Coronary Microvascular Dysfunction Assessments in Myocardial Infarction With Non-Obstructive Coronary Arteries

Background Approximately 5~10% of patients with acute myocardial infarction (AMI) have been reported as myocardial infarction with non-obstructive coronary arteries (MINOCA) in the contemporary clinical setting. Although those with MINOCA have a better prognosis than with obstructive coronary artery disease, several observational studies continuously reported that patients with MINOCA showed comparable outcomes. One plausible explanation of this discrepancy is the heterogeneous and variable definition of MINOCA. Possible causes of MINOCA include plaque erosion and/or rupture, vasospasm, and CMD. Therefore, it is natural that heterogeneous pathophysiology of MINOCA causes diagnostic challenges and proper management.

Recently, there have been efforts for establishing the diagnosis of MINOCA and standardizing the systematic management according to the cause of MINOCA. According to the AHA scientific statement, patients who suspected MINOCA have been recommended to perform multimodality approach, including intravascular imaging (i.e., OCT). Although non-invasive methods, such as N-13 ammonia positron emission tomography (PET), can be used for evaluating the CMD, invasive coronary physiologic assessment using pressure-temperature wire has been recommended. CMD has been known as a major cause of MINOCA, and it may be required specific treatment.

Nevertheless, there has no data on the outcomes of MINOCA with or without CMD. Therefore, the aim of CMD-MINOCA sought to assess the MINOCA patients regarding the latest clinical pathway for diagnosis of CMD and evaluate their clinical outcomes at 2 years.

Inclusion criteria

• Subject with age ≥19 years and acute myocardial infarction

• Rise and/or fall of cardiac troponin with one level >99 percentile plus ischemic signs/symptoms

• Subject with non-obstructive coronary arteries
• <50% diameter stenosis or
• fractional flow reserve (FFR) >0.80 ③ Subject without previous history of coronary artery disease

• Subject who performed invasive coronary angiography within 24 hours after presentation ⑤ Subject who eligible for invasive and non-invasive coronary physiologic assessment

Exclusion criteria

• Subject with obstructive coronary arteries

• Subject with alternate diagnosis including sepsis, pulmonary embolism, myocarditis, Takotsubo syndrome, spontaneous coronary dissection, and other cardiomyopathies.

• Subject with cardiogenic shock or cardiac arrest ④ Subject who has non-cardiac co-morbid conditions with life expectancy <1 year ⑤ Subject or lactating women ⑥ Subject unable to provide consent