Abstract 19008: Is Cold Pressor Cardiac Magnetic Resonance Imaging Testing Useful for Detection of Coronary Endothelial Dysfunction?

Abstract

Background: Coronary endothelial dysfunction is typically assessed by invasive coronary reactivity testing (CRT) to measure coronary blood flow ([[Unable to Display Character: ∆]]CBF) and diameter responses to acetylcholine (Ach). We evaluated if cold pressor testing (CPT) during noninvasive cardiac magnetic resonance imaging (CMRI) measurement of myocardial perfusion reserve index (MPRI) reflects invasive measurements with Ach and CPT in subjects suspected of having endothelial dysfunction. Methods: CRT was performed in 137 symptomatic women using incremental infusions of Ach in the left coronary artery for 3 minutes and with CPT using ice pack on their hand and forearm for 2 minutes. Quantitative coronary angiography was performed 5 mm distal to the Doppler wire positioned in the proximal left anterior descending artery. In 132 women, [[Unable to Display Character: ∆]]CBF was calculated from average peak velocity and vessel cross sectional area. Invasive CPT could not be completed on 4 women. All women underwent CPT CMRI (1.5 T) to measure MPRI as a ratio of stress and rest upslopes of the whole myocardium. Five definitions of normal invasive CPT and Ach diameter response (dilation > 0, 5, 10, 15 or 20%) were compared to two abnormal definitions (≤ 0 or - 5%) of endothelial function. Normal [[Unable to Display Character: ∆]]CBF was defined as ≤ 50%. We used Wilcoxon Two-Sample statistical test to compare MPRI in each group. Results: CPT MPRI was significantly different in those with normal versus abnormal invasive Ach when Ach diameter response was defined as ≥ 20% or < - 5 % (p=0.04), though not with other thresholds (Table). Conclusion: Noninvasive CPT CMRI may not be useful for detection of endothelial dysfunction in symptomatic women as no significant difference in MPRI was found in those with normal and abnormal invasive CRT. However, there may be a role for CPT MPRI in detecting endothelial dysfunction at higher thresholds of normal diameter response. Additional investigation will evaluate CPT CMRI and cardiovascular outcomes.