Enhanced external counterpulsation in the treatment of chronic refractory angina: a long-term follow-up outcome from the International Enhanced External Counterpulsation Patient Registry

Enhanced External Counterpulsation Outcomes Study: Retrospective Analyses of Data Obtained from Patients at a Single Medical Center in United States

The aim was to explore the effectiveness of enhanced external counterpulsation (EECP) therapy in patients with severe angina pectoris/ chronic heart failure symptoms, who were not suitable candidates for invasive treatment. This retrospective study employed a comprehensive methodology that includes individualized treatment, continuous monitoring, and thorough pre- and postprogram evaluations to assess the efficacy of EECP therapy. The standard protocol involved 35 one-hour treatments, with flexibility for extensions based on therapeutic progress. When pre- and posttreatment results were analyzed, EECP improved the original functional class compared with pretreatment. The mean difference in the functional class was 1.32 (0.92), p  < 0.0001. Six-minute walk (6MW) distance improved from 383.6 m (110.24) to 423.1 m (121.50) with mean difference of 37.1 (44.99), p  < 0.0001. Duke Activity Status Index (DASI) score improved from 3.9 (2.75) to 6.0 (4.17) with mean difference of 2.16 (3.8), p  < 0.0001. Training metabolic equivalents (METs) improved from 3.0 (0.74) to 4.0 (1.57) with mean difference of 1.04 (1.2), p  < 0.0001. Weekly anginal events decreased from 13.1 (13.19) to 3.2 (7.38) with mean difference of -9.78 (11.7), p  < 0.0001. EECP resulted in improvement of angina pectoris functional class, the 6MW distance, reduction in the number of hospitalizations in first year posttreatment, a significant decrease in sublingual nitroglycerin use, improvement of systolic and diastolic blood pressure, and improvement of DASI score.

A Randomized Controlled Study of Enhanced External Counterpulsation with Cardiac Rehabilitation in Patients with Nonobstructive Coronary Artery Disease and Coronary Microvascular Dysfunction

Treatment with enhanced external counterpulsation (EECP) or cardiac rehabilitation (CR) benefits patients with coronary heart disease; this paper intends to explore the feasibility of EECP combined with CR in patients with nonobstructive coronary heart disease (NOCAD) and coronary microcirculation disorders (CMD).In January 2021-2022 month June our income NOCAD patients as the research object, the line of cardiac magnetic resonance (CMR), myocardial perfusion reserve (MPR) < 2.0 coronary microcirculation disorders (CMD, 80 cases). Random indicator method 80 CMD patients divided into two groups, 40 cases in each. Usual treatment group: conventional drugs and CR therapy. EECP treatment group: on the basis of standard treatment group, employ EECP therapy. Comparing the two groups before and after the treatment curative effect cardiac function index, endothelial unction index, adverse cardiovascular events, etc.After EECP treatment, the treatment group showed a higher effective rate compared to the usual treatment group (P < 0.05). EECP group curative effect, left ventricular ejection fraction,plasma NO and vascular endothelial growth factor levels higher than the usual group, the incidence of adverse cardiovascular events is lower than the usual group. The difference was statistically significant (P < 0.05).EECP combined with cardiac rehabilitation in patients with CMD symptoms has better effect and safety and provides reference for treatment of CMD patients.

Nonpharmacological interventions for 'no-option' refractory angina patients

Refractory angina pectoris (RAP) defined as chronic anginal chest pain because of coronary artery disease (CAD) is a major problem. The increase in the number of patients with RAP in recent years is because of the increasing aging population and improved survival rates among patients with CAD. Management of patients with RAP is often extremely challenging. In this review, we present several interventional approaches for RAP, including device therapies, lifestyle intervention, and cell therapies. Some of these treatments are currently used in the management of RAP, whereas other treatments are under investigation.

Enhanced External Counterpulsation for Management of Postacute Sequelae of SARS-CoV-2 Associated Microvascular Angina and Fatigue: An Interventional Pilot Study

Background

Postacute sequelae of SARS-CoV-2 infection (PASC) are a novel clinical syndrome characterized in part by endothelial dysfunction. Enhanced external counterpulsation (EECP) produces pulsatile shear stress, which has been associated with improvements in systemic endothelial function.

Objective

To explore the effects of EECP on symptom burden, physical capacity, mental health, and health-related quality of life (HRQoL) in patients with PASC-associated angina and microvascular dysfunction (MVD).

Methods

An interventional pilot study was performed, including 10 patients (male = 5, mean age 50.3 years) recruited from a tertiary specialized PASC clinic. Patients with angina and MVD, defined as index of microcirculatory resistance (IMR) ≥25 and/or diagnosed through stress perfusion cardiac magnetic resonance imaging, were included. Patients underwent one modified EECP course (15 one-hour sessions over five weeks). Symptom burden, six-minute walk test, and validated generic self-reported instruments for measuring psychological distress and HRQoL were assessed before and one month after treatment.

Results

At baseline, most commonly reported PASC symptoms were angina (100%), fatigue (80%), and dyspnea (80%). Other symptoms included palpitations (50%), concentration impairment (50%), muscle pain (30%), and brain fog (30%). Mean IMR was 63.6. After EECP, 6MWD increased (mean 29.5 m, median 21 m) and angina and fatigue improved. Mean depression scores showed reduced symptoms (-0.8). Mean HRQoL scores improved in seven out of eight subscales (+0.2 to 10.5).

Conclusions

Patients with PASC-associated angina and evidence of MVD experienced subjective and objective benefits from EECP. The treatment was well-tolerated. These findings warrant controlled studies in a larger cohort.

Safety and effectiveness of enhanced external counterpulsation (EECP) in refractory angina patients: A systematic reviews and meta-analysis

Enhanced external counterpulsation (EECP) is believed to be a non-invasive treatment for coronary artery disease and angina. The aim of this study was to determine the safety and effectiveness of EECP in refractory angina patients through a systematic reviews and meta-analysis. We conducted a comprehensive search of the literature published on PubMed, Cochrane library, Scopus, ScienceDirect, Trip Database and Google Scholar databases using appropriate keywords and specific strategy with no time limit. Having selected and screened the studies based on the defined inclusion and exclusion criteria and evaluating their quality based on the Cochrane checklist. For the meta-analysis,the Mantel-Haenszel method or the generic Inverse Variance was used. Analyses were done with Review Manager 5.2 software. A number of 299 studies were initially reviewed and finally, seventeen studies were included in the meta-analysis based on the inclusion and exclusion criteria. Also, thirteen outcomes were analyzed and the results of meta-analysis in twelve outcomes including (Systolic Blood Pressure (7 studies), Diastolic Blood Pressure (7 studies), Pulse Pressure (4 studies), Mean Arterial Pressures (4 studies), Heart Rate (6 studies), Angina episodes (7 studies), Walking distance (2 studies),Canadian Cardiovascular Society classification (6 studies), Flow-Mediated Dilation (3 studies), Daily Nitrate Usage (4 studies), Exercise Treadmill Test-Time (2 studies), ST-segment depression (2 studies)demonstrated a significant clinical advantage in the EECP treatment effectiveness in patients with angina. No significant difference was observed regarding EECP usefulness (P = 0.18) in the outcome of brachial artery diameter (2 studies). Based on the meta-analysis, the results indicate the safety and effectiveness of EECP in patients with angina pectoris and indicate the usefulness of this treatment in these patients. In general, the authors believe that the general conclusion in this regard requires some studies with a large sample size and a control group assignment.

External Counterpulsation Improves Angiogenesis by Preserving Vascular Endothelial Growth Factor-A and Vascular Endothelial Growth Factor Receptor-2 but Not Regulating MicroRNA-92a Expression in Patients With Refractory Angina

Objective: External counterpulsation (ECP) provides long-term benefits of improved anginal frequency and exercise tolerance in patients with refractory angina (RA). This is postulated as a result of improved angiogenesis and endothelial function through an increase in shear stress. Angiogenesis is mainly represented by vascular endothelial growth factor-A (VEGF-A) and its receptor, vascular endothelial growth factor receptor-2 (VEGFR-2). The microRNA-92a (miR-92a) is a flow-sensitive miRNA that regulates atherosclerosis and angiogenesis in response to shear stress. Thus, ECP beneficial effect might be achieved through interaction between VEGF-A, VEGFR-2, and miR-92a. This study aims to evaluate the ECP effect on VEGF-A, VEGFR-2, and miR-92a in patients with RA in a sham-controlled manner. Methods: This was a randomized sham-controlled trial, enrolling 50 patients with RA who have coronary artery disease (CAD). Participants were randomized (1:1 ratio) to 35 sessions of either ECP (n = 25) or sham (n = 25), each session lasting for 1 h. Plasma levels of VEGF-A and VEGFR-2 were assayed by the ELISA technique. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to measure miR-92a circulating levels in plasma. Result: External counterpulsation significantly preserved VEGF-A and VEGFR-2 level compared to sham [ΔVEGF-A: 1 (-139 to 160) vs.-136 (-237 to 67) pg/ml, p = 0.026; ΔVEGFR-2: -171(-844 to +1,166) vs. -517(-1,549 to +1,407) pg/ml, p = 0.021, respectively]. Circulating miR-92a increased significantly in ECP [5.1 (4.2-6.4) to 5.9 (4.8-6.4), p < 0.001] and sham [5.2 (4.1-9.4) to 5.6 (4.8-6.3), p = 0.008] post-intervention. The fold changes tended to be higher in ECP group, although was not statistically different from sham [fold changes ECP = 4.6 (0.3-36.5) vs. sham 2.8 (0-15), p = 0.33)]. Conclusion: External counterpulsation improved angiogenesis by preserving VEGF-A and VEGFR-2 levels. Both ECP and sham increased miR-92a significantly, yet the changes were not different between the two groups. (Study registered on www.clinicaltrials.gov, no: NCT03991871, August 8, 2019, and received a grant from the National Health Research and Development of Ministry of Health of Indonesia, No: HK.02.02/I/27/2020).

Son of a Lesser God: The Case of Cell Therapy for Refractory Angina

In the last decades, various non-pharmacological solutions have been tested on top of medical therapy for the treatment of patients affected by refractory angina (RA). Among these therapeutics, neuromodulation, external counter-pulsation and coronary sinus constriction have been recently introduced in the guidelines for the management of RA in United States and Europe. Notably and paradoxically, although a consistent body of evidence has proposed cell-based therapies (CT) as safe and salutary for RA outcome, CT has not been conversely incorporated into current international guidelines yet. As a matter of fact, published randomized controlled trials (RCT) and meta-analyses (MTA) cumulatively indicated that CT can effectively increase perfusion, physical function and well-being, thus reducing angina symptoms and drug assumption in RA patients. In this review, we (i) provide an updated overview of novel non-pharmacological therapeutics included in current guidelines for the management of patients with RA, (ii) discuss the Level of Evidence stemmed from available clinical trials for each recommended treatment, and (iii) focus on evidence-based CT application for the management of RA.

Effectiveness of Enhanced External Counterpulsation Treatment on Symptom Burden, Medication Profile, Physical Capacity, Cardiac Anxiety, and Health-Related Quality of Life in Patients With Refractory Angina Pectoris

BACKGROUND

Patients with refractory angina pectoris experience recurrent symptoms that limit their functional capacity, including psychological distress and impaired health-related quality of life (HRQoL), despite optimized medical therapy. Enhanced external counterpulsation (EECP) is an evidence-based alternative noninvasive treatment. Although physical well-being and mental well-being are equally important components of health, few studies have investigated the psychological effects of EECP in patients with refractory angina pectoris.

OBJECTIVE

The aim of this study was to evaluate the effects of EECP treatment in patients with refractory angina pectoris regarding medication profile, physical capacity, cardiac anxiety, and HRQoL.

METHODS

This quasi-experimental study with 1-group pretest-posttest design includes a 6-month follow-up of 50 patients (men, n = 37; mean age, 65.8 years) who had undergone 1 EECP course. The following pretreatment and posttreatment data were collected: medication use, 6-minute walk test results, functional class according to the Canadian Cardiovascular Society, and self-reported (ie, questionnaire data) cardiac anxiety and HRQoL. In addition, the questionnaires were also completed at a 6-month follow-up.

RESULTS

After EECP treatment, patients used significantly less nitrates (P < .001), walking distance increased on average by 46 m (P < .001), and Canadian Cardiovascular Society class improved (P < .001). In addition, all but 1 subscale of cardiac anxiety and all HRQoL components improved significantly (P < .05). The positive effects for cardiac anxiety and HRQoL were maintained at the 6-month follow-up.

CONCLUSIONS

Enhanced external counterpulsation treatment resulted in reduced symptom burden, improved physical capacity, and less cardiac anxiety, leading to increased physical activity and enhanced life satisfaction for patients with refractory angina pectoris. Enhanced external counterpulsation treatment should be considered to improve the life situation for these patients.

Therapeutic Approaches for the No-Option Refractory Angina Patient

The combination of an aging population and improved survival rates among patients with coronary artery disease has resulted in an increase in the number of patients with refractory angina or anginal equivalent symptoms despite maximal medical therapy. Patients with refractory angina are often referred to the cardiac catheterization laboratory; however, they have often exhausted conventional revascularization options; thus, this population is often deemed as having "no options." We review the definition, prevalence, outcomes, therapeutic options, and treatment considerations for no-option refractory angina patients and focus on novel therapies for this complex and challenging population. We propose a multidisciplinary team approach for the evaluation and management of patients with refractory angina, ideally in a designated clinic. The severe limitations and symptomatology experienced by these patients highlight the need for additional research into the development of innovative treatments.

Predictors of treatment benefits after enhanced external counterpulsation in patients with refractory angina pectoris

Background

Enhanced external counterpulsation (EECP) is a noninvasive treatment that can decrease limiting symptoms in patients with refractory angina pectoris (RAP). Identifying responders to EECP is important as EECP is not widely available and relatively time intensive.

Hypothesis

The effect of EECP treatment on physical capacity in patients with RAP can be predicted from baseline patient characteristics and clinical factors.

Methods

This explorative study includes all patients from a cardiology clinic who had finished one EECP treatment and a 6 min walk test pre and post EECP. Clinical data, including Canadian Cardiovascular Society (CCS) classification and left ventricular ejection fraction (LVEF), were assessed before treatment. If patients increased their 6 min walking distance (6MWD) by 10% post EECP, they were considered responders.

Results

Of the 119 patients (men = 97, 40–91 years), 49 (41.2%) were responders. Multinomial regression analysis showed that functional status (i.e., CCS class ≥3) (OR 3.10, 95% CI 1.12–8.57), LVEF <50% (OR 2.82, 95% CI 1.02–7.80), and prior performed revascularization (i.e., ≤ 1 type of intervention) (OR 2.77, 95% CI 1.06–7.20) were predictors of response to EECP (p < .05, Accuracy 63.6%). Traditional risk factors (e.g., gender, smoking, and comorbidities) did not predict response.

Conclusions

EECP treatment should be considered preferentially for patients that have a greater functional impairment, evidence of systolic left ventricular dysfunction, and exposure to fewer types of revascularization, either PCI or CABG. Improvement in 6MWD post EECP could imply improvement in physical capacity, which is a likely contributor to improved well‐being among patients with RAP.

The improvement of the shear stress and oscillatory shear index of coronary arteries during Enhanced External Counterpulsation in patients with coronary heart disease

Background

Enhanced External Counterpulsation (EECP) can chronically relieve ischemic chest pain and improve the prognosis of coronary heart disease (CHD). Despite its role in mitigating heart complications, EECP and the mechanisms behind its therapeutic nature, such as its effects on blood flow hemodynamics, are still not fully understood. This study aims to elucidate the effect of EECP on significant hemodynamic parameters in the coronary arterial tree.

Methods

A finite volume method was used in conjunction with the inlet pressure wave (surrogated by the measured aortic pressure) before and during EECP and outlet flow resistance, assuming the blood as newtonian fluid. The time-average wall shear stress (TAWSS) and oscillatory shear index (OSI) were determined from the flow field.

Results

Regardless of the degree of vascular stenosis, hemodynamic conditions and flow patterns could be improved during EECP. In comparison with the original tree, the tree with a severe stenosis (75% area stenosis) demonstrated more significant improvement in hemodynamic conditions and flow patterns during EECP, with surface area ratio of TAWSS risk area (SAR-TAWSS) reduced from 12.3% to 6.7% (vs. SAR-TAWSS reduced from 7.2% to 5.6% in the original tree) and surface area ratio of OSI risk area (SAR-OSI) reduced from 6.8% to 2.5% (vs. SAR-OSI of both 0% before and during EECP in the original tree because of mild stenosis). Moreover, it was also shown that small ratio of diastolic pressure (D) and systolic pressure (S) (D/S) could only improve the hemodynamic condition mildly. The SAR-TAWSS reduction ratio significantly increased as D/S became larger.

Conclusions

A key finding of the study was that the improvement of hemodynamic conditions along the LMCA trees during EECP became more significant with the increase of D/S and the severity degree of stenoses at the bifurcation site. These findings have important implications on EECP as adjuvant therapy before or after percutaneous coronary intervention (PCI) in patients with diffuse atherosclerosis.

New Advances in the Management of Refractory Angina Pectoris

Refractory angina is a significant clinical problem and its successful management is often extremely challenging. Defined as chronic angina-type chest pain in the presence of myocardial ischaemia that persists despite optimal medical, interventional and surgical treatment, current therapies are limited and new approaches to treatment are needed. With an ageing population and increased survival from coronary artery disease, clinicians will increasingly encounter this complex condition in routine clinical practice. Novel therapies to target myocardial ischaemia in patients with refractory angina are at the forefront of research and in this review we discuss those in clinical translation and assess the evidence behind their efficacy.

Acute physical exercise and long-term individual shear rate therapy increase telomerase activity in human peripheral blood mononuclear cells

AIM

Physical activity is a potent way to impede vascular ageing. However, patients who suffer from peripheral artery disease (PAD) are often unable to exercise adequately. For those patients, we have developed individual shear rate therapy (ISRT), which is an adaptation of external counterpulsation and enhances endovascular fluid shear stress to increase collateral growth (arteriogenesis). To evaluate the effects of physical exercise and ISRT on the telomere biology of peripheral blood mononuclear cells (PBMCs), we conducted two clinical trials.

METHODS

In the ISRT-1 study, we assessed PBMC telomerase activity in 26 young healthy volunteers upon a single (short-term) ISRT session and a single treadmill running session. In the ISRT-2 study, we investigated PBMC telomere biology of 14 elderly patients with PAD, who underwent 30 h of (long-term) ISRT within a 5-week period.

RESULTS

We demonstrate that telomerase activity significantly increased from 39.84 Total Product Generated (TPG) Units ± 6.15 to 58.10 TPG ± 10.46 upon a single treadmill running session in healthy volunteers. In the ISRT-2 trial, PBMC telomerase activity and the mRNA expression of the telomere-protective factor TRF2 increased from 40.87 TPG ± 4.45 to 60.98 TPG ± 6.83 and 2.10-fold ± 0.40, respectively, upon long-term ISRT in elderly patients with PAD.

CONCLUSION

In summary, we show that acute exercise and long-term ISRT positively affect PBMC telomerase activity, which is indicative for an improved regenerative potential of immune cells and vascular tissues. Long-term ISRT also enhances the gene expression of the telomere-protective factor TRF2.

Cardiac shock-wave therapy in the treatment of coronary artery disease: systematic review and meta-analysis

AIM

To systematically review currently available cardiac shock-wave therapy (CSWT) studies in humans and perform meta-analysis regarding anti-anginal efficacy of CSWT.

METHODS

The Cochrane Controlled Trials Register, Medline, Medscape, Research Gate, Science Direct, and Web of Science databases were explored. In total 39 studies evaluating the efficacy of CSWT in patients with stable angina were identified including single arm, non- and randomized trials. Information on study design, subject's characteristics, clinical data and endpoints were obtained. Assessment of publication risk of bias was performed and heterogeneity across the studies was calculated by using random effects model.

RESULTS

Totally, 1189 patients were included in 39 reviewed studies, with 1006 patients treated with CSWT. The largest patient sample of single arm study consisted of 111 patients. All selected studies demonstrated significant improvement in subjective measures of angina symptoms and/or quality of life, in the majority of studies left ventricular function and myocardial perfusion improved. In 12 controlled studies with 483 patients included (183 controls) angina class, Seattle Angina Questionnaire (SAQ) score, nitrates consumption were significantly improved after the treatment. In 593 participants across 22 studies the exercise capacity was significantly improved after CSWT, as compared with the baseline values (in meta-analysis standardized mean difference SMD = -0.74; 95% CI, -0.97 to -0.5; p < 0.001).

CONCLUSIONS

Systematic review of CSWT studies in stable coronary artery disease (CAD) demonstrated consistent improvement of clinical variables. Meta-analysis showed a moderate improvement of exercise capacity. Overall, CSWT is a promising non-invasive option for patients with end-stage CAD, but evidence is limited to small sample single-center studies. Multi-center adequately powered randomised double blind studies are warranted.

Enhanced External Counterpulsation Therapy: Past, Present, and Future

External counterpulsation therapy was first developed over half a century ago as a resuscitative tool to support the failing heart and was based on hemodynamic principles of the intraaortic balloon pump. Over the course of last few decades, it has evolved into the modern enhanced external counterpulsation (EECP) therapy, which has proven to be a safe, effective, and low-cost noninvasive treatment for patients with debilitating angina and chronic heart failure who are poor candidates for revascularization procedures and have suboptimal results from other therapies. Numerous studies have shown EECP to be efficacious in patients with chronic angina, with its effects lasting for several years after completion of therapy. Besides being safe in patients with coexisting left ventricular dysfunction, there is emerging evidence that EECP therapy may result in improvement in exercise capacity and oxygen consumption in heart failure patients. Several mechanisms have been postulated to explain the therapeutic effects of EECP, including improvement in endothelial function, promotion of angiogenesis and new collaterals, reduction in atherosclerotic burden, improvement in ventricular function, and peripheral training effects analogous to that of exercise. With greater understanding of these complex mechanisms, possible applications of EECP have broadened in recent years, with its use being studied in conditions like hepatorenal syndrome, erectile dysfunction, and restless leg syndrome. This review article offers a historical perspective on the origins of EECP, an overview of our current understanding of its physiological effects, and a glimpse at its future utilization in clinical practice.

Management standards for stable coronary artery disease in India

Coronary artery disease (CAD) is one of the important causes of cardiovascular morbidity and mortality globally, giving rise to more than 7 million deaths annually. An increasing burden of CAD in India is a major cause of concern with angina being the leading manifestation. Stable coronary artery disease (SCAD) is characterised by episodes of transient central chest pain (angina pectoris), often triggered by exercise, emotion or other forms of stress, generally triggered by a reversible mismatch between myocardial oxygen demand and supply resulting in myocardial ischemia or hypoxia. A stabilised, frequently asymptomatic phase following an acute coronary syndrome (ACS) is also classified as SCAD. This definition of SCAD also encompasses vasospastic and microvascular angina under the common umbrella.

A prospective study of patients with refractory angina: outcomes and the role of high-sensitivity troponin T

BACKGROUND

The predictors of cardiovascular events in patients with chronic refractory angina are limited. High-sensitivity cardiac troponin T (hs-cTnT) assays are biomarkers that may be used to determine the prognosis of patients with stable coronary artery disease.

HYPOTHESIS

Hs-cTnT is a predictor of death and nonfatal myocardial infarction (MI) in patients with refractory angina.

METHODS

We prospectively enrolled 117 consecutive patients in this study. A heart team ruled out myocardial revascularization feasibility after assessing recent coronary angiograms; evidence of myocardial ischemia served as an inclusion criterion. Optimal medical therapy was encouraged via outpatient visits every 6 months; plasma hs-cTnT levels were determined at baseline. The primary endpoint was the composite incidence of death and nonfatal MI.

RESULTS

During a median follow-up period of 28.0 months (interquartile range, 18.0-47.5 months), an estimated 28.0-month cumulative event rate of 13.4% was determined via the Kaplan-Meier method. Univariate predictors of the composite endpoint were hs-cTnT levels and LV dysfunction. Following a multivariate analysis, only hs-cTnT was independently associated with the events in question, either as a continuous variable (hazard ratio per unit increase in the natural logarithm: 2.83, 95% confidence interval: 1.62-4.92, P < 0.001) or as a categorical variable (hazard ratio for concentrations above the 99th percentile: 5.14, 95% confidence interval: 2.05-12.91, P < 0.001).

CONCLUSIONS

In patients with chronic refractory angina, plasma concentration of hs-cTnT is the strongest predictor of death and nonfatal MI. Notably, none of the outcomes in question occurred in patients with baseline plasma levels <5.0 ng/L.

The Impact of Peripheral Nerve Stimulation on Coronary Blood Flow and Endothelial Function

PURPOSE

The geko™ device is a small transcutaneous nerve stimulator that is applied non-invasively to the skin over the common peroneal nerve to stimulate peripheral blood flow. The purpose of this study was to investigate the effect of peripheral nerve stimulation on coronary flow dynamics and systemic endothelial function.

METHODS

We enrolled 10 male patients, age 59 ± 11 years, with symptomatic obstructive coronary disease undergoing percutaneous coronary intervention (PCI). Coronary flow dynamics were assessed invasively using Doppler flow wire at baseline and with nerve stimulation for 4 min. Measurements were taken in the stenotic coronary artery and in a control vessel without obstructive disease. At a separate visit, peripheral blood flow at the popliteal artery (using duplex ultrasound assessment) and endothelial function assessed by peripheral artery tonometry (PAT) were measured at baseline and after one hour of nerve stimulation.

RESULTS

Compared to baseline, there was a significant increase in coronary blood flow as measured by average peak velocity (APV) in the control vessel with nerve stimulation (20.3 ± 7.7 to 23.5 ± 10 cm/s; p = 0.03) and non-significant increase in the stenotic vessel (21.9 ± 12 to 23.9 ± 12.9 cm/s; p = 0.23). Coronary flow reserve did not change significantly. Reactive hyperemia-peripheral arterial tonometry (Rh-PAT) increased from 2.28 ± 0.39 to 2.67 ± 0.6, p = 0.045.

CONCLUSIONS

A few minutes of peripheral nerve stimulation may improve coronary blood flow. This effect is more prominent in non-stenotic vessels. Longer stimulation improved endothelial function.

Cardiac Rehabilitation: Underrecognized/Underutilized

OPINION STATEMENT

Unfortunately, too many patients continue to rely on costly coronary revascularization procedures, cardioprotective medications, or both, as first-line strategies to stabilize the course of coronary heart disease. However, these palliative therapies do not address the foundational or most proximal risk factors for coronary disease, that is, unhealthy dietary habits, physical inactivity, and cigarette smoking. Because most acute myocardial infarctions evolve from mild-to-moderate coronary artery stenosis (<70 % obstruction), rather than at the more severe obstructions that are commonly treated with coronary revascularization, these findings help explain the inability to demonstrate a reduction in acute cardiac events in most studies examining coronary artery bypass graft surgery and/or percutaneous coronary interventions. The delivery of comprehensive cardiovascular risk reduction, including exercise-based cardiac rehabilitation as an integral component, offers patients a bona fide treatment intervention to prevent recurrent cardiovascular events and the need for repeated revascularization procedures, while simultaneously providing referring physicians with ongoing surveillance data to potentially enhance their medical management.

Enhanced External Counterpulsation Is Cost-Effective in Reducing Hospital Costs in Refractory Angina Patients

BACKGROUND

Enhanced external counterpulsation (EECP) is effective in the treatment of refractory angina, a condition suffered by 1.7 million Americans. Declining cardiovascular mortality and appropriate use criteria may further increase this number.

HYPOTHESIS

EECP is hypothesized to be cost-effective in reducing hospitalizations in refractory angina patients.

METHODS

The data used in this analysis were collected in phase II of the International EECP Patient Registry (IEPR-II). Data were collected on changes in Canadian Cardiovascular Society functional class, Duke Activity Status Index, and number of hospitalizations in the 6 months prior to EECP and in the 6- and 12-month intervals following EECP. Estimates of the changes in annual cost of all-cause hospitalization before and after EECP therapy were calculated by the product of the differences in hospitalization rates in the 6-month interval before and after EECP treatment and estimated hospitalization and physician charges after subtracting the average cost of EECP.

RESULTS

Data for 1015 patients were analyzed. Hospitalization occurred in 55.2% of patients, an average of 1.7 ± 1.4 hospitalizations/patient, in the 6-month period before 35 hours of EECP; and in 24.4%, an average of 1.4 ± 1.0 hospitalizations/patient, during the 6- to 12-month period after EECP. The average hospitalization and physician charge in the US was $17,995, and the average EECP cost was $4880, yielding an annual cost savings/patient of $17,074.

CONCLUSIONS

Treatment of refractory angina patients with EECP resulted in improvement in angina and functional class accompanied by a sustained reduction in health care costs over 1 year of follow-up.

Alternative therapy for medically refractory angina: enhanced external counterpulsation and transmyocardial laser revascularization

Medically refractory angina pectoris (RAP) is defined by presence of severe angina with objective evidence of ischemia and failure to relieve symptoms with coronary revascularization. Medication and invasive revascularization are the most common approaches for treating coronary artery disease (CAD). Although symptoms are eliminated or alleviated by these invasive approaches, the disease and its causes are present after treatment. New treatment approaches are needed to prevent the disease from progressing and symptoms from recurring. External enhanced counterpulsation therapy provides a treatment modality in the management of CAD and can complement invasive revascularization procedures. Data support that it should be considered a first-line treatment of RAP.

Predictors of long-term clinical endpoints in patients with refractory angina

Background

Clinical outcomes in patients with refractory angina (RA) are poorly characterized and variably described. Using the Duke Database for Cardiovascular Disease (DDCD), we explored characteristics that drive clinical endpoints in patients with class II to IV angina stabilized on medical therapy.

Methods and Results

We explored clinical endpoints and associated costs of patients who underwent catheterization at Duke University Medical Center from 1997 to 2010 for evaluation of coronary artery disease (CAD) and were found to have advanced CAD ineligible for additional revascularization, and were clinically stable for a minimum of 60 days. Of 77 257 cardiac catheterizations performed, 1908 patients met entry criteria. The 3‐year incidence of death; cardiac rehospitalization; and a composite of death, myocardial infarction, stroke, cardiac rehospitalization, and revascularization were 13.0%, 43.5%, and 52.2%, respectively. Predictors of mortality included age, ejection fraction (EF), low body mass index, multivessel CAD, low heart rate, diabetes, diastolic blood pressure, history of coronary artery bypass graft surgery, cigarette smoking, history of congestive heart failure (CHF), and race. Multivessel CAD, EF<45%, and history of CHF increased risk of mortality; angina class and prior revascularization did not. Total rehospitalization costs over a 3‐year period per patient were $10 185 (95% CI 8458, 11912) in 2012 US dollars.

Conclusions

Clinically stable patients with RA who are medically managed have a modest mortality, but a high incidence of hospitalization and resource use over 3 years. These findings point to the need for novel therapies aimed at symptom mitigation in this population and their potential impact on health care utilization and costs.

Transcatheter treatment for refractory angina with the Coronary Sinus Reducer

AIMS

To evaluate the clinical efficacy of the coronary sinus (CS) Reducer in attenuating angina severity in patients suffering from severe refractory angina.

METHODS AND RESULTS

Patients with refractory angina, objective evidence of myocardial ischaemia and no option for revascularisation were treated with CS Reducer implantation at two medical centres. Six-month follow-up evaluation consisted of clinical assessment of angina severity. Objective assessment of ischaemia at six-month follow-up was performed in one of the two centres. Successful CS Reducer implantation was achieved in 21 of 23 eligible patients, at both centres. No device-related adverse effects were observed during the procedure or the follow-up period. Canadian Cardiovascular Society (CCS) score diminished from a mean of 3.3 at baseline to 2.0 at six months (n=20, p<0.01), exercise duration was prolonged from 3:16 to 5:16 min (min:sec; n=8, p=0.05). Thallium SPECT summed stress score and summed difference score were both reduced (n=9, 21.5±10 vs.13.2±9, p=0.01, and 11.1±6 vs. 4.7±4, p=0.007, respectively). Wall motion score index at peak dobutamine infusion was also significantly improved (n=8, 1.9±0.4 vs. 1.4±0.4, p=0.046).

CONCLUSIONS

CS Reducer implantation was safe and resulted in significant improvement of angina class. The results of the ongoing randomised sham-control trial will address the concern regarding the possible placebo effect, and hopefully further support our encouraging observations.

The role of enhanced external counter pulsation therapy in clinical practice

Enhanced external counterpulsation (EECP) has been approved by the United States Food and Drug Administration (FDA) for management of refractory angina (Class IIb). EECP uses three sets of pneumatic cuffs that sequentially contract during diastole, increasing aortic diastolic pressure, augmenting coronary blood flow and central venous return. EECP improves anginal symptoms and exercise tolerance, and reduces nitroglycerin use in patients with chronic, stable angina. EECP has also been shown to be safe and beneficial in patients with symptomatic stable congestive heart failure. It has been postulated that cardiac benefits of EECP are mediated though vascular endothelial growth factor (VEGF) and nitric oxide mediated vasodilatation and angiogenesis. In June 2002, the FDA also approved EECP therapy for heart failure patients.

Pneumatically-driven external pressure applicator to augment Fontan hemodynamics: preliminary findings

BACKGROUND

This study investigated the application of circumferentially applied, external pressure to the lower extremities as a preventative measure and long-term clinical treatment strategy for Fontan patients.

OBJECTIVE

We hypothesized that the application of circumferential pressure to the lower limbs will augment venous return and thus cardiac output.

METHODS

Two patients (an extra-cardiac and intra-atrial Fontan) were evaluated. Both trials were conducted during a routine cardiac catheterization. The aortic and inferior vena cava (IVC) pressures were recorded. We applied three different external pressures to the lower limbs based on the patient's diastolic pressure. Each pressure was applied with a one-minute rapid inflate/deflate period for a total of five cycles and a rest period between pressure intervals.

RESULTS

Patient 1 (age 37, female) demonstrated pressure rises of 10-15 mmHg in both the aortic and IVC pressures. Patient 2 (age 24, male) had undetectable pressure rise during the first pressure cycles and notable pressures rise of approximately 8-12 mmHg during the third cycle.

CONCLUSIONS

External pressure application redistributes blood volume or cardiac output as a result of impedance in the lower extremities, enhancing venous pressure and return. Our findings strongly suggest an acute benefit from the implementation of external mechanical compression of the lower vasculature to increase cardiac output in Fontan patients.

Effect of enhanced external counterpulsation treatment on renal function in cardiac patients

Background

Enhanced external counterpulsation (EECP) enhances coronary perfusion and reduces left ventricular afterload. However, the role of EECP on renal function in cardiac patients is unknown. Our aim was to assess renal function determined by serum cystatin C in cardiac patients before and after EECP treatment.

Methods

A prospective observational longitudinal study was conducted in order to evaluate renal function using serum cystatin C (Cys C) and estimated glomerular filtration rate (GFR) after 35 sessions of EECP treatment in 30 patients with chronic stable angina and/or heart failure. The median (IQR) time for follow-up period after starting EECP treatment was 16 (10–24) months.

Results

Cys C significantly declined from 1.00 (0.78-1.31) to 0.94 (0.77-1.27) mg/L (p < 0.001) and estimated GFR increased from 70.47 (43.88-89.41) to 76.27 (49.02-91.46) mL/min/1.73 m² (p = 0.006) after EECP treatment. Subgroup analysis showed that patients with baseline GFR <60 mL/min/1.73 m² or NT-proBNP >125 pg/mL had a significant decrease in Cys C when compared to other groups (p < 0.01).

Conclusions

The study demonstrated that EECP could improve long-term renal function in cardiac patients especially in cases with declined renal function or with high NT-proBNP.

Trial registration

The study was registered in the clinical trial as International Standard Randomized Controlled Trial Number ISRCTN11560035.

Predictors of good functional outcome in counterpulsation-treated recent ischaemic stroke patients

OBJECTIVES

External counterpulsation (ECP) is a non-invasive method being investigated for ischaemic stroke. We aimed to explore predictors of good functional outcome for ECP-treated ischaemic stroke patients who completed a minimum of 10 sessions.

METHODS

We analysed our ECP registry of ischaemic stroke patients with cerebral large artery stenosis who underwent ECP therapy at the Prince of Wales Hospital from 2004 to 2010. We included 155 patients who completed at least 10 sessions of ECP and had 3-month follow-up data as well as 52 medical controls. Functional outcomes were dichotomised into good outcome (modified Rankin Scale (mRS) 0-2) and bad outcome (mRS 3-6). We compared the differences in two groups in terms of demographics, medical history and parameters of ECP treatment.

RESULTS

At 3 months after stroke, 70.5% of patients who finished the whole course of ECP had a good outcome (only 46.5% in the unfinished group and 38.5% in the medical group). Among all 207 recruited cases, 119 (57.5%) patients had a good outcome at 3 months after stroke. Compared with the bad outcome group, patients in the good outcome group were younger and had a lower baseline National Institutes of Health Stroke Scale (NIHSS) and longer ECP therapy duration. Multivariate logistic regression showed that ECP duration (OR 1.032), baseline NIHSS (OR 0.734) and age (OR 0.961) were independent predictors for a favourable outcome.

CONCLUSIONS

Duration of ECP therapy is first found to be an important predictor for good outcome of ECP-treated ischaemic stroke patients, in addition to the well-known prognostic factors such as age and NIHSS.

The safety and efficacy of enhanced external counterpulsation as a treatment for angina in patients with aortic stenosis

BACKGROUND

Comorbid aortic stenosis (AS) has been considered a precaution when applying enhanced external counterpulsation (EECP) to individuals with angina due to concerns about treatment-related hemodynamic changes.

HYPOTHESIS

The aim of this study was to determine whether EECP safely reduces symptoms of myocardial ischemia and improves hemodynamics in individuals with AS.

METHODS

Forty-three patients with AS (average age, 73 years; 86% male) and 43 comparison patients without AS were chosen from a database of 1327 EECP patients. Canadian Cardiovascular Society (CCS) Functional Angina Classification, diastolic augmentation ratio, and blood pressure were measured at baseline and on completion of the course of EECP.

RESULTS

Thirty-five of the 43 patients with AS (81%, 95% CI: 66.6% to 91.6%) and 38 of the 43 without AS (88%, 95% CI: 74.9% to 96.1%) improved in angina class (P < 0.0001). There was no statistical difference between the percentages in patients with and without AS (P = 0.54). CCS angina class outcome was not associated with AS severity (P = 0.55). The percentage of patients with diastolic augmentation ratio ≥1.0 was 16.3% in both groups at baseline and improved to 39.5% in AS patients and 37.2% in non-AS patients after EECP (both P = 0.002). The average decreases in systolic blood pressure in subjects with AS (-15 mm Hg, 95% CI: 11 to 20, P < 0.0001) and without AS (-18 mm Hg, 95% CI: 14 to 22, P < 0.0001) were similar (P = 0.31). No major adverse cardiac events were reported.

CONCLUSIONS

Angina patients with AS who undergo EECP had clinically important symptomatic and hemodynamic improvements comparable to their non-AS counterparts.

Vasculoprotective properties of enhanced external counterpulsation for coronary artery disease: beyond the hemodynamics

A growing pool of evidence has shown that enhanced external counterpulsation (EECP) is a non-invasive, safe, low-cost, and highly beneficial therapy for patients with coronary artery disease. However, the exact mechanisms of benefit exerted by EECP therapy remain only partially understood. The favorable hemodynamic effects of EECP were previously considered as the primary mechanism of action. Nevertheless, recent advances have shed light on the shear stress-increasing effects of EECP which are vasculoprotective and anti-atherosclerotic. EECP-induced endothelial shear stress increase may lead to improvement in endothelial function and morphology, attenuation of oxidative stress and inflammation, and promotion of angiogenesis and vasculogenesis. This review summarizes evidence of the potential mechanisms contributing to the immediate and long-term benefits of EECP, from the perspective of its shear stress-increasing effects.

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.

A novel external counterpulsation system for coronary artery disease and heart failure: pilot studies and initial clinical experiences

External counterpulsation (ECP) is a beneficial and noninvasive treatment for coronary artery disease or heart failure; however, it still has a lot of limitations. We used a novel ECP system, Compact CP, the main feature of which is the double-lumen cuff that reduces the impact of cuff inflation and the size of the air compressor. The first lumen was a contact cuff that was attached to the legs with a constant pressure (8 kPa). The second lumen was a main cuff that was inflated and deflated with a driving pressure and synchronized to the cardiac cycle. In this report, we describe the results of four pilot studies in a total number of 39 healthy volunteers and initial clinical experiences of this system in three patients. The pilot studies demonstrated that the ECP system provided significant diastolic augmentation and systolic unloading. It also achieved a satisfactory diastolic/systolic pressure ratio (1.00 ± 0.06) with a high comfort level at a driving pressure of 40 kPa. Higher pressure (50-70 kPa) increased the assist performance but decreased the comfort level. ECP was also applied with a patient with chronic refractory angina and two patients with postoperative heart failure following cardiac surgery. The clinical conditions improved. No adverse effect was observed. Our novel ECP system is safe, effective, and promising in the treatment of coronary artery disease or heart failure. Further clinical investigations are needed to support the significance of this system.

Therapeutic goals in patients with refractory chronic angina

Refractory angina presents a major clinical challenge for everyday medical practice. Despite the widespread use of statins and improvements in revascularization techniques, a substantial proportion of patients with preserved left ventricular function and no life-threatening arrhythmias remain symptomatic, with severe debilitating angina. Because the rate of major cardiac events in this population is relatively low, the major aim of therapy should be not only to prolong survival but also to improve quality of life. The cornerstone of therapy for all these patients should be the aggressive modification of risk factors using evidence-based treatment, with the aim of stabilizing the disease process and improving overall survival. No opportunity for revascularization should be overlooked. Complementary approaches should be implemented to raise the angina threshold by either reducing oxygen demand or improving hemodynamics to increase myocardial oxygen supply. This review provides an update on therapeutic techniques and goals, and reinforces the need for a multidisciplinary approach to the management of patients with refractory angina.

Enhanced external counterpulsation: an innovative physical therapy for refractory angina

The prevalence of refractory angina in the United States is 600,000 to 1.8 million. Improved pharmacological, invasive, and surgical therapies for cardiovascular diseases during the last few decades have led to an increase in life expectancy of such individuals. Despite treatment with multiple medications and invasive procedures, these patients remain symptomatic and functionally limited. Enhanced external counterpulsation (EECP) is a safe, noninvasive, well-tolerated, and clinically effective outpatient physical therapy for many patients with refractory angina. Numerous trials demonstrate positive clinical responses among at least 80% of patients undergoing EECP, including reductions in angina and nitrate use, increases in exercise tolerance, and enhanced quality of life. Several mechanisms, including the promotion of collateral blood flow, improvement in endothelial function, reduction in inflammation, and the production of peripheral training effects similar to exercise, are thought to be responsible for the clinical benefits of this therapy. Despite the marked success rates EECP achieves with appropriately selected patients who have end-stage coronary artery disease, the treatment remains largely unknown, particularly among physiatrists. This review will summarize the current evidence for the use of EECP and spark a better understanding of the potential role of this treatment in cardiac rehabilitation.

Assessment of the effect of external counterpulsation on myocardial adaptive arteriogenesis by invasive functional measurements--design of the arteriogenesis network trial 2

BACKGROUND

Stimulation of collateral artery growth is a promising therapeutic option for patients with coronary artery disease. External counterpulsation is a non-invasive technique suggested to promote the growth of myocardial collateral arteries via increase of shear stress. The Art.Net.2 Trial tests invasively and functionally for the first time the hypothesis whether a treatment course with external counterpulsation (over 7 weeks) can induce the growth of myocardial collateral arteries.

METHODS

This study is designed as a prospective, controlled, proof-of-concept study. Inclusion criteria are (1) age 40 to 80 years, (2) stable coronary disease, (3) a residual significant stenosis of at least one epicardial artery and (4) a positive ischemic stress-test for the region of interest. As primary endpoint serves the pressure-derived collateral flow index (CFIp), the invasive gold-standard to assess myocardial collateral pathways. CFIp is determined by simultaneous measurement of mean aortic pressure (Pa, mm Hg), distal coronary occlusive (wedge) pressure (Pw, mm Hg) and central venous pressure (Pv, mm Hg). The index is calculated as CFIp=(Pw-Pv)/(Pa-Pv). The pressure derived fractional flow reserve (FFR) and the index of microcirculatory resistance (IMR) are assessed as secondary invasive endpoints to investigate the effect of ECP on the myocardial vasculature. The non-invasive secondary endpoints include symptoms (CCS and NYHA classification), treadmill-testing and analysis of shear-stress related soluble proteins.

CONCLUSIONS

The Art.Net.-2 Trial will report within the next months whether direct evidence can be brought that ECP promotes coronary collateral growth in patients with stable angina pectoris.

A systematic approach to refractory angina

PURPOSE OF REVIEW

Refractory angina pectoris is a common clinical condition associated with significant morbidity and mortality. This review aims to provide a systematic approach to the assessment and treatment of patients with this condition, focusing particularly on recent data.

RECENT FINDINGS

Recent registry-based data have confirmed that a significant proportion of patients referred to cardiologists are suffering from refractory angina pectoris and that this is associated with poor quality of life and increased mortality. A number of novel antianginal drugs have been developed, although there has been little consensus on their use in the treatment of refractory angina. In addition, multiple interventional treatments are available but detailed evaluation is sparse. More recent studies have begun to address some of the major concerns associated with the use of these technologies, including the placebo effect. Studies comparing the different techniques are now beginning to emerge, allowing clinicians and patients to make informed choices.

SUMMARY

A systematic approach is needed for the assessment and treatment of patients with refractory angina pectoris. Further research must include carefully designed randomized placebo-controlled trials to enable the role and application of the different techniques to be defined.