Abstract 11515: Noninvasive Quantitation of Coronary Collateral Flow Capacity in Patients with Chronic Total Occlusion Treated with External Counter Pulsation: Dobutamine Compared with Vasodilator Stress Pet Identifies Collaterogenesis

Abstract

Introduction: FDA approved external counterpulsation (ECP) improves coronary collateral flow index measured invasively, using intracoronary wedge pressure beyond a severe stenosis. However, there is presently no noninvasive method to measure coronary collateral flow capacity (CCFC), in patients with total coronary occlusion (CTO). Hypothesis: CCFC can be measured noninvasively by comparing the improvement in flow in the ischemic bed beyond CTO, using dobutamine stress (DBT), which supports supply side pressure, compared with vasodilator stress (DIP), which lowers supply side pressure, causing coronary steal. Methods: Seven patients with CTO were treated with 35 sessions of ECP, and studied with both DIP and DOB stress PET myocardial perfusion imaging. Coronary flow capacity (CFC), which integrates absolute rest and stress flow with coronary flow reserve on a per pixel basis, was measured objectively with FDA approved HeartSee software. Results: As shown in the Table, all patients demonstrated a decrease in the size of the ischemic zone at risk, defined as moderate or severely reduced CFC, when CFC with DIP was compared with DOB: 28% LV mass vs. 5%; p &lt 0.01. Five of 7 patients also demonstrated significant improvement in global CFC by Kolmogorov-Smirnoff analysis. Absolute stress flow into the ischemic zone improved significantly in all ECP treated patients during demand ischemia compared with vasodilator stress (1.9 vs. 1 ml/min/g; p &lt 0.01). One of the two patients who did not improve global CFC, despite ECP treatment, underwent coronary arteriography demonstrating a new flow limiting stenosis in the supply side vessel, which was successfully stented. Conclusion: ECP treatment is associated with improved coronary collateralization in patients with CTO, which can be identified noninvasively with quantitative PET myocardial perfusion imaging.