Letter by Sheikh et al Regarding Article, “Invasive Evaluation Of Patients With Angina in the Absence of Obstructive Coronary Artery Disease”

Abstract

who demonstrated an occult coronary abnormality in more than three quarters of these patients. Identifying the underlying abnormality is especially important for potentially life-threatening conditions that are amenable to treatment such as coronary artery spasm. Coronary spasm is associated with myocardial infarction, arrhythmias, and sudden death yet is responsive to calcium channel blockers and nitrates. Surprisingly, as stated in the accompanying editorial, 2 no patient had inducible spasm on acetylcholine provocation. This observation warrants closer scrutiny, particularly in relation to the acetylcholine provocation method used.Intracoronary acetylcholine administration is used to assess the presence of coronary endothelial function and coronary spasm. Its use is ideal, given its very short half-life and established safety record.Endothelial function studies use low-dose acetylcholine infusion (generally 10 −6 mol/L=0.18 μg/min and 10 −5 mol/L=1.8 μg/min) administered over 2 to 3 minutes. In this protocol, coronary vasodilation is indicative of intact endothelium-dependent vasodilation, whereas vasoconstriction implicates its impairment. The validity of this protocol has been established in relation to endothelial function 3 and long-term cardiac events. 4Coronary spasm provocation testing with acetylcholine was established in Japan with high-dose bolus administration. Doses of 20 to 100 μg administered over 20 seconds have been detailed in vasospastic angina guidelines 5 and validated for the clinical syndrome. 6Of note, this rapid-bolus, high-dose acetylcholine protocol requires temporary pacemaker backup because of predictable transient severe bradycardia. 5 However, temporary pacemaker insertion is often not undertaken in contemporary endothelial function studies of low-dose acetylcholine infusion. In the study by Lee et al, 1 a hybrid acetylcholine protocol is used in which 50 μg acetylcholine was administered over 2 to 3 minutes (slow bolus). Moreover, if significant bradycardia occurred, the higher 100-μg acetylcholine dose was not used. Considering the very short half-life of acetylcholine, intracoronary plasma acetylcholine concentrations would be considerably less with this protocol than the conventional 20-second rapid-bolus administration. 5,6 Consistent with this pharmacokinetic interpretation, no patients in the present study experienced "clinically relevant bradycardia," and none exhibited coronary spasm to the acetylcholine administration. 1 We use both standard protocols for invasive coronary assessment: low-dose acetylcholine infusion (0.18 and 1.8 μg/min over 2 minutes) for endothelial function testing and rapid-bolus, high-dose acetylcholine (25-100 μg over 20 seconds) for coronary spasm provocation. In 25 patients with angina and nonobstructive coronaries undergoing both protocols, only 2 patients required demand pacing (threshold set at 50 bpm) with the endothelial function testing protocol, whereas 84% of the same patients needed pacing during the coronary spasm protocol. Furthermore...

Improved heat and particle flux mitigation in high core confinement, baffled, alternative divertor configurations in the TCV tokamak

“…Details on the LP analysis can be found in reference [57]. The newly installed RADCAM system with five camera modules containing gold foil bolometers with 120 line of sights have been used to estimate the radiated power and its spatial distribution [59]. MANTIS (Multispectral Advanced Narrowband Tokamak Imaging System) [60] captures images from the divertor region that are inverted using the CalCam package [61] to obtain 2D poloidal maps of the emissivity of the selected radiation lines.…”

“…Radiation emission profiles are studied using the newly upgraded RADCAM system in TCV [59]. Figure 13 plots the 2D emissivity profiles (filtered to remove ELM times) for detached H-mode for the SN and the ADCs with high power (1.3 MW).…”

Management of ischaemia with non-obstructive coronary arteries (INOCA)

“…Patients in the intervention arm showed improved angina status on the Seattle Angina Questionnaire summary score at six months (11.68 points, 95% confidence interval 4.99 to 18.37; P=0.001) and at one year (13.6 points; 7.3 to 19.9; P<0.001) 1314. The use of functional coronary angiography is further evident from other reports,1516 where 80-90% of patients evaluated have had abnormal coronary haemodynamic findings, thereby providing explanations for their chest pain. Considering the clinical use of functional coronary angiography, its techniques have been recommended in professional society guidelines 17…”

Impact of glycemic variability on coronary and peripheral endothelial dysfunction in patients with coronary artery disease

“…At follow-up coronary angiography, coronary endothelial function was invasively assessed by low-dose ACh test [19] , measuring the coronary vasoreactivity in response to ACh infusion into the target coronary artery as previously reported [ 20 -22 ]. All antianginal agents that influence vasomotor tone, including long-acting nitrates, calcium channel blockers, and beta-blockers, were withheld for > 48 h before angiography.…”

“…They performed coronary spasm provocation test to diagnose vasospastic angina using bolus injection of ACh at doses of 20 to 100 μg (i.e. high-dose) [38][39][40], while we employed low-dose ACh test with serial ACh infusion (10 −7 mol/l) for 2 min at a rate of 2.0 ml/min in order to exclusively evaluate coronary endothelial function [19] .…”