Exercise Testing and Training in Heart Failure Patients Robert S. McKelvie, MD, PhD, FRCPC, Hamilton Health Sciences - General Division

Transcription

1 Exercise Testing and Training in Heart Failure Patients Robert S. McKelvie, MD, PhD, FRCPC, Hamilton Health Sciences - General Division Studies have demonstrated that there is no relationship between left ventricular ejection fraction (LVEF) and peak exercise performance (1). These studies suggest the reduction in exercise capacity experienced by heart failure (HF) patients may be more significantly influenced by factors other than ventricular function. In the last few years a theory has been proposed which implicates abnormalities of the skeletal muscles as being responsible in part for the clinical presentation and progression of HF in these patients (2). The theory suggests there will be a delay in improvement of the exercise response after instituting treatment to correct the hemodynamics until there has been a resolution of skeletal muscle abnormalities. This theory suggests specifically improving skeletal muscle function, for example by exercise training, should also improve functional capacity. Peripheral Factors Affecting Exercise Performance A number of peripheral factors may be responsible for the exercise intolerance experienced by HF patients. Skeletal muscle atrophy is often observed in HF patients and can occur early on in the course of the disease (3). Studies dating back to the 1930s have suggested impaired blood flow to the skeletal muscle in HF patients. Studies have demonstrated that HF patients have differences in muscle phosphocreatine and ph levels compared to healthy controls during exercise (4). It has been demonstrated these changes are not due to a loss of muscle mass or a reduction in skeletal muscle blood flow (4). There are reductions in type I (slow twitch) muscle fibres and although the number is not reduced there have been reductions in the size of type II (fast twitch) muscle fibres (5). There have been reductions observed in oxidative enzyme levels (5,6) and in mitochondrial volume of skeletal muscle (6). Mechanisms for Improvement of Exercise Performance Improvement in maximal cardiac output has been found in some but not all studies examining the effects of exercise training (7,8). Regular exercise training has not been found to have significant adverse effects on left ventricular volumes, wall thickness, or result in thinning of the infarcted area (9). A study in post myocardial infarction patients with left ventricular dysfunction found exercise training attenuated the unfavorable effects of left ventricular remodeling (10). A number of studies have demonstrated exercise training improves skeletal muscle blood flow (7,11). The increase in blood flow is likely due to enhanced endothelium-dependent vasodilatation (11) and contributes to the improvement in leg VO 2 that is observed with training HF patients (7). Exercise training results in a slower increase in inorganic phosphate and a slower decline in creatine phosphate with a decrease in the inorganic phosphate to creatine phosphate ratio during exercise (12). There has also been an increase in the total volume of mitochondria found following training (7). A shift in the ratio of type I fibres to type II fibres has also been observed.

2 Studies Assessing the Effects of Exercise Training Generally, the uncontrolled or nonrandomized studies have demonstrated improvements in peak performance (13). As well, measurements of quality of life or well-being have improved. The randomized controlled trials have generally demonstrated improvements in peak VO 2 and quality of life or well-being following exercise training (13). The European Heart Failure Training Group have published a pooled analysis of the data from a number of their smaller studies examining the effects of exercise training (14). A total of 134 patients had been studied in randomized controlled trials of exercise training. The results demonstrated a significant training effect with a 13% increase in peak VO 2 and 17% increase in exercise duration. Also there was a significant improvement reported for NYHA functional class. A study by Belardinelli et al (15) examined 99 patients with NYHA functional class II-IV symptoms, 50 of these patients were randomized to the one year exercise group at the hospital gymnasium under the supervision of a cardiologist and 49 to the no-exercise control group. Peak VO 2 increased by 18% by the two-month follow up and remained increased at one year, with no further increase observed with further training compared to changes at two months. Exercise training was associated with significantly lower mortality and hospital re-admissions for heart failure. However, these data must be interpreted cautiously as the numbers are small and the findings require confirmation in a large clinical trial powered to examine clinical outcomes. The Exercise Rehabilitation Trial (EXERT) examined 181 patients with NYHA functional class II-III symptoms, ejection fraction < 0.40 and 6 minute walk distance < 500 metres (16). Patients randomly received either three months of supervised exercise training in a rehabilitation programme, followed by nine months of home-based exercise training or just usual care. After three months of training there was a significant 10% increase in peak VO 2 with a 14% increase after 12 months of training. No significant differences were observed for cardiac function, mortality, hospitalization for HF or worsening HF. Adherence to exercise was good during the supervised training but was reduced during home-based training. Therefore patients have significant improvements in functional capacity in a supervised setting, but it would appear more difficult for these patients to remain compliant when they are in a home-based programme with less supervision. Exercise Testing and Training Exercise testing should be performed by patients prior to starting a training programme. Testing can be performed using either a cycle ergometer or a treadmill and the accepted contraindications to exercise testing apply for the HF failure population. Properly supervised exercise testing of HF patients has been found to be safe (17). Standardized guidelines for exercise training of HF patients have not been established, although some recommendations have been made for this patient population (18). Aerobic exercise has been most commonly used in studies examining the effects of exercise training in patients and is most often used to train patients in programmes (13).

3 Resistance (weightlifting) training can improve muscle strength but has not been used frequently in HF. Although there has been some concern about applying resistance training in HF patients, recent studies suggest this should not be the case (19). Another potential way to improve exercise performance is to use interval exercise training (20). Interval exercise training appears acceptable to train HF patients. However, experience with this form of training is relatively limited and more experience is needed before a more general recommendation can be provided. References 1. Franciosa JA, Park JA, Levine B. Lack of correlation between exercise capacity and indices of resting left ventricular performance in heart failure. Am J Cardiol 1981;47: Piepoli M, Clark AL, Volterrani M, et al. Contribution of muscle afferents to the hemodynamic, autonomic, and ventilatory responses to exercise in patients with chronic heart failure. Effects of physical training. Circulation 1996;1996: Mancini D, Walter G, Reichek N, et al. Contribution of skeletal muscle atrophy to exercise intolerance and altered muscle metabolism in heart failure. Circulation 1992;85: Massie B, Conway M, Rajagopalan B, et al. Skeletal muscle metabolism during exercise under ischemic conditions in congestive heart failure. Evidence for abnormalities unrelated to blood flow. Circulation 1988;78: Sullivan MJ, Green HJ, Cobb FR. Skeletal muscle biochemistry and histology in ambulatory patients with long-term heart failure. Circulation 1990;81: Drexler H, Riede U, Munzel T, et al. Alterations of skeletal muscle in chronic heart failure. Circulation 1992;85: Hambrecht R, Niebauer J, Fiehn E, et al. Physical training in patients with stable chronic heart failure: Effects on cardiorespiratory fitness and ultrastructural abnormalities of leg muscles. J Am Coll Cardiol. 1995;25: Dubach P, Meyers J, Dziekan G, et al. Effect of high intensity exercise training on central hemodynamic responses to exercise in man with reduced left ventricular function. J Am Coll Cardiol. 1997;29: Giannuzzi P, Tavazzi L, Temporelli PL, et al. Long-term physical training and left ventricular remodeling after anterior myocardial infarction: results of the Exercise in Anterior Myocardial Infarction (EAMI) Study Group. J Am Coll Cardiol. 1993;22: Giannuzzi P, Temporelli PL, Corra' U, et al. Attenuation of unfavorable remodeling by exercise training in postinfarction patients with left ventricular dysfunction: results of the exercise in left ventricular dysfunction (ELVD) trial. Circulation 1997; Sep 16;96(6): Hambrecht R, Fiehn E, Weigl C, et al. Regular physical exercise corrects endothelial dysfunction and improves exercise capacity in patients with chronic heart failure. Circulation 1998;98: Adamopoulos S, Coats AJ, Brunotte F, et al. Physical training improves skeletal muscle metabolism in patients with chronic heart failure. J Am Coll Cardiol. 1993;21: Lloyd-Williams F, Mair FS, Leitner M. Exercise training and heart failure: a systematic review of current evidence. Br J Gen Pract Jan;52(474): European Heart Failure Training Group. Experience from controlled treats of physical training in chronic heart failure. Protocol and patient factors in effectiveness in the improvement in exercise tolerance. Eur Heart J. 1998;19: Belardinelli R, Georgiou D, Cianci G, et al. Randomized, controlled trial of long-term moderate exercise training in chronic heart failure. Effects on functional capacity,

4 quality of life, and clinical outcome. Circulation 1999;99: McKelvie RS, Teo KK, Roberts R, et al. Effects of exercise training in patients with heart failure: The Exercise Rehabilitation Trial (EXERT). Am Heart J. 2002;144: Tristani FE, Hughes CV, Archibald DG, et al. Safety of graded symptom-limited exercise testing in patients with congestive heart failure. Circulation 1987;VI:VI-54- VI Gianuzzi P, Tavazzi L, Meyer K, et al. Recommendations for exercising training in chronic heart failure patients. Eur Heart J. 2001;22: McKelvie RS, McCartney N, Tomlinson CW, et al. Comparis on of hemodynamic responses to cycling and resistance exercise in congestive heart failure secondary to ischemic cardiomyopathy. Am J Cardiol 1995;76: Meyer K, Samek L, Schwaberger G, et al. Physical responses to different modes of interval exercise in patients with chronic heart failure-application to exercise training. Eur Heart J. 1996;17:

5 Copyright 2003 Canadian Association of Cardiac Rehabilitation. All rights reserved For more information please contact: the Association Manager CACR, 1390 Taylor Avenue Winnipeg, MB R3M 3V8