Effects of enhanced external counterpulsation on stress radionuclide coronary perfusion and exercise capacity in chronic stable angina pectoris

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Abstract

Enhanced external counterpulsation (EECP) is an effective noninvasive treatment for patients with coronary artery disease (CAD). EECP has been demonstrated to improve anginal class and time to ST-segment depression during exercise stress testing. This study assesses the efficacy of EECP in improving stress-induced myocardial ischemia using radionuclide perfusion treadmill stress tests (RPSTs). The international study group enrolled patients from 7 centers with chronic stable angina pectoris and a baseline ischemic pre-EECP RPST. Patients’ demographic and clinical characteristics were recorded. A baseline pre-EECP maximal RPST was performed within 1 month before EECP treatment. The results were compared with a follow-up RPST performed within 6 months of completion of a 35-hour course of EECP. Four centers performed post-EECP RPST to the same level of exercise as pre-EECP, whereas 3 centers performed maximal RPST post-EECP. The study enrolled 175 patients (155 men and 20 women). Improvement in angina, defined by ≥1 Canadian Cardiovascular Society angina class change, was reported in 85% of patients. In the centers performing the same level of exercise, 81 of 97 patients (83%) had significant improvement in RPST perfusion images. Patients who underwent maximal RPST revealed improvement in exercise duration (6.61 ± 1.88 pre-EECP vs 7.41 ± 2.03 minutes post-EECP, p <0.0001); 42 of the 78 patients (54%) in this group showed significant improvement in RPST perfusion images. Thus, EECP was effective in improving stress myocardial perfusion in patients with chronic stable angina at both comparable (baseline) and at maximal exercise levels.

Section snippets

Methods

The international study group enrolled patients from 7 centers with chronic stable angina and a baseline ischemic pre-EECP RPST over a period of 7 years. Exclusion criteria were: congestive heart failure, aortic insufficiency, myocardial infarction within the previous 3 months, significant ventricular ectopic activity or atrial fibrillation, nonischemic cardiomyopathy, severe occlusive peripheral vascular disease, recurrent or active deep vein thrombophlebitis, uncontrolled systemic

Results

The study enrolled 175 consecutive patients with follow-up (155 men and 20 women, mean age 61 ± 9.5 years). Patients characteristically exhibited multiple risk factors for cardiovascular diseases, had had prior cardiac events and interventions, and were considered refractory to medical therapy and unsuitable for further revascularization (Table 1).

Overall, 85% of patients reported improvement in angina of ≥1 CCS angina class, and 15% reported improvement by ≥2 CCS angina classes (Figure 1).

In

Discussion

Patients in this study, who underwent maximal RPSTs, showed a significant improvement in exercise duration after EECP therapy without significant alteration of the double product. Thus, in these patients, the observed improvement in RPST perfusion was not caused by an alteration in the determinants of myocardial oxygen demand, but was rather a reflection of improved myocardial perfusion (increased supply). This supports the hypothesis that EECP improves myocardial perfusion via collateral

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