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

Abstract

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.