Acute hemodynamic effects and angina improvement with enhanced external counterpulsation

Enhanced external counter-pulsation (EECP) is an effective noninvasive trea tment for coronary artery disease. The mechanism of action is felt to be he modynamic. The complex hemodynamic effects have been simply quantified by c alculating a previously described effectiveness ratio (ER). The EECP Clinical Consortium, a clinical registry of 37 centers, prospectiv ely enrolled 395 chronic stable angina patients (79 women, 316 men, mean ag e 66 years) to examine the relation of the ER to posttreatment improvement in Canadian Cardiovascular Society angina class (CCS). Women and the elderl y underwent planned subgroup analysis. The ER was calculated during the fir st and last hours of a 35-hour course of EECP treatment. After EECP, CCS improved by at least 1 class in 88% of patients, 87% of men and 92% of women (p = NS), and in 89% of patients less than or equal to 66 years and 88% of patients > 66 years old (p = NS), The initial and final E R were similar in patients with and without improvement in CCS. Significant first-hour ER differences were seen between men and women (0.96 +/- 0.03 v s 0.76 +/- 0.04, p < 0.005), and between ages less than or equal to 66 and > 66 years old (1.04 +/- 0.04 vs 0.81 +/- 0.03, p < 0.0001). However, all s ubgroups responded equally well to EECP treatment. EECP is effective in improving CCS in chronic stable angina patients; it ha s comparable effects in men and women and across a broad range of ages. The hemodynamic effect of EECP (ER) does not predict improvement in CCS and ma y indicate that other factors, such as neurohormonal changes, may have a si gnificant role in mediating the observed EECP benefits.