Description:
Enhanced external counterpulsation (EECP), also known as external counterpulsation (ECP), is a noninvasive treatment that uses sequential inflation of pressure cuffs on the calves, thighs and buttocks to augment diastolic pressure, decrease left ventricular afterload and increase venous return. The mechanism of action for EECP is to increase diastolic aortic pressure and displace a volume of blood backwards into the coronary arteries during diastole when the heart is in a state of relaxation and the resistance of the coronary arteries is at a minimum. The resulting increase in coronary artery perfusion is thought to enhance coronary collateral development or increase blood flow through existing collaterals. Other factors, such as neurohormonal changes, may play a role in mediating the observed benefits.

A course of treatment typically includes 35 sessions performed in one- to two-hour sessions in the physician’s office. The multiple components of the procedure should include the use of the device itself, finger plethysmography to follow the blood flow, continuous EKGs to trigger inflation and deflation and the optional use of pulse oximetry to measure oxygen before and after treatment.

Related Policies
70154 Transmyocardial Revascularization

Policy:
Enhanced external counterpulsation for the treatment of angina is considered investigational except in the case of patients with angina pectoris who meet ALL of the following criteria:

• Have disabling angina defined as Class III or Class IV*, Canadian Cardiovascular Society Classification (CCSF)¹ or equivalent
• Must be refractive to maximum medical therapy and not amenable to surgical intervention such as PTCA or cardiac bypass because, in the opinion of the cardiologist or cardiothoracic surgeon, one or more of the following conditions exists:
  • The condition is inoperable.
  • There is a high risk of operative complications or postoperative failure.
  • The coronary anatomy is not readily amenable to such procedures.
  • There are comorbid states, which create excessive surgical risk.

EECP for the treatment of any other cardiac condition, including but not limited to congestive heart failure, is considered INVESTIGATIONAL.

Rationale:
The literature base consists of a small number of randomized controlled trials (RCTs), some of which report relevant clinical outcomes and others that report intermediate, or physiologic, outcome measures. In addition to the small number of RCTs, there are a large number of observational studies, including publications from enhanced external counterpulsation (EECP) registries and case series, which generally report pre- and post-treatment measures of EECP effectiveness.

Chronic Stable Angina
 

In 1999, Arora and colleagues presented results of the MUST-EECP trial. MUST-EECP applied a randomized, controlled, double-blinded protocol that compared active treatment to placebo (inactive counterpulsation [CP] sham treatment) among 139 patients with Canadian Cardiovascular Society (CCS) Classification Scales (a functional assessment tool based on the level of exertion that elicits symptoms) class I – III chronic, stable angina.³ Four outcomes were examined:

• Self-reported frequency of angina, analyzed two ways
• Self-reported use of on-demand nitroglycerin
• Exercise duration tolerance testing
• Time to exercise-induced ischemia (defined as time to depression of ≥ 1 mm in the ST segment on electrocardiogram)

All patients underwent the same 35-hour protocol, followed by an exercise tolerance test within one week of completion of therapy. Follow-up beyond the treatment period was not conducted.

Intention-to-treat analyses were reported for the angina count and nitroglycerin usage outcomes only. There was a statistically significant difference (p = 0.01) between groups in the change in time to ≥ 1 mm ST segment depression. Patients in the EECP group had an average difference of 37 seconds longer time to ST segment depression compared to the sham-treated group. There was no significant difference between treatment groups in the change in exercise duration from baseline to the post-treatment period (p < 0.31). In addition, there were no statistically significant differences between groups with respect to angina counts (p < 0.09) or nitroglycerin use (p > 0.1).

In addition to a number of methodologic limitations found in the design, execution and reporting of this study, the magnitude of the benefit reported is not large. Of the 4 endpoints of interest, only the time to ST segment depression was statistically different in the EECP group compared to the sham-treated group. The clinical significance of a 37-second improvement in time to ST segment depression is unknown, but given that it occurred while the other three endpoints were statistically unchanged with therapy, does not suggest a marked improvement. That both groups showed increased exercise duration suggests a degree of placebo effect; exercise duration possesses a motivational component that time to ST segment depression does not.

In 2002, Arora and colleagues published a 12-month follow-up study to the MUST-EECP trial.⁴ However, only 71 (54 percent) of the original 139 subjects were included in the study. Subjects treated with EECP reported greater improvement in several quality-of-life scales. However, such findings could not be correlated with treatment response reported in the first study (because of data limitations).

A small unblinded RCT published in 2012⁷ addressed one health outcome, change after seven weeks in CCS angina class, along with multiple intermediate outcomes. Twenty patients with refractory angina (CCS class III) were randomized to EECP or no EECP. Mean CCS class was significantly improved in the EECP group but not in the no EECP group. At seven-week follow-up, soluble interleukin-2 receptor measurements significantly increased in the EECP group and significantly decreased in the no EECP group. There were no differences between groups at seven weeks in resting cutaneous microvascular blood flow or response to acetylcholine, sodium nitroprusside or local heating.

Some small RCTs have reported on intermediate, or physiologic, outcomes. One such RCT (n = 20) was published in 2010 comparing intracoronary blood flows in patients treated with EECP against those treated with a sham procedure.⁸ This trial was designed to detect statistically significant differences in collateral flow rates by angiography, not anginal symptoms. After seven weeks of treatment, collateral flow index increased significantly in the EECP group compared to sham treatment. Similar findings were noted in a comparative study by Buschmann and colleagues of 23 patients published in 2009.⁹

Two publications from a single study reported on blood flow and other measures of arterial function.^10,11 This study randomized 42 patients with coronary artery disease (CAD) and chronic angina to EECP or sham EECP. EECP improved flow-mediated dilation in the brachial and femoral arteries and improved numerous serum markers of blood flow and inflammation. The same study also reported that measures of arterial stiffness were improved in the EECP group. Martin et al.¹² randomized 18 patients with abnormal glucose tolerance to EECP or standard care and reported that measures of glucose tolerance, as well as measures of arterial function, were improved in the EECP group.

A number of systematic reviews of the literature have been performed evaluating EECP for chronic stable angina. In 2010, Amin and colleagues published a Cochrane review of major databases through 2008 on evidence of the effectiveness of EECP for chronic angina pectoris.¹³ The solitary RCT identified was the MUST-EECP trial. The authors of this review highlighted patient selection for this study. They comment that limiting the study population to patients with CCS class below IV diminishes the study’s generalizability to patients of interest, that is, patients with the most severe symptoms of chronic angina pectoris.

Also in 2010, Shah and colleagues published a meta-analysis of prospective studies, not limited to RCTs, of EECP in stable angina in which CCS class was adequately reported before and after treatment.¹⁴ The MUST-EECP RCT was not included, as change in CCS class was not one of the reported outcomes. Thirteen studies met these inclusion criteria (n = 949 patients). Overall, improvement of at least one level of angina class occurred in 86 percent of patients (95 percent confidence interval [CI]: 82 – 90 percent, p = 0.008).

In a 2009 paper, McKenna and colleagues report on a systematic review and economic analysis of EECP for the treatment of stable angina and heart failure.¹⁵ Four studies (one RCT and three non-randomized comparative studies) comparing EECP treatment with no treatment in adults with chronic stable angina were included in the analysis.^3,4,5,6 The systematic review included a study by Barsheshet and colleagues in which 25 patients (15 EECP and 10 controls) were evaluated at the end of treatment.¹⁶ Similar to the previously reviewed Schechter et al. study,⁶ “CCS classification improved with EECP but not with usual care; however, statistical analysis of between-group differences was not reported and, for CCS classification, the data were treated as continuous data, which is inappropriate for this four-category classification.”

Registry-based studies have been published that report on relatively large numbers of patients. In a registry-based study, 450 patients with left ventricular dysfunction (ejection fraction, EF ≤ 40) and refractory angina had 0.7 fewer emergency department visits and 0.8 fewer hospitalizations six months after treatment with EECP compared to the 6 months before EECP; six-month data were available on only 81 patients.¹⁷

Another registry-based study (the International Enhanced External Counterpulsation Patient [IECP] Registry) reported long-term (three-year) results on patients with chronic refractory angina for patients in this registry.¹⁸ The registry enrolled 5,000 patients from 99 U.S. and nine international centers between 1999 and 2001. However, analysis was completed only for those centers that had at least 80 percent compliance with follow-up data submission; the study reported results on 1,427 patients. In this selective group, 220 patients (15.4 percent) died, while 1,061 patients (74.4 percent) completed their follow-up. Immediately post-EECP, the proportion of patients with severe angina (Canadian Cardiovascular Angina Classification [CCS] III/IV) were reduced from 89 percent to 25 percent, p < 0.001. This was sustained in 74 percent of the patients during follow-up. More severe baseline angina and a history of heart failure or diabetes were independent predictors of unfavorable outcome.

The IECP data have also been examined to determine the safety and efficacy of the use of this device in patients with peripheral arterial disease. Peripheral arterial disease, while a common comorbidity of coronary artery disease, has been regarded as a relative contraindication to EECP due to concerns of compression on peripheral blood flow and a potentially greater risk of aortic rupture. Thakker and colleagues compared registry data in patients with peripheral arterial disease to those without.¹⁹ Based on a reduction of one or more CCS angina classes, patients with peripheral arterial disease had a similar rate (76.6 percent vs. 79.0 percent, respectively; p = 0.27) of improvement as did the group without peripheral arterial disease. Rates of hospitalization for all cardiac causes (6.1 percent vs. 4.4 percent, respectively; p = 0.17) and for unstable angina (5.4 percent vs. 3.5 percent, respectively; p = 0.25) were also similar between groups.

Numerous individual observational studies have been detailed in previous reviews and are included in systematic reviews described above.^{4,5,6,9,16,20} For example, two prospective cohort studies (n = 55 and n = 61) with one-year outcomes have been reported.^21,22 Improved CCS classification was the main reported outcome, which persisted for one year in 79 percent and 78 percent of patients in the respective studies. Both studies had higher rates of treatment completion and follow-up than the previously reported (registry) studies of long-term outcomes.

Heart Failure
The 510(k) approval of the Vasomedical devices states that objective measures such as peak oxygen consumption, exercise duration and pre-load-adjusted maximal left ventricular power are improved following EECP therapy, as well as subjective measures of patient response to therapy, such as quality of life and functional ability measures.¹⁵ However, no clinical details of these studies are provided in the FDA summary, and these data are not from controlled trials.

The 2005 TEC Assessment¹ included heart failure in the analysis and concluded the evidence supporting the role of EECP as an effective treatment for heart failure is lacking in both quantity and quality. A single randomized, multicenter study of EECP compared to usual care in 187 optimally medically managed patients with New York Heart Association (NYHA) functional class II/III heart failure with EF ≤ 35 percent of ischemic or idiopathic etiology, the “Prospective Evaluation of EECP in Congestive Heart Failure” (PEECH trial), was mostly inconclusive.²³ The design and methods of the PEECH trial were published by Feldman and colleagues. (24) The results of the PEECH trial found statistically improved, but modest, changes in exercise duration and improved functional classification but not in quality of life or peak oxygen uptake.²³

A subgroup analysis from the PEECH trial for heart failure was published.²⁵ It showed that subjects aged 65 years and older treated with EECP (n = 41) were more likely to meet the exercise duration (35 percent vs. 25 percent increased by ≥ 60 seconds) and peak VO2 (30 percent vs. 11 percent increased by ≥ 1.25 ml/kg per min) improvement thresholds compared to those undergoing sham treatment (n = 45); there was no difference at six months in NYHA class. This post-study analysis must be viewed as a preliminary result.

Registry studies for heart failure use angina outcomes and contribute little to the body of evidence.^26,27,28,29 The single-arm study by Soran et al.³⁰ indicates that patients respond with some improvements, but the lack of a comparison arm precludes inference about the true effects of therapy. Treatment durability for either angina or heart failure has yet to be addressed with long-term studies. Therefore, the evidence is insufficient to determine whether EECP improves the net health outcome or is as beneficial as any established alternatives in patients with chronic stable heart failure.

The previously described 2009 review by McKenna and colleagues¹⁵ included the single trial of EECP for heart failure included in the systematic review, the PEECH study.²³ The authors conclude that the studies do not provide firm evidence of the clinical effectiveness of EECP in refractory stable angina or in heart failure and that high quality studies are required to investigate the benefits of EECP and whether these outweigh the common adverse effects.

In summary, evidence for the use of EECP in heart failure is insufficient to form conclusions on efficacy. The single RCT that includes clinical outcomes reported modest improvements on some outcomes and no improvement on others. The observational studies add little to the evaluation of efficacy due to the variable natural history of heart failure, the multiple confounding variables for cardiac outcomes and the potential for a placebo effect. Further high-quality RCTs are needed to determine whether EECP is a useful treatment for heart failure.

Other Indications
The use of EECP for other conditions of ischemia has been investigated. In 2009, Fraser and Adams produced a Cochrane review on interventions for central retinal artery occlusion (CRAO).³¹ One of the two RCTs identified compared hemodilution with EECP against hemodilution without further intervention. In this case, the EECP intervention was a single, two-hour treatment. According to the reviewers, in this study (n = 20), patients were randomized but not blinded; no sham treatment was given. Primary outcomes were Doppler flowmetry of retinal perfusion and visual acuity.³² While acknowledging the relative safety of the technique, the authors remark, “The small size of the stud[y], potential for bias and the lack of data on final vision mean that we do not have convincing evidence at present to support the routine use of … EECP in patients with CRAO.”

Published registry studies also demonstrated improvements in erectile function.³³ Erectile function was improved in a study of 120 men prospectively enrolled from 16 centers. Three of five domains of the International Index of Erectile Function were statistically improved with EECP treatment (erectile function, intercourse satisfaction and overall satisfaction), and the total score improved from 28 to 32, a statistically significant improvement.³³ The non-comparative design of this study makes it difficult to draw conclusions on treatment efficacy. This indication is added as investigational due to lack of adequate data on clinical outcomes. Preliminary studies from Asia are also reporting early results on use of EECP to the lower extremities in the treatment of acute ischemic stroke.³⁴ A 2012 Cochrane review of two RCTs of EECP in acute ischemic stroke³⁵ concluded that the methodologic quality of the studies was poor and reliable conclusions could not be reached from this evidence.

Practice Guidelines and Position Statements
The ACC/AHA 2002 guideline update for the management of patients with chronic stable angina assigns a level of evidence of Class IIb for EECP.³⁶ This level of evidence maintains that procedures and treatments may be considered for patients and that additional studies with broad objectives are needed and further registry data would be helpful. This classification finds that the benefits of treatments are greater than or equal to the risk of treatment. In November 2012, the guideline was updated. It retained the same IIb recommendation. EECP therapy was also given a B rating for Level of Evidence (LOE).

Appendix:

New York Heart Association and Canadian Cardiovascular Society Functional Classifications 

References: