A randomized comparison of exercise training in patients with normal vs reduced ventricular function

Changes and prognostic value of cardiopulmonary exercise testing parameters in elderly patients undergoing cardiac rehabilitation: The EU-CaRE observational study

Objective

We aimed 1) to test the applicability of the previously suggested prognostic value of CPET to elderly cardiac rehabilitation patients and 2) to explore the underlying mechanism of the greater improvement in exercise capacity (peak oxygen consumption, VO₂) after CR in surgical compared to non-surgical cardiac patients.

Methods

Elderly patients (≥65 years) commencing CR after coronary artery bypass grafting, surgical valve replacement (surgery-group), percutaneous coronary intervention, percutaneous valve replacement or without revascularisation (non-surgery group) were included in the prospective multi-center EU-CaRE study. CPETs were performed at start of CR, end of CR and 1-year-follow-up. Logistic models and receiver operating characteristics were used to determine prognostic values of CPET parameters for major adverse cardiac events (MACE). Linear models were performed for change in peak VO₂ (start to follow-up) and parameters accounting for the difference between surgery and non-surgery patients were sought.

Results

1421 out of 1633 EU-CaRE patients performed a valid CPET at start of CR (age 73±5.4, 81% male). No CPET parameter further improved the receiver operation characteristics significantly beyond the model with only clinical parameters. The higher improvement in peak VO₂ (25% vs. 7%) in the surgical group disappeared when adjusted for changes in peak tidal volume and haemoglobin.

Conclusion

CPET did not improve the prediction of MACE in elderly CR patients. The higher improvement of exercise capacity in surgery patients was mainly driven by restoration of haemoglobin levels and improvement in respiratory function after sternotomy.

Trial registration

Netherlands Trial Register, Trial NL5166.

Determinants of the effects of physical training and of the complications requiring resuscitation during exercise in patients with cardiovascular disease

BACKGROUND

Benefits of cardiac rehabilitation with exercise therapy are well-established, although individual reactions are heterogeneous. The identification of determinants of training effects is useful from a prognostic point of view, but data regarding this are scarce. Furthermore, limited data exist on the determinants of complications during exercise in cardiac patients. This study aimed to investigate the determinants (1) of training effects in cardiac rehabilitation and (2) of complications requiring resuscitation during exercise activities at the hospital and during continued exercise at a sports club for cardiac patients.

DESIGN

Clinical association study.

METHODS

Determinants of changes in peak oxygen uptake (VO2) after 3 months of cardiac rehabilitation were determined by multiple regression analysis (n=1909). Determinants of events requiring resuscitation (n=21) were assessed by logistic regression analysis.

RESULTS

Improvements in peak VO2 and exercise duration averaged 26%. Eighteen per cent of the variance in absolute improvements of peak VO2 was explained, with age and training characteristics as the strongest determinants. Twenty-one per cent of the variation in relative improvements was explained, with baseline exercise performance and training characteristics being the strongest determinants. The intake of anti-arrhythmics (odds ratio=5.5; P<0.001) and the presence of ST-segment depression (> or =1 mm) at baseline exercise testing (odds ratio=1.6; P<0.001) were predictive for serious complications. The occurrence of events requiring resuscitation was higher at the sports club (1/16,533 versus 1/29,214 patient-hours).

CONCLUSIONS

Age, baseline exercise performance and training characteristics were predictive for training effects in cardiac rehabilitation. Anti-arrhythmics and ST-segment depression at baseline exercise testing were predictive for complications.

Effect of exercise training on ventilatory efficiency in patients with heart disease: a review

The analysis of ventilatory efficiency in cardiopulmonary exercise testing has proven useful for assessing the presence and severity of cardiorespiratory diseases. During exercise, efficient pulmonary gas exchange is characterized by uniform matching of lung ventilation with perfusion. By contrast, mismatching is marked by inefficient pulmonary gas exchange, requiring increased ventilation for a given CO2 production. The etiology of increased and inefficient ventilatory response to exercise in heart disease is multifactorial, involving both peripheral and central mechanisms. Exercise training has been recommended as non-pharmacological treatment for patients with different chronic cardiopulmonary diseases. In this respect, previous studies have reported improvements in ventilatory efficiency after aerobic exercise training in patients with heart disease. Against this background, the primary objective of the present review was to discuss the pathophysiological mechanisms involved in abnormal ventilatory response to exercise, with an emphasis on both patients with heart failure syndrome and coronary artery disease. Secondly, special focus was dedicated to the role of aerobic exercise training in improving indices of ventilatory efficiency among these patients, as well as to the underlying mechanisms involved.

The influence of aerobic fitness status on ventilatory efficiency in patients with coronary artery disease

OBJECTIVE

To test the hypotheses that 1) coronary artery disease patients with lower aerobic fitness exhibit a lower ventilatory efficiency and 2) coronary artery disease patients with lower initial aerobic fitness exhibit greater improvements in ventilatory efficiency with aerobic exercise training.

METHOD

A total of 123 patients (61.0±0.7 years) with coronary artery disease were divided according to aerobic fitness status into 3 groups: group 1 (n = 34, peak VO₂<17.5 ml/kg/min), group 2 (n = 67, peak VO₂>17.5 and <24.5 ml/kg/min) and group 3 (n = 22, peak VO₂>24.5 ml/kg/min). All patients performed a cardiorespiratory exercise test on a treadmill. Ventilatory efficiency was determined by the lowest VE/VCO₂ ratio observed. The exercise training program comprised moderate-intensity aerobic exercise performed 3 times per week for 3 months. Clinicaltrials.gov: NCT02106533 RESULTS: Before intervention, group 1 exhibited both lower peak VO2 and lower ventilatory efficiency compared with the other 2 groups (p<0.05). After the exercise training program, group 1 exhibited greater improvements in aerobic fitness and ventilatory efficiency compared with the 2 other groups (group 1: ▵ = -2.5±0.5 units; group 2: ▵ = -0.8±0.3 units; and group 3: ▵ = -1.4±0.6 units, respectively; p<0.05).

CONCLUSIONS

Coronary artery disease patients with lower aerobic fitness status exhibited lower ventilatory efficiency during a graded exercise test. In addition, after 3 months of aerobic exercise training, only the patients with initially lower levels of aerobic fitness exhibited greater improvements in ventilatory efficiency.

Evidence-based risk assessment and recommendations for physical activity clearance: Consensus Document 2011

The Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) are internationally known preparticipation screening tools developed on the basis of expert opinion. The primary purposes of this consensus document were to seek evidence-based support for the PAR-Q and PARmed-X forms, to identify whether further revisions of these instruments are warranted, to determine how people responding positively to questions on the PAR-Q can be safely cleared without medical referral, and to develop exercise clearance procedures appropriate for various clinical conditions across the human lifespan. Seven systematic reviews were conducted, examining physical-activity-related risks and effective risk-stratification procedures for various prevalent chronic conditions. An additional systematic review assessed the risks associated with exercise testing and training of the general population. Two gap areas were identified and evaluated systematically: the role of the qualified exercise professional and the requisite core competencies required by those working with various chronic conditions; and the risks associated with physical activity during pregnancy. The risks associated with being physically inactive are markedly higher than transient risks during and following an acute bout of exercise in both asymptomatic and symptomatic populations across the lifespan. Further refinements of the PAR-Q and the PARmed-X (including online versions of the forms) are required to address the unique limitations imposed by various chronic health conditions, and to allow the inclusion of individuals across their entire lifespan. A probing decision-tree process is proposed to assist in risk stratification and to reduce barriers to physical activity. Qualified exercise professionals will play an essential role in this revised physical activity clearance process.

Effects of oxygen on exertional dyspnoea and exercise performance in patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVE

The results of studies on the oxygen response in patients with COPD should provide important clues to the pathophysiology of exertional dyspnoea. We investigated the exercise responses to hyperoxia in relation to dyspnoea profile, as well as cardiopulmonary, acidotic and sympathetic parameters in 35 patients with stable COPD (mean FEV(1) 46% predicted).

METHODS

This was a single-blind trial, in which patients breathed 24% O(2) or compressed air (CA) in random order during two incremental cycle exercise tests.

RESULTS

PaO(2) and PaCO(2) were higher (P < 0.0001 and P < 0.05, respectively) at each exercise point while patients were breathing 24% O(2) compared with CA. At a standardized time point near peak exercise, use of O(2) resulted in reduced plasma lactate and plasma noradrenaline concentrations (P < 0.01). Peak minute ventilation/indirect maximum voluntary ventilation was similar while breathing 24% O(2) and CA. At peak exercise, the dyspnoea score, pH and plasma noradrenaline concentrations were similar while breathing 24% O(2) and CA. The dyspnoea-ratio (%) of Δoxygen uptake (peak minus resting oxygen uptake) curve reached a break point that occurred at a similar exercise point while breathing 24% O(2) or CA.

CONCLUSIONS

Regardless of whether they breathed CA or 24% O(2) , patients with COPD did not develop ventilatory compensation for exertional acidosis, and the pH values measured were similar. Hyperoxia during a standardized exercise protocol did not alter the pattern of exertional dyspnoea in these patients, compared with breathing CA, although hyperoxia resulted in miscellaneous effects.

Evidence-based risk assessment and recommendations for physical activity clearance: established cardiovascular disease1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Physical activity is an effective lifestyle therapy for patients at risk for, or with, documented cardiovascular disease (CVD). Current screening tools — the Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) — require updating to align with risk/benefit evidence. We provide evidence-based recommendations to identify individuals with CVD at lower risk, intermediate risk, or higher risk of adverse events when participating in physical activity. Forms of exercise and the settings that will appropriately manage the risks are identified. A computer-assisted search of electronic databases, using search terms for CVD and physical activity risks and benefits, was employed. The Appraisal of Guidelines for Research and Evaluation were applied to assess the evidence and assign a strength of evidence rating. A strength rating for the physical activity participation clearance recommendation was assigned on the basis of the evidence. Recommendations for physical activity clearance were made for specific CVD groups. Evidence indicates that those who are medically stable, who are involved with physical activity, and who have adequate physical ability can participate in physical activity of lower to moderate risk. Patients at higher risk can exercise in medically supervised programs. Systematic evaluation of evidence indicates that clinically stable individuals with CVD may participate in physical activity with little risk of adverse events. Therefore, changes in the PAR-Q should be undertaken and a process of assessment and consultation to replace the PARmed-X should be developed. Patients at lower risk may exercise at low to moderate intensities with minimal supervision. Those at intermediate risk should exercise with guidance from a qualified exercise professional. Patients at higher risk should exercise in medically supervised programs.

Principles of exercise prescription for patients with chronic heart failure

Chronic heart failure (CHF) is a common and debilitating condition characterized by reduced exercise tolerance. While exercise training was once thought to be contraindicated for patients with CHF, a substantial body of data has been published over the last two decades to support the use of exercise programs for these patients. Improvements in exercise capacity, quality of life, and mortality have been demonstrated among patients with CHF who have participated in formal exercise programs. Exercise prescription is a means of assessing and interpreting clinical information and applying the principles of training to develop an appropriate regimen so that these benefits are achieved. The major principles of the exercise prescription are the mode, frequency, duration, and intensity. Importantly, safe and effective exercise prescription for patients with CHF requires more than the application of these principles; it also requires careful consideration of the individual patients' functional status, comorbid conditions, medications, contraindications, and personal goals and preferences. Recent studies have demonstrated that a wide spectrum of patients with CHF benefit from appropriately applied exercise training, including those with both systolic and diastolic dysfunction, atrial fibrillation, pacemakers, implantable cardioversion devices, and post-cardiac transplantation. Increasingly, the principles of exercise prescription are included as a component of comprehensive CHF management programs. Evidence has accumulated that CHF patients who participate in rehabilitation programs have better health outcomes in terms of reduced morbidity and mortality, as well as lower hospitalization rates and lower overall health care costs.

Patients with large myocardial infarction gain a greater improvement in exercise capacity after exercise training than those with small to medium infarction

BACKGROUND

It remains unclear whether patients with large-size myocardial infarction (MI) achieve the same benefit from exercise training as do those with small- to medium-size MI.

HYPOTHESIS

This study was designed to determine the magnitude and mechanisms underlying improvement in exercise capacity in patients with large-size MI after cardiac rehabilitation.

METHODS

In all, 296 patients who participated in a cardiac rehabilitation program after acute MI were divided into two groups according to the peak serum creatine phosphokinase (CPK) level: the group with large infarction (Group 1) (> or = 5000 U/l peak CPK, 64 patients) and the group with less extensive infarction (Group 2) (< 5000 U/I, 232 patients). Exercise capacity was assessed before and after a 3-month cardiac rehabilitation program that included exercise training.

RESULTS

Before exercise training, both the peak work rate (p < 0.05) and peak oxygen uptake (VO2) (p < 0.01) were significantly lower in Group 1 than in Group 2. After exercise training, the changes in peak work rate and peak VO2 were significantly greater in Group 1 than in Group 2 (both p < 0.01). The infarction size measured by the peak CPK level correlated significantly with both the baseline exercise capacity and its improvement after exercise training, although these correlations were insignificant in a multivariate analysis. In the multivariate analysis, the improvement in exercise capacity is determined by age and baseline exercise capacity, which is determined by the duration of inactivity, minute ventilation (VE)/VCO2 slope and left ventricular end-diastolic pressure.

CONCLUSIONS

Compared with patients with small- to medium-size myocardial infarction, patients with large infarction gain a greater improvement in exercise capacity after exercise training due to reversal of physical deconditioning and improvement in congestive heart failure.

Exercise based rehabilitation for heart failure

BACKGROUND

The prevalence of chronic heart failure is increasing, and increases with increasing age. Major symptoms include breathlessness and restricted activities of daily living due to reduced functional capacity, which in turn affects quality of life. Exercise training has been shown to be effective in patients with coronary heart disease and has been proposed as an intervention to improve exercise tolerance in patients with heart failure.

OBJECTIVES

To determine the effectiveness of exercise based interventions compared with usual medical care on the mortality, morbidity, exercise capacity and health related quality of life, of patients with heart failure.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register (The Cochrane Library Issue 2, 2001), MEDLINE (2000 to March 2001), EMBASE (1998 to March 2001), CINAHL (1984 to March 2001) and reference lists of articles. We also sought advice from experts.

SELECTION CRITERIA

RCTs of exercise based interventions. The comparison group was usual medical care as defined by the study, or placebo. Adults of all ages with chronic heart failure. Only those studies with criteria for diagnosis of heart failure (based on clinical findings or objective indices) have been included.

DATA COLLECTION AND ANALYSIS

Studies were selected, and data were abstracted, independently by two reviewers. Authors were contacted where possible to obtain missing information.

MAIN RESULTS

Twenty-nine studies met the inclusion criteria, with 1126 patients randomised. The majority of studies included both patients with primary and secondary heart failure, NYHA class II or III. None of the studies specifically examined the effect of exercise training on mortality and morbidity as most were of short duration. Exercise training significantly increased VO(2) max by (WMD random effects model) 2.16 ml/kg/min (95% CI 2.82 to 1.49), exercise duration increased by 2.38 minutes (95% CI 2.85 to 1.9), work capacity by 15.1 Watts (95% CI 17.7 to 12.6) and distance on the six minute walk by 40.9 metres (95% CI 64.7 to 17.1). Improvements in VO(2) max were greater for training programmes of greater intensity and duration. HRQoL improved in the seven of nine trials that measured this outcome.

REVIEWERS' CONCLUSIONS

Exercise training improves exercise capacity and quality of life in patients mild to moderate heart failure in the short term. There is currently no information regarding the effect of exercise training on clinical outcomes. The findings are based on small-scale trials in patients who are unrepresentative of the total population of patients with heart failure. Other groups (more severe patients, the elderly, women) may also benefit. Large-scale pragmatic trials of exercise training of longer duration, recruiting a wider spectrum of patients are needed to address these issues.

Effect of exercise training on heart rate variability in patients with new-onset left ventricular dysfunction after myocardial infarction

BACKGROUND

Cardiac rehabilitation with exercise training alters sympathovagal control of heart rate variability (HRV) toward parasympathetic dominance in patients after acute myocardial infarction (MI). However, its effects on HRV in patients after MI with new-onset left ventricular dysfunction are yet unknown. We aimed to investigate the effects of 8 weeks of supervised, high-intensity exercise training on time- and frequency-domain measures of HRV in this selected patient population.

METHODS AND RESULTS

Twenty-five men with an acute MI and a low ejection fraction were randomly assigned to enter or not to enter a training program in a regional rehabilitation center. HRV was evaluated before and after 1 and 2 months of training and at 12 months. Maximal exercise testing with respiratory gas exchange was performed at baseline and after training. Resting heart rate decreased (P <. 01) and the percentage of R-R intervals differing >50 ms from the preceding one (pNN50) increased (P <.05) after training. The standard deviation of R-R intervals (SDRR) tended to increase, but frequency-domain indexes remained unchanged. There was a significant decrease in SDRR (P <.05) and high-frequency power (P <.01) at 12 months in untrained patients. Exercise time increased by 38% and maximal oxygen uptake increased by 29% in the training group (P <. 01).

CONCLUSIONS

Despite beneficial effects on clinical variables, exercise training did not markedly alter HRV indexes. A significant decrease in SDRR and high-frequency power in the control group suggests an ongoing process of sympathovagal imbalance in favor of sympathetic dominance in untrained patients after MI with new-onset left ventricular dysfunction.

Influence of high-intensity exercise training on the ventilatory response to exercise in patients with reduced ventricular function

BACKGROUND

Exercise training increases exercise capacity in patients with reduced ventricular function in part through improved skeletal muscle metabolism, but the effect training might have on abnormal ventilatory and gas exchange responses to exercise has not been clearly defined.

METHODS

Twenty-five male patients with reduced ventricular function after a myocardial infarction were randomized to either a 2-month high-intensity residential exercise training program or to a control group. Before and after the study period, upright exercise testing was performed with measurements of ventilatory gas exchange, lactate, arterial blood gases, cardiac output, and pulmonary artery and wedge pressures.

RESULTS

In the exercise group, peak VO2 and VO2 at the lactate threshold increased 29 and 39%, respectively, whereas no increases were observed among controls. Maximal cardiac output increased only in the exercise group (1.7 L x min(-1), P < 0.05), and no changes in rest or peak exercise pulmonary pressures were observed in either group. At baseline, modest inverse relationships were observed between pulmonary wedge pressure and peak VO2 both at rest (r = -0.56, P < 0.05) and peak exercise (r = -0.43, P < 0.05). Maximal VE/VCO2 was inversely related to maximal cardiac output (r = -0.72, P < 0.001). Training did not have a significant effect on these relationships. Training lowered VE/VO2, heart rate, and blood lactate levels at matched work rates throughout exercise and tended to lower maximal Vd/Vt. The slope of the relationship between VE and VCO2 was reduced after training in the exercise group (0.33 pre vs 0.27 post, P < 0.01), whereas control patients did not differ.

CONCLUSIONS

Exercise training among patients with reduced left ventricular function results in a systematic improvement in the ventilatory response to exercise. Training increased maximal cardiac output, tended to lower Vd/Vt, and markedly improved the efficiency of ventilation. Peak VO2 and ventilatory responses to exercise were only modestly related to pulmonary vascular pressures, and training had no effect on the relationships between exercise capacity, ventilatory responses, and pulmonary pressures.

Central and peripheral adaptations after 12 weeks of exercise training in post-coronary artery bypass surgery patients

PURPOSE

Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients.

METHODS

Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined.

RESULTS

A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training.

CONCLUSIONS

These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.