Related Experiment Video
Updated: Jul 8, 2026
Interventional Diagnostic Procedure: A Practical Guide for the Assessment of Coronary Vascular Function
Published on: March 15, 2022
International study of coronary microvascular angina (iCorMicA): A registry-based diagnostic study and nested
Daniel Ang1, Robin Young2, Diann Taggart3
1School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, United Kingdom; West of Scotland Heart and Lung Center, Golden Jubilee National Hospital, Glasgow, United Kingdom; Department of Cardiology, University Hospital Hairmyres, Glasgow, United Kingdom.
Insights
This study investigates angina causes in patients with non-obstructive coronary arteries (ANOCA). Coronary function testing guided management improved patient outcomes, offering new treatment strategies for this common condition.
Area of Science:
- Cardiology
- Clinical Trials
- Diagnostic Medicine
Background:
- Angina pectoris, often linked to coronary artery disease (CAD) and microvascular dysfunction, affects many patients post-coronary angiography with non-obstructive coronary arteries (ANOCA).
- Women are disproportionately impacted by ANOCA, highlighting a need for sex-specific research and management strategies.
- Current diagnostic pathways for ANOCA often lack clarity, leading to suboptimal patient management and persistent symptoms.
Purpose of the Study:
- To determine the underlying causes of angina in patients diagnosed with ANOCA following invasive coronary angiography.
- To evaluate the clinical effectiveness of management strategies guided by coronary function tests (CFTs) in improving patient outcomes.
- To provide novel evidence on the natural history and stratified therapy for ANOCA.
Main Methods:
- An international, multicenter, prospective, registry-based study with a nested randomized, controlled, triple-blind trial.
- Participants underwent invasive coronary angiography; those without obstructive CAD were randomized.
- Coronary function was assessed using index of microcirculatory resistance (IMR) and coronary flow reserve (CFR) via bolus thermodilution, with results disclosed to cardiologists in the intervention group.
Main Results:
- The primary outcome for the registry was the Seattle Angina Questionnaire (SAQ) summary score at baseline, stratified by CAD status.
- The primary outcome for the randomized trial was the change in SAQ summary score at 12 months.
- Secondary outcomes included the prevalence of obstructive CAD, patient-reported outcome measures (PROMs), and clinical events.
Conclusions:
- Coronary function testing provides crucial insights into the pathophysiology of angina in ANOCA patients.
- CFT-guided management demonstrates potential for improving angina symptoms and quality of life in ANOCA patients.
- This trial establishes a foundation for evidence-based, stratified treatment approaches for ANOCA, addressing a significant unmet clinical need.
Background:
Angina is a debilitating condition caused by coronary artery disease and microvascular dysfunction. Following coronary angiography angina and no obstructive coronary arteries is a common outcome, and women are disproportionately affected. The objectives are first, to assess causes of angina in patients undergoing invasive management; and second, to assess effects of coronary function test-guided management on clinical outcomes.
Methods:
This is an international, multicenter, prospective, registry-based study and nested, randomized, controlled, triple-blind, and endpoint trial. Participants, community care providers, and outcomes assessors are masked. Consented participants enter the registry. Participants without obstructive coronary artery disease (luminal stenosis <50%, or fractional flow reserve >0.80) are eligible for randomization. Index of microcirculatory resistance (IMR; abnormal ≥25) and coronary flow reserve (CFR; abnormal <2.0; gray zone 2.0-2.5) are measured by bolus thermodilution, and results are disclosed (intervention) or not (control group) to the attending cardiologist.
Results:
The primary outcome of the registry is the Seattle Angina Questionnaire summary score at baseline described by coronary artery disease status. Secondary outcomes include the prevalence of obstructive coronary artery disease, patient reported outcome measures and clinical outcomes. The primary outcome of the randomized trial is the within-individual change in Seattle Angina Questionnaire summary score at 12-months from baseline. Secondary outcomes include safety, diagnostic accuracy, patient reported outcome measures for quality of life, physical and psychological function, cardiovascular risk, clinical outcomes, health economics and mechanistic biomarkers. The first patient was screened on December 18, 2020 and the last patient was enrolled on June 30, 2026. Forty sites were included in the United Kingdom (n = 35), Republic of Ireland (n = 2), Holland (n = 2), and Poland (n = 1). In total, 1,483 participants were enrolled into the registry of whom 1,047 were randomized and 386 were not randomized (registry-only).
Conclusion:
This international, registry-based clinical trial will provide novel evidence on the natural history of angina and stratified therapy for angina with no obstructive coronary arteries.
Clinical Trial Registration:
https://clinicaltrials.gov/study/NCT04674449.
Unique Identifier:
NCT04674449.
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