Effects of exercise training on peak performance and quality of life in congestive heart failure patients

Journal of Cardiac Failure Vol. 5 No. 3 1999

Effects of Exercise Training on Peak Performance and Quality of Life in Congestive Heart Failure Patients STEPHEN S. GOTTLIEB, MD, *t MICHAEL L. FISHER, MD, *t RONALD FREUDENBERGER, MD,* SHAWN ROBINSON, MD,* GRETCHEN ZIETOWSKI, MS, RN, t LYNETTE ALVES, MS, t CATHERINE KRICHTEN, RN, CRNP,* PETER VAITKEVICUS, MD, ** ROBERT McCARTER, ScD* Baltimore, Maryland

ABSTRACT Background: Exercise programs for patients with heart failure have often enrolled and evaluated relatively healthy, young patients. They also have not measured the impact of exercise performance on daily activities and quality of life. Methods and Results: We investigated the impact of a 6-month supervised and graded exercise program in 33 elderly patients with moderate to severe heart failure randomized to usual care or an exercise program. Six of 17 patients did not tolerate the exercise program. Of those who did, peak oxygen consumption increased by 2.4 ± 2.8 mL/kg/min (P < .05) and 6-minute walk increased by 194 ft (P < .05). However, outpatient energy expenditure did not increase, as measured by either the doubly labeled water technique or Caltrac accelerometer. Perceived quality of life also did not improve, as measured by the Medical Outcomes Study, Functional Status Assessment, or Minnesota Living With Heart Failure questionnaires. Conclusion: Elderly patients with severe heart failure can safely exercise, with an improvement in peak exercise tolerance. However, not all patients will benefit, and daily energy expenditure and quality of life do not improve to the same extent as peak exercise. Key words: exercise therapy, heart failure, quality of life, functional status.

As recently as 1992, standard teaching was that restriction of physical activity should be considered early in the treatment of congestive heart failure (1). More recently, many studies have suggested the opposite; exercise programs can actually improve exercise tolerance in these patients. However, these studies are often un-

controlled and have generally enrolled young and relatively healthy patients (2-5). The impact of exercise in sicker patients remains little explored. The end points of exercise studies also raise questions. Most evaluations of exercise programs use changes in m a x i m u m exercise as the goal. Thus, documentation of increases in peak oxygen consumption or maximal exercise tolerance has been used as proof of the efficacy of such programs. However, these end points may not be not clinically relevant. It is unknown whether an increase in maximal exercise reflects improved quality of life or ability to perform daily activities. W e therefore investigated the impact of a 6-month supervised and graded exercise program in elderly patients with moderate to severe heart failure. In a rigorous, controlled study, we evaluated maximal exercise (indicated by peak oxygen consumption and exercise duration

From the *Division of Cardiology, Department of Medicine, University of Maryland School of Medicine; and the ¢Department of Veterans Affairs Medical Center, Baltimore, Maryland. Supported in part by grant no. P60AG12583 from the National Institute of Aging, Claude D. Pepper Older Americans Independence Center, Bethesda, MD. Manuscript received February 15, 1999; revised manuscript received April 19, 1999; revised manuscript accepted April 19, 1999. Reprint requests: Stephen S. Gottlieb, MD, Division of Cardiology, University of Maryland School of Medicine, 22 South Greene Street, Baltimore, MD 21201. Copyright © 1999 by Churchill Livingstone ® 1071-9164/99/0503-0002510.00/0

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on a maximal stress test) and submaximal exercise (indicated by 6-minute walk). In addition, we looked at the impact of an exercise program on daily activity. A patient' s usual outpatient energy expenditure was evaluated using a hip accelerometer and the doubly labeled water technique. The former estimates activity energy expenditure by assessing hip acceleration. The latter provides a direct, integrated measure of daily energy expenditure over an extended period of time by calculating carbon dioxide production using ingested hydrogen and oxygenlabeled water. The Minnesota Living With Heart Failure, Functional Status Assessment (FSA), Medical Outcomes Study (MOS), and Center for Epidemiologic Studies Depression (CES-D) questionnaires were used to assess the patients' perceptions of their disease and its impact on their life.

Methods Patients were eligible for inclusion on this study if they had symptomatic congestive heart failure (New York Heart Association [NYHA] classes II and III) for at least 3 months and were on stable medications for at least 1 month. All patients were on maximal medical therapy with angiotensin-converting enzyme inhibition, diuretics, and digoxin. The mean lisinopril dose was 27 + 10 mg. Seventeen of the patients were receiving beta-blockers. All patients had an ejection fraction by nuclear ventriculography of less than 40%. No patient had obstructive valvular disease, myocardial infarction within 3 months, or limitation of exercise secondary to angina or arrhythmias.

Baseline Assessments Maximal exercise tolerance and maximal oxygen consumption were assessed in all subjects before randomization. Exercise tests were performed at least twice, and peak oxygen consumption of the final test needed to be within 10% of the previous test. To enroll patients with markedly impaired oxygen consumption, as well as those with milder symptoms, a protocol was developed to permit the detection of small (but clinically important) differences in severely ill patients, as well as clinically important larger differences in less ill patients. The grade of the treadmill was increased by 2% every 2 minutes, beginning at 0%. The speed was initially 1.2 mph. After 6 minutes, this was increased to 1.5 mph and subsequently increased every 4 minutes to 1.7, 2.0, 2.4, and 2.6 mph. Submaximal exercise was assessed using the 6-minute walk. Patients are instructed to walk from end to end of a 100-foot course at a comfortable pace while attempting to cover as much ground as possible. After 6 minutes, the distance covered is measured to the nearest foot.

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Functional activity was assessed in two different ways. Total kilocalories expended were measured over a 10day period using the doubly labeled water technique (6). After providing a baseline urine sample, each subject consumed a mixed oral dose of 2H20 (0.78 g/kg of body mass) and H21so (0.092 g/kg of body mass). Urine samples were obtained the next morning and 10 days later. The rate of carbon dioxide production (rCO 2, in moles per day) was calculated using the equation: rCO 2 = 0.4554 × N(Ko - (DSR)Kh) where N is body water pool, K o and K h a r e the turnover rates of H2180 and 2HzO, and DSR is the dilution space ratio ( N h / N o ) . Carbon dioxide production rates were used to calculate daily energy expenditure using the equation: Energy expenditure = [3.9(rCO2/0.9) + (1.1 × rCO2)] × 22.4 assuming a respiratory quotient of 0.85. Free activity can be estimated by subtracting directly determined resting metabolic rate and estimated digestion caloric expenditure. Exercise energy expenditure was also estimated using a hip accelerometer (Caltrac, Muscle Dynamics, Torrence, CA). This is placed on the hip, measures the acceleration of hip movement, and thereby estimates kilocalories expended (7). Quality of life was assessed using questionnaires. The CES-D scale was used to evaluate depression (8). The FSA was used to evaluate basic activities of daily living and intermediate activity (9). The MOS was used to assess physical functioning, role limitations secondary to physical health, social functioning, mental health, general health perceptions, and pain (10). Only the parameters directly related to heart failure are reported. The Minnesota Living With Heart Failure questionnaire was used as a specific heart failure tool (11).

Randomization and Exercise After baseline assessment, patients were randomly assigned to either exercise rehabilitation or the nonintervention control groups. The exercise rehabilitation program consisted of 6 months of supervised aerobic training sessions three times per week at the Baltimore Veterans Affairs Medical Center. Patients initially rode a Schwinn Aerdyne bike (Boulder, CO), which uses both arms and legs. After adequate familiarization and increasing exercise capacity, subjects were gradually introduced to walking on a treadmill. Patients were monitored and supervised by a nurse or exercise physiologist. The final exercise program consisted of 15 ft on bike and 30 ft on treadmill to a perceived level on the Borg Scale of 12 to 13. The intensity of training increased as tolerated by the patient.

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Randomized| 33

I

Control i Fig. 1. Flow diagram of the patients randomized in this study. Eleven patients completed 6 months of exercise after randomization and five additional patients exercised for 6 months after 6 months of usual care.

Exercise /

Compl-e| Complete| 14

|

11

I

Non-c-omp-iian-i

1 plianI

Crossoverj

xTis° ]

Control patients were provided with usual care. Medical follow-up of both the control and intervention patients was provided by specialized heart failure physicians.

Follow-Up At the end of the 6-month intervention or control period, all initial tests were repeated, with the exercise test obtained only once.

Crossover After final assessment, the control group was offered the exercise intervention. This crossover group was used for comparisons of the primary end points because there is no adequate control for these crossover patients. However, the crossover group was used for analysis of the secondary end points. Because there were no changes in the control groups regarding daily energy expenditure and questionnaire outcomes, we evaluated the change from baseline in these parameters for the combined group of 5 crossover patients and 11 patients randomized to exercise.

not

Statistics Pre- and postintervention comparisons are based on two-tailed paired t-tests, and groupwise comparisons are based on two-tailed unpaired t-tests. Means _ SD are given.

Results Patient Population Thirty-three patients were randomized to the study, 16 patients to usual care and 17 patients to exercise. Of the patients randomized to exercise, 11 patients completed 6 months of follow-up. Of the six patients who dropped out, one patient died, one patient was noncompliant, and four patients believed they were too ill to continue. (Fig. 1) Of the 16 patients randomized to the control group, 2 patients had surgery and were not reevaluated. Fourteen patients completed follow-up. Five of these patients accepted the opportunity to enter the exercise program after the randomization period, and all tests were repeated in these five patients after 6 months of exercise. As seen in Table 1, there were no differences at baseline between patients randomized to the control group and those randomized to the exercise program. The patients were relatively ill, with most patients classified as N Y H A class III. The mean peak oxygen consumption was 14.0 mL/kg/min. The patients were elderly, with a mean age of 65 years. Patients believed their heart failure limited their activities, indicated by the questionnaire findings.

Compliance The 11 patients who exercised after randomization to the exercise program attended 75% + 8% of their thriceweekly sessions (range, 54% to 85%). Of all 16 patients who exercised, 78% of the sessions were attended. The maximum mets attained on treadmill were 3.8 + 1.1.

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Table 1. Comparison of Patients Who Completed 6 Months of Randomization Control Age (y) Race Black White Ejection fraction (%) Sex (F/M) NYHA class II III Cause Ischemic Primary Activity by doubly labeled water (kcal/d) Hip accelerometer (kcal/d) Exercise duration (min) Peak VO 2 (mL/kghnin) 6-Minute walk (ft) MQOL FSA Activities of daily living Intermediate activity MOS Physical functioning Physical role limitations General health perceptions CES-D

Exercise

Drop-Outs

64 ± 10

67 ± 7

66 + 8

10 4 25 +_ 10 3/11

8 3 22 _+ 8 0/11

3 3 19 _+ 5 1/5

4

5

2

10

6

4

11 3 584 ± 328 293 ± 151 10 ± 4 14.0 ± 2.9 1,291 _+ 160 47 ± 24

7 4 466 ± 329 ± 13 ± 14.1 + 1,340 ± 30 +

392 192 3 1.9 127 29

4 2 327 _+ 212 193 _+ 106 10 _+ 4 13.1 _+ 2.3 1,152 ± 253 45 ± 16

99 + 3 72 _+ 17

96 ± 8 75 ± 12

91 ± 13 67 _+ 29

58 ± 41 ± 48 + 15 +

55 ± 58 ± 65 ± 11 ±

56 ± 14 33 _+ 41 32 ± 10~ 14 ± 8

20 30 14 12

20 19 17 11

NYHA, New York Heart Association; FSA, Functional Status Assessment questionnaire; MOS, Medical Outcomes Study; MQOL, Minnesota Living With Heart Failure questionnaire; CES-D, Center for Epidemiologic Studies Depression questionnaire; VO2, oxygen consumption. * P < .05 versus exercise group.

E i g h t o f the 11 patients e x e r c i s e d for at least the goal of 30 minutes, as did all the patients switched o v e r f r o m control. In addition to the treadmill exercise, the patients e x e r c i s e d for 15 minutes on the bicycle, r e a c h i n g maxim u m activity o f 3.5 + 0.9 mets.

Impact on Daily Activities Despite i m p r o v e d m a x i m a l exercise, w e could not detect a difference in daily activities (Table 2). B y the

Peak V O 2 (ml/kg/min)

Maximal Exercise Patients w h o e x e r c i s e d for 6 m o n t h s i m p r o v e d their p e r f o r m a n c e on m a x i m a l treadmill tests (Fig. 2). This was m o s t p r o n o u n c e d in duration of exercise, w h i c h increased by 4.9 _+ 3.4 minutes in the patients w h o exercised, but was u n c h a n g e d ( - 0 . 2 +_ 3.4 minutes) in the control group (P < .005). P e a k o x y g e n c o n s u m p t i o n also increased in the exercise group (2.4 -+ 2.8 m L / k g / rain) c o m p a r e d with the controls (0.1 + 2.6 m L / k g / m i n ; P < .05). T h e changes w e r e not simply m o t i v a t i o n a l because the p e a k respiratory quotient (RQ) did not c h a n g e in either group. (The value in control patients was 0.98 at baseline and 0.97 after 6 months, and in the exercise group, the v a l u e was 1.00 at baseline and 1.02 after 6 months.) E x e r c i s e also p r o d u c e d a c h a n g e in s u b m a x i m a l exercise, indicated by the 6 - m i n u t e w a l k (Fig. 3). T h e distance w a l k e d in 6 minutes increased by 147 + 194 ft in the e x e r c i s e group, but d e c r e a s e d 61 + 134 ft in the control group (P < .05).

30

20

Exercise Duration (minutes) 30

t

TI

.

[

20-

r 10-

Control

Exercise

Control

Exercise

Fig. 2. Time and peak oxygen consumption (VO2) on the maximal exercise test increased in the exercise group but was unchanged in the control group. (Sym 22), Baseline values; (Sym 23), values obtained at 6 months. The change in time was different between the groups, P < .05. *P < .05 versus baseline.

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6 Minute Walk (Feet) 2000

soo-

l

These results were compared with the 11 patients who completed the exercise program. The patients who did not complete exercise tended to have worse baseline function, indicated by maximal exercise, the 6-minute walk, and energy expenditure. These patients also tended to perceive themselves as more ill, with a statistically significant lower MOS general health perception score and trend to worse scores on the FSA intermediate activity scale, MOS role limitations (secondary to physical status) scale, and Minnesota Living with Heart Failure questionnaire.

T

Discussion Elderly sick patients can have the same response as younger patients when they participate in an exercise program. The present study shows that such patients can safely exercise, and that they can improve maximal and submaximal exercise capability. There were clear improvements in time on a maximal exercise test, peak oxygen consumption, and 6-minute walk. However, there were no differences detected in daily activity energy expenditure or in the patients' self-assessment of the impact of heart failure in their lives.

1000

500

Exercise Performance

0 Control

Exercise

Fig. 3. Distance walked in 6 minutes increased in the exercise group but was unchanged in the control group. (Sym 22), Baseline values; (Sym 23), values obtained at 6 months. The change in time was different between the groups, P < .05. *P < .05 versus baseline. doubly labeled water technique, total-activity energy expenditure decreased by 113 + 287 kcal in the six patients in whom it was measured before and after exercise (P = not significant). Similarly, in the 15 patients assessed with the Caltrac hip accelerometer, total energy expenditure increased nonsignificantly by 36 _ 234 kcal.

Perceived Quality of Life By the Minnesota Living With Heart Failure, FSA, MOS, and CES-D questionnaires, there was no change in quality of life or depression (Table 2).

Characteristics of Patients Who Did Not Complete the Exercise Program Table 1 shows the baseline characteristics of the six patients who did not complete the exercise program.

The observed improvement in maximal exercise is consistent with many previous studies. However, many of those studies both were uncontrolled and evaluated relatively healthy patients (1-4). Others were uncontrolled (12) or tested relatively healthy patients (13). It has been clear that these reports needed to be confirmed (]4). The present study extends previous findings to sick,

Table 2. Effects of 6 Months of Exercise in 16 Patients Pre

Post

P

FSA Activities of daily living Intermediate activity MQOL CES-D MOS Physical functioning Role limitations General health perceptions Hip accelerometer Activity by doubly labeled water (kcal/d) Peak VO 2 (mL/kg/min) Exercise duration (min)

95 74 29 9 60 53 58 286

_+ 8 + 15 ± 25 + 9 -+ 24 _+ 43 ± 16 -+ 149

386 _+ 357 15 -+ 3 13 _+ 4

87 76 22 8 68 50 61 361

_+ 29 ± 22 _+ 20 _+ 8

NS NS NS NS

+- 28 + 42 -+ 23 ± 224

NS NS NS NS

273 -- 133 17 -+ 3 18 _+ 4

NS <.05 <.001

FSA, Functional Status Assessment questionnaire; MOS, Medical Outcomes Study, MQOL, Minnesota Living With Heart Failure questionnaire; CES-D, Center for Epidemiologic Studies Depression questionnaire; NS, not significant; VO2, oxygen consumption.

Exercise and Quality of Life

elderly patients. Patients with an initial peak oxygen consumption of only 14 mL/kg/min were able to tolerate a sustained exercise program and substantially increase oxygen consumption. Patients with a mean age of 67 years were safely able to participate in an exercise program and increase maximal oxygen consumption. It must be noted, however, that 6 of the 17 patients randomized to the exercise program did not complete it. Four of these patients stated they were too ill, with the program making them feel worse. One patient just stopped coming to the hospital for exercise. These patients were more severely ill than the patients who completed the exercise program and perceived themselves as more ill. Whether it was the severity of disease or their reaction to it, a supervised exercise program was not successful in six patients who were willing to undergo extensive baseline testing. It was not possible to identify which patients would tolerate the exercise program; no single variable showed either good sensitivity or specificity. However, clinical judgment might be more successful. It is conceivable that a patient with a low peak oxygen consumption because of deconditioning would tolerate (and benefit from) exercise, whereas an individual limited by heart failure would not. Physicians will need to use their judgment when recommending exercise programs, but should understand that it is not appropriate for all patients with heart failure.

Effect on Daily Activities Previous controlled studies have not evaluated the impact of improved exercise on either daily activities or a patient's self-assessment of their condition (15,16). One study showed patients who exercised showed improvement in the MOS scale. However, it was uncontrolled and did not indicate the severity of the patients' illness (17). The present study, despite an increase in exercise capability, did not find an improvement in perceived quality of life or a change in daily energy expenditure. These findings can be explained in two different ways. First, it might reflect the lack of correlation between peak exercise and ability to perform daily activities. Another possibility is that the tests used did not have the sensitivity to detect an improvement. However, the total absence of any change (significant or not) in our multiple assessments of daily activity raises the concern that improvement in peak exercise performance may not translate to an improved quality of life. Patients who exercised were able to walk further on a 6-minute walk, a finding that has been previously reported (18). This assessment of submaximal exercise may indicate a greater ability to perform daily chores, but could also reflect an improvement in gait. It is possible

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patients had improved performance but did not perceive the improvement because it was gradual or because of increased expectations. It is also possible that the patients did not increase their daily activities because of the lack of realization that they could.

Limitations The present study is limited by the small numbers of patients with assessments of daily energy expenditure or quality of life. Furthermore, analyses regarding these secondary end points were not evaluated in a doubleblind, randomized fashion. In addition, such assessments may have important limitations in detecting improvement in quality of life. For these reasons, a lack of statistical significance does not indicate there was no improvement. However, the questionnaires were able to show the worse clinical status of the patients who were unable to exercise, and the consistency of scores over time in the patients who exercised suggests the impact of exercise was minimal on perceived quality of life. The mean RQ value of approximately 1.0 indicates these patients may not have exercised to cardiac exhaustion. However, the consistency of RQ values for pre- and post-intervention tests suggests the improvement in maximal exercise was secondary to the exercise program and not to motivation.

Conclusion The present study supports the concept that elderly patients with severe heart failure can safely exercise. Physicians should encourage exercise, and, at the least, patients can be reassured that it is safe to be active. We can also reliably say there is objective evidence of increased exercise capability after exercise training. However, exercise programs should be tailored to individuals. A substantial proportion of older and severely ill patients will not tolerate a supervised and graded exercise program. Identification of the patients who benefit is essential and warrants further research.

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