Identification of ischemia with no obstructive coronary arteries using 13N-ammonia positron emission tomography-derived myocardial strain ratio

Abstract Background Ischemia with no obstructive coronary arteries (INOCA) is a chronic health problem with poor prognosis and remains challenging to diagnose. 13N-ammonia positron emission tomography (NH3-PET) is the most reliable method for detecting INOCA. We recently developed a unique myocardial strain analysis for NH3-PET to detect ischemia-related motion abnormalities. Purpose We examined the usefulness of NH3-PET strain analysis to identify patients with INOCA. Methods Overall, 98 patients with non-obstructive coronary arteries who underwent adenosine-stress NH3-PET were enrolled. INOCA was defined based on the ESC guidelines. Using an original feature-tracking algorithm dedicated to NH3-PET, the circumferential strain was calculated. Myocardial strain ratio (MSR) was defined as the ratio of strains at stress and rest. In addition, global myocardial flow reserve (MFR) was obtained. Results Finally, forty-seven patients were diagnosed with INOCA, and 51 without INOCA. Global MFR were significantly lower in patients with INOCA than in those without INOCA (1.82 ± 0.52 vs. 2.65 ± 0.65, p