Effects of cardiac rehabilitation in patients with metabolic syndrome after coronary artery bypass grafting

Prognostic impact of peak oxygen uptake and heart rate reserve in patients after off-pump coronary artery bypass grafting

BACKGROUND

Peak oxygen uptake (peak VO₂ ) and heart rate reserve (HRR) are independent prognostic markers of cardiovascular disease. However, the impact of peak VO₂ and HRR on long-term prognosis after off-pump coronary artery bypass grafting (OP-CABG) remains unclear.

HYPOTHESIS

To determine the prognostic impact of peak VO₂ and HRR in patients after OP-CABG.

RESULTS

We enrolled 327 patients (mean age, 65.1 ± 9.3 years; male, 80%) who underwent OP-CABG and participated in early phase II cardiac rehabilitation. All participants underwent cardiopulmonary exercise testing (CPET) at the beginning of such rehabilitation. Overall, 48 (14.6%) patients died during the median follow-up period of 103 months. The non-survivor had significantly lower levels of peak VO₂ (10.6 ± 0.5 vs. 13.7 ± 0.2 ml/kg/min, p < .01) and HRR (24.2 ± 1.8 vs. 32.7 ± 0.8 beats/min, p < .01) than the survivor. In both groups, peak VO₂ significantly correlated with HRR (p < .01). Moreover, patients were divided into four groups according to the peak VO₂ and HRR levels for predicting total mortality. The low-peak VO₂ /low-HRR group had a significantly higher mortality risk than the other groups (hazards ratio, 5.61; 95% confidence interval, 2.59-12.16; p < .01). After adjusted the confounding factors, peak VO₂ and HRR were independently associated with total mortality (both p < .05).

CONCLUSIONS

HRR is a simple parameter of CPET and an important prognostic marker for the risk stratification of total mortality even in patients with low-peak VO₂ after OP-CABG.

Preliminary Pilot Study of Combined Effects of Physical Activity and Achievement of LDL-Cholesterol Target on Coronary Plaque Volume Changes in Patients with Acute Coronary Syndrome

BACKGROUND

We investigated the combined effects of physical activity (PA) and aggressive low-density lipoprotein cholesterol (LDL-C) reduction on the changes in coronary plaque volume (PV) in patients with acute coronary syndrome (ACS) using volumetric intravascular ultrasound (IVUS) analysis.

METHODS

We retrospectively analyzed data from two different prospective clinical trials that involved 101 ACS patients who underwent percutaneous coronary intervention (PCI) and assessed the non-culprit sites of PCI lesions using IVUS at baseline and at the follow-up. After PCI, all the patients participated in early phase II comprehensive cardiac rehabilitation. Patients were divided into four groups based on whether the average daily step count, measured using a pedometer, was 7000 steps of more and whether the follow-up LDL-C level was <70 mg/dL. At the time of follow-up, we examined the correlation of changes in the PV with LDL-C and PA.

RESULTS

The baseline characteristics of the four study groups were comparable. At the follow-up, plaque regression in both the achievement group (PA and LDL-C reduction) was higher than that in the other three groups. In addition, plaque reduction independently correlated with increased PA and reduction in LDL-C level.

CONCLUSIONS

Combined therapy of intensive PA and achievement of LDL-C target retarded coronary PV in patients with ACS.

Exercise Parameters and Outcome Measures Used in Cardiac Rehabilitation Programs Following Median Sternotomy in the Elderly: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of this systematic review was to identify exercise parameters and outcome measures used in cardiac rehabilitation programs following median sternotomy, in the elderly cardiac population.

DATA SOURCES

Five (5) electronic databases were searched for relevant studies published in English after 1997.

STUDY SELECTION

The screening process was completed by two independent researchers, with a third independent reviewer for overall agreement. Studies were selected if they included only cardiac patients aged ≥65 years who had undergone valve surgery and/or coronary artery bypass grafting via median sternotomy, and who had undertaken a postoperative cardiac rehabilitation exercise intervention assessing physical function and/or cognitive recovery as outcomes.

DATA EXTRACTION

Two researchers independently completed the data extraction and quality assessment. Quality was assessed using a modified Downs and Black tool.

DATA SYNTHESIS

In total, 11 articles were included for appraisal with respect to the quality of the study. Only two randomised controlled trials were suitable for meta-analysis. A higher volume of exercise was shown to have a positive effect on functional recovery, assessed using the 6-minute walk test (6MWT) (mean difference=26.97m; 95% confidence interval [CI], 6.96-46.97; p=0.008; I²=0%). No significant improvement was shown between additional exercise compared to standard care in improving VO_2peak, maximal power output or quality of life. No studies evaluated the effect of exercise on cognitive recovery.

CONCLUSIONS

Exercise significantly improves functional recovery in the post-surgical elderly cardiac population, however uncertainty still exists with regard to which modes of exercise and their specific parameters are most effective in improving cognitive recovery.

Impact of Physical Activity on Coronary Plaque Volume and Components in Acute Coronary Syndrome Patients After Early Phase II Cardiac Rehabilitation

BACKGROUND

Cardiac rehabilitation (CR) is an established multidisciplinary secondary preventive program. We investigated the effects of CR involving intensive physical activity (PA) on coronary plaque volume and components in patients with acute coronary syndrome (ACS).Methods and Results:We enrolled 32 consecutive patients with ACS in early phase II CR and randomly assigned them to an intensive CR group (n=18; CR participation ≥twice/week, daily PA ≥9,000 steps) or a standard CR group (n=14; CR participation ≥once/2weeks, daily PA ≥6,000 steps). Serial integrated backscatter intravascular ultrasound was performed for non-culprit lesions at baseline and after 8 months. Baseline clinical data were identical between the 2 groups. Unexpectedly, CR participation and PA did not differ significantly between the 2 groups, and there was no significant difference in plaque volume (PV) or components between the 2 groups. Subsequently, we classified the patients into 2 groups according to median PA (7,000 steps). There were significant differences in percent change of PV and of lipid volume between these 2 groups. In addition, these changes were negatively and independently correlated with PA.

CONCLUSIONS

No significant difference was observed in PV or components between the intensive CR and the standard CR groups. Intensive PA, however, may retard coronary PV and ameliorate lipid component in patients with ACS participating in late phase II CR.

Safety and efficacy of aerobic exercise commenced early after cardiac surgery: A systematic review and meta-analysis

BACKGROUND

Aerobic exercise is a critical component of cardiac rehabilitation following cardiac surgery. Aerobic exercise is traditionally commenced 2-6 weeks following hospital discharge and most commonly includes stationary cycling or treadmill walking. The initiation of aerobic exercise within this early postoperative period not only introduces the benefits associated with aerobic activity sooner, but also ameliorates the negative effects of immobilization associated with the early postoperative period.

METHODS

A systematic review identified all studies reporting safety and efficacy outcomes of aerobic exercise commenced within two weeks of cardiac surgery. A meta-analysis was performed comparing functional, aerobic and safety outcomes in patients receiving early postoperative aerobic exercise compared with usual postoperative care.

RESULTS

Six-minute walk test distance at hospital discharge was 419 ± 88 m in early aerobic exercise patients versus 341 ± 81 m in those receiving usual care (mean difference 69.5 m, 95% confidence interval (CI) 39.2-99.7 m, p < 0.00001). Peak aerobic power was 18.6 ± 3.8 ml·kg^-1·min^-1 in those receiving early exercise versus 15.0 ± 2.1 ml·kg^-1·min^-1 in usual care (mean difference 3.20 ml·kg^-1·min^-1, 95% CI 1.45-4.95, p = 0.0003). There was no significant difference in adverse events rates between the two groups (odds ratio 0.41, 95% CI 0.12-1.42, p = 0.16).

CONCLUSION

Aerobic exercise commenced early after cardiac surgery significantly improves functional and aerobic capacity following cardiac surgery. While adverse event rates did not differ significantly, patients included were very low risk. Further studies are required to adequately assess safety outcomes of aerobic exercise commenced early after cardiac surgery.

Effect of cardiac rehabilitation on metabolic syndrome and its components: A systematic review and meta-analysis

BACKGROUND

Although the effect of cardiac rehabilitation (CR) on cardiovascular disease (CVD) prognosis has been well-documented by several systematic reviews, none have focused on the effect of CR on metabolic syndrome (MetS) and its related components. Therefore, the present systematic review and meta-analysis was conducted to assess the effect of CR on MetS and its components.

MATERIALS AND METHODS

PubMed, SCOPUS, Cochrane library, and Google Scholar database were searched up to February 2014 with no date and language restrictions. The random effects model was used to assess the overall effect of CR on MetS prevalence and the change in metabolic or anthropometric measures.

RESULTS

Fifteen studies with 19,324 subjects were included in the present systematic review and meta-analysis. Our analysis showed that the CR could significantly reduce MetS prevalence [reduction rate: 0.25, 95% confidence interval (CI): 0.21, 0.3, P value <0.001; P value for heterogeneity <0.001, I-squared: 86.2%]. Additionally, results showed the protective role of CR on all MetS components including high density lipoprotein cholesterol [mean difference (MD): 2.13 mg/dL, 95% CI: 1.17, 3.1], triglyceride (MD: -27.45 mg/dL, 95% CI: -36.92, -17.98), systolic blood pressure (SBP) (MD: -6.20 mmHg, 95% CI: -8.41, -3.99), diastolic blood pressure (DBP) (MD: -2.53 mmHg, 95% CI: -3.64, -1.41), fasting blood sugar (FBS) (MD: -6.42 mg/dL, 95% CI: -6.85, -5.99), and waist circumference (WC) (MD: -2.25 cm, 95% CI: -3.15, -1.35).

CONCLUSION

CR has resulted in improvement in MetS and its entire components, and could be considered as a useful tool for MetS patients, especially among those with CVD.

Short-term inspiratory muscle training potentiates the benefits of aerobic and resistance training in patients undergoing CABG in phase II cardiac rehabilitation program

OBJECTIVE

To investigate the efficiency of short-term inspiratory muscle training program associated with combined aerobic and resistance exercise on respiratory muscle strength, functional capacity and quality of life in patients who underwent coronary artery bypass and are in the phase II cardiac rehabilitation program.

METHODS

A prospective, quasi-experimental study with 24 patients who underwent coronary artery bypass and were randomly assigned to two groups in the Phase II cardiac rehabilitation program: inspiratory muscle training program associated with combined training (aerobic and resistance) group (GCR + IMT, n=12) and combined training with respiratory exercises group (GCR, n=12), over a period of 12 weeks, with two sessions per week. Before and after intervention, the following measurements were obtained: maximal inspiratory and expiratory pressures (PImax and PEmax), peak oxygen consumption (peak VO2) and quality of life scores. Data were compared between pre- and post-intervention at baseline and the variation between the pre- and post-phase II cardiac rehabilitation program using the Student's t-test, except the categorical variables, which were compared using the Chi-square test. Values of P<0.05 were considered statistically significant.

RESULTS

Compared to GCR, the GCR + IMT group showed larger increments in PImax (P<0.001), PEmax (P<0.001), peak VO2 (P<0.001) and quality of life scores (P<0.001).

CONCLUSION

The present study demonstrated that the addition of inspiratory muscle training, even when applied for a short period, may potentiate the effects of combined aerobic and resistance training, becoming a simple and inexpensive strategy for patients who underwent coronary artery bypass and are in phase II cardiac rehabilitation.

Effect of cardiac rehabilitation on muscle mass, muscle strength, and exercise tolerance in diabetic patients after coronary artery bypass grafting

BACKGROUND

The effects of cardiac rehabilitation (CR) on muscle mass, muscle strength, and exercise tolerance in patients with diabetes mellitus (DM) who received CR after coronary artery bypass grafting (CABG) have not been fully elucidated.

METHODS

We enrolled 78 consecutive patients who completed a supervised CR for 6 months after CABG (DM group, n=37; non-DM group, n=41). We measured mid-upper arm muscle area (MAMA), handgrip power (HGP), muscle strength of the knee extensor (Ext) and flexor (Flex), and exercise tolerance at the beginning and end of CR.

RESULTS

No significant differences in confounding factors, including age, gender, ejection fraction, or number of CR sessions, were observed between the two groups. At the beginning of CR, the levels of Ext muscle strength and peak VO2 were significantly lower in the DM group than in the non-DM group. At the end of CR, significant improvement in the levels of muscle strength, HGP, and exercise tolerance was observed in both groups. However, the levels of Ext muscle strength, HGP, peak VO2, thigh circumference, and MAMA were significantly lower in the DM group than in the non-DM group. In addition, no significant improvement in thigh circumference and MAMA was observed in the DM group. At the end of CR, the levels of thigh circumference and MAMA correlated with Ext and Flex muscle strength as well as with HGP. Percent changes in the levels of Ext muscle strength were significantly correlated with those of MAMA and hemoglobin A1c.

CONCLUSIONS

These data suggest that improvement in muscle strength may be influenced by changes in muscle mass and high glucose levels in DM patients undergoing CR after CABG. A CR program, including muscle mass intervention and blood glucose control, may improve deterioration in exercise tolerance in DM patients after CABG.

The metabolic syndrome, oxidative stress, environment, and cardiovascular disease: the great exploration

The metabolic syndrome affects 30% of the US population with increasing prevalence. In this paper, we explore the relationship between the metabolic syndrome and the incidence and severity of cardiovascular disease in general and coronary artery disease (CAD) in particular. Furthermore, we look at the impact of metabolic syndrome on outcomes of coronary revascularization therapies including CABG, PTCA, and coronary collateral development. We also examine the association between the metabolic syndrome and its individual component pathologies and oxidative stress. Related, we explore the interaction between the main external sources of oxidative stress, cigarette smoke and air pollution, and metabolic syndrome and the effect of this interaction on CAD. We discuss the apparent lack of positive effect of antioxidants on cardiovascular outcomes in large clinical trials with emphasis on some of the limitations of these trials. Finally, we present evidence for successful use of antioxidant properties of pharmacological agents, including metformin, statins, angiotensin II type I receptor blockers (ARBs), and angiotensin II converting enzyme (ACE) inhibitors, for prevention and treatment of the cardiovascular complications of the metabolic syndrome.

Exercise intervention and inflammatory markers in coronary artery disease: a meta-analysis

BACKGROUND

Inflammatory activity plays a role in the development and progression of coronary artery disease (CAD), and exercise confers survival benefit. We performed a meta-analysis of changes in inflammatory biomarkers over the course of exercise interventions in patients with CAD.

METHODS

We searched MEDLINE, Embase, the Cochrane Collaboration, AMED, and CINAHL for studies reporting peripheral inflammatory biomarker concentrations before and after exercise interventions of ≥ 2 weeks in patients with CAD. Data were summarized using standard mean differences (SMD) and 95% CIs.

RESULTS

Twenty-three studies were included. Concentrations of C-reactive protein (CRP; SMD -0.345, 95% CI -0.444 to -0.246, n = 1,466, P < .001), interleukin 6 (SMD -0.546, 95% CI -0.739 to -0.353, n = 280, P < .001), fibrinogen (SMD -0.638, 95% CI -0.953 to -0.323, n = 247, P < .001), and vascular cell adhesion molecule 1 (SMD -0.413, 95% CI -0.778 to -0.048, n = 187, P = .027) were lower postintervention. Higher total cholesterol (B = -0.328, 95% CI -0.612 to -0.043, P = .026) and higher total/high-density lipoprotein cholesterol ratios (B = -0.250, 95% CI -0.425 to -0.076, P = .008) at baseline were associated with greater reductions in CRP. In controlled studies, follow-up concentrations of CRP (SMD -0.500, 95% CI -0.844 to -0.157, n(exercise/control) = 485/284, P = .004), and fibrinogen (SMD -0.544, 95% CI -1.058 to -0.030, n(exercise/control) = 148/100, P = .038) were lower in subjects who exercised compared with controls.

CONCLUSION

Exercise training is associated with reduced inflammatory activity in patients with CAD. C-reactive protein and fibrinogen have provided the strongest evidence. Higher baseline CRP and adverse baseline lipid profiles predicted greater reductions in CRP.

Effect of external counterpulsation on cardiac work following cardiac surgery: implications of the mechanism responsible for clinical benefits

BACKGROUND

External counterpulsation (ECP) has been recognized as a non-invasive treatment for chronic refractory angina or heart failure. However, the mechanisms responsible for the clinical benefits of ECP therapy remain elusive. Moreover, the clinical significance of ECP therapy for postoperative patients has not been established yet.

METHODS

Six adult patients received ECP therapy for 60 min under pulmonary artery catheter monitoring after cardiac surgery. Hemodynamic data were obtained before ECP therapy (pre-ECP), 20 min after ECP was commenced (20-min-ECP), 40 min after ECP was commenced (40-min-ECP), and after ECP therapy (post-ECP).

RESULTS

The mean right atrial pressure (pre-ECP: 9 ± 4 mmHg; 20-min-ECP: 12 ± 5 mmHg; 40-min-ECP: 12 ± 4 mmHg; and post-ECP: 9 ± 4 mmHg), pulmonary wedge pressure (16 ± 6 mmHg, 20 ± 7 mmHg, 20 ± 7 mmHg, and 17 ± 7 mmHg, respectively), cardiac index (2.4 ± 0.4 l/min/m(2), 2.8 ± 0.6 l/min/m(2), 2.7 ± 0.5 l/min/m(2), and 2.5 ± 0.4 l/min/m(2), respectively), cardiac work index (2.5 ± 0.4 kgm/m(2), 3.3 ± 0.8 kgm/m(2), 3.1 ± 0.8 kgm/m(2), and 2.6 ± 0.5 kgm/m(2), respectively), and left ventricular stroke work index (32 ± 7 gm/m(2), 41 ± 12 gm/m(2), 39 ± 12 gm/m(2), and 33 ± 8 gm/m(2), respectively) significantly (p<0.05) increased after ECP was commenced (pre-ECP vs. 20-min-ECP) and decreased after ECP was discontinued (40-min-ECP vs. post-ECP). Significant (p<0.001) diastolic augmentation (20-min-ECP: 24 ± 6%, 40-min-ECP: 23 ± 5%) and systolic unloading (3 ± 1%, and 3 ± 1%, respectively) were obtained. No clinical adverse effects were observed.

CONCLUSIONS

ECP increases venous return, cardiac output, and cardiac work in addition to diastolic augmentation and systolic unloading. These actions may play important roles in the clinical benefits of ECP therapy. Our data also suggest that ECP is beneficial for patients undergoing cardiac surgery.

Impact of diabetes on muscle mass, muscle strength, and exercise tolerance in patients after coronary artery bypass grafting

BACKGROUND

The impact of diabetes mellitus (DM) on muscle mass, muscle strength, and exercise tolerance in patients who had undergone coronary artery bypass grafting (CABG) has not been fully elucidated.

METHODS

We enrolled 329 consecutive patients who received cardiac rehabilitation (CR) after CABG (DM group, n=178; non-DM group, n=151) and measured lean body weight, mid-upper arm muscle area (MAMA), and handgrip power (HGP) at the beginning of CR. We also performed an isokinetic strength test of the knee extensor (Ext) and flexor (Flex) muscles and a cardiopulmonary exercise testing at the same time.

RESULTS

No significant differences in risk factors, including age, gender, number of diseased vessels, or ejection fraction were observed between the 2 groups. The levels of Ext muscle strength, peak oxygen uptake, and anaerobic threshold were significantly lower in the DM group than in the non-DM group (all p<0.05). Both peak oxygen uptake and MAMA correlated with Ext and Flex muscle strength as well as HGP (all p<0.005). The MAMA, HGP, and Ext muscle strength were lower in patients who received insulin therapy than in those who did not. Interestingly, fasting glucose levels significantly and negatively correlated with Ext muscle strength.

CONCLUSIONS

These data suggest that DM patients had a lower muscle strength and exercise tolerance than non-DM patients. Moreover, a high glucose level may affect these deteriorations in DM patients after CABG.

Exercise therapy correlates with improving renal function through modifying lipid metabolism in patients with cardiovascular disease and chronic kidney disease

BACKGROUND

Patients with cardiovascular disease (CVD) and chronic kidney disease (CKD) are at high risk of cardiovascular mortality, thus therapies to improve renal function should be clinically investigated.

METHODS AND RESULTS

We divided consecutive patients with CVD and CKD (n=19) into exercise (n=10) and non-exercise (n=9) therapy groups. Exercise therapy for 12 weeks significantly improved the anaerobic metabolic threshold (AT-V O₂) and high-density lipoprotein cholesterol (HDL-C) levels, and reduced triglyceride levels. Exercise therapy also improved estimated glomerular filtration rate (eGFR). Change in eGFR correlated significantly and positively with change in AT-V O₂ and HDL-C, and negatively with change in triglyceride levels.

CONCLUSIONS

Exercise therapy correlates with improving renal function in CVD patients with CKD through modifying lipid metabolism. Exercise therapy could be an effective clinical strategy to improve renal function.