Effect of 8-week exercise-based cardiac rehabilitation on cardiac autonomic function: A randomized controlled trial in myocardial infarction patients

Beneficial impacts of physical activity on heart rate variability: A systematic review and meta-analysis

BACKGROUND

Cardiovascular diseases (CVD) are the leading causes of morbidity and mortality. Heart rate variability (HRV) represents the modulatory capacity of the autonomous nervous system and influences mortality. By surveying this meta-analysis, we investigated the impact of physical activity on HRV.

METHODS

Databases, online journal libraries and clinical trial registries were searched for publications of randomized controlled and non-randomized controlled trials concerning adults with coronary artery disease (CAD)/ischemic heart disease (IHD), congestive heart failure (CHF), peripheral arterial disease (PAD) or after acute coronary syndrome (ACS) joining an intervention group with physical activity or a control group with usual care or no intervention. Extracted time-domain and frequency-domain parameter of HRV were analyzed in a meta-analysis using a random effect model. Subgroup analyses concerning intervention type, study design and type of heart disease and sensitivity analysis were performed.

RESULTS

Significant results were obtained for RR-Interval (p = 0.05) and standard deviation of Normal-to-Normal intervals (SDNN) (p = 0.01) for short-term assessment and for the ratio of low-frequency power (LF) to high-frequency power (HF) (p = 0.05) for 24-hour assessment. Subgroup analyses also resulted significant: root-mean-square difference of successive normal R-R intervals (RMSSD) (p = 0.01), SDNN (p = 0.02) and HF (p < 0.01) concerning CHF.

CONCLUSION

We were able to demonstrate the positive impact of physical activity on HRV, especially in patients with CHF. Cardiac rehabilitation exercise programs need to be individualized to identify the most beneficial method of training for improving the prognosis of patients with CVD.

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.

Exercise-Based Interventions in Middle-Aged and Older Adults after Myocardial Infarction: A Systematic Review

This study summarized the relevant literature and aimed to determine the effect of exercise-based interventions after myocardial infarction in middle-aged and older adults. Studies were identified and analyzed according to the PRISMA guidelines. The following electronic databases were used: Google Scholar, PubMed, Mendeley, Science Direct, and Scopus. The identified studies had to be longitudinal, be published in English, have taken place between 2010 and 2020, involve participants who had suffered myocardial infarction, and address different types of exercise-based interventions to be included. Of the 592 relevant studies identified, 20 were included in the qualitative analysis. After analyzing the results obtained, it could be concluded that different types of exercise-based interventions or their combination have a positive effect after myocardial infarction in middle-aged and elderly adults. It can also be suggested that the combination of a cycle ergometer and a treadmill may be the most effective exercise-based intervention. An adequate choice of intensity and volume is crucial, with the optimal duration of the experimental program and the type(s) of exercises adapted to participants after myocardial infarction.

Effect of different physical training modalities on peak oxygen consumptions in post-acute myocardial infarction patients: systematic review and meta-analysis

Physical training can increase peak oxygen uptake (VO2peak) in people who have suffered acute myocardial infarction (AMI). However, there is still a gap in the literature in relation to the effectiveness of different types of interventions. Therefore, the aim of the present study was to evaluate the effects of different physical training modalities on VO2peak in post-AMI patients. The following databases were used: PubMed (MEDLINE), Cochrane Library, Scopus, and Pedro. Studies that evaluated aerobic exercise, strength exercise, or combined exercise were included. Six studies met eligibility criteria. Aerobic exercise increased VO2peak by 6.07 ml.kg-1.min-1 when compared to the control group (CG) (p = 0.013). The comparison between combined exercise and control group detected a difference of 1.84 ml.kg-1.min-1, but this was not significant (p = 0.312). We therefore conclude that aerobic exercise is the only modality that is effective for increasing VO2peak compared to a control group.

Location-Based Sedentary Time and Physical Activity in People Living With Coronary Artery Disease

PURPOSE

Sedentary time (ST) and lack of physical activity increase the risk of adverse outcomes for those living with coronary artery disease (CAD). Little is known about how much ST, light physical activity (LPA), and moderate to vigorous physical activity (MVPA) that CAD participants not attending cardiac rehabilitation engage in, the locations where they engage in these behaviors, and how far from home the locations are.

METHODS

Participants completed a survey and wore an accelerometer and global positioning system receiver for 7 d at baseline and 6 mo later.

RESULTS

Accelerometer analyses (n = 318) showed that participants averaged 468.4 ± 102.7 of ST, 316.1 ± 86.5 of LPA, and 32.9 ± 28.9 of MVPA min/d at baseline. ST and LPA remained stable at 6 mo, whereas MVPA significantly declined. The global positioning system (GPS) analyses (n = 315) showed that most of participant ST, LPA, and MVPA time was spent at home followed by other residential, retail/hospitality, and work locations at baseline and 6 mo. When not at home, the average distance to a given location ranged from approximately 9 to 18 km.

CONCLUSIONS

Participants with CAD spent the majority of their time being sedentary. Home was the location used the most to engage in ST, LPA, and MVPA. When not home, ST, LPA, and MVPA were distributed across a variety of locations. The average distance from home to a given location suggests that proximity to home may not be a barrier from an intervention perspective.

Effects of physical exercise on the autonomic nervous system in patients with coronary artery disease: a systematic review

BACKGROUND

Imbalance in autonomic modulation can occur after a cardiac event, which can lead to deleterious consequences. Exercise has proven to be a therapy which affects this modulation and can be assessed through heart rate variability (HRV).

AREAS COVERED

The objective of this systematic review was to investigate the effects of physical exercise on heart rate variability in individuals with coronary artery disease (CAD). The PubMed, PEDro, Scielo, Lilacs and Cochrane databases were systematically searched, for articles which performed supervised exercises in phase II of cardiac rehabilitation in patients with CAD.

EXPERT OPINION

Given the differences between studies on interventions and population characteristics, it is difficult to justify similarities or divergences in terms of results. In addition to the variation in sample size, intervention duration, carrying out an additional program at home, and patients with different clinical presentations, it can be inferred that responses to exercise may vary for certain types/clinical profile of individuals with CAD. Thus, it is necessary to carry out more studies with greater methodological rigor, greater standardization of the variables studied and the evaluation forms, in order to increase the veracity of the results and the consequent clinical relevance and therapeutic application.

Effects of a short health education intervention on physical activity, arterial stiffness and cardiac autonomic function in individuals with moderate-to-high cardiovascular risk

OBJECTIVE

This study evaluated the effects of a short health education and counseling intervention program, in a primary healthcare setting, on daily physical activity (PA), arterial stiffness, and cardiac autonomic function in individuals with moderate-to-high risk of cardiovascular disease.

METHODS

This was a parallel-group study with a 4-month-long intervention, plus 8 months of follow-up. 164 individuals with moderate-to-high cardiovascular risk were allocated to either an intervention (n = 87) or a control group (n = 77). The intervention consisted of 3 walking and face-to-face group sessions plus text messages. Primary outcome was daily PA (sedentary time, light and moderate-to-vigorous PA, all in min/day); secondary outcomes were arterial stiffness i.e., carotid-femoral pulse wave velocity (cfPWV, m/s)] and cardiac autonomic function [(i.e., standard deviation of all N-N intervals (SDNN, ms) and absolute high frequency (HF, ms²)].

RESULTS

There were not significant group*time interactions for sedentary time [-7.4 (7.6); p = 0.331)], light PA [4.4 (6.4); p = 0.491] or moderate-to-vigorous PA [0.1 (2.6); p = 0.938]. Considering secondary outcomes, there were not significant group*time interactions for cfPWV [0.09 (0.18); p = 0.592], Ln_SDNN [0.09 (0.06); p = 0.148], or Ln_HF [0.16 (0.14); p = 0.263].

CONCLUSION

The program did not improve daily PA, arterial stiffness, or the autonomic cardiac function.

PRACTICE IMPLICATIONS

Primary care staff should consider longer or other types of intervention to improve daily PA.

Are the Current Cardiac Rehabilitation Programs Optimized to Improve Cardiorespiratory Fitness in Patients? A Meta-Analysis

Previous meta-analyses have shown that high-intensity interval training (HIIT) is more suitable than moderate continuous training (MCT) for improving peak oxygen uptake (VO2peak) in patients with coronary artery disease. However, none of these meta-analyses have tried to explain the heterogeneity of the empirical studies in optimizing cardiac rehabilitation programs. Therefore, our aims were (a) to estimate the effect of MCT and HIIT on VO2peak, and (b) to find the potential moderator variables. A search was conducted in PubMed, Scopus, and ScienceDirect. Out of the 3,110 references retrieved, 29 studies fulfilled the selection criteria to be included in our meta-analysis. The mean difference was used as the effect size index. Our results showed significant enhancements in VO2peak after cardiac rehabilitation based on MCT and HIIT (mean difference = 3.23; 95% confidence interval [2.81, 3.65] ml·kg-1·min-1 and mean difference = 4.61; 95% confidence interval [4.02, 5.19] ml·kg-1·min-1, respectively), with greater increases after HIIT (p < .001). Heterogeneity analyses reached statistical significance with moderate heterogeneity for MCT (p < .001; I2 = 67.0%), whereas no heterogeneity was found for the effect of HIIT (p = .220; I2 = 22.0%). Subgroup analyses showed significant between-group heterogeneity of the MCT-induced effect based on the training mode (p < .001; I2 = 90.4%), the risk of a new event (p = .010; I2 = 77.4%), the type of cardiovascular event (p = .009; I2 = 84.8%), the wait time to start cardiac rehabilitation (p = .010; I2 = 76.6%), and participant allocation (p = .002; I2 = 89.9%). Meta-regressions revealed that the percentages of patients undergoing a revascularization procedure (B = -0.022; p = .041) and cardiorespiratory fitness at baseline (B = -0.103; p = .025) were inversely related to the MCT-induced effect on the VO2peak.

The Effect of Exercise-Based Cardiac Rehabilitation on Objectively Measured Physical Activity and Sedentary Behavior: A Systematic Review and Meta-analysis

Objective: Adequate physical activity following cardiac rehabilitation (CR) is required to reduce secondary cardiovascular disease risk. The aim of this review and meta-analysis was to determine the effect of exercise-based CR on objectively measured physical activity (PA) and sedentary behavior (SB) comparing pre- to postintervention, pre- to postchange compared to a control group, and in a longer term follow-up. Methods: Five databases were searched (PubMed, MEDLINE [OVID], Scopus, SPORTDiscus, and CINAHL) from inception to January 2019. Two reviewers screened and selected 15 studies involving 1434 participants. Data were synthesized descriptively and by meta-analyses. Results: CR resulted in an improvement in activity behaviors compared with preintervention levels (standardized mean difference [SMD] 0.50, 95% CI 0.25-0.55, P < .0001). CR resulted in a greater improvement in activity behaviors in the intervention compared with the control group (SMD 0.25, 95% CI 0.02-0.49, P = .04). Increased PA was maintained (SMD 0.32, 95% CI 0.22-0.41, P < .0001). Eight out of 15 studies showed an improvement in PA outcomes while 7 reported that objectively measured PA did not change immediately following the intervention compared to preintervention levels and/or compared with the control group. Of the 7 studies that reported changes in SB, 4 observed a reduction following CR while 3 reported no change. Conclusion: Participation in exercise-based CR programs is effective in improving PA and SB. However, our descriptive synthesis indicates that only half the studies were successful in improving activity behaviors following exercise-based CR. Standard guidelines for the assessment of activity behaviors following CR would be valuable in understanding of the effects of CR on long-term activity participation.

Exercise-based cardiac rehabilitation and parasympathetic function in patients with coronary artery disease: a systematic review and meta-analysis

PURPOSE

The effects of exercise-based cardiac rehabilitation (CR) on parasympathetic modulation are controversial. This systematic review and meta-analysis aims to (a) determine the effect of exercise-based CR on heart-rate-derived indices associated with cardiac parasympathetic modulation in resting and post-exercise conditions in coronary artery disease (CAD) patients and (b) identify the possible moderator variables of the effect of exercise-based CR on parasympathetic modulation.

METHODS

We searched CENTRAL and Web of Science up to November 2018 for the following terms: adult CAD patients, controlled exercise-based CR interventions and parasympathetic modulation measured in resting (vagal-related heart rate variability [HRV] indices of the root mean square of the differences in successive in RR interval [RMSSD] and high frequency [HF]) and post-exercise (heart rate recovery [HRR]) pre- and post-intervention. We estimated a random-effects model of standardised mean difference (SMD) and mean difference (MD) for vagal-related HRV indices and HRR, respectively. We assessed the influence of categorical and continuous variables.

RESULTS

The overall effect size showed significant differences in RMSSD (SMD₊ = 0.30; 95% confidence interval [CI] = 0.12-0.49) and HRR (MD₊ = 5.35; 95% CI = 4.08-6.61 bpm) in favour of the exercise-based CR group. The overall effect size showed no differences in HF between groups (SMD₊ = 0.14; 95% CI,  -0.12-0.40). Heterogeneity analyses reached statistical significance, with high heterogeneity for HF (p < 0.001; I² = 70%) and HRR (p < 0.001; I² = 85%). Analysis of the moderator variables showed that the effect on HRR is greater in young patients (p = 0.008) and patients treated with percutaneous intervention (p = 0.020).

CONCLUSIONS

Exercise-based CR improves the post-exercise parasympathetic function, with greater effects in younger CAD patients and in those who were revascularised with percutaneous intervention. The effects on resting parasympathetic function are more controversial due to methodological inconsistencies in measuring HRV, with the use of RMSSD recommended instead of HF because its results show higher consistency. Future studies involving women, focusing on methodological issues, and performing other training methods are needed to increase our knowledge about this topic.

Effects of 6 Months of Exercise-Based Cardiac Rehabilitation on Autonomic Function and Neuro-Cardiovascular Stress Reactivity in Coronary Artery Disease Patients

Background Autonomic dysregulation represents a hallmark of coronary artery disease (CAD). Therefore, we investigated the effects of exercise-based cardiac rehabilitation (CR) on autonomic function and neuro-cardiovascular stress reactivity in CAD patients. Methods and Results Twenty-two CAD patients (4 women; 62±8 years) were studied before and following 6 months of aerobic- and resistance-training-based CR. Twenty-two similarly aged, healthy individuals (CTRL; 7 women; 62±11 years) served as controls. We measured blood pressure, muscle sympathetic nerve activity, heart rate, heart rate variability (linear and nonlinear), and cardiovagal (sequence method) and sympathetic (linear relationship between burst incidence and diastolic blood pressure) baroreflex sensitivity during supine rest. Furthermore, neuro-cardiovascular reactivity during short-duration static handgrip (20s) at 40% maximal effort was evaluated. Six months of CR lowered resting blood pressure (P<0.05), as well as muscle sympathetic nerve activity burst frequency (48±8 to 39±11 bursts/min; P<0.001) and burst incidence (81±7 to 66±17 bursts/100 heartbeats; P<0.001), to levels that matched CTRL and improved sympathetic baroreflex sensitivity in CAD patients (P<0.01). Heart rate variability (all P>0.05) and cardiovagal baroreflex sensitivity (P=0.11) were unchanged following CR, yet values were not different pre-CR from CTRL (all P>0.05). Furthermore, before CR, CAD patients displayed greater blood pressure and muscle sympathetic nerve activity reactivity to static handgrip versus CTRL (all P<0.05); yet, responses were reduced following CR (all P<0.05) to levels observed in CTRL. Conclusions Six months of exercise-based CR was associated with marked improvement in baseline autonomic function and neuro-cardiovascular stress reactivity in CAD patients, which may play a role in the reduced cardiac risk and improved survival observed in patients following exercise training.

A Preliminary Study of the Effect of Early Aerobic Exercise Treatment for Sport-Related Concussion in Males

OBJECTIVE

To study the effect of early prescribed aerobic exercise versus relative rest on rate of recovery in male adolescents acutely after sport-related concussion (SRC).

DESIGN

Quasi-experimental design.

SETTING

University sports medicine centers.

PARTICIPANTS

Exercise group (EG, n = 24, 15.13 ± 1.4 years, 4.75 ± 2.5 days from injury) and rest group (RG, n = 30, 15.33 ± 1.4 years, 4.50 ± 2.1 days from injury).

INTERVENTIONS

Exercise group performed a progressive program of at least 20 minutes of daily subthreshold aerobic exercise. Rest group was prescribed relative rest (no structured exercise). Both groups completed daily online symptom reports (Postconcussion Symptom Scale) for 14 days.

MAIN OUTCOME MEASURES

Days to recovery after treatment prescription. Recovery was defined as return to baseline symptoms, exercise tolerant, and judged recovered by physician examination.

RESULTS

Recovery time from initial visit was significantly shorter in EG (8.29 ± 3.9 days vs 23.93 ± 41.7 days, P = 0.048). Mixed-effects linear models showed that all symptom clusters decreased with time and that there was no significant interaction between treatment group and time. No EG participants experienced delayed recovery (>30 days), whereas 13% (4/30) of RG participants experienced delayed recovery.

CONCLUSIONS

These preliminary data suggest that early subthreshold aerobic exercise prescribed to symptomatic adolescent males within 1 week of SRC hastens recovery and has the potential to prevent delayed recovery.

Cardiac rehabilitation and physical activity: systematic review and meta-analysis

Objective

To undertake a systematic review and meta-analysis to assess the impact of cardiac rehabilitation (CR) on physical activity (PA) levels of patients with heart disease and the methodological quality of these studies.

Methods

Databases (MEDLINE, EMBASE, CENTRAL, CINAHL, PsychINFO and SportDiscus) were searched without language restriction from inception to January 2017 for randomised controlled trials (RCTs) comparing CR to usual care control in adults with heart failure (HF) or coronary heart disease (CHD) and measuring PA subjectively or objectively. The direction of PA difference between CR and control was summarised using vote counting (ie, counting the positive, negative and non-significant results) and meta-analysis.

Results

Forty RCTs, (6480 patients: 5825 CHD, 655 HF) were included with 26% (38/145) PA results showing a statistically significant improvement in PA levels with CR compared with control. This pattern of results appeared consistent regardless of type of CR intervention (comprehensive vs exercise-only) or PA measurement (objective vs subjective). Meta-analysis showed PA increases in the metrics of steps/day (1423, 95% CI 757.07 to 2089.43, p<0.0001) and proportion of patients categorised as physically active (relative risk 1.55, 95% CI 1.19 to 2.02, p=0.001). The included trials were at high risk of bias, and the quality of the PA assessment and reporting was relatively poor.

Conclusion

Overall, there is moderate evidence of an increase in PA with CR participation compared with control. High-quality trials are required, with robust PA measurement and data analysis methods, to assess if CR definitely leads to important improvements in PA.

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.

The influence of training characteristics on the effect of exercise training in patients with coronary artery disease: Systematic review and meta-regression analysis

BACKGROUND

Although exercise-based cardiac rehabilitation improves exercise capacity of coronary artery disease patients, it is unclear which training characteristic determines this improvement. Total energy expenditure and its constituent training characteristics (training intensity, session frequency, session duration and programme length) vary considerably among clinical trials, making it hard to compare studies directly. Therefore, we performed a systematic review and meta-regression analysis to assess the effect of total energy expenditure and its constituent training characteristics on exercise capacity.

METHODS

We identified randomised controlled trials comparing continuous aerobic exercise training with usual care for patients with coronary artery disease. Studies were included when training intensity, session frequency, session duration and programme length was described, and exercise capacity was reported in peakVO₂. Energy expenditure was calculated from the four training characteristics. The effect of training characteristics on exercise capacity was determined using mixed effects linear regression analyses. The analyses were performed with and without total energy expenditure as covariate.

RESULTS

Twenty studies were included in the analyses. The mean difference in peakVO₂ between the intervention group and control group was 3.97ml·min^-1·kg^-1 (p<0.01, 95% CI 2.86 to 5.07). Total energy expenditure was significantly related to improvement of exercise capacity (effect size 0.91ml·min^-1·kg^-1 per 100J·kg, p<0.01, 95% CI 0.77 to 1.06), no effect was found for its constituent training characteristics after adjustment for total energy expenditure.

CONCLUSIONS

We conclude that the design of an exercise programme should primarily be aimed at optimising total energy expenditure rather than on one specific training characteristic.

Depressive symptoms, functional measures and long-term outcomes of high-risk ST-elevated myocardial infarction patients treated by primary angioplasty

The presence of major depressive symptoms is usually considered a negative long-term prognostic factor after an acute myocardial infarction (AMI); however, most of the supporting research was conducted before the era of immediate reperfusion by percutaneous coronary intervention. The aims of this study are to evaluate if depression still retains long-term prognostic significance in our era of immediate coronary reperfusion, and to study possible correlations with clinical parameters of physical performance. In 184 patients with recent ST-elevated AMI (STEMI), treated by immediate reperfusion, moderate or severe depressive symptoms (evaluated by Beck Depression Inventory version I) were present in 10 % of cases. Physical performance was evaluated by two 6-min walk tests and by a symptom-limited cardiopulmonary exercise test: somatic/affective (but not cognitive/affective) symptoms of depression and perceived quality of life (evaluated by the EuroQoL questionnaire) are worse in patients with lower levels of physical performance. Follow-up was performed after a median of 29 months by means of telephone interviews; 32 major adverse cardiovascular events (MACE) occurred. The presence of three vessels disease and low left ventricle ejection fraction are correlated with a greater incidence of MACE; only somatic/affective (but not cognitive/affective) symptoms of depression correlate with long-term outcomes. In patients with recent STEMI treated by immediate reperfusion, somatic/affective but not cognitive/affective symptoms of depression show prognostic value on long-term MACE. Depression symptoms are not predictors "per se" of adverse prognosis, but seem to express an underlying worse cardiac efficiency, clinically reflected by poorer physical performance.

Effectiveness of endurance exercise training in patients with coronary artery disease: A meta-analysis of randomised controlled trials

BACKGROUND

Exercise interventions apparently reduce the risks of and prevent coronary artery disease (CAD). Developing an exercise intervention for patients with CAD is a rapidly expanding focus worldwide. The results of previous studies are inconsistent and difficult to interpret across various types of exercise programme.

AIM

This study aimed to update prior systemic reviews and meta-analyses in order to determine the overall effects of endurance exercise training on patients with CAD.

METHODS

The databases (PubMed, Medline, CINAHL, EMBASE and Cochrane Library) were searched for the interventions published between January 1, 2000, and May 31, 2015. Comprehensive meta-analysis software was used to evaluate the heterogeneity of the selected studies and to calculate mean differences (MDs) while considering effect size.

RESULTS

A total of 18 studies with 1286 participants were included. Endurance exercise interventions at a moderate to high training intensity significantly reduced resting systolic blood pressure (MD: -3.8 mmHg, p = 0.01) and low-density lipoprotein cholesterol (MD: -5.5 mg/dL, p = 0.02), and increased high-density lipoprotein cholesterol (MD: 3.8 mg/dL, p < 0.001). There were also significant positive changes in peak oxygen consumption (MD: 3.47 mL/kg/min, p < 0.001) and left ventricular ejection fraction (MD: 2.6%, p = 0.03) after the interventions. Subgroup analysis results revealed that exercise interventions of 60-90 minutes per week with a programme duration of >12 weeks had beneficial effects on functional capacity, cardiac function and a number of cardiovascular risk factors.

CONCLUSIONS

Endurance exercise training has a positive effect on major modifiable cardiovascular risk factors and functional capacity. Nurses can develop endurance exercise recommendations for incorporation into care plans of clinically stable CAD patients following an acute cardiac event or revascularisation procedure.

Improvement in aerobic capacity during cardiac rehabilitation in coronary artery disease patients: Is there a role for autonomic adaptations?

Background It has been previously shown in patients with heart failure that exercise-based rehabilitation programmes may improve functional capacity and autonomic response. The aim of this study was to investigate this issue further by evaluating whether an association exists between autonomic adaptations and improvements of aerobic capacity in a general population of coronary artery disease patients undergoing cardiac rehabilitation. Methods Ninety consecutive patients (age 60 ± 11 years) attended a rehabilitation programme of moderate continuous training (25 ± 8 sessions, 2-3 sessions/week). Functional capacity expressed as oxygen uptake (peak VO₂) and autonomic function expressed as chronotropic response and heart rate recovery were evaluated by cardiopulmonary exercise tests before and after the rehabilitation programme. According to the expected mean increase in functional capacity, coronary artery disease patients were divided into two groups: those who improved peak VO₂ by more than 2.6 ml/kg/min (R group) and those who did not (NR group). Effects of the rehabilitation programme were compared in R and NR groups. Results The number and intensity of exercise sessions did not differ between R ( N = 39) and NR ( N = 51) groups. However, only R patients improved chronotropic response (R: from 45.1 ± 16.9% to 72.7 ± 34.1%, P < 0.01; NR: from 49.3 ± 18.6% to 48.2 ± 36.5%, P = NS) and heart rate recovery (R: from 16.9 ± 7.0 bpm to 21.0 ± 8.7 bpm, P < 0.01; NR: from 15.2 ± 9.9 bpm to 15.8 ± 8.5 bpm, P = NS). After training both chronotropic response and heart rate recovery were significantly higher in R than NR patients. Conclusions The improvement in aerobic capacity of coronary artery disease patients following exercise-based cardiac rehabilitation programmes is associated with positive adaptations of autonomic function.

Effects of circuit exercise on autonomic nerve system of survivors after surgery of breast cancer

[Purpose] This study aimed to investigate the effects of exercise on the autonomic nervous system of breast cancer survivors by measuring heart rate variability during an 8-week circulation exercise program. [Subjects and Methods] This intervention study included 22 volunteer female participants, younger than 65 years, who were selected from patients who had been diagnosed with carcinoma in situ and primary invasive breast cancer, stage I-III, in accordance with the American Joint Committee on Cancer (2009) and had undergone breast surgery. [Results] Despite the statistically significant differences in the low-frequency range (log), the high-frequency range (log), the standard deviation of the N-N interval, and the root mean square of differences values, which are heart rate variability indicators after exercise, between the two groups, no statistically significant difference was found in the low-frequency range/the high-frequency range values between the two groups. [Conclusion] The improvement in heart rate variability during the 8-week circulation exercise program confirms the increase in the activity of the autonomic nervous system of breast cancer patients after surgery.

Functional parameters but not heart rate variability correlate with long-term outcomes in St-elevation myocardial infarction patients treated by primary angioplasty

BACKGROUND

Depressed heart rate variability (HRV) is usually considered a negative long-term prognostic factor after acute myocardial infarction. Anyway, most of the supporting research was conducted before the era of immediate reperfusion by percutaneous coronary intervention (PCI). Main aim of this study was to evaluate if HRV still retains prognostic significance in our era of immediate PCI.

METHODS AND RESULTS

Two weeks after STEMI treated by primary PCI, time-domain HRV was assessed from 24-h Holter recordings in 186 patients: markedly depressed HRV (SDNN <70ms or <50ms) was present in 16% and in 5% of cases, respectively; patients with left ventricle ejection fraction (LVEF) <40% presented more often SDNN values in the lowest quartile. Physical performance was also assessed, by 6-minute walk tests (6MWT) and by cardiopulmonary exercise test (CPET). After >2years from infarction, occurrence of major clinical events (MCE) was investigated. Cases with or without MCE did not differ by initial HRV parameters; Kaplan-Meier events-free survival curves were similar between patients with lowest quartile SDNN and the remaining ones (χ² 0.981, p=0.322). By the contrary, events-free survival was worse if patients walked shorter distances at 6MWT (χ² 6.435, p=0.011), developed poorer ventilatory efficiency at CPET (χ² 10.060, p=0.002), or presented LVEF <40% (χ² 7.085, p=0.008).

CONCLUSIONS

In primary-PCI STEMI patients, markedly abnormal HRV was found in a small percentage of cases. HRV seems to have lost its prognostic significance, while parameters indicating LV function (LVEF and physical performance) could allow better prognostication in primary-PCI STEMI patients.

Hemodynamic, Autonomic, Ventilatory, and Metabolic Alterations After Resistance Training in Patients With Coronary Artery Disease: A Randomized Controlled Trial

OBJECTIVE

The aim of this work was to evaluate the hemodynamic, autonomic, and metabolic responses during resistance and dynamic exercise before and after an 8-week resistance training program using a low-intensity (30% of 1 repetitium maximum), high-repetition (3 sets of 20 repetitions) model, added to an aerobic training program, in a coronary artery disease cohort.

DESIGN

Twenty male subjects with coronary artery disease (61.1 ± 4.7 years) were randomly assigned to a combined training group (resistance + aerobic) or aerobic training group (AG). Heart rate, stroke volume, cardiac output, minute ventilation, blood lactate, and parasympathetic modulation indices of heart rate (square root of the mean squared differences of successive RR intervals [RMSSD] and dispersion of points perpendicular to the line of identity that provides information about the instantaneous beat-to-beat variability [SD1]) were obtained before and after an 8-week RT program while performing exercise on a cycle ergometer and a 45-degree leg press.

RESULTS

Resistance training resulted in an increase in maximal and submaximal load tolerance (P < 0.01), a decreased hemodynamic response (P < 0.01), and a reduction in blood lactate in the combined training group compared to the aerobic training group during the 45-degree leg press. During exercise on a cycle ergometer, there was a decreased hemodynamic response and increased minute ventilation (P < 0.01). The 8-week RT program resulted in greater parasympathetic tone (RMSSD and SD1) and an increase in the SDNN index during exercise on a cycle ergometer and 45-degree leg press (P < 0.05).

CONCLUSIONS

An 8-week resistance training program associated with aerobic training may attenuate hemodynamic stress, and modify metabolic and autonomic responses during resistance exercise. The training program also appeared to elicit beneficial cardiovascular and autonomic effects during exercise.

Exercise-based cardiac rehabilitation increases daily physical activity of patients following myocardial infarction: subanalysis of two randomised controlled trials

OBJECTIVE

To assess the effects of an exercise-based cardiac rehabilitation programme on daily physical activity levels of patients following myocardial infarction.

DESIGN

Subanalysis of two randomised, prospective controlled trials.

SETTING

Outpatient clinic of a secondary hospital.

PARTICIPANTS

Fifty consecutive patients randomised to the exercise group {n=25; 23 males; mean age 54 [standard deviation (SD) 9] years} or the control group [n=25; 20 males; mean age 58 (SD 9) years].

INTERVENTIONS

The exercise group participated in an 8-week aerobic exercise programme plus usual medical care and follow-up. The control group received usual medical care and follow-up.

MAIN OUTCOME MEASURES

The primary outcome measure was change in time spent undertaking moderate-to-vigorous physical activity per day, assessed by accelerometer over 7 consecutive days. Secondary outcome measures were cardiorespiratory fitness, body mass, and resting blood pressure and heart rate.

RESULTS

Moderate-to-vigorous physical activity levels increased significantly in the exercise group [43.2 (SD 36.3) to 53.5 (SD 31.9) minutes/day, P=0.030], and remained unchanged in the control group [40.8 (SD 26.2) to 36.8 (SD 26.5) minutes/day, P=0.241] from baseline to the end of the programme. Cardiorespiratory fitness increased significantly in the exercise group (mean difference 2.8; 95% of the difference 1.3 to 4.4ml/kg/minute, P=0.001) after the 8-week programme.

CONCLUSIONS

In patients under optimal medication following myocardial infarction, participation in an 8-week exercise-based cardiac rehabilitation programme was found to improve physical activity levels consistent with health-related benefits. Future studies are needed to determine whether the increase in physical activity is maintained in the long term.

Heart rate variability after myocardial infarction: what we know and what we still need to find out

Heart rate variability (HRV) is represented by the variation of the time intervals between consecutive heartbeats or the instantaneous heart rates, and can be assessed with linear and non-linear parameters. It is a sensitive indicator of an overall system complexity and adaptability and can be used to diagnose the autonomic dysfunction and quantify the associated risk in a variety of cardiac and non-cardiac disorders. The aim of this review is to summarize the current literature on the value of HRV in predicting the risk of long-term all cause, cardiac, and arrhythmic mortality in survivors of myocardial infarction (MI). We also emphasize the lack of evidence on the role of therapeutic interventions such as medications, bio-behavioral treatments, cardiac rehabilitation, and exercise, in modifying the HRV in post-MI patients.