Improvement of regional myocardial and coronary blood flow reserve in a patient treated with enhanced external counterpulsation: evaluation by nitrogen-13 ammonia PET

Overview of the 2012 Food and Drug Administration circulatory system devices panel meeting on the reclassification of external counterpulsation, intra-aortic balloon pump, and non-roller-type cardiopulmonary bypass blood pump devices

The Food and Drug Administration held a Circulatory System Devices Advisory Panel meeting, December 5 and 6, 2012, to review the classification or potential reclassification of the following device types: external counterpulsation, intra-aortic balloon pump (IABP), and non-roller-type cardiopulmonary bypass blood pumps. These 3 devices are preamendment (Medical Device Amendments of 1976) class III devices. The advisory panel discussed the data and provided recommendations for reclassification of these devices. The panel recommended reclassification of ECP to class II for stable angina pectoris and to retain a class III for all other indications. For IABP, the recommendation was to reclassify IABP to class II for several indications (acute coronary syndrome, cardiac and noncardiac surgery, and heart failure complications) and remain class III for all other indications. As for non-roller type, the panel recommended that for cardiopulmonary bypass and temporary circulatory bypass, these devices should be reclassified to class II while retaining a class III device status for all other indications, including ventricular support both for hemodynamically unstable patients and for prophylactic support in high-risk percutaneous interventions.

Does higher diastolic augmentation predict clinical benefit from enhanced external counterpulsation?: Data from the International EECP Patient Registry (IEPR)

BACKGROUND

Enhanced external counterpulsation (EECP) has been demonstrated to be an effective treatment for stable angina in patients with coronary disease. The hemodynamic effects of EECP are maximized when the ratio of diastolic to systolic pressure area is in the range of 1.5 to 2.0.

HYPOTHESIS

It is hypothesized that patients undergoing EECP who are able to achieve higher diastolic augmentation (DA) ratios may derive greater clinical benefit. This study examines the relationship between the DA ratio and clinical outcomes in patients undergoing EECP.

METHODS

We analyzed demographic, noninvasive hemodynamic, and clinical outcome data on 1,004 patients enrolled in the International EECP Patient Registry (IEPR) for treatment of chronic angina between January 1998 and August 1999. Blood pressure waveforms were recorded from finger plethysmography. Six-month clinical outcomes were obtained by telephone interview.

RESULTS

At the end of EECP treatment, 370 (37%) patients had a higher DA ratio (defined as > or = 1.5) and 634 (63%) had a lower DA ratio (defined as < 1.5). Factors associated with a lower DA ratio included age > or =65 years (p <0.001), female gender (p < 0.001), left ventricular ejection fraction < 35% (p < 0.05), hypertension (p < 0.01), prior coronary bypass surgery (p < 0.01), noncardiac vascular disease (p < 0.001), multivessel disease (p < 0.01), congestive heart failure (p < 0.01), current smoking (p < 0.01), unsuitability for further revascularization (p < 0.001), and higher baseline angina class (p < 0.001). There were no significant differences regarding diabetes mellitus, prior coronary angioplasty, prior myocardial infarction, or antianginal medication use between patients with higher or lower DA ratios. Based on a multiple logistic regression model, independent predictors of a DA ratio < 1.5 at the end of EECP included current smoking (odds ratio 3.3; 95% confidence intervals 2.0-5.4); multivessel disease (1.7; 1.3-2.3); female gender (2.2; 1.7-3.0); no prior EECP (1.9; 1.1-3.3); noncardiac vascular disease (2.3; 1.7-2.9); age > or = 65 years (1.7; 1.4-2.2), and patients not suitable for revascularization (1.6; 1.2-2.0). By the end of therapy, there were no significant differences in myocardial infarction, revascularization rates, or nitroglycerin use with respect to higher DA ratios. At 6-month follow-up, patients with higher DA had a trend toward a greater reduction in angina class compared with those with lower DA (p = 0.069). There was a significantly higher rate of unstable angina and congestive heart failure in the group not achieving higher augmentation (p < 0.05).

CONCLUSIONS

Patients who are younger, male, nonsmoking, and without multivessel coronary or noncardiac vascular disease are most likely to have higher DA with EECP. Patients with higher DA tended to have a greater reduction in angina class at 6-month follow-up compared with those with lower DA ratios. There is evidence that higher DA ratios are associated with improved short- or long-term clinical outcomes, suggesting that clinical benefit from EECP is associated with the magnitude of DA.

Long-term effect of enhanced external counterpulsation on endothelial function in the patients with intractable angina

BACKGROUND

Enhanced external counterpulsation (EECP) is a noninvasive, pneumatic technique that provides favourable effects in patients with coronary artery disease. The objective of this study was to describe the long-term effect of EECP on endothelial function in patients with ischaemic cardiomyopathy.

METHOD

The study was performed in 15 patients with ischaemic cardiomyopathy. All subjects were treated with EECP 1-h per day, 5 days a week, over 7 weeks (totally 35h). Endothelium-dependent and -independent relaxation was assessed by flow-mediated dilation (FMD) and nitroglycerine-mediated dilatation (NMD). In each patient, FMD and NMD measurements were performed before, at midcourse (day 17th) and after completion of EECP course (day 35th). In addition, FMD index was assessed 1 month after completion of EECP therapy.

RESULTS

Results showed that EECP was associated with a significant improvement in FMD index after 35 hours of EECP (10.95+/-4.1% vs. 7.40+/-4.9% for baseline, p<0.05). NMD index didn't significantly alter during the EECP therapy. Also, 1 month after completion of EECP, FMD index returned to baseline (7.51+/-4.4% vs. 7.40+/-4.9%, respectively, p<0.05). EECP acutely improved endothelial function in ischaemic cardiomyopathic patients. However, after 1 month completion of treatment, endothelium-dependent vasorelaxation returned to baseline.

CONCLUSION

It seems that improvement of endothelial function is not the main mechanism of long-term EECP treatment and other mechanisms should be considered.

Impact of External Counterpulsation Treatment on Emergency Department Visits and Hospitalizations in Refractory Angina Patients With Left Ventricular Dysfunction

Patients with refractory angina and left ventricular (LV) dysfunction exert an enormous burden on health care resources primarily because of the number of recurrent emergency department (ED) visits and hospitalizations. Enhanced external counterpulsation (EECP) therapy has emerged as a treatment option for patients with angina and LV dysfunction and has been shown to improve clinical outcomes and LV function. Improvements in symptoms and laboratory assessments in these patients, however, do not necessarily correlate with a reduction in ED visits and hospitalizations. This is the first study to assess the impact of EECP therapy on ED visits and hospitalization rates at 6-month follow-up. This prospective cohort study included 450 patients with LV dysfunction (ejection fraction <or=40%) treated with EECP therapy for refractory angina. Clinical outcomes, number of all-cause ED visits, and hospitalizations within the 6 months before EECP therapy were compared with those at 6-month follow-up. Despite the unfavorable risk profile, refractory angina patients with LV dysfunction achieved a substantial reduction in all-cause ED visits and hospitalization rates at 6-month follow-up. EECP therapy appears to offer an effective adjunctive treatment option for this group of patients.

Two-year clinical outcomes after enhanced external counterpulsation (EECP) therapy in patients with refractory angina pectoris and left ventricular dysfunction (report from The International EECP Patient Registry)

Enhanced external counterpulsation (EECP) is a noninvasive circulatory assist device that has recently emerged as a treatment option for refractory angina in left ventricular (LV) dysfunction. This 2-year cohort study describes the long-term follow-up of patients who had severe LV dysfunction that was treated with EECP for angina pectoris and reports clinical outcomes, event-free survival rates, and the incidence of repeat EECP. This study included 363 patients who had refractory angina and LV ejection fraction < or =35%. Most patients reported quality of life as poor. After completion of treatment, there was a significant decrease in severity of angina class (p < 0.001), and 72% improved from severe angina to no angina or mild angina. Fifty-two percent of patients discontinued nitroglycerin use. Quality of life improved substantially. At 2 years this decrease in angina was maintained in 55% of patients. The 2-year survival rate was 83%, and the major adverse cardiovascular event-free survival rate was 70%. Forty-three percent had no reported cardiac hospitalization; 81% had no reported congestive heart failure events. Repeat EECP was performed in 20% of these patients. The only significant independent predictor of repeat EECP in a proportional hazard model was failure to complete the first EECP treatment course (hazard ratio 2.9, 95% confidence interval 1.7 to 4.9). Improvements in angina symptoms and quality of life were maintained at 2 years. In conclusion, for patients who have high-risk LV dysfunction, EECP offers an effective, durable therapeutic approach for refractory angina. Decreased angina and improvement in quality of life were maintained at 2 years, with modest repeat EECP and low major cardiovascular event rates.

Predictors of benefit in angina patients one year after completing enhanced external counterpulsation: initial responders to treatment versus nonresponders

Enhanced external counterpulsation (EECP) has been shown to reduce Canadian Cardiovascular Society angina class. This study examines the factors that affect the reduction at 1 year, especially in patients who do not demonstrate an initial response. The data of 2,007 consecutive patients enrolled in the International EECP Patient Registry were analyzed. After 36.6 +/- 4.9 h of EECP, angina was reduced by at least one class in 82.7%. At 1 year, 35.4% of initial nonresponders and 70.6% of responders remained improved by at least one angina class and free of major adverse cardiovascular events. Multivariate predictors of 1-year benefit are initial response to treatment (odds ratio 4.5, 95% CI 3.5-5.8), baseline angina class compared with class IV (odds ratios: class I 2.1, CI 0.93-4.81; class II 0.62, CI 0.43-0.87; class III 0.80, CI 0.62-1.01) and no history of congestive heart failure (odds ratio 1.41, CI 1.14-1.74).

Effects of enhanced external counterpulsation on hemodynamics and its mechanism

BACKGROUND

The hemodynamic effects of enhanced external counterpulsation (EECP) and its mechanism(s) were investigated in relation to neurohumoral factors in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

Twenty-four patients with AMI were studied before, during and after EECP treatment for 60 min. Heart rate (HR), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were determined. In addition, circulating concentrations of neurohumoral factors were determined at each time point. HR did not change following EECP treatment. However, RAP and PCWP increased significantly and CI was significantly elevated during EECP and thereafter. Blood atrial natriuretic peptide (ANP) concentration was significantly increased 15 and 60 min after the start of EECP treatment, but brain natriuretic peptide (BNP) did not change. Renin, aldosterone and catecholamine concentrations also did not change.

CONCLUSION

Treatment with EECP resulted in an increased preload because of increased venous return, and CI was increased thereafter. In patients with AMI, EECP increased blood ANP concentration, but not BNP, which suggests that an increase in ANP without an increase in BNP is an important mechanism for the effects of EECP treatment.

Effectiveness of enhanced external counterpulsation in patients with left main disease and angina

BACKGROUND

Enhanced external counterpulsation (EECP) is a noninvasive device that uses three pairs of sequentially inflated pneumatic cuffs applied to the lower extremities and synchronized with the heart beat to provide diastolic augmentation, increase coronary blood pressure and flow, venous return and cardiac output, and decrease afterload.

HYPOTHESIS

This study examines the safety and effectiveness of EECP therapy in patients with significant left main coronary artery disease (LMD).

METHODS

In all, 2,861 patients enrolled in the International EECP Patient Registry (IEPR) were divided into three groups, those without LMD (n = 2,377), those with LMD and prior CABG (n = 431), and those with unbypassed LMD (n = 53).

RESULTS

Patients with LMD, with or without prior CABG, were significantly more likely to have triple-vessel disease (98.1 and 88.7%, respectively) than patients without LMD (41.9%). Post-EECP, 74% without LMD, 75% with LMD with prior CABG, and 65% with unbypassed LMD improved their Canadian Cardiovascular Society (CCS) angina by at least one class (p = NS). There were no differences in the mean decrease in weekly angina episodes (7.1 vs. 8.0 vs. 7.6) and in the mean frequency of weekly nitroglycerin use (6.6 vs. 8.1 vs. 8.9). At 6-month follow-up, the CCS class improved further in all three groups, and there was a further reduction in mean weekly angina episodes (4.7 vs. 4.6 vs. 5.3) and nitroglycerin use (6.5 vs. 6.8 vs. 8.2). Kaplan-Meier life table analysis 8 months after starting EECP demonstrated a major cardiovascular event rate of 11.2% in patients without LMD, 15.6% in LMD with CABG, and 24.3% in LMD without prior CABG. Late mortality in unbypassed LMD was 13.2% (confidence interval [CI] 3.3-23.1) versus 4.8% (CI 2.7-7.1) in LMD with CABG, and 2.8% (CI 2.1-3.5) without LMD (p = 0.0039 by log-rank test).

CONCLUSION

Enhanced external counterpulsation is equally effective in relieving angina in patients with or without LMD. However, the significantly increased late mortality in patients with LMD without prior CABG suggests that early revascularization should be considered in these patients.

A new treatment modality in heart failure enhanced external counterpulsation (EECP)

Heart failure remains a significant health problem in the United States and in the world. Despite a surfeit of recent diagnostic and therapeutic advances, patients with heart failure remain inadequately helped. The overwhelming need for new and better therapies continues to stimulate scientists to investigate new technologies. Over the past several years the use of enhanced external counterpulsation as a treatment for chronic angina has steadily increased. Recently, its potential role in heart failure management has been shown. We review the role of enhanced external counterpulsation in heart failure management as an emerging noninvasive outpatient therapy.

External counterpulsation therapy improves endothelial function in patients with refractory angina pectoris

OBJECTIVES

The goal of this study was to investigate the influence of short-term external counterpulsation (ECP) therapy on flow-mediated dilation (FMD) in patients with coronary artery disease (CAD).

BACKGROUND

In patients with CAD, the vascular endothelium is usually impaired and modification or reversal of endothelial dysfunction may significantly enhance treatment. Although ECP therapy reduces angina and improves exercise tolerance in patients with CAD, its short-term effects on FMD in patients with refractory angina pectoris have not yet been described.

METHODS

We prospectively assessed endothelial function in 20 consecutive CAD patients (15 males), mean age 68 +/- 11 years, with refractory angina pectoris (Canadian Cardiovascular Society [CCS] angina class III to IV), unsuitable for coronary revascularization, before and after ECP, and compared them with 20 age- and gender-matched controls. Endothelium-dependent brachial artery FMD and endothelium-independent nitroglycerin (NTG)-mediated vasodilation were assessed before and after ECP therapy, using high-resolution ultrasound.

RESULTS

External counterpulsation therapy resulted in significant improvement in post-intervention FMD (8.2 +/- 2.1%, p = 0.01), compared with controls (3.1 +/- 2.2%, p = 0.78). There was no significant effect of treatment on NTG-induced vasodilation between ECP and controls (10.7 +/- 2.8% vs. 10.2 +/- 2.4%, p = 0.85). External counterpulsation significantly improved anginal symptoms assessed by reduction in mean sublingual daily nitrate consumption, compared with controls (4.2 +/- 2.7 nitrate tablets vs. 0.4 +/- 0.5 nitrate tablets, p <0.001 and 4.5 +/- 2.3 nitrate tablets vs. 4.4 +/- 2.6 nitrate tablets, p = 0.87, respectively) and in mean CCS angina class compared with controls (3.5 +/- 0.5 vs. 1.9 +/- 0.3, p <0.0001 and 3.3 +/- 0.6 vs. 3.5 +/- 0.5, p = 0.89, respectively).

CONCLUSIONS

External counterpulsation significantly improved vascular endothelial function in CAD patients with refractory angina pectoris, thereby suggesting that improved anginal symptoms may be the result of such a mechanism.

Enhanced external counterpulsation as treatment for chronic angina in patients with left ventricular dysfunction: a report from the International EECP Patient Registry (IEPR)

The International Enhanced External Counterpulsation (EECP) Patient Registry tracks acute and long-term outcome for consecutive patients treated for chronic angina. Although EECP has previously been shown to be a safe and effective treatment for angina, little information is available on its use in patients with left ventricular (LV) dysfunction. This report compares the acute outcome and 6-month follow-up for a group of patients with severe LV dysfunction and a group of patients without LV dysfunction. Of 1,402 patients in the registry recruited in 1998-1999 who had recorded values of LV ejection fraction (LVEF) at baseline, 1,090 (77.7%) had preserved LV function (LVEF >35%) and 312 (22.3%) had LV dysfunction (LVEF </=35%). Six-month follow-up was available on 84% of these patients. Pre-EECP patients with LV dysfunction had a longer history of coronary artery disease (12.9 years vs. 9.1 years; p<0.001), a higher rate of congestive heart failure (60.6% vs. 20.1%; p<0.001) and myocardial infarction (83.5% vs. 61.9%; p<0.001). Patients with LV dysfunction had more severe pre-EECP angina, with 86.2% presenting with Canadian Cardiovascular Society Class III/IV vs. 73.6%; p<0.01. Patients with LV dysfunction, consistent with their more severe baseline profile, suffered more adverse events (death, unstable angina, and exacerbation of heart failure) during the treatment period and were less likely to complete the full course. Immediately post-EECP, angina decreased by at least one class in 67.8% of patients with LV dysfunction (vs. 76.2%; p<0.01), and 35.9% of LV dysfunction patients vs. 39.0% had discontinued nitroglycerin use (p=ns). At 6-month follow-up, patients with LV dysfunction showed higher rates of death (9.3% vs. 2.2%; p<0.001) and exacerbation of congestive heart failure (9.9% vs. 3.7%; p<0.001). Rates of the composite outcome of death/myocardial infarction/coronary artery bypass grafting/percutaneous coronary intervention (15.4% vs. 8.3%; p<0.001) were also higher for patients with LV dysfunction. However, patients not reporting such an event showed maintenance of their improved anginal status, with 81% of LV dysfunction vs. 83.8% of patients without LV dysfunction (p=ns) reporting angina at 6 months equal to or less severe than immediately post-EECP, and nitroglycerin use was still reduced at 46.1% for LV dysfunction vs. 37.4% (p<0.05). The rate of event-free angina maintenance at 6 months was 67.0% for patients with LV dysfunction and 70.6% of patients with preserved LV function (p=ns). Patients with LV dysfunction achieved a less robust reduction in angina than did those without LV dysfunction. For the majority of the patients in the registry, this reduction was maintained at 6 months.