Influence of Autonomic Nervous Dysfunction Characterizing Effect of Diabetes Mellitus on Heart Rate Response and Exercise Capacity in Patients Undergoing Cardiac Rehabilitation for Acute Myocardial Infarction

Exercise training affects hemodynamics and exercise capacity in cases of heart failure with preserved ejection fraction: a non-randomized controlled trial in individuals aged 65-80 years

Introduction

Exercise training is an established intervention method for improving exercise capacity and survival rates in patients with heart failure with preserved ejection fraction (HFpEF). However, most reports have focused on European and American patients, with limited data regarding the effects of exercise training on cardiac function, hemodynamics, and exercise capacity in East Asian patients. This study investigated the effects of exercise training on cardiac function, hemodynamics, and exercise capacity in Japanese patients aged 65-80 years with HFpEF.

Methods

This single-center, open-label, non-randomized, controlled trial prospectively enrolled 99 outpatients. Eligibility criteria for HFpEF patients were an HFA score ≥5 in addition to clinical symptoms of heart failure and left ventricular diastolic dysfunction. Exercise training in the intervention group consisted of aerobic exercise and strength training thrice weekly for 5 months. Patients in the control group continued the usual treatment for 5 months. Resting cardiac function was evaluated using echocardiography. Peak oxygen uptake (peakVO2), ventilatory equivalent (VE) vs. carbon dioxide output (VCO2) slope, peak cardiac output index, and arteriovenous oxygen difference were calculated using cardiopulmonary exercise testing combined with impedance cardiography.

Results

After 5 months of exercise training, remarkable interactions were observed, with peakVO2 as the primary outcome. Additionally, significant interactions were observed between hemodynamic indices and some echocardiographic parameters. The mean percentage change in peakVO2 from baseline was 8.3% in the intervention group. Fifteen study participants (30.1%) in the intervention group achieved a clinically meaningful change of 3.0 ml/min/kg (10% improvement) in peakVO2 from baseline. The group with 3.0 ml/min/kg or 10% improvement in peakVO2 from baseline had a considerably lower prevalence of diabetes mellitus and VE vs. VCO2 slope and considerably higher left atrial-global longitudinal strain values than the group without any notable improvements.

Conclusions

Although exercise training can help improve exercise intolerance in Japanese patients aged 65-80 years with HFpEF, its benefits are limited. Our results suggest that HFpEF, complicated by diabetes mellitus and decreased ventilatory efficiency during exercise, may require reconsideration of intervention strategies. This trial was registered with the University Hospital Medical Information Network, a trial registry in Japan (registration number: UMIN000045474).

Epicardial adipose tissue is associated with cardiorespiratory fitness and hemodynamics among Japanese individuals of various ages and of both sexes

Epicardial adipose tissue may affect hemodynamics and cardiorespiratory fitness as it is a metabolically active visceral adipose tissue and a source of inflammatory bioactive substances that can substantially modulate cardiovascular morphology and function. However, the associations between epicardial adipose tissue and hemodynamics and cardiorespiratory fitness remain unclear. This cross-sectional study aimed to examine the association between epicardial adipose tissue volume and hemodynamics, and cardiorespiratory fitness among Japanese individuals of various ages and of both sexes. Epicardial adipose tissue volume was measured in 120 participants (age, 21-85 years) by cardiac magnetic resonance imaging. To evaluate cardiorespiratory fitness, peak oxygen uptake was measured by cardiopulmonary exercise testing. Peak cardiac output and arteriovenous oxygen difference were calculated by impedance cardiography. The epicardial adipose tissue volume was significantly increased in middle-aged and older women. The epicardial adipose tissue volume was significantly and negatively correlated to peak cardiac output and peak oxygen uptake, regardless of age and sex; furthermore, epicardial adipose tissue showed a strong negative correlation with peak heart rate. Epicardial adipose tissue and peak cardiac output were significantly associated (β = -0.359, 95% confidence interval, -0.119 to -0.049, p < 0.001), even after multivariate adjustment (R2 = 0.778). However, in the multiple regression analysis with peak oxygen uptake as a dependent variable, the epicardial adipose tissue volume was not an independent predictor. These data suggest that increased epicardial adipose tissue volume may be correlated with decreased peak oxygen uptake, which might have mediated the abnormal hemodynamics among Japanese people of various ages and of both sexes. Interventions targeting epicardial adipose tissue could potentially improve hemodynamics and cardiorespiratory fitness.

Predicting a target exercise heart rate that reflects the anaerobic threshold in nonbeta-blocked hemodialysis patients: The Karvonen and heart rate reserve formulas

The aim of this study was to evaluate constants of the Karvonen (k) and heart rate reserve (HRR) (α) formulas that correspond to the anaerobic threshold (AT) to conveniently estimate the intensity of exercise therapy in nonbeta-blocked patients undergoing hemodialysis. Twenty-three patients undergoing hemodialysis performed cardiopulmonary exercise testing (CPX) and their HR at AT was measured. The predictor coefficients for a target HR corresponding to AT were calculated for each patient based on CPX. Interclass correlation coefficients (ICC) and Bland-Altman analysis were used to evaluate the reliability of the formulas. Mean values of coefficient k of the Karvonen formula and α of the HRR formula were 0.24 ± 0.11 and 17.4 ± 8, respectively. The target HR calculated with k = 0.24 and α = 17 had significant ICC between HR at AT (0.74 and 0.77, respectively; P < 0.05). Using the Karvonen and HRR formulas to determine a target HR corresponding to AT is a simple and easy method that can be used to develop exercise programs for hemodialysis patients.

Epicardial adipose tissue is tightly associated with exercise intolerance in patients with type 2 diabetes mellitus with asymptomatic left ventricular structural and functional abnormalities

AIMS

This study aimed to elucidate whether the volume of epicardial adipose tissue (EAT) is associated with left ventricular (LV) structural and functional abnormalities and exercise capacity in patients with type 2 diabetes mellitus (T2DM).

METHODS

EAT thickness and LV structural and functional abnormality components (e.g., global longitudinal strain, E/e', LV mass index, relative wall thickness) were measured using echocardiography in 176 patients with asymptomatic stage A and B heart failure (SAHF and SBHF, respectively) and 62 healthy controls (HC). Peak oxygen uptake (peakVO2) was measured by using cardiopulmonary exercise testing.

RESULTS

Even when matching study participants for age, sex, and body mass index, the EAT was thicker (HCs 5.5 ± 1.2 versus SAHF 6.4 ± 1.0 and SBHF 9.3 ± 1.7 mm) and peakVO2 was lower (HC 24.1 ± 3.3 versus SAHF 19.1 ± 2.0 and SBHF 16.9 ± 3.1 ml/kg/min) in the heart failure (HF) group than in the HC group (p < 0.001). EAT thickness (β = -0.189, p < 0.001) and peakVO2 were significantly associated, even after adjusting for multivariates (R² = 0.457).

CONCLUSIONS

In T2DM patients with asymptomatic HF, EAT may be associated with LV structural and functional abnormalities and exercise intolerance.

Reduced exercise capacity and clinical outcomes following acute myocardial infarction

Reduced exercise capacity is known to be an important predictor of poor prognosis and disability in patients with cardiovascular diseases and chronic heart failure, and even members of the general population. However, data about exercise capacity assessed by cardiopulmonary exercise testing (CPX) in acute myocardial infarction (AMI) patients who underwent primary percutaneous coronary intervention (PCI) is scarce. Among 594 consecutive AMI patients who underwent primary PCI, we examined 136 patients (85.3% men, 64.9 ± 11.9 years) who underwent CPX during hospitalization for AMI. CPX was usually performed 5 days after the onset of AMI. Reduced exercise capacity was defined as peak VO₂ ≤ 12. Clinical outcomes including all-cause death, myocardial infarction, and hospitalization due to heart failure were followed. Among 136 patients, reduced exercise capacity (peak VO₂ ≤ 12) was seen in 38 patients (28%). Patients with reduced exercise capacity were older, more likely to have hypertension, and had lower renal function. In echocardiography, patients with reduced exercise capacity had higher E/e' and larger left atrial dimension. Multivariate logistic analysis showed that E/e' (OR 1.19, 95% CI 1.09-1.31, p < 0.001) was an independent predictor of reduced exercise capacity (peak VO₂ ≤ 12). Median follow-up term was 12 months (IQR 9-22). The occurrence of composite endpoints of all-cause death, myocardial infarction, and hospitalization due to heart failure was significantly higher in patients with peak VO₂ ≤ 12 than those with peak VO₂ > 12 (p < 0.001). Reduced exercise capacity following primary PCI in AMI patients is associated with diastolic dysfunction and may lead to poorer clinical outcomes.

Influence of Complications of Diabetes Mellitus on Exercise Tolerance of Patients with Heart Failure: Focusing on autonomic nervous activity and heart rate response during cardiopulmonary exercise tests

PURPOSE

The purpose of this study was to clarify the influence of complications of diabetes on the exercise tolerance of patients with heart failure.

METHODS

The subjects of this study were 69 patients (44 men; mean age: 62.2 ± 13.4 years) who were hospitalized and diagnosed with heart failure between November 2016 and November 2017. The subjects all took part in a cardiopulmonary exercise test. The patients' medical background, indexes obtained from lower-limb muscle strength and the cardiopulmonary exercise test, heart rate response indexes [Δ heart rate (ΔHR)], and autonomic nervous activities were measured, and these individual indexes were compared between the diabetic group and the non-diabetic group.

RESULTS

Compared with the non-diabetic group, the peak oxygen uptake (peak V̇O₂) and ΔHR in the diabetic group were significantly lower (13.0 ± 2.2 vs. 14.9 ± 4.4 ml/kg/min and 27.2 ± 11.7 vs. 36.7 ± 14.7 bpm, respectively) (p<0.05). Regarding the autonomic nervous activity during the cardiopulmonary exercise test in the diabetic group, there was a significant decrease of parasympathetic nerve activity and a significant lack of increase in sympathetic nerve activity (p<0.05).

CONCLUSIONS

Patients with heart failure and diabetes had lower levels of exercise tolerance, as compared with patients without complications. It was suggested that the decrease in heart rate response was due to the decrease of autonomic nervous activity and that this may play a role in reduced exercise tolerance.

Effects of αβ-Blocker Versus β1-Blocker Treatment on Heart Rate Response During Incremental Cardiopulmonary Exercise in Japanese Male Patients with Subacute Myocardial Infarction

A simplified substitute for heart rate (HR) at the anaerobic threshold (AT), i.e., resting HR plus 30 beats per minute or a percentage of predicted maximum HR, is used as a way to determine exercise intensity without cardiopulmonary exercise testing (CPX) data. However, difficulties arise when using this method in subacute myocardial infarction (MI) patients undergoing beta-blocker therapy. This study compared the effects of αβ-blocker and β1-blocker treatment to clarify how different beta blockers affect HR response during incremental exercise. MI patients were divided into αβ-blocker (n = 67), β1-blocker (n = 17), and no-β-blocker (n = 47) groups. All patients underwent CPX one month after MI onset. The metabolic chronotropic relationship (MCR) was calculated as an indicator of HR response from the ratio of estimated HR to measured HR at AT (MCR-AT) and peak exercise (MCR-peak). MCR-AT and MCR-peak were significantly higher in the αβ-blocker group than in the β1-blocker group (p < 0.001, respectively). Multiple regression analysis revealed that β1-blocker but not αβ-blocker treatment significantly predicted lower MCR-AT and MCR-peak (β = -0.432, p < 0.001; β = -0.473, p < 0.001, respectively). Based on these results, when using the simplified method, exercise intensity should be prescribed according to the type of beta blocker used.

Effect of carvedilol on heart rate response to cardiopulmonary exercise up to the anaerobic threshold in patients with subacute myocardial infarction

Resting heart rate (HR) plus 20 or 30 beats per minute (bpm), i.e., a simplified substitute for HR at the anaerobic threshold (AT), is used as a tool for exercise prescription without cardiopulmonary exercise testing data. While resting HR plus 20 bpm is recommended for patients undergoing beta-blocker therapy, the effects of specific beta blockers on HR response to exercise up to the AT (ΔAT HR) in patients with subacute myocardial infarction (MI) are unclear. This study examined whether carvedilol treatment affects ΔAT HR in subacute MI patients. MI patients were divided into two age- and sex-matched groups [carvedilol (+), n = 66; carvedilol (-), n = 66]. All patients underwent cardiopulmonary exercise testing at 1 month after MI onset. ΔAT HR was calculated by subtracting resting HR from HR at AT. ΔAT HR did not differ significantly between the carvedilol (+) and carvedilol (-) groups (35.64 ± 9.65 vs. 34.67 ± 11.68, P = 0.604). Multiple regression analysis revealed that old age and heart failure after MI were significant predictors of lower ΔAT HR (P = 0.039 and P = 0.013, respectively), but not carvedilol treatment. Our results indicate that carvedilol treatment does not affect ΔAT HR in subacute MI patients. Therefore, exercise prescription based on HR plus 30 bpm may be feasible in this patient population, regardless of carvedilol use, without gas-exchange analysis data.

Effectiveness of Moderate Intensity Interval Training as an Index of Autonomic Nervous Activity

The purpose of this study was to examine the effects of moderate intensity interval training from the change of the autonomic nervous activity. Ten male volunteers aged 21-22 years were studied. After 10-minute rest in a seated position, the subjects were asked to perform the strength of moderate cycling exercise in ergometer. Cycling rate was done in 50 times/min. Load resistance of the ergometer was set to 2.0 kgm. Subjects paused the exercise when the heart rate becomes 120 beats/min. Subjects have resumed the exercise when the heart rate returns to the value at rest. This trial was repeated twice. The experiment was ended when the heart rate of the subjects has returned to resting level. When the heart rate during exercise is maintained to less than 120 beats/min, sympathetic nerve activity during exercise did not work actively compared to the baseline. Vagus nerve activity after exercise cessation exceeds the baseline. It is clarified that the exercise as well as activating the vagus nerve activity stimulates the total autonomic nervous activity. It has revealed that at the time of interval training at moderate load the vagus nerve activity can be carried out.

Effects of prolonged expiration breathing on cardiopulmonary responses during incremental exercise

This study was designed to clarify the effects of breathing with prolonged expiration on cardiopulmonary responses and autonomic nervous activity during incremental exercise. Eleven healthy men were randomly assigned to breathing mode: a prolonged expiration breathing with a 2-s inspired time and 4-s expired time and a spontaneous breathing without any constraints. Oxygen uptake (V(O2)), ventilation efficiency (V(E)/V(CO2)) and rate pressure product were measured. Low- (LF) and high-frequency (HF) components of blood pressure and heart rate variability were analyzed to assess sympathetic and parasympathetic nervous activities, respectively. V(E)/V(CO2), rate pressure product and LF were significantly lower, and [Formula: see text] and HF were significantly higher during exercise with prolonged expiration than with spontaneous breathing. Striking effects of prolonged expiration breathing included the improvement of ventilation efficiency, the suppression of sympathetic nervous activity and the activation of parasympathetic one during incremental exercise. Furthermore, prolonged expiration breathing may have suppressed the exercise-induced increase in myocardial V(O2).

Association of the purinergic receptor P2Y, G-protein coupled, 2 (P2RY2) gene with myocardial infarction in Japanese men

BACKGROUND

Atherosclerosis leads to myocardial infarction (MI) and P2RY2 plays an important role in this process. The aim of the present study was to investigate the association between human P2RY2 and MI via a haplotype-based case-control study that additionally analyzed the group by sex.

METHODS AND RESULTS

The 310 MI patients and 254 controls were genotyped for 5 single-nucleotide polymorphisms (SNPs) of the human P2RY2 gene (rs4944831, rs1783596, rs4944832, rs4382936, rs10898909). Data were separately analyzed for the total, male, and female subjects. For men, the GA+AA genotype of rs10898909 was significantly higher in MI patients as compared with controls (P=0.040). Logistic regression analysis found a significant difference for the genotype (P=0.016). As compared with controls, the frequencies of the C-A and T-C-A haplotypes were significantly higher (P=0.016, and P=0.045, respectively) in men, whereas the frequencies of the C-G and T-A-A haplotypes were significantly lower (P=0.023, and P=0.025, respectively) in MI patients.

CONCLUSIONS

The GA+AA genotype, as well as the C-A and T-C-A haplotypes, of human P2RY2 could be genetic markers for MI in Japanese men.

Daily exercise and bone marrow-derived CD34+/133+ cells after myocardial infarction treated by bare metal stent implantation

BACKGROUND

The aims of the present study were to explore the mobilization of bone marrow-derived CD34(+)/133(+) cells in patients with acute myocardial infarction (AMI) and bare metal stent implantation who participated in daily exercise training, and associations with exercise capacity and restenosis.

METHODS AND RESULTS

Participants comprised 23 Japanese men with AMI (Killip 1) who had been treated with a bare metal stent. All patients were advised to walk for 30-60 min/day, at least 4 times per week starting at 11 days after AMI, and were instructed to record the amount of time spent walking each day. At 10 days and then at 3 months after onset of AMI, symptom-limited cardiopulmonary exercise tests were performed and the number of CD34(+)/133(+) cells in the peripheral blood were measured by fluorescence-activated cell sorter analysis. At 3 months after AMI, the number of CD34(+)/133(+) cells and oxygen consumption at anaerobic threshold were higher in the high exercise group (ie, exercise duration >4 h/week) than the low exercise group (ie, exercise duration <2 h/week). At 3 months after AMI, the number of CD34(+)/133(+) cells significantly correlated with oxygen consumption at the anaerobic threshold (p=0.002).

CONCLUSION

Moderate daily exercise of >4 h/week increases exercise capacity and the number of circulating CD34(+)/133(+) cells at 3 months after AMI.

Hypotensive effects of exercise performed around anaerobic threshold in type 2 diabetic patients

AIM

To verify the occurrence of post-exercise hypotension (PEH) in type 2 diabetics (DM(2)) and the effects of exercise intensity on post-exercise blood pressure (BP).

METHODS

Eleven men and women with DM(2) (58.5+/-10.2 years; 160+/-0.1cm; 80.6+/-13.5kg; 31.2+/-3.8kg/m(2), 19+/-3.2mLkgmin(-1) of VO(2max), 155.0+/-39.2mgdL(-1) of fasting blood glucose and 126+/-10/75+/-7mmHg of resting BP) performed an incremental test (IT) for cardiovascular evaluation and anaerobic threshold (AT) determination. Then, participants randomly underwent 2 exercise sessions (90% and 110% AT) and a control session (CON). In all sessions, BP was measured at resting, during 20min of exercise/control and at each 15min through 120min of post-exercise recovery (R15-R120).

RESULTS

The mean results of systolic BP (SBP)/diastolic BP (DBP) over the 120min of recovery were 125+/-16/76+/-7mmHg, 122+/-13/75+/-6mmHg and 129+/-16/78+/-7mmHg, respectively for 90%, 110% and CON. Significant reductions of SBP occurred after 90% (R15-R45) and 110% (R15-R90), while only after 110% there were reductions of DBP (R15, R45) and MAP (R15, R45, R75, R90, R105).

CONCLUSIONS

Both exercise intensities evoked reductions in SBP while DBP and MAP were reduced only after 110%. Despite the higher intensity exercise to be more effective in promoting BP reductions, we suggest caution while prescribing exercise for DM(2).