaerobic threshold and evaluate exercise tolerance. Therefore, exercise-based CR based on individual exercise prescription could decrease adverse cardiovascular events during recovery-phase CR.

Although the benefits of CR have been established, participation rates for eligible patients with CVD are poor (in the USA 14–35% after AMI and 31% after coronary artery bypass graft surgery; 29% after AMI in the UK; 23% after AMI in France).¹³ In a Japanese survey, the implementation rate of recovery-phase CR was 11.8% overall and only 19.8% even in the Japanese Circulation Society training hospitals. The estimated participation rate in outpatient recovery-phase CR was 4–8% in Japan.¹⁴ Thus, patient participation in recovery-phase CR is the lowest in Japan (Figure).¹⁵

Figure.

Comparison of patient participation rates in cardiac rehabilitation according to clinical background and country. (Adapted with permission from Goto Y.¹⁵)

Unlike other developed countries, the incidence of CVD has been increasing in Japan in association with increases in coronary risk factors.¹⁶ Despite exercise-based CR, in which the individual exercise prescription is determined by exercise testing, being remarkably safe,⁸ it is still underused in Japan, so widespread use of exercise-based CR could contribute to a decrease in incidence of CVD, leading to reductions in morbidity and mortality.

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