Abstract 13134: Prevalence of Abnormal Coronary Microcirculatory Resistance Among Patient With Ischemia and Non-Obstructive CAD
Background: Registry data indicates that 10-30% of patients undergoing coronary angiography for objective evidence of myocardial ischemia have non-obstructive epicardial CAD. Some patients among this group are thought to have microcirculatory (MC) ischemia.
Objective: To study the prevalence of MC ischemia using index of microcirculatory resistance (IMR) among patients undergoing cardiac cath for objective evidence of ischemic and non-obstructive epicardial CAD.
Methods: From Aug 2010-May 2013, 39 patients presenting with chest pain and objective evidence of ischemia with non-obstructive epicardial CAD underwent invasive evaluation for MC ischemia using IMR. In the absence of epicardial CAD, increased resistance after hyperemia in the MC bed is thought to mediate MC ischemia. Detailed clinical data was collected. Groups were compared using student t test and fishers exact for continuous and categorical variables respectively. IMR is calculated as: hyperemic transit time*distal hyperemic pressure. IMR>20=abnormal.
Results: A total of 39 patients were enrolled. Majority were female (32/39; 80%) with significant CAD risk factors. Indication for cath included chest pain and positive stress test (8/39; 20%), positive biomarkers (9/39; 26%) and ischemic ECG (20/39; 50%). IMR was abnormal in 18/39 patients (46%). See Table for additional comparisons.
Conclusion: Increased coronary MC resistance and ischemia is prevalent among patients presenting with objective evidence of ischemia and non-obstructive epicardial CAD. Measuring IMR provides additional insight into mechanisms of ischemia in patients with non-obstructive CAD and may identify patients who require aggressive secondary prevention.
- © 2013 by American Heart Association, Inc.