04.01 Enhanced External Counterpulsation Treatment Improves Arterial Wall Properties and Wave Reflection Characteristics in Patients with Refractory Angina

Abstract

Background

Early return of reflected pressure waves from the lower body, resulting from increased arterial stiffness, augments central aortic pressure and increases left ventricular (LV) afterload and myocardial oxygen demand. Enhanced external counterpulsation (EECP) acutely enhances coronary perfusion (supply) and reduces LV afterload (demand). However, the mechanism(s) responsible for the sustained beneficial effects of EECP treatment are unclear.

Objectives

To determine if arterial properties and wave reflection characteristics are favourably altered after EECP treatment in patients with refractory angina.

Methods

Radial artery pressure waveforms were recorded by applanation tonometry and central aortic pressure waveforms generated using a mathematical transfer function in 20 patients with stable refractory angina. Data were collected before and after 34 one-hour EECP sessions. Augmentation index (AI_a) and timing of the reflected pressure wave were calculated from the aortic waveform.

Results

EECP treatment caused a decline in AI_a and an increase in reflected wave travel time. These modifications in wave reflection characteristics caused a decrease in aortic systolic pressure and wasted LV pressure energy. The average number of angina episodes and Canadian Cardiovascular Society (CCS) class, both decreased in concordance with the physiologic changes due to EECP treatment.

Conclusions

EECP treatment reduces arterial stiffness and improves wave reflection characteristics in patients with refractory angina. These changes decrease LV afterload and myocardial oxygen demand and reduce the number of angina episodes and therefore, enables patients to participate in continuous exercise programs which in turn may provide long term benefits and sustained improved quality of life.