Intensive home-based exercise training in cardiac rehabilitation increases exercise capacity and heart rate variability

Aerobic Exercise Improves Heart Rate Variability After an Implantable Cardioverter Defibrillator (ICD)

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov: NCT00522340.

Exercise training and cardiac autonomic function following coronary artery bypass grafting: a systematic review and meta-analysis

BACKGROUND

Exercise training improves cardiac autonomic function is still debatable in patients with coronary artery bypass grafting (CABG). The aim of the present review is to assess the effect of exercise on CABG patient's heart rate variability (HRV) and heart rate recovery (HRR) parameters.

MAIN BODY

Databases (PubMed, Web of Science and PEDro) were accessed for systematic search from inception till May 2022. Eleven potential studies were qualitatively analyzed by using PEDro and eight studies were included in the quantitative synthesis. Meta-analysis was conducted by using a random-effect model, inverse-variance approach through which standardized mean differences (SMDs) were estimated. The analysis of pooled data showed that exercise training improved HRV indices of standard deviation of the R-R intervals (SDNN) [SMD 0.44, 95% CI 0.17, 0.71, p = 0.002], square root of the mean squared differences between adjacent R-R intervals (RMSSD) [SMD 0.68, 95% CI 0.28, 1.08, p = 0.0008], high frequency (HF) [SMD 0.58, 95% CI 0.18, 0.98, p = 0.005] and low frequency-to-high frequency (LF/HF) ratio [SMD - 0.34, 95% CI - 0.65, - 0.02, p = 0.03].

CONCLUSIONS

Exercise training enhances cardiac autonomic function in CABG patients. Owing to the methodological inconsistencies in assessing HRV, the precise effect on autonomic function still remains conflicted. Future high-quality trials are needed focusing on precise methodological approach and incorporation of various types of exercise training interventions will give clarity regarding autonomic adaptations post-exercise training in CABG. Trial registration CRD42021230270 , February 19, 2021.

The effect of a home-based coaching program on heart rate variability in subacute stroke patients: a randomized controlled trial

Autonomic imbalance in stroke is characterized by increased sympathetic activity and reduced vagal nerve activity. Physical activity could be a strategy to counteract autonomic control impairments after a stroke. The aim of the study was to evaluate the effect on heart rate variability of a 6-month coaching program in a home setting in subacute stroke patients. Eighty-four stroke patients participated in the study. They were randomly assigned to the experimental group or the control group. The intervention was a coaching program, consisting of physical activity, home visits and a weekly phone call. Patients were evaluated after hospital discharge (T0) and at the end of the 6-month period (T1). Heart rate variability measures were recorded in the supine and orthostatic positions. Time and frequency domain values were treated using Kubios. Distance on 6 minutes walking test (6MWT), Barthel and motricity index and modified functional ambulation categories were evaluated. No effects were found on time and frequency domain values in the supine and orthostatic positions in either group. Walking distance on 6MWT increased significantly between T0 and T1 in experimental group (377 ± 141-448 ± 140 m; P < 0.02) with no effects in control group (373.6 ± 150.6-394.6 ± 176.4 m). No other functional effects were found. A coaching program in a home setting had no effect on heart rate variability, probably due to time of recovery and exercise intensity. Future research is needed to understand the lack of changes in heart rate variability by physical activity in subacute stroke patients.

The relationship between phobic anxiety and 2-year readmission after Acute Coronary Syndrome: What is the role of heart rate variability?

OBJECTIVE

Phobic anxiety is a risk factor for poor prognosis following Acute Coronary Syndrome (ACS). A psychophysiological marker of vagal function, autonomic dysfunction may play a critical role in this relationship. The aim of the study was two-fold: to assess whether phobic anxiety was characterised by autonomic dysfunction (heart rate variability) in the short (1-month) and longer term (12-months) following ACS, and (ii) to quantify the extent to which HRV parameters modified the effect of phobic anxiety on all-cause hospital readmission over 2 years.

METHODS

The ADVENT study followed 416 ACS patients. At 1-month following discharge (T0), phobic anxiety and autonomic functioning were assessed using the Crown Crisp Index (CCI) and 11 indices of heart rate variability (HRV), respectively. HRV was measured again at 12-months (T1) (n = 359). Hospital readmission (all cause) was derived from an audit of hospital records by two medically trained research fellows. Generalised linear modelling (GLM) was used to first determine the association between CCI score at T0 and HRV parameters at T0 and T1. Binary logistic regression was used to measure the relationship between CCI scores and readmission (yes/no) and the extent to which HRV parameters modified this effect.

RESULTS

CCI scores were associated with 7 of the 11 indices of HRV: Average RR (ms), SDRR (ms), RMSSD (ms), SDSD (ms), pRR50 (%), LF Powers (ms2) and HF Powers (ms2) at T0 but not T1. CCI scores at T0 significantly predicted likelihood of readmission to hospital in the subsequent 2 year period. No parameter of HRV at T0 modified this effect.

LIMITATIONS

We were unable to provide adjudicated major adverse coronary events outcome data, or account for changes in medication adherence, diet or physical activity.

CONCLUSIONS

While phobic anxiety is associated with both reduced vagal function in the short term after an ACS event and 2 year all cause readmission, HRV does not appear to be the pathway by which phobic anxiety drives this outcome.

Heart rate recovery of individuals undergoing cardiac rehabilitation after acute coronary syndrome

BACKGROUND

An efficient cardiac rehabilitation programme (CRP) can improve the functional ability of patients after acute coronary syndrome (ACS).

OBJECTIVE

To examine the effect of a CRP on parasympathetic reactivation and heart rate recovery (HRR) measured after a 6-min walk test (6MWT), and correlation with 6MWT distance and well-being after ACS.

METHODS

Eleven normoweight patients after ACS (BMI<25kg/m²; 10 males; mean [SD] age 61 [9] years) underwent an 8-week CRP. Before (pre-) and at weeks 4 (W4) and 8 (W8) during the CRP, they performed a 6MWT on a treadmill, followed by 10-min of seated passive recovery, with HRR and HR variability (HRV) recordings. HRR was measured at 1, 3, 5 and 10min after the 6MWT (HRR1, HRR3, HRR5, HRR10), then modelized by a mono-exponential function. Time-domain (square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals [RMSSD]) and frequency-domain (with high- and low-frequency band powers) were used to analyse HRV. Participants completed a mental and physical well-being questionnaire at pre- and W8. Exhaustion after tests was assessed by the Borg scale. Pearson correlation was used to assess correlations.

RESULTS

HRR3, HRR5 and HRR10 increased by 37%, 36% and 28%, respectively, between pre- and W8 (P<0.05), and were positively correlated with change in 6MWT distance (r=0.58, 0.66 and 0.76; P<0.05). Percentage change in HRR3 was positively correlated with change in well-being (r=0.70; P=0.01). Parasympathic reactivation (RMSSD) was improved only during the first 30sec of recovery (P=0.04).

CONCLUSION

Among patients undergoing a CRP after ACS, increased HRR after a 6MWT, especially at 3min, was positively correlated with 6MWT distance and improved well-being. HRR raw data seem more sensitive than post-exercise HRV analysis for monitoring functional and autonomic improvement after ACS.

Home-based versus centre-based cardiac rehabilitation

BACKGROUND

Cardiovascular disease is the most common cause of death globally. Traditionally, centre-based cardiac rehabilitation programmes are offered to individuals after cardiac events to aid recovery and prevent further cardiac illness. Home-based cardiac rehabilitation programmes have been introduced in an attempt to widen access and participation. This is an update of a review previously published in 2009 and 2015.

OBJECTIVES

To compare the effect of home-based and supervised centre-based cardiac rehabilitation on mortality and morbidity, exercise-capacity, health-related quality of life, and modifiable cardiac risk factors in patients with heart disease.

SEARCH METHODS

We updated searches from the previous Cochrane Review by searching the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid), PsycINFO (Ovid) and CINAHL (EBSCO) on 21 September 2016. We also searched two clinical trials registers as well as previous systematic reviews and reference lists of included studies. No language restrictions were applied.

SELECTION CRITERIA

We included randomised controlled trials, including parallel group, cross-over or quasi-randomised designs) that compared centre-based cardiac rehabilitation (e.g. hospital, gymnasium, sports centre) with home-based programmes in adults with myocardial infarction, angina, heart failure or who had undergone revascularisation.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all identified references for inclusion based on pre-defined inclusion criteria. Disagreements were resolved through discussion or by involving a third review author. Two authors independently extracted outcome data and study characteristics and assessed risk of bias. Quality of evidence was assessed using GRADE principles and a Summary of findings table was created.

MAIN RESULTS

We included six new studies (624 participants) for this update, which now includes a total of 23 trials that randomised a total of 2890 participants undergoing cardiac rehabilitation. Participants had an acute myocardial infarction, revascularisation or heart failure. A number of studies provided insufficient detail to enable assessment of potential risk of bias, in particular, details of generation and concealment of random allocation sequencing and blinding of outcome assessment were poorly reported.No evidence of a difference was seen between home- and centre-based cardiac rehabilitation in clinical primary outcomes up to 12 months of follow up: total mortality (relative risk (RR) = 1.19, 95% CI 0.65 to 2.16; participants = 1505; studies = 11/comparisons = 13; very low quality evidence), exercise capacity (standardised mean difference (SMD) = -0.13, 95% CI -0.28 to 0.02; participants = 2255; studies = 22/comparisons = 26; low quality evidence), or health-related quality of life up to 24 months (not estimable). Trials were generally of short duration, with only three studies reporting outcomes beyond 12 months (exercise capacity: SMD 0.11, 95% CI -0.01 to 0.23; participants = 1074; studies = 3; moderate quality evidence). However, there was evidence of marginally higher levels of programme completion (RR 1.04, 95% CI 1.00 to 1.08; participants = 2615; studies = 22/comparisons = 26; low quality evidence) by home-based participants.

AUTHORS' CONCLUSIONS

This update supports previous conclusions that home- and centre-based forms of cardiac rehabilitation seem to be similarly effective in improving clinical and health-related quality of life outcomes in patients after myocardial infarction or revascularisation, or with heart failure. This finding supports the continued expansion of evidence-based, home-based cardiac rehabilitation programmes. The choice of participating in a more traditional and supervised centre-based programme or a home-based programme may reflect local availability and consider the preference of the individual patient. Further data are needed to determine whether the effects of home- and centre-based cardiac rehabilitation reported in the included short-term trials can be confirmed in the longer term and need to consider adequately powered non-inferiority or equivalence study designs.

Home-based versus centre-based cardiac rehabilitation

BACKGROUND

Cardiovascular disease is the most common cause of death globally. Traditionally, centre-based cardiac rehabilitation programmes are offered to individuals after cardiac events to aid recovery and prevent further cardiac illness. Home-based cardiac rehabilitation programmes have been introduced in an attempt to widen access and participation. This is an update of a review originally published in 2009.

OBJECTIVES

To compare the effect of home-based and supervised centre-based cardiac rehabilitation on mortality and morbidity, health-related quality of life, and modifiable cardiac risk factors in patients with heart disease.

SEARCH METHODS

To update searches from the previous Cochrane review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 9, 2014), MEDLINE (Ovid, 1946 to October week 1 2014), EMBASE (Ovid, 1980 to 2014 week 41), PsycINFO (Ovid, 1806 to October week 2 2014), and CINAHL (EBSCO, to October 2014). We checked reference lists of included trials and recent systematic reviews. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared centre-based cardiac rehabilitation (e.g. hospital, gymnasium, sports centre) with home-based programmes in adults with myocardial infarction (MI), angina, heart failure or who had undergone revascularisation.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the eligibility of the identified trials and data were extracted by a single author and checked by a second. Authors were contacted where possible to obtain missing information.

MAIN RESULTS

Seventeen trials included a total of 2172 participants undergoing cardiac rehabilitation following an acute MI or revascularisation, or with heart failure. This update included an additional five trials on 345 patients with heart failure. Authors of a number of included trials failed to give sufficient detail to assess their potential risk of bias, and details of generation and concealment of random allocation sequence were particularly poorly reported. In the main, no difference was seen between home- and centre-based cardiac rehabilitation in outcomes up to 12 months of follow up: mortality (relative risk (RR) = 0.79, 95% confidence interval (CI) 0.43 to 1.47, P = 0.46, fixed-effect), cardiac events (data not poolable), exercise capacity (standardised mean difference (SMD) = -0.10, 95% CI -0.29 to 0.08, P = 0.29, random-effects), modifiable risk factors (total cholesterol: mean difference (MD) = 0.07 mmol/L, 95% CI -0.24 to 0.11, P = 0.47, random-effects; low density lipoprotein cholesterol: MD = -0.06 mmol/L, 95% CI -0.27 to 0.15, P = 0.55, random-effects; systolic blood pressure: mean difference (MD) = 0.19 mmHg, 95% CI -3.37 to 3.75, P = 0.92, random-effects; proportion of smokers at follow up (RR = 0.98, 95% CI 0.79 to 1.21, P = 0.83, fixed-effect), or health-related quality of life (not poolable). Small outcome differences in favour of centre-based participants were seen in high density lipoprotein cholesterol (MD = -0.07 mmol/L, 95% CI -0.11 to -0.03, P = 0.001, fixed-effect), and triglycerides (MD = -0.18 mmol/L, 95% CI -0.34 to -0.02, P = 0.03, fixed-effect, diastolic blood pressure (MD = -1.86 mmHg; 95% CI -0.76 to -2.95, P = 0.0009, fixed-effect). In contrast, in home-based participants, there was evidence of a marginally higher levels of programme completion (RR = 1.04, 95% CI 1.01 to 1.07, P = 0.009, fixed-effect) and adherence to the programme (not poolable). No consistent difference was seen in healthcare costs between the two forms of cardiac rehabilitation.

AUTHORS' CONCLUSIONS

This updated review supports the conclusions of the previous version of this review that home- and centre-based forms of cardiac rehabilitation seem to be equally effective for improving the clinical and health-related quality of life outcomes in low risk patients after MI or revascularisation, or with heart failure. This finding, together with the absence of evidence of important differences in healthcare costs between the two approaches, supports the continued expansion of evidence-based, home-based cardiac rehabilitation programmes. The choice of participating in a more traditional and supervised centre-based programme or a home-based programme should reflect the preference of the individual patient. Further data are needed to determine whether the effects of home- and centre-based cardiac rehabilitation reported in these short-term trials can be confirmed in the longer term. A number of studies failed to give sufficient detail to assess their risk of bias.

Diet and exercise interventions following coronary artery bypass graft surgery: a review and call to action

Coronary artery bypass graft (CABG) surgery has been used for the treatment of coronary artery disease (CAD) for approximately 50 years, and has been performed on millions of people globally. However, little is known about the impact of diet and exercise on long-term outcomes of patients who have undergone CABG surgery. Although clinical practice guidelines on the management of this patient population have been available for approximately 2 decades, evidence regarding secondary prevention behavioral interventions, lifestyle modifications and self-management to slow the progressive decline of CAD, reduce cardiac hospitalizations, and prevent reoperation remains virtually absent from the literature. Diet and exercise are modifiable factors that affect secondary CAD risk. This article reviews the relevant current literature on long-term diet and exercise outcomes in patients who underwent CABG. The limited available literature shows the positive impacts of exercise on psychosocial well-being and physical fitness. Current evidence indicates diet and exercise interventions are effective in the short-term, but effects fade over time. Potential age and sex differences were found across the reviewed studies; however, further research is needed with more rigorous designs to replicate and confirm findings, and to define optimal management regimens and cost-effective prevention strategies.

Heart rate variability in myocardial infarction patients: effects of exercise training

Heart rate variability (HRV) is a simple and noninvasive measure that estimates cardiac autonomic modulation, mainly the parasympathetic contribution. Increased sympathetic and/or decreased parasympathetic nervous activity is seen in post-myocardial infarction (MI) patients. Consequently, these patients present reduced HRV, which has been associated with increased risk of adverse events and mortality. Exercise training, recommended as a complementary therapy for patients with cardiovascular disease, has shown numerous beneficial effects. The main aim of the present manuscript was to provide a critical review of studies investigating the effects of exercise training on cardiac autonomic modulation, through HRV, in MI patients and the possible mechanisms involved. Despite conflicting evidence, exercise training appears to be a useful therapeutic intervention to improve the unbalanced autonomic function of MI patients. Finally, the mechanisms involved are not yet well understood, but nitric oxide bioavailability and angiotensin II levels seem to play an important role.

Impact of home-based exercise training with wireless monitoring on patients with acute coronary syndrome undergoing percutaneous coronary intervention

Recent studies have suggested a favorable effect of cardiac rehabilitation (CR) on patients with cardiovascular disease. This study aimed to evaluate the impact of home-based exercise training with wireless monitoring on acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI). A total of 55 ACS patients undergoing PCI were randomly divided into home based exercise training with wireless monitoring cardiac rehabilitation (CR, n = 26) and usual care (UC, n = 29). Exercise capacity and quality of life (QOL) were evaluated at baseline and after 12 weeks. Change of metabolic equivalent of the tasks, maximal exercise time and QOL were significantly increased (+2.47 vs +1.43, P = 0.021; +169.68 vs +88.31 sec, P = 0.012; and +4.81 vs +0.89, P = 0.022, respectively), and the change of submaximal rate pressure product, and of submaximal rate of perceived exertion were significantly decreased (-28.24 vs -16.21, P = 0.013; and -1.92 vs -1.62, P = 0.018, respectively) in the CR group compared to the UC group after 12 weeks. CR using home-based exercise training with wireless monitoring led to improvement of exercise capacity and QOL relative to conventional care in ACS patients undergoing PCI. Our findings suggest that early scheduled CR may be considered in ACS patients undergoing PCI.

A randomized controlled trial of exercise training on cardiovascular and autonomic function among renal transplant recipients

BACKGROUND

There are conflicting data regarding the effects of renal transplantation (RT) on uraemic autonomic dysfunction. Moreover, no study has examined the impact of physical training on the cardiac autonomic function in RT patients. Thus, we studied the effects of exercise training on heart rate variability (HRV) and arterial baroreflex sensitivity (BRS), which are sensitive markers of cardiac autonomic outflow, in RT recipients.

METHODS

Eleven patients (Exercise group-aged 52.1 ± 5.6 years) were studied before and after 6 months of exercise training. Twelve age- and sex- matched RT patients (Sedentary) and 12 healthy sedentary individuals (Healthy), who remained untrained, served as controls. At baseline and follow-up, all the subjects underwent cardiopulmonary exercise testing for the evaluation of peak oxygen consumption (VO2peak), a tilt test for the evaluation of BRS and baroreflex effectiveness index (BEI) and an ambulatory 24-h Holter monitoring for time- and frequency-domain measures of HRV.

RESULTS

In the exercise group, VO2peak increased by 15.8% (P < 0.05) and all depressed HRV and BRS indices were significantly improved after training. Specifically, the standard deviation of all normal-to-normal (NN) intervals (SDNN) significantly increased by 92.5%, the root-mean-square of the differences between consecutive NN intervals by 45.4%, the percentage value of NN50 count by 58.2%, the high-frequency by 74.8% and low-frequency spectral power by 41.6%, BRS by 43.7% and BEI by 57.3%. None of the variables studied was altered over time in either control group.

CONCLUSIONS

The increased cardiorespiratory fitness by exercise training was associated with an improved BRS function and a modification of the sympathovagal control of HRV towards a persistent increase in parasympathetic tone. These alterations may lead to a better cardiovascular prognosis in RT recipients.

The relationship between physical activity and heart rate variability in orthotopic heart transplant recipients

AIMS AND OBJECTIVES

To investigate the relationship between physical activity and heart rate variability in orthotopic heart transplant recipients, to compare the difference in heart rate variability between patients one year after orthotopic heart transplant and healthy adults matched to the heart transplant recipients in terms of age, gender and physical activity levels.

BACKGROUND

Although physical activity affects the heart rate variability in patients with heart disease, there is a paucity of literature discussing the correlation between physical activity and heart rate variability among heart transplant recipients.

DESIGN

This was a descriptive and cross-sectional study.

METHODS

A total of 120 eligible subjects were divided into the orthotopic heart transplant recipient group (n = 60) and the healthy adult group (n = 60). The Seven-day Physical Activity Recall questionnaire was used to record the subjects' amount of physical activity per week. Heart rate variety parameters were determined by separate frequency domain components.

RESULTS

Results indicated heart transplant recipients' heart rate variety was significantly lower than that of healthy adults in terms of mean, sdr, total power (ms(2)), low frequency (ms(2)), low frequency (nu), high frequency (ms(2)) and low frequency/high frequency. Heart transplant recipients' heart rate variety including total power (ms(2)), low frequency (ms(2)) and high frequency (ms(2)) was 18·2, 2 and 7·2% of healthy controls, respectively; the amount of absolutely and relatively moderate physical activity was positively related to high frequency (ms(2)) and high frequency (nu), but was negatively related to low frequency/high frequency. High frequency (nu) increases while the total amount of weekly physical activity increases.

CONCLUSIONS

Results confirmed that the more the moderate physical activity performed, the better the patient's heart rate variability.

RELEVANCE TO CLINICAL PRACTICE

We suggest that clinical care providers have to encourage heart transplant recipients to engage in moderate physical activity.

The impact of training modalities on the clinical benefits of exercise intervention in patients with cardiovascular disease risk or type 2 diabetes mellitus

Exercise training intervention represents an effective means to reduce adipose tissue mass, improve glycaemic control and increase whole-body oxygen uptake capacity (VO(2peak)) in obesity, metabolic syndrome, type 2 diabetes mellitus (T2DM) and heart disease patients. In this manuscript, we review the impact of different exercise training modalities on clinical benefits of prolonged exercise intervention in these patient (sub)populations. By changing training modalities, significantly greater clinical benefits can be obtained. Greater training frequency and longer programme duration is associated with greater reduction in adipose tissue mass in obesity patients. A greater training frequency (up to 2 days/week) and a longer programme duration (up to 38 weeks) seems to be associated with greater improvements in VO(2peak) in heart disease patients. Longer programme duration and addition of resistance-type exercise further improve glycaemic control in T2DM patients. The first line of evidence seems to indicate that high-intensity interval exercise training has a greater impact on VO(2peak) in heart disease patients and insulin sensitivity in subjects with metabolic syndrome, but not on adipose tissue mass in obese subjects. However, it remains unclear whether addition of resistance-type exercise and continuous higher-intensity endurance-type exercise training are accompanied by greater improvements in VO(2peak) in heart disease patients. Furthermore, the impact of training session duration/volume on adipose tissue mass loss and glycaemic control in obesity and T2DM patients, respectively, is currently unknown. The impact of training frequency on glycaemic control remains to be investigated in T2DM patients.

Effects of progressive exercise during phase I cardiac rehabilitation on the heart rate variability of patients with acute myocardial infarction

PURPOSE

Heart rate variability (HRV) decreases after an acute myocardial infarction (AMI) due to changes in cardiac autonomic balance. The purpose of the present study, therefore, was to evaluate the effects of a progressive exercise protocol used in phase I cardiac rehabilitation on the HRV of patients with post-AMI.

MATERIAL AND METHODS

Thirty-seven patients who had been admitted to hospital with their first non-complicated AMI were studied. The treated group (TG, n=21, age=52±12 years) performed a 5-day programme of progressive exercise during phase I cardiac rehabilitation, while the control group (CG, n=16, age=54±11 years) performed only respiratory exercises. Instantaneous heart rate (HR) and RR interval were acquired by a HR monitor (Polar®S810i). HRV was analysed by frequency domain methods. Power spectral density was expressed as normalised units (nu) at low (LF) and high (HF) frequencies, and as LF/HF.

RESULTS

After 5 days of progressive exercise, the TG showed an increase in HFnu (35.9±19.5 to 65.19±25.4) and a decrease in LFnu and LF/HF (58.9±21.4 to 32.5±24.1; 3.12±4.0 to 1.0±1.5, respectively) in the resting position (p<0.05). No changes were observed in the CG.

CONCLUSIONS

A progressive physiotherapeutic exercise programme carried out during phase I cardiac rehabilitation, as supplement to clinical treatment increased vagal and decreased sympathetic cardiac modulation in patients with post-AMI.

Increase in the heart rate variability with deep breathing in diabetic patients after 12-month exercise training

Autonomic neuropathy in diabetes leads to impaired regulation of blood pressure and heart rate variability (HRV), which is due to a shift in cardiac autonomic balance towards sympathetic dominance. Lower HRV has been considered a predictor of cardiac mortality and morbidity. Deep breathing test is a simple method to measure HRV and it provides a sensitive measure of cardiac autonomic function. The effect of long-term physical activity on HRV in type-2 diabetes mellitus is inconclusive. We aimed to evaluate the effects of regular physical exercise on HRV with deep breathing in type 2 diabetes (n = 105). Thirty normotensive diabetic patients and 25 hypertensive diabetic patients underwent physical exercise program for 12 months, and the other 50 patients (22 normotensive and 28 hypertensive diabetic patients) were considered the non-exercised group. Electrocardiogram was recorded during deep breathing and HRV was measured. Regular exercise significantly increased HRV in diabetic patients with and without hypertension. The degree of the increase in HRV was greater in hypertensive diabetic patients (p < 0.01) than in normotensive diabetic patients (p < 0.05). After exercise, glycosylated hemoglobin levels were decreased in both groups of diabetic patients. Moreover, the hypertensive diabetic patients showed a decrease (p < 0.05) in blood pressure after regular exercise. Thus, regular exercise training increases HRV, suggesting that there is a shift in the cardiac sympathovagal balance in favor of parasympathetic dominance in diabetic patients. Long-term physical training may be an effective means to reverse the autonomic dysregulation seen in type 2 diabetes.

Home-based versus centre-based cardiac rehabilitation

BACKGROUND

The burden of cardiovascular disease world-wide is one of great concern to patients and health care agencies alike. Traditionally centre-based cardiac rehabilitation (CR) programmes are offered to individuals after cardiac events to aid recovery and prevent further cardiac illness. Home-based cardiac rehabilitation programmes have been introduced in an attempt to widen access and participation.

OBJECTIVES

To determine the effectiveness of home-based cardiac rehabilitation programmes compared with supervised centre-based cardiac rehabilitation on mortality and morbidity, health-related quality of life and modifiable cardiac risk factors in patients with coronary heart disease.

SEARCH STRATEGY

We updated the search of a previous review by searching the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2007, Issue 4), MEDLINE, EMBASE and CINAHL from 2001 to January 2008. We checked reference lists and sought advice from experts. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared centre-based cardiac rehabilitation (e.g. hospital, gymnasium, sports centre) with home-based programmes, in adults with myocardial infarction, angina, heart failure or who had undergone revascularisation.

DATA COLLECTION AND ANALYSIS

Studies were selected independently by two reviewers, and data extracted by a single reviewer and checked by a second one. Authors were contacted where possible to obtain missing information.

MAIN RESULTS

Twelve studies (1,938 participants) met the inclusion criteria. The majority of studies recruited a lower risk patient following an acute myocardial infarction (MI) and revascularisation. There was no difference in outcomes of home- versus centre-based cardiac rehabilitation in mortality risk ratio (RR) was1.31 (95% confidence interval (C) 0.65 to 2.66), cardiac events, exercise capacity standardised mean difference (SMD) -0.11 (95% CI -0.35 to 0.13), as well as in modifiable risk factors (systolic blood pressure; diastolic blood pressure; total cholesterol; HDL-cholesterol; LDL-cholesterol) or proportion of smokers at follow up or health-related quality of life. There was no consistent difference in the healthcare costs of the two forms of cardiac rehabilitation.

AUTHORS' CONCLUSIONS

Home- and centre-based cardiac rehabilitation appear to be equally effective in improving the clinical and health-related quality of life outcomes in acute MI and revascularisation patients. This finding, together with an absence of evidence of difference in healthcare costs between the two approaches, would support the extension of home-based cardiac rehabilitation programmes such as the Heart Manual to give patients a choice in line with their preferences, which may have an impact on uptake of cardiac rehabilitation in the individual case.

Cardiac autonomic neural remodeling and susceptibility to sudden cardiac death: effect of endurance exercise training

Sudden cardiac death resulting from ventricular tachyarrhythmias remains the leading cause of death in industrially developed countries, accounting for between 300,000 and 500,000 deaths each year in the United States. Yet, despite the enormity of this problem, both the identification of factors contributing to ventricular fibrillation as well as the development of safe and effective antiarrhythmic agents remain elusive. Subnormal cardiac parasympathetic regulation coupled with an elevated cardiac sympathetic activation may allow for the formation of malignant ventricular arrhythmias. In particular, myocardial infarction can reduce cardiac parasympathetic regulation and alter beta-adrenoceptor subtype expression enhancing beta(2)-adrenoceptor sensitivity that can lead to intracellular calcium dysregulation and arrhythmias. As such, myocardial infarction can induce a remodeling of cardiac autonomic regulation that may be required to maintain cardiac pump function. If alterations in cardiac autonomic regulation play an important role in the genesis of life-threatening arrhythmias, then one would predict that interventions designed to either augment parasympathetic activity and/or reduce cardiac adrenergic activity would also protect against ventricular fibrillation. Recently, studies using a canine model of sudden death demonstrate that endurance exercise training (treadmill running) enhanced cardiac parasympathetic regulation (increased heart rate variability), restored a more normal beta-adrenoceptor balance (i.e., reduced beta(2)-adrenoceptor sensitivity and expression), and protected against ventricular fibrillation induced by acute myocardial ischemia. Thus exercise training may reverse the autonomic neural remodeling induced by myocardial infarction and thereby enhance the electrical stability of the heart in individuals shown to be at an increased risk for sudden cardiac death.

Exercise training and cardiac rehabilitation in primary and secondary prevention of coronary heart disease

Substantial data have established a sedentary lifestyle as a major modifiable risk factor for coronary heart disease (CHD). Increased levels of physical activity, exercise training, and overall cardiorespiratory fitness have provided protection in the primary and secondary prevention of CHD. This review surveys data from observational studies supporting the benefits of physical activity, exercise training, and overall cardiorespiratory fitness in primary prevention. Clearly, cardiac rehabilitation/secondary prevention (CRSP) programs have been greatly underused by patients with CHD. We review the benefits of CRSP programs on CHD risk factors, psychological factors, and overall CHD morbidity and mortality. These data support the routine referral of patients with CHD to CRSP programs. Patients should be vigorously encouraged to attend these programs.

Physiological and functional impact of an unsupervised but supported exercise programme for claudicants

OBJECTIVES

To evaluate an unsupervised home-based exercise programme for physiological, functional, and quality of life impact in patients with symptomatic peripheral arterial disease.

DESIGN

Prospective cohort with exercise intervention.

MATERIALS

Human performance laboratory with non-invasive haemodynamic assessment facilities.

METHODS

Forty-seven patients with symptomatic peripheral arterial disease (mean age 67.6+/-7 years, 33 males) participated in an unsupervised home-based exercise programme. Heart rate (HR), ankle brachial blood pressure index (ABPI), leg blood flow (BF), and blood lactate were measured before and after a graded treadmill walk at baseline and after the 12-week exercise programme. Maximum walking distance (MWD) during the treadmill walk was measured at baseline and 12 weeks. Exercise compliance, functional parameters, and quality of life (VascuQoL) were assessed by questionnaire.

RESULTS

MWD, leg BF, and VascuQoL scores increased significantly, while resting HR, exercise HR, and end of walk rate-pressure-product (RPP) decreased significantly after 12 weeks. Exercise compliance was significantly correlated with increase in MWD (r=0.89, p<0.001) and QOL score improvement (r=0.61, p<0.001).

CONCLUSIONS

This supported but unsupervised exercise programme generated improvements in walking distance and leg blood flow without detectable increases in cardiorespiratory work. Exercise compliance is related to MWD and VascuQoL score in a dose-response manner.

Changes in short-term measures of heart rate variability after eight weeks of cardiac rehabilitation

BACKGROUND

In coronary artery disease (CAD) and following myocardial infarction (MI), activity of the autonomic nervous system is altered. Reduced heart rate variability (HRV) is a risk factor for future cardiac event. Studies reporting changes in HRV post-cardiac rehabilitation (CR) are heterogeneous, due possibly to varied data collection and analysis protocols.

AIM

To evaluate changes in spectral measures of HRV derived from 5-minute ECG recordings in patients completing an 8 weeks CR programme.

METHODS

Thirty-eight patients (21 males, 17 females, aged 65.6 +/- 11.6 years) underwent 5 minutes, supine ECG recordings and standard physiological and psychological assessment pre- and post-CR. A further 23 patients (14 males, 9 females aged 64.9 +/- 9 years) acted as controls. Outcome measures were: low frequency power, (LF, 0.04-0.15 Hz) high frequency power (HF, 0.15-0.40 Hz), LF:HF ratio and mean RR interval. Change was assessed by ANCOVA and paired t-tests.

RESULTS

When compared with the CT group, the CR group showed significant increases in: SDNN (Delta +6 ms, CR vs. 0 ms CT), HFln (Delta 0.4 log units CR vs. 0 log units CT), LFln (Delta +0.6 log units CR, vs. +0.1 log units CT) and RR interval (Delta +30 ms, CR vs. -28 ms CT).

CONCLUSIONS

This is the first study to show significant increases in raw LF and HF power derived from short-term ECG recordings in CR patients. These measures are risk factors for future cardiac event. As CR is associated with increases in these measures it may be viewed as an effective therapy capable of bringing about favourable alterations in autonomic control.

Rehabilitation in Cardiac Patients

This article discusses the effects of training in cardiac rehabilitation and describes the influence of various training modalities on the evolution of exercise capacity in cardiac patients. Both home- and hospital-based studies are analysed separately. From the collected studies, a very heterogeneous character of the content of the rehabilitation programmes appears. Direct comparison of the effects of the training programmes on exercise capacity remains difficult. Baseline factors for predicting a better training outcome are: low exercise capacity and peripheral oxygen extraction; presence of hibernating myocardium; high myocardial perfusion; low degree of coronary vessel occlusion; working status; and improved feelings of wellbeing. The increased work capacity as a result of rehabilitation is associated with: an increased volume density of skeletal muscle mitochondria; peripheral muscular vasodilatory capacity; cardiac output and a decreased left ventricular end-diastolic pressure; depletion of muscular phosphocreatine levels; and degree of restenosis. Home- and hospital-based interventions induce comparable training effects. More research is needed concerning the training modalities in cardiac rehabilitation. There is an influence of weekly training frequency and programme duration on the training outcome. A higher training frequency and/or duration might induce greater training effects. The evolution of the anaerobic threshold is sensitive to the training intensity and inclusion of strength training, which remains to be established for maximal exercise capacity. However, insufficient information is available on the influence of training session duration on the evolution of exercise capacity.

Effects of cardiac rehabilitation on self-reported health status after coronary artery bypass surgery

PURPOSE

To examine the effectiveness of cardiac rehabilitation on health status following coronary artery bypass surgery.

METHODS

A prospective cohort study of patients having coronary artery bypass surgery at 14 centers in the state of Washington. Baseline clinical and demographic data were collected, as was information from the Rand Short Form, 36 (SF-36), the Seattle Angina Questionnaire, and other questions regarding health status before surgery and at 6 and 12 months after surgery. In the 12-month follow-up survey, subjects were asked to complete questions pertaining to their participation in postdischarge cardiac rehabilitation programs.

RESULTS

A total of 947 subjects from 13 centers received 1-year follow-up surveys, with 75% responding. Of these, 691 (95%) answered questions about participation in cardiac rehabilitation programs. SF-36 and Seattle Angina Questionnaire scores improved significantly after surgery for both cardiac rehabilitation participants and nonparticipants. Although more than 90% of subjects who participated in the cardiac rehabilitation programs stated that they were beneficial, for eight SF-36 domains and five Seattle Angina Questionnaire domains, no significant associations were found with participation in cardiac rehabilitation. When the participation status was defined as only those participants who completed at least 8 weeks of cardiac rehabilitation, only 1 of 13 health status domains favored cardiac rehabilitation. Responses to a series of questions about perceptions of change in general and cardiac-specific health did not differ among participants and nonparticipants.

CONCLUSIONS

Although patients report favorable impressions of cardiac rehabilitation after coronary artery bypass surgery, it does not appear to provide a measurable benefit in self-reported health status beyond that achieved from the revascularization procedure itself.

Mortality, cardiac vagal control and physical training--what's the link?

There is little doubt that regular exercise results in increases in life expectancy and protects against adverse cardiac events in both healthy subjects and patients with cardiovascular disease. The mechanism of action of physical training remains unclear but a variety of evidence points towards an enhancement in cardiac vagal activity protecting against lethal arrhythmias. Just how physical training increases cardiac vagal activity is an area that is ill understood but plausible mechanisms include mediation via angiotensin II or NO. Further research is needed in this area. Exercise training is demanding and difficult, particularly for patients with cardiac disease. If the mechanism of increase in cardiac vagal activity with training can be determined it may be possible to use pharmacological approaches to mimic the effects of exercise with potentially beneficial effects.

Functional assessment of heart rate variability: physiological basis and practical applications

The autonomic nervous system dynamically controls the response of the body to a range of external and internal stimuli, providing physiological stability in the individual. With the progress of information technology, it is now possible to explore the functioning of this system reliably and non-invasively using comprehensive and functional analysis of heart rate variability. This method is already an established tool in cardiology research, and is increasingly being used for a range of clinical applications. This review describes the theoretical basis and practical applications for this emerging technique.