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Investigator: Gregory W. Barsness, MD, FACC The Challenge: Despite advances in the treatment of angina, a substantial number of patients continue to have symptoms that can significantly impair their quality of life despite optimal medical therapy. For patients who are not candidates for revascularization, enhanced external counterpulsation (EECP) is a promising noninvasive outpatient therapy for the treatment of chronic angina. EECP treatment produces an acute hemodynamic effect that is similar to that produced by the invasive intra-aortic balloon pump. Clinical trials of EECP have been conducted since the 1960s and have demonstrated the benefits of this approach in terms of reduction in anginal episodes, increased exercise times, and improvement in health-related quality of life scores.1 The Data: An EECP treatment course consists of 35 one-hour sessions over a seven-week period and is generally well tolerated with a low risk of adverse events. This has been shown to provide long-term symptom relief in patients with ischemic heart disease in several case series, as well as in a randomized trial. In one review of the literature, Barsness reported that up to 80% of patients selected for treatment have a positive clinical response.2 Likewise, an associated objective improvement has been demonstrated by functional imaging in several case series. In one recent study, EECP was found to be a low-risk intervention for octogenarians, offering even these older patients the ability to return to more normal activity and a better quality of life.3 EECP has substantial hemodynamic effects; there is diastolic augmentation, improvements in diastolic coronary flow, and improved flow in other vascular beds. The mechanism by which it imparts its improvement in angina is unclear. Development and enhancement of collateral channels, as well as peripheral conditioning and neurohumoral effects, may play a role in providing symptomatic relief. Studies are ongoing to determine the mechanism of action and to further define subsets of patients who might benefit. Interpretation: Dr. Barsness: This is primarily used for patients with class III or IV angina who are not candidates for revascularization. It is a large and growing population of patients, although one problem is the lack of firm prevalence data; the estimates range from 800,000 patients in the United States to 2.5 million. That variability in size estimate underscores that this is an understudied population despite its overwhelming prevalence. We know exercise is helpful in these patients, many are so debilitated that it precludes even mildly strenuous activity. One advantage to EECP is that it can help get these patients back on their feet so they can do the exercises, like walking, that we know is very helpful. Both exercise time and time to ST-segment depression are improved following EECP. This is why we ask patients to begin cardiac rehabilitation soon after they finish EECP, because prior to therapy they simply cannot tolerate rehabilitation. At just one month from the initiation of therapy, we have demonstrated that endothelial function is improved to a level consistent with that seen in patients with normal coronary endothelial function, so we have taken them from a markedly abnormal level of endothelial dysfunction to what we would consider normal endothelial function. Second Opinion: Dr. Chesebro: For these patients with class III or IV angina, who are otherwise not candidates for revascularization, EECP is safe, approved, clinically effective, and reimbursed by Medicare. So, this is a good option for this large group of patients. Guidelines: ACC/AHA 2002 guideline update for the management of patients with chronic stable angina - summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Chronic Stable Angina). Circulation 2003 Jan 7;107(1):149-58. References: 1. Beller GA. A review of enhanced external counterpulsation clinical trials. Clin Cardiol 2002;25(12 Suppl 2):II6-10. 2. Barsness GW. Enhanced external counterpulsation in unrevascularizable patients. Curr Interv Cardiol Rep 2001;3:37-43. 3. Linnemeier G, Michaels AD, Soran O, Kennard ED; International Enhanced External Counterpulsation Patient Registry (IEPR) Investigators. Enhanced external counterpulsation in the management of angina in the elderly. Am J Geriatr Cardiol 2003;12:90-6. |
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