Current Practice and Safety of Invasive Coronary Function Testing: A Nationwide Multicenter Survey in Japan

Background: Coronary vasomotor dysfunction—including vasospastic angina and coronary microvascular dysfunction—is a key mechanism underlying ischemia or myocardial infarction with nonobstructive coronary arteries (INOCA/MINOCA). While invasive coronary function testing (CFT) provides important diagnostic insights, its real-world use and safety—especially in emergency settings—remain poorly defined. Objectives: The purpose of this study was to assess the current practice, diagnostic yield, and safety of CFT, including acetylcholine (ACh) and ergonovine (ERG) provocation tests and coronary microvascular assessments using coronary flow reserve (CFR) and index of microcirculatory resistance (IMR), in Japan. Methods: We conducted a nationwide cross-sectional survey of 235 institutions affiliated with the Japanese Cardiovascular Intervention and Therapeutics Society. Data on procedure volume, positivity rates, and complications were collected for tests performed between January 2022 and December 2023. Results: Among 6,983 provocation tests, 4,700 were ACh (4,327 elective and 373 emergency) and 2,283 were ERG (2,009 elective and 274 emergency). CFR/IMR was measured in 2,192 cases. Positivity rates were 50.9% for ACh and 32.5% for ERG. Major complications occurred in 1.4% of ACh and 0.4% of ERG tests, with no significant difference between emergency and elective settings. Abnormal CFR/IMR findings were more common in emergency cases (45.9% vs 34.8%; P < 0.001), while complications remained rare (0.05%). Conclusions: This large-scale survey confirms the feasibility and safety of invasive CFT, even in emergency settings. These findings support its broader adoption in the diagnostic workup of INOCA and MINOCA.