Invasive Endotyping in Patients With Angina and No Obstructive Coronary Artery Disease: A Randomized Controlled Trial

BACKGROUND

We investigated the usefulness of invasive coronary function testing to diagnose the cause of angina in patients with no obstructive coronary arteries.

METHODS

Outpatients referred for coronary computed tomography angiography in 3 hospitals in the United Kingdom were prospectively screened. After coronary computed tomography angiography, 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 coronary computed tomography angiography 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 4-fold (odds ratio, 4.05 [95% CI, 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 (ie, no vasomotor disorder) was not different between the groups before randomization (51.3% versus 50.9%) but was reduced in the intervention group after randomization (23.5% versus 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 versus 61.7±26.9, P=0.013).

CONCLUSIONS

For patients with angina and no obstructive coronary arteries, a diagnosis informed by invasive functional assessment had no effect on long-term angina burden, whereas treatment satisfaction improved.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03477890.

Biventricular takotsubo cardiomyopathy: case report and general discussion

In recent years, our understanding of the physiologic mechanisms of transient takotsubo cardiomyopathy has improved because of the growing use of emergent heart catheterization in patients who present with severe ischemic syndromes. However, even this procedure has revealed only that, in most patients with takotsubo syndrome, the sudden onset of ventricular dysfunction is not due to fixed coronary artery occlusions. We present a case of transient takotsubo cardiomyopathy with an exceptional feature--uneven impairment of both right and left ventricular function, or biventricular takotsubo--and we discuss a novel, comprehensive theory that we have devised to explain the pathophysiology of this syndrome's many manifestations.

Differential local spasticity in myocardial bridges

To illustrate the effect of myocardial bridges on coronary vascular tone, we describe the cases of 2 patients with different clinical presentations in the context of reproducible increased spasticity at the site of myocardial bridging. One had an episode of takotsubo cardiomyopathy, and one developed typical Prinzmetal angina while receiving desmopressin treatment for pituitary insufficiency. In both patients, acetylcholine challenge clearly revealed both the presence and the severity of myocardial bridging while producing several recognizable degrees of abnormal spastic tendency.Both baseline functional states and responses to different medications correlate with spastic tendency and enable the characterization of individual cases. Understanding the spectrum of spastic conditions might help to clarify the causes of atypical ischemic events, especially in patients with myocardial bridging.

Changes of coronary blood flow in vasospastic angina under cold stimulation by transthoracic Doppler echocardiography

This study was done to evaluate changes of microvascular function under cold stimulation by measuring coronary flow velocities (CFVs) in vasospastic angina (VA) patients using transthoracic Doppler echocardiography (TTDE). 14 patients with VA and 15 healthy controls were included. CFVs were measured at the distal left anterior descending coronary artery by TTDE at baseline and under cold stimulation. Hyperemia was induced by intravenous adenosine infusion (140 microg/kg/min). At baseline, CFVs and coronary flow reserve (CFR) were not different between controls and VA patients. Under cold stimulation, the degree of increment of CFV with adenosine was lower in VA patients than in controls. Comparing baseline with cold stimulation, coronary flow reserve (CFR) increased (3.1+/-0.7 to 3.8 +/-1.0, p=0.06) in controls. In contrast, in VA patients, CFR was decreased (2.8 +/-0.9 to 2.6 +/-0.7, p=0.05) and coronary vascular resistance index markedly increased (0.35 to 0.43, p=0.01). Throughout the study, no patient experienced chest pain or ECG changes. In VA patients, CFR was preserved at baseline, but coronary blood flow increase in response to cold stimulation was blunted and CFR was decreased. These findings suggest that endothelial dependent vasodilation is impaired at the coronary microvascular and the epicardial artery level in VA under cold stimulation.

Coronary artery spasm as a cause of chest pain in a patient with anomalous origin of the right coronary artery from the left sinus of valsalva

The cause of chest pain in patients with anomalous origin of the right coronary artery from the left sinus of Valsalva has not yet been elucidated. In the following case, this anomaly was demonstrated, upon angiography, in a patient with recurrent chest pain and a negative stress test; in addition, spasm of the left anterior descending coronary artery was documented during ergonovine provocation. To our knowledge, this is the first time coronary artery spasm has been documented in a patient with this anomaly. On the basis of this case, we recommend ergonovine testing for all angina patients with aberrant coronary arteries in whom no other cause of chest pain is found at cardiac catheterization.