(Chest. 2002;122:338-343.)
© 2002
American College of Chest Physicians
Effects of a Contemporary, Exercise-Based Rehabilitation and Cardiovascular Risk-Reduction Program on Coronary Patients With Abnormal Baseline Risk Factors*
Barry Franklin, PhD;
Kimberly Bonzheim, MSA;
JoAnne Warren, BSc;
Sue Haapaniemi, MS;
Nancy Byl, RN, BSN and
Neil Gordon, MD, PhD, MPH
* From the Department of Medicine (Dr. Franklin and Mss. Bonzheim, Warren, Haapaniemi, and Byl), Division of Cardiology (Cardiac Rehabilitation), William Beaumont Hospital, Royal Oak, MI; and the Center for Heart Disease Prevention (Dr. Gordon), St. Joseph’s/Candler Health System, Savannah, GA.
Correspondence to: Barry A. Franklin, PhD, Director, Cardiac Rehabilitation and Exercise Laboratories, Beaumont Rehabilitation and Health Center, 746 Purdy St, Birmingham, MI 48009; e-mail: bfranklin{at}beaumont.edu
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Abstract
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Phase II cardiac rehabilitation programs are associated with improvements in exercise tolerance, coronary risk factors, and psychosocial well-being. Nevertheless, previous reports have generally evaluated the global effectiveness of these programs (ie, on all subjects, collectively), which may serve to camouflage or attenuate the impact of these interventions on specific patient subsets. In this study, we investigated the effectiveness of a contemporary, exercise-based cardiac rehabilitation program that included a cardiovascular risk-reduction intervention, using a computerized database on 117 patients (average age, 66.5 years; 68% men; 96% white) who completed pre-phase II and post-phase II evaluations. Exercise training involved three 45- to 60-min sessions per week at minimum of 40 to 50% to a maximum of 75% oxygen uptake for 6 to 8 weeks. The effectiveness of the exercise training program was substantiated by significant (p 
0.05) reductions in heart rate (- 8 beats/min), systolic BP (- 11 mm Hg), and rating of perceived exertion (- 2, 6 to 20 scale) at a standard submaximal workload. Initial and follow-up ratings of overall health were improved: excellent (2.6 to 4.3%) and very good (20.7 to 35.7%). Average changes (p 0.05 unless otherwise indicated) for all participants and those with abnormal baseline risk factors were as follows: systolic BP (- 4 mm Hg and - 16 mm Hg); diastolic BP (- 5 mm Hg and - 18 mm Hg); total cholesterol (- 19 mg/dL and - 75 mg/dL); low-density lipoprotein cholesterol (- 17 mg/dL and - 61 mg/dL); high-density lipoprotein cholesterol (- 1 mg/dL [not significant] and + 11 mg/dL); and triglycerides (- 5 mg/dL [not significant] and - 82 mg/dL), respectively. The present findings suggest that a positive correlation generally characterizes the change in coronary risk factors subsequent to a contemporary phase II cardiac rehabilitation program. Patients with the worst coronary risk factor profiles at baseline demonstrated the greatest improvements.
Key Words: cardiac rehabilitation • coronary risk factors • exercise testing • exercise training • high-density lipoprotein cholesterol • low-density lipoprotein cholesterol • total cholesterol • triglycerides
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Introduction
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Despite major technologic advances in the field of cardiovascular medicine, coronary artery disease (CAD) remains the leading cause of death in the United States and most developed countries.1
Contemporary studies2
3
now suggest that multifactorial risk factor modification—especially more intensive measures to control hyperlipidemia with diet, drugs, and exercise—may slow, halt, and even reverse the progression of atherosclerotic CAD. Added benefits include a reduction in anginal symptoms, decreases in exercise-induced ischemic ST-segment depression, fewer recurrent cardiac events, and a diminished need for coronary revascularization procedures.4
5
Several mechanisms may contribute to these improved clinical outcomes, including partial (albeit small) anatomic regression of coronary artery stenoses, a reduced incidence of plaque rupture, and improved coronary artery vasomotor function.6
These findings suggest a new paradigm in the treatment of patients with CAD.7
Only 11 to 38% of patients with CAD participate in formal cardiac rehabilitation programs, highlighting the vast underutilization of these comprehensive services (eg, medical evaluation, prescribed exercise, cardiac risk factor modification, and education, counseling, and behavioral interventions), especially in older adults and women.8
9
Phase II cardiac rehabilitation programs are associated with significant improvements in exercise tolerance and psychosocial well-being, and more modest changes in coronary risk factors.10
However, previous studies have generally evaluated the global effectiveness of these programs (ie, on all patients, collectively), which may serve to camouflage or attenuate the impact of these interventions on specific patient subsets.10
The present study was designed to investigate the effectiveness of a contemporary, exercise-based cardiac rehabilitation program that included a cardiovascular risk-reduction intervention (INTERxVENT),11
using a computerized database on coronary patients who completed pre-phase II and post-phase II evaluations, with specific reference to patients with abnormal baseline (that is, at program entry) coronary risk factors.
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Materials and Methods
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Subjects
Our study population included 117 consecutive patients (average age, 66.5 years; 68% men; 96% white) who completed pre-phase II and post-phase II evaluations using the INTERxVENT computerized database. Demographics of participants (n = 117) who completed both program entry and exit evaluations are summarized in Table 1 . Table 2
provides details on the prevalence of cardiovascular-related diagnoses among these participants.
Health History Questionnaire
An extensive health history questionnaire, including information on clinical variables, coronary risk factors, submaximal and peak exercise test performance, subject demographics, and psychosocial well-being was jointly completed by program participants and staff at program (phase II) entry. A modified (shortened) version of the questionnaire was completed at program exit.
Laboratory Measures and Submaximal Exercise Testing
Height, weight, resting systolic and diastolic BP, fasting serum lipids and lipoproteins, and fasting glucose were measured at program entry and exit. To evaluate the effectiveness of the physical training program (ie, physiologic evidence of a training effect), we assessed heart rate, systolic BP, and rating of perceived exertion (6 to 20 scale)12
at an individually determined standard submaximal workload at program entry and exit. The same treadmill speed and grade, which initially evoked a heart rate response within the patient’s prescribed training zone, was used for both evaluations.
Physical Training Program
The aerobic circuit training program included three 45- to 60-min sessions per week for 6 to 8 weeks. Each session included a warm-up period (5 to 10 min), an endurance phase (30 min), and a cool-down period. Training involved two upper-extremity and/or lower-extremity exercise devices, 15 min at each station. Potential training modalities included treadmill walking, rowing, automated stair climbing, recumbent ergometry, and arm, leg, or combined arm-leg ergometry.
Each patient’s work rate (intensity) during the endurance phase was directed at achieving a minimum of 40 to 50% to a maximum of 75% of their estimated maximum oxygen uptake achieved on baseline exercise testing.13
When appropriate, the relative training intensity was gradually increased over the duration of the phase II program. Actual intensity was verified by continuous ECG-telemetry monitoring, using the relative heart rate corresponding to the prescribed metabolic work rate (approximately 55 to 80% of maximum heart rate). Participants were instructed to adjust their work rate to meet their target intensity range, using perceived exertion (ie, fairly light [score of 11] to somewhat hard [score of 13]) as an adjunctive intensity modulator.
INTERxVENT
In addition to participating in exercise training, patients received education on cardiovascular disease (CVD), coronary risk factors, and lifestyle modification with the use of the INTERxVENT program.11
Patient education was provided during cardiac rehabilitation sessions and included the use of written materials, audio compact disks (nutrition, physical activity and exercise, stress management, prevention, and health promotion), group education, and one-on-one counseling. On initiation of the cardiac rehabilitation program, patients were provided a computer-generated report outlining their current coronary risk factors, the goal level for each risk factor based on national guidelines (Table 3
),4
13
14
15
16
17
18
19
and an individualized lifestyle management action plan for achieving these goals, based on several behavior change models (ie, social learning theory, stages of change, and single-concept learning theory). The action plan focused on lifestyle modification, but also identified the need for prescribed medications and/or medication changes to optimize coronary risk factor management in accordance with national guidelines. Based on the recommendations in each patient’s action plan, patients were referred to their personal physicians for consideration of medication changes.
Statistical Analysis
Statistical analyses included calculations of means, SDs, and SEs. Student t test for paired observations was used to calculate differences between before and after exercise-based cardiac rehabilitation. All t tests were two tailed, and statistical significance was established at p 0.05. Statistical methods were those outlined by Steel and Torrie.20
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Results
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The effectiveness of the exercise training program was substantiated by significant (p 0.05) reductions in heart rate (- 8 beats/min), systolic BP (- 11 mm Hg), and rating of perceived exertion (- 2, 6 to 20 scale) at a standard submaximal workload. Initial and follow-up ratings of overall health were also improved: excellent (2.6 to 4.3%) and very good (20.7 to 35.7%). Figure 1 summarizes the prevalence of potentially modifiable coronary risk factors for all participants (n = 117) at baseline and follow-up. Overall, there were modest to appreciable reductions in the percentage of participants with systolic/diastolic hypertension, abnormal low-density lipoprotein (LDL) cholesterol levels, and elevated blood glucose levels, whereas the proportion of overweight patients and cigarette smokers remained essentially unchanged.
Patients who completed the initial and follow-up evaluations were categorized according to subsets with abnormal baseline coronary risk factors. These included systolic BP 
130 mm Hg (n = 53); diastolic BP 85 mm Hg (n = 19); total cholesterol 200 mg/dL (n = 11); LDL cholesterol 100 mg/dL (n = 36); high-density lipoprotein (HDL) cholesterol 35 mg/dL (n = 14); triglycerides 200 mg/dL (n = 12); obesity, body mass index 30 (n = 48); and blood glucose 126 mg/dL (n = 15). Figure 2
summarizes the effect of the program on key cardiovascular risk factors in these patient subsets. All variables demonstrated statistically significant changes (p 0.05), with individual total cholesterol, LDL cholesterol, and triglyceride reductions averaging 75 mg/dL, 61 mg/dL, and 82 mg/dL, respectively. Moreover, HDL cholesterol increased by 11 mg/dL in program participants with low baseline values, whereas blood glucose decreased by 48 mg/dL in those with high baseline values.
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Discussion
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Previous studies3
10
21
have documented the clinical effectiveness of phase II cardiac rehabilitation programs and physician-supervised, nurse case-managed cardiovascular risk-reduction programs in patients with documented CAD. The present investigation evaluated the effectiveness of a contemporary, exercise-based phase II cardiac rehabilitation program that included INTERxVENT, using a computerized database, educational notebook, and lifestyle modification audiotapes that were played during the exercise sessions. However, in contrast to previous investigations, patient subsets with abnormal baseline risk factors were identified and evaluated separately.
Although previous reports generally evaluated the global effectiveness of exercise-based cardiac rehabilitation programs (ie, on all subjects, collectively), this methodology may serve to camouflage or attenuate the impact of these interventions on specific patient subsets. Our findings suggest that a positive correlation generally characterizes the change in coronary risk factors subsequent to a phase II cardiac rehabilitation program. Patients with the worst coronary risk factor profiles at baseline demonstrated the greatest relative improvements (Fig 2)
.
A reduced rate-pressure product at a given submaximal workload is compatible with a training effect and suggests increased exercise tolerance that most likely reflects improved aerobic fitness.22
This is particularly beneficial, since most patients with clinically manifest heart disease have a subnormal aerobic capacity (50 to 70% age, gender predicted). Because a given submaximal task or work rate requires a relatively constant aerobic requirement, the cardiac patient finds that after an exercise training program, he or she is working at a lower percentage of his or her peak oxygen uptake, with greater reserve. Moreover, it has been reported that aerobic capacity is an independent predictor for all-cause and cardiovascular mortality in patients referred to a cardiac rehabilitation program.23
According to the cardiac rehabilitation clinical practice guideline,10
exercise training has only modest effects in reducing BP levels in patients with CAD. However, a review of the scientific evidence revealed that no study was specifically designed to address hypertension control in patients with elevated BP participating in exercise-based cardiac rehabilitation. More than one half of the present population had either elevated systolic BP ( 130 mm Hg) and/or diastolic BP ( 85 mm Hg) on entry to the program. When these patients were individually reviewed, the average decreases in systolic and diastolic BP were 16 mm Hg and 18 mm Hg, respectively. Such reductions, if maintained, are compatible with a reduced risk of subsequent cardiovascular events.15
Numerous studies2
3
24
25
26
in patients with documented CAD have now shown that lipid lowering retards the progression of angiographically demonstrated coronary arterial narrowing, causes reduction in the size of atherosclerotic plaque, and decreases the frequency of recurrent cardiac events. The present findings were especially impressive relative to changes in lipids and lipoproteins among those patients with abnormal values at baseline, particularly in the subset with an elevated LDL subfraction ( 100 mg/dL; n = 36). Overall, these patients demonstrated an average reduction in LDL cholesterol of 61 mg/dL that, in most cases, was likely attributed to the concomitant initiation of and/or bolstering of lipid-lowering medications by these patients’ physicians.
Given that type 2 diabetes mellitus is a factor that commonly predisposes patients to coronary atherosclerosis, careful regulation of blood glucose is an important component of secondary prevention.7
17
For all patients (n = 117), blood glucose levels decreased from an average entry value of 111 mg/dL to 95 mg/dL at follow-up. In addition, the subset with elevated blood glucose levels at baseline ( 126 mg/dL; n = 15) demonstrated an average reduction of 48 mg/dL.
In recent years, psychosocial factors, including stress, anxiety, hostility, social isolation, and depression, have been increasingly implicated in the development of CAD, as well as potential triggers for recurrent cardiac events.27
Nearly 20% of the current subjects reported a significant problem with anxiety, often attributed to health concerns, during their initial evaluation. Nevertheless, as a result of their participation in the program, those who reported their health as "excellent" increased from 2.6 to 4.3%, whereas those providing ratings of "very good" increased from 20.7 to 35.7%. Compared with the prior year, the percentage reporting "much better" health increased more than threefold at the conclusion of the program (9.5% vs 33.6%, respectively). These findings are in agreement with previous reports indicating that exercise-based cardiac rehabilitation often results in improvement in measures of psychosocial status and well-being.10
28
Finally, we acknowledge several limitations to this prospective study. These include the absence of a usual-care control group; regression to the mean in patients with abnormal baseline risk factors; the small number of female study participants (n = 37); a well-educated, upper middle-class population that was predominantly white (96%), limiting the generalizability of our findings to less affluent minorities and other ethnic groups; and the relatively short duration of follow-up. Nevertheless, these results have important implications regarding outcomes assessment and third-party reimbursement issues.
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Footnotes
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Abbreviations: CAD = coronary artery disease; CVD = cardiovascular disease; HDL = high-density lipoprotein; INTERxVENT = cardiovascular risk-reduction intervention; LDL = low-density lipoprotein
Received for publication January 15, 2002.
Accepted for publication January 16, 2002.
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References
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- . Centers for Disease Control and Prevention. (2001) Mortality from coronary heart disease and acute myocardial infarction-United States, 1998. MMWR Morb Mortal Wkly Rep 50,90-93[Medline]
- Ornish, D, Brown, SE, Scherwitz, LW, et al (1990) Can lifestyle changes reverse coronary heart disease? Lancet 336,129-133[CrossRef][ISI][Medline]
- Haskell, WL, Alderman, EL, Fair, JM, et al (1994) Effects of intensive multiple risk factor reduction on coronary atherosclerosis and clinical cardiac events in men and women with coronary artery disease: the Stanford Coronary Risk Intervention Project (SCRIP). Circulation 89,975-990[Abstract/Free Full Text]
- Smith, SC, Blair, SN, Bonow, RO, et al (2001) AHA/ACC guidelines for preventing heart attack and death in patients with atherosclerotic cardiovascular disease: 2001 update. Circulation 104,1577-1579[Free Full Text]
- Pearson, TA, Fuster, V (1996) 27th Bethesda Conference: executive summary. J Am Coll Cardiol 27,961-963
- Franklin, BA, Kahn, JK (1996) Delayed progression or regression of coronary atherosclerosis with intensive risk factor modification: effects of diet, drugs, and exercise. Sports Med 22,306-320[ISI][Medline]
- Franklin, BA, Shephard, RJ (2000) Avoiding repeat cardiac events: the ABCDESs of tertiary prevention. Phys Sports Med 28,31-58
- Ades, PA, Waldmann, ML, Polk, DM, et al (1992) Referral patterns and exercise response in the rehabilitation of female coronary patients aged 62 years. Am J Cardiol 69,1422-1425[CrossRef][ISI][Medline]
- Ades, PA, Waldmann, ML, McCann, WJ, et al (1992) Predictors of cardiac rehabilitation participation in older coronary patients. Arch Intern Med 152,1033-1035[Abstract]
- Wenger, NK, Froelicher, ES, Smith, LK, et al (1995) Cardiac rehabilitation guideline No. 17. U.S. Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research, National Heart, Lung, and Blood Institute Rockville, MD. publication No. 96–0672
- Gordon, NF, Salmon, RD, Mitchell, BS, et al (2001) Innovative approaches to comprehensive cardiovascular disease risk reduction in clinical and community-based settings. Curr Atheroscler Rep 3,498-506[Medline]
- Borg, G (1982) Psychophysical bases of perceived exertion. Med Sci Sports Exerc 14,377-381[ISI][Medline]
- Franklin, BA Whaley, MH Howley, ET eds. American College of Sports Medicine. Guidelines for exercise testing and prescription 6th ed. 2000 Lippincott, Williams and Wilkins Baltimore, MD.
- Grundy, SM, Balady, GJ, Criqui, MH, et al (1997) Guide to primary prevention of cardiovascular diseases: a statement for health care professionals from the task force on risk reduction. Circulation 95,2329-2331[Free Full Text]
- . Joint National Committee. (1997) The sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Arch Intern Med 157,2413-2446[Abstract]
- Expert panel on detection, evaluation, and treatment of high blood cholesterol in adults: executive summary of the third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (ATP III). JAMA 2001;285,2486-2497[Free Full Text]
- . American Diabetes Association. (2000) Clinical practice recommendations 2000. Diabetes Care 23,S1-S112
- . National Heart, Lung, and Blood Institute. (1998) Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults. National Institutes of Health Bethesda, MD. publication No. 98–4083
- . American Association of Cardiovascular and Pulmonary Rehabilitation. (1998) Guidelines for cardiac rehabilitation and secondary prevention programs. Human Kinetics Publishers Champaign, IL.
- Steel, RG, Torrie, JH (1960) Principles and procedures of statistics. McGraw-Hill New York, NY.
- DeBusk, RF, Miller, NH, Superko, HR, et al (1994) A case-management system for coronary risk factor modification after acute myocardial infarction. Arch Intern Med 120,721-729
- Balady, GJ, Fletcher, BJ, Froelicher, ES, et al (1994) Cardiac rehabilitation programs: a statement for healthcare professionals from the American Heart Association. Circulation 90,1602-1610[Free Full Text]
- Vanhees, L, Fagard, R, Thijs, L, et al (1994) Prognostic significance of peak exercise capacity in patients with coronary artery disease. J Am Coll Cardiol 23,358-363[Abstract]
- Blankenhorn, DH, Nessim, SA, Johnson, RL, et al (1987) Beneficial effects of combined colestipol-niacin therapy on coronary atherosclerosis and coronary venous bypass grafts. JAMA 257,3233-3240[Abstract]
- Brown, G, Albers, JJ, Fisher, LD, et al (1990) Regression of coronary artery disease as a result of intensive lipid-lowering therapy in men with high levels of apolipoprotein B. N Engl J Med 323,1289-1298[Abstract]
- Schuler, G, Hambrecht, R, Schlierf, G, et al (1992) Regular physical exercise and low-fat diet: effects on progression of coronary artery disease. Circulation 86,1-11[Abstract/Free Full Text]
- Franklin, BA (2001) Psychosocial considerations in heart disease. JHK Coll Cardiol 9(suppl),16-22
- Linden, W, Stossel, C, Maurice, J (1996) Psychosocial interventions for patients with coronary artery disease: a meta-analysis. Arch Intern Med 156,745-752[Abstract]
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Abstract
Introduction
