Among 2,486 patients enrolled in the International EECP Patient Registry (IEPR) who underwent EECP therapy for symptomatic coronary artery disease,the median diastolic augmentation (DA) ratio increased from 0.7 to 1.0 from the beginning to the end of treatment.Patients who had the greatest increase in the DA ratio had the greatest reduction in angina class,whereas those with a relative decrease in the DA ratio had the lowest reduction in angina class immediately after EECP and at 6 months of follow-up.These data suggest that improved vascular tone during EECP treatment may play a mechanistic role in the relation between DA and clinical benefit with EECP.