The goal of this observational study is to learn more about the diagnosis of coronary endothelium function and coronary vasospasm using a dedicated invasive protocol in patients who has angina without obstruction in their main heart arteries. The main question it aims to answer is the feasibility, reproducibility, and safety of this invasive protocol: Does this invasive protocol diagnose coronary endothelial dysfunction and vasospasm without issues? Participants already having invasive coronary angiogram and physiological studies will undergo additional physiological measurements during the same procedure. Participants will enrol in a symptoms and quality of life questionnaire using dedicated questionnaires and a mobile application to assess the burden of their symptoms before and after the invasive procedure and up to 12 months follow up. A subset of participants will undergo a repeat set of these measurements to assess reproducibility of the invasive protocol. A subset of the participants will also undergo a cardiac MRI to assess correlation with the invasive protocol measurements.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
100
Invasive assessment of changes in coronary blood flow, resistance, and distal pressure in response to acetylcholine infusion. These will be measured during a clinical indicated invasive coronary angiogram procedure and physiological studies using a standard coronary pressure wire and a dedicated infusion catheter.
Feasibility outcome
Proportion of patients in whom the full invasive protocol (baseline and post-stimulation measurements) is successfully completed without major technical issues or protocol deviations.
Time frame: At baseline
Reproducibility outcome
Intra- and inter-operator variability of measurements quantified using intraclass correlation coefficients and Bland-Altman plots in a predefined reproducibility subset.
Time frame: At baseline
Safety outcome
Incidence of adverse events related to the procedure or medications.
Time frame: At Baseline and up to 12 months
Correlation between invasive and non-invasive measures of endothelial-dependent coronary microvascular dysfunction.
Strength of correlation (unit of measure = correlation coefficient, r) between invasive indices of endothelial-dependent coronary microvascular function obtained during the study protocol (absolute coronary blood flow and absolute microvascular resistance measured by continuous thermodilution during intracoronary acetylcholine testing) and non-invasive measures of myocardial perfusion (myocardial perfusion reserve obtained from cardiac stress perfusion imaging). Diagnostic agreement for identifying endothelial-dependent microvascular dysfunction will also be assessed (unit of measure = area under ROC curve, sensitivity, and specificity), using the invasive assessment as the reference standard.
Time frame: From baseline and up to 3 months
Correlation between invasive physiological indices of coronary microvascular function and symptom burden at baseline.
The strength of correlation (Pearson or Spearman correlation coefficient; unit of measure = correlation coefficient, r) between invasive physiological measurements of coronary microvascular function obtained during the study protocol (e.g., absolute coronary blood flow and absolute microvascular resistance derived by continuous thermodilution during acetylcholine testing) and patient-reported symptom burden assessed at baseline using validated questionnaires (Seattle Angina Questionnaire-7 \[SAQ-7\] and EQ-5D-5L scores).
Time frame: Baseline (at time of invasive coronary function testing).
Change in symptoms, quality of life, and need for further investigation or treatment during follow-up.
Change from baseline to follow-up in patient-reported symptoms and quality of life (unit of measure = change in questionnaire score) as assessed using the SAQ-7 and EQ-5D-5L questionnaires, and the proportion of patients (%) requiring additional cardiac investigations or treatment changes during follow-up.
Time frame: From baseline to 12 months follow-up
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.