Functional Coronary Angiography for the Diagnosis of Coronary Vasomotor Disorders

Abstract

Microvascular and/or vasospastic angina are two common forms of coronary vasomotor disorders that may occur in patients with ischaemia and non-obstructed coronary arteries (INOCA) or myocardial infarction with non-obstructive coronary arteries (MINOCA). Functional coronary angiography involves invasive guidewire-based assessment of the coronary circulation using pharmacological vasoactive agents to assess small and large vasomotor dysfunction. Typically, responses to adenosine (microvascular vasodilator) and acetylcholine (large and small vessel vasospastic agent) are sequentially assessed. Currently, the assessment and treatment of INOCA and MINOCA patients varies widely. We therefore provide a standard protocol for 'functional coronary angiography' for use in Australia and New Zealand. Ischaemic heart disease (IHD) due to disorders of coronary vasomotion causes angina and impairs quality of life and prognosis. INOCA is prevalent in both men and women, however relative to obstructive CAD, INOCA is over-represented in women. This may also be a relevant contributor to sex differences which persist in IHD outcomes (notably in young women). Recent European Society of Cardiology guidelines make a class I recommendation in support of the use of functional coronary angiography in INOCA. Despite this, testing for disorders of coronary vasomotion is performed in very few centres in Australia and New Zealand. Barriers to more widespread clinical adoption include the lack of a standard protocol for testing, additional time and training required, lack of funding, concerns over safety and physician knowledge pertaining to over diagnosis and treatment options. Taken together, it is not surprising that local prevalence and outcome data are lacking. We summarise indications for functional assessment of coronary vasomotor disorders with a simple standardised operating protocol for use in cardiac catheter laboratories throughout Australia and New Zealand. We provide guidance on training recommendations for clinical proficiency in undertaking and interpreting functional coronary angiography. Clinical performance and research will be enhanced with the establishment of a national clinical quality registry for functional coronary angiography. By unifying the clinical approach, we hope to facilitate better care for this frequently overlooked heterogenous group of patients.