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Invasive Endotyping in Patients With Angina and No Obstructive CAD
Quick Takes
- Three quarters of the outpatient population with angina in patients with no obstructive coronary arteries (ANOCA) had evidence of coronary microvascular dysfunction and epicardial coronary spasm.
- While invasive endotyping improved diagnosis of the cause of angina and related treatment satisfaction, it did not improve well-being.
- Clinical trials to identify disease-modifying therapy for ANOCA endotypes are indicated to optimally treat this condition.
Study Questions:
What is the usefulness of invasive coronary function testing to diagnose the cause of angina in patients with no obstructive coronary arteries (ANOCA)?
Methods:
The investigators prospectively screened outpatients referred for coronary computed tomography angiography (CCTA) in three hospitals in the United Kingdom. After CCTA, patients with unobstructed coronary arteries, and who consented, underwent invasive endotyping. The diagnostic assessments included coronary angiography, fractional flow reserve (patient excluded if ≤0.80), and, for those without obstructive coronary artery disease, coronary flow reserve (abnormal <2.0), index of microvascular resistance (abnormal ≥25), and intracoronary infusion of acetylcholine (0.182, 1.82, and 18.2 μg/mL; 2 mL/min for 2 minutes) to assess for microvascular and coronary spasm. Participants were randomly assigned to disclosure of the results of the coronary function tests to the invasive cardiologist (intervention group) or nondisclosure (control group, blinded). In the control group, a diagnosis of vasomotor angina was based on medical history, noninvasive tests, and coronary angiography. The primary outcome was the between-group difference in the reclassification rate of the initial diagnosis on the basis of CCTA versus the final diagnosis after invasive endotyping. The Seattle Angina Questionnaire summary score and Treatment Satisfaction Questionnaire for Medication were secondary outcomes.
Results:
Of 322 eligible patients, 250 (77.6%) underwent invasive endotyping; 19 (7.6%) had obstructive coronary disease, 127 (55.0%) had microvascular angina, 27 (11.7%) had vasospastic angina, 17 (7.4%) had both, and 60 (26.0%) had no abnormality. A total of 231 patients (mean age, 55.7 years; 64.5% women) were randomly assigned and followed up (median duration, 19.9 [12.6-26.9] months). The clinician diagnosed vasomotor angina in 51 (44.3%) patients in the intervention group and in 55 (47.4%) patients in the control group. After randomization, patients in the intervention group were fourfold (odds ratio, 4.05; 95% confidence interval, 2.32-7.24; p < 0.001) more likely to be diagnosed with a coronary vasomotor disorder; the frequency of this diagnosis increased to 76.5%. The frequency of normal coronary function (i.e., no vasomotor disorder) was not different between the groups before randomization (51.3% vs. 50.9%) but was reduced in the intervention group after randomization (23.5% vs. 50.9%, p < 0.001).
At 6 and 12 months, the Seattle Angina Questionnaire summary score in the intervention versus control groups was 59.2 ± 24.2 (2.3 ± 16.2 change from baseline) versus 60.4 ± 23.9 (4.6 ± 16.4 change) and 63.7 ± 23.5 (4.7 ± 14.7 change) versus 66.0 ± 19.3 (7.9 ± 17.1 change), respectively, and not different between groups (global p = 0.36). Compared with the control group, global treatment satisfaction was higher in the intervention group at 12 months (69.9 ± 22.8 vs. 61.7 ± 26.9, p = 0.013).
Conclusions:
The authors report that for patients with ANOCA, a diagnosis informed by invasive functional assessment had no effect on long-term angina burden.
Perspective:
This study reports that three quarters of the outpatient population with ANOCA had evidence of coronary microvascular dysfunction and epicardial coronary spasm. While invasive endotyping improved diagnosis of the cause of angina and related treatment satisfaction and reduced referrals for onward investigations, it did not improve well-being. At this time, the medical management of ANOCA involves repurposing antianginal medications. Clinical trials to identify disease-modifying therapy for ANOCA endotypes are indicated to optimally treat this condition.
Clinical Topics: Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Interventions and Imaging, Computed Tomography, Nuclear Imaging, Chronic Angina
Keywords: Angina Pectoris, Computed Tomography Angiography, Microvascular Angina
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