Main
Diagnosing the cause of stable chest pain can be challenging. The causes include angina due to obstructive coronary artery disease, microvascular angina and vasospastic angina (that is, angina with unobstructed coronary arteries (ANOCA)/ischemia with no obstructed coronary arteries (INOCA)) or a non-cardiac etiology. The diagnostic management of chest pain is described in guidelines. Based on functional imaging, the prevalence of endotypes of ANOCA in patients referred for diagnostic evaluation is approximately 40% and 43% (range, 16−73%), respectively. Coronary angiography provides an anatomical assessment of atherosclerosis, whereas the evaluation of vasomotor causes of angina requires functional testing.
Coronary computed tomography angiography (CCTA) is recommended as a first-line test for the evaluation of suspected angina. However, in patients selected for invasive coronary angiography with or without prior CCTA, half have no obstructed coronary arteries identified. In contemporary practice, most of these individuals do not undergo functional tests.
Coronary microvascular dysfunction is associated with persistent anginal symptoms, impaired quality of life, increased risk of major adverse cardiovascular events and considerable health resource utilization due to recurrent hospitalizations and repeat coronary angiography. The Coronary Microvascular Angina (CorMicA) trial demonstrated that coronary function testing during invasive management of suspected ANOCA is associated with improvements in symptoms, health-related quality of life and health economics. These results were recently validated in the ILIAS ANOCA trial. However, the effect of adjunctive diagnostic tests differs according to the test modality and population. Cardiovascular magnetic resonance (CMR) and nuclear stress positron emission tomography quantify myocardial blood flow and may be used to diagnose coronary microvascular dysfunction, but evidence of clinical utility from randomized trials is lacking.
Among patients with chest pain without obstructive coronary artery disease defined by invasive angiography, we aimed to assess whether re-evaluation of the endotype informed by stress CMR imaging (myocardial blood flow disclosed to inform endotyping) versus no functional assessment (myocardial blood flow measured but not disclosed), with endotype-specific treatment algorithms applied to all participants, affected the final diagnosis, angina burden and health-related quality of life.
We hypothesized that coronary vasomotor endotypes are prevalent in a post-angiography population with no obstructive coronary arteries, and, compared to angiography-guided management, CMR-guided management changes the diagnosis and improves symptoms and health-related quality of life.
Results
Between 9 February 2021 and 18 August 2023, 273 outpatients who had undergone clinically indicated invasive coronary angiography for investigation of chest pain and had a report of no obstructive coronary artery disease were screened and provided written informed consent within 3 months of the angiogram (Extended Data Fig. 1).
Two hundred and fifty of these patients attended for CMR imaging and were randomized before the scan (Table 1 and Fig. 1). One randomized participant was unable to complete the scan due to claustrophobia. Twenty-three patients who had provided consent did not attend for CMR imaging due to logistical and other reasons (Fig. 1).
Fig. 1: Flow diagram of the clinical trial.
An illustration showing the number of patients enrolled with informed consent in the catheter laboratory, reasons for exclusion, the number of patients in each randomized group and the follow-up process.
