Enhanced external counterpulsation: U.S. clinical research

In U.S. clinical research, EECP (Vasomedical) has been shown to be an effective treatment for angina pectoris, with reported response rates ranging from a 75% success rates in unselected patients to 92% in patients with single vessel CAD (Table; Fig.). EECP effectively augments diastolic pressure and retrograde aortic flow, thereby increasing transmyocardial perfusion pressure. Demonstrable improvement of myocardial perfusion achieved by EECP may be due to collateral formation or recruitment. One or more proximally patent conduits (e.g., native coronary or bypass graft) improves the success of EECP, and is consistent with the concept that distal transmission of diastolic flow and pressure is necessary. Improvement in exercise tolerance after EECP may also be augmented by peripheral effects. The effects of EECP have been shown to be maintained in a majority of responders over a 3 year period. Over a 4-7 year period, the majority of treated patients remained free of interim events or need for hospitalization, with mortality results comparable to reported historical medical and surgical treatment. The patients enrolled in the reported clinical trials present the full spectrum of CAD severity; from the patient with single vessel disease and good left ventricular function to the triple vessel disease patient with stenotic grafts and compromised left ventricular function. The reported findings support the effectiveness of EECP used in three strategies of CAD treatment. EECP is highly effective in lessening ischemic symptoms in the patient with single or double vessel disease who wishes to defer more aggressive means of revascularization. Also, it is effective as an adjunct to angioplasty or bypass grafting in patients with incomplete revascularization, further decreasing the ischemic burden. EECP finds its third clinical role in treating patients who are poor revascularization candidates because of comorbidity and technical reasons, though results in this group are less impressive.