Introduction
Angina with non-obstructive coronary arteries (ANOCA) remains a common clinical finding among patients undergoing invasive coronary angiography for the investigation of suspected ischaemic syndromes. ANOCA may result from coronary microvascular disease or vasospasm (microvascular or epicardial spasm), which may be diagnosed using comprehensive physiology testing such as invasive functional coronary angiography (FCA).
Current guidelines (European Society of Cardiology, American College of Cardiology/American Heart Association, and Japanese Circulation Society) recommend the application of FCA in routine clinical practice among patients with signs and/or symptoms of myocardial ischaemia in the absence of obstructive coronary artery disease, given the demonstrated improvement in cardiovascular outcome, quality of life, and health care cost savings associated with endotype identification and stratified medical therapy.
However, whilst expert consensus exists about the criteria needed to diagnose ANOCA, wide variation exists within testing protocols, which most probably reflects individual clinician training and experience, centre familiarisation, and access to equipment required for testing. The influence of protocol variation on test results and subsequent clinical management remains poorly understood.
Currently there are no national or international data detailing protocol variation in routinely performed FCA. In preparing a binational position statement on FCA, the Cardiac Society of Australia and New Zealand (CSANZ) Coronary Vasomotor Dysfunction Working Group pursued an understanding of current practices within these countries and thus commissioned a comprehensive survey. Accordingly, the objective of this survey was to establish a nationwide perspective on attitudes and procedural practices in FCA across Australia and New Zealand sites, thereby providing insights into institutional protocol variations.
Methods
The Survey Cohort Setting
The survey cohort included members of the CSANZ Coronary Vasomotor Dysfunction Working Group and additional individuals from centres that were known to be actively performing coronary physiology assessments.
The CSANZ Coronary Vasomotor Dysfunction Working Group was established in 2021 to facilitate clinical and research activities in coronary vasomotor disorders within Australia and New Zealand. The group members included physicians and researchers with significant experience in the field. With an initial objective to develop a position paper on FCA, the group conducted quarterly and out-of-session meetings to obtain a consensus on the procedure. Hence, the study cohort was an enthusiastic, well-informed, collaborative group that included experienced centres undertaking FCA in Australia and New Zealand.
The Survey
To establish a snapshot of current practice across testing centres within Australia and New Zealand, a Google Forms–based survey was designed (Appendix 1 – survey). The survey covered the following domains: (1) respondent characteristics (age, gender, occupation, time in practice, whether they worked predominantly in the public or private sector); (2) pre-testing instructions (e.g., cessation of regularly used vasoactive medications); (3) testing technique, including access site preference, order of testing (acetylcholine [ACh] or adenosine-based testing first), pressure–temperature sensor guidewire–based thermodilution vs Doppler wire technique, left vs right coronary artery testing, and routine use of pre-medication/radial cocktail/temporary pacing wire (TPW); (4) perceived barriers to testing, and (5) future research areas and ideas. Upon discussion with the chair of the Royal Perth Hospital Human Research Ethics Committee, it was deemed that formal ethics approval was not required for the survey, since it represented an observational snapshot of contemporary clinical practice.
Center Selection
Between July 2022 and July 2023, an electronic link to the survey was sent to the following: (1) members of the Working Group, (2) centres known to have an active FCA program, or (3) centres known to have equipment for assessing coronary blood flow (ComboWire and ComboMap, Philips Volcano Corporation, San Diego, CA, USA; and/or PressureWire X, Abbott Vascular, Santa Clara, CA, USA and CoroFlow Cardiovascular System, Coroventis Research AB, Uppsala, Sweden). Centres were confirmed to have an active FCA program if respondents confirmed that their centre was performing both (1) measurement of hyperaemia resistance indices (index of microcirculatory resistance [IMR]/index of hyperaemic microvascular resistance [hMR]) and (2) vasospasm testing (with approved institutional access to ACh).
Survey results from all respondents were analysed with regard to respondent characteristics, attitudes towards invasive coronary physiology, and barriers to expanding physiology programs. Responses relating to procedure (FCA)-specific variables were only taken from centres identified to have an active FCA program, and for which procedure-specific information was available so that a per-centre analysis of FCA protocol variation could be performed.
Results
Between July 2022 and July 2023, 46 individuals from 37 centres in Australia and New Zealand were invited to participate in the survey. Of these, 39 individuals from 33 centres responded (Figure 1 and Table 1), yielding an overall response rate of 89% from clinical centres. Responses were received from representative centres within all Australian states and territories and both North and South Islands of New Zealand (Figure 2). Some centres provided several responses, and given that responses were consistent among respondents from the same centre, these responses were combined to allow a per-centre analysis to be performed for the 33 responding centres.
Figure 1 Flowchart of survey responses. The asterisk denotes an active FCA centre, defined as centres confirming the following: (1) measurement of microcirculatory resistance indices and (2) approved institutional access to acetylcholine for coronary vasomotor testing.
Figure 2 Location of responding centres within Australia and New Zealand. The asterisk denotes an active FCA centre, defined as centres confirming the following: (1) measurement of microcirculatory resistance indices and (2) approved institutional access to acetylcholine for coronary vasomotor testing.
