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The importance of indicators of the initial phase of atherosclerosis in patients with microvascular angina.

Endothelial dysfunction (ED) is generally considered to be the initial step in the progression to atherosclerosis but there is still much uncertainty about the role of the microvascular form of angina in patients with a normal coronary angiogram with regard to ED. The authors investigated the extent of endothelial perturbation and thereby whether the microvascular form of angina precedens macroscopic atherosclerosis by means of non-invasive ultrasound measurement of the intima-media thickening (IMT) in common carotid artery and flow mediated dilatation (FMD) in the brachial artery. 28 patients with stable angina with positive exercise test and ST segment depression (22 females, 6 males, average age 54 years) were compared with a control group consisting of 28 patients with no clinical signs of coronary artery disease (18 females, 10 males, average age 53 years). No significant difference in FMD% (7.3 vs. 10.8, p = 0.07) was found between the groups, though specific measurements (average dilatation of the brachial artery induced by ischemic insult, peak blood flow and peak hyperemic flow) differed considerably. Also IMT did not vary significantly between the groups (0.74 vs. 0.65, p = 0.08). In patients with IMT > 0.8 mm (6 patients in each group) a significant decrease of FMD was found as compared with patients with normal IMT (p < 0.05). It was concluded that in patients with increased IMT an inverse relationship between FMD and IMT exists both in patients with microvascular angina and in the healthy control subjects whereas in the group of patients with normal IMT no ED was demonstrated. This supports the hypothesis that the microvascular form of angina is the early stage of coronary artery atherosclerosis and this escapes angiographic recognition.

Adult↗

Coronary microvascular dysfunction in patients with microvascular angina: analysis by TIMI frame count.

We have previously reported that angina pectoris persists in patients with coronary microvascular spasm (MVS) even on calcium channel blockers. Because measurement of myocardial lactate production in the coronary sinus is necessary to diagnose MVS, a more feasible diagnostic method needs to be developed. In this study, we examined the diagnostic significance of Thrombolysis in Myocardial Infarction (TIMI) frame count, a marker of coronary blood flow, in 131 consecutive patients who underwent provocation test for coronary spasm with acetylcholine (ACh). Epicardial coronary spasm (ES) was diagnosed as more than 75% of ACh-induced vasoconstriction noted by coronary angiography. MVS was diagnosed as ACh-induced myocardial ischemia (chest pain, ischemic ECG changes, and myocardial lactate production) without ES. TIMI frame count was significantly increased in patients with MVS alone (n = 35) and those with ES + MVS (n = 16) compared with those with ES alone (n = 53) or those with no myocardial ischemia (Normal, n = 27) either before and after intracoronary ACh and even after intracoronary isosorbide dinitrate (ISDN) in both the left anterior descending (LAD) and the left circumflex coronary artery (LCX). TIMI frame count in LAD correlated well to that in LCX in patients with MVS, suggesting diffuse impaired coronary microcirculation in the myocardium. These results suggest that increased TIMI frame count in response to ACh reflects microvascular dysfunction in MVS and that ISDN may not be enough to relieve MVS. Thus, TIMI frame count may be useful to diagnose MVS without requiring coronary sinus catheterization or myocardial lactate production measurement.

Acetylcholine↗

Microvascular angina and the sensitive heart: historical perspective.

As our understanding of the etiology of chest pain of undetermined origin has evolved, the focus for studying this problem has switched from individual subspecialties to a multidisciplinary approach. In the subspecialties of gastroenterology and cardiology, the focus has shifted from organ-specific diagnoses to concepts of altered pain thresholds. Cardiologists began to look for functional causes of ischemia following the recognition that many patients with chest pain had normal coronary arteries. Abnormal responses of the coronary microcirculation to stress were identified in this population, and the concept of "microvascular angina" originated. Further evaluation, however, demonstrated that many of these patients did not have evidence of ischemia. In addition, a significant overlap with esophageal motility disorders was shown, and multiple sensitivities to otherwise nonirritating stimuli, whether in the heart or the esophagus, could be elicited in these patients. This finding led to the concept of abnormal visceral nociception, that is, the "sensitive heart" and the "tender esophagus," both the focus of ongoing clinical research.

Angina Pectoris↗

Microvascular angina in systemic hypertension: diagnosis and treatment with enalapril.

The causes of hypertensive microvascular ischemia are reviewed along with diagnostic factors. Stress/rest thallium-201 scintigraphy is shown to have a predictive value of 78% for a diagnosis of microvascular disease in hypertensive patients with exertional angina and left ventricular hypertrophy. Lack of isotope uptake at peak stress correlates well with the decrease in coronary flow reserve in ischemic segments, which is 2-3 times lower than in normal subjects. Treatment with enalapril produces regression of left ventricular hypertrophy, normalization of thallium-201 uptake, and an increase in exercise capacity in patients with microvascular angina.

Angina Pectoris↗

International study of coronary microvascular angina (iCorMicA): A registry-based diagnostic study and nested randomized trial.

BACKGROUND: Angina is a debilitating condition caused by coronary artery disease and microvascular dysfunction. Following coronary angiography angina and no obstructive coronary arteries is a common outcome, and women are disproportionately affected. The objectives are first, to assess causes of angina in patients undergoing invasive management; and second, to assess effects of coronary function test-guided management on clinical outcomes. METHODS: This is an international, multicenter, prospective, registry-based study and nested, randomized, controlled, triple-blind, and endpoint trial. Participants, community care providers, and outcomes assessors are masked. Consented participants enter the registry. Participants without obstructive coronary artery disease (luminal stenosis <50%, or fractional flow reserve >0.80) are eligible for randomization. Index of microcirculatory resistance (IMR; abnormal &#x2265;25) and coronary flow reserve (CFR; abnormal <2.0; gray zone 2.0-2.5) are measured by bolus thermodilution, and results are disclosed (intervention) or not (control group) to the attending cardiologist. RESULTS: The primary outcome of the registry is the Seattle Angina Questionnaire summary score at baseline described by coronary artery disease status. Secondary outcomes include the prevalence of obstructive coronary artery disease, patient reported outcome measures and clinical outcomes. The primary outcome of the randomized trial is the within-individual change in Seattle Angina Questionnaire summary score at 12-months from baseline. Secondary outcomes include safety, diagnostic accuracy, patient reported outcome measures for quality of life, physical and psychological function, cardiovascular risk, clinical outcomes, health economics and mechanistic biomarkers. The first patient was screened on December 18, 2020 and the last patient was enrolled on June 30, 2026. Forty sites were included in the United Kingdom (n = 35), Republic of Ireland (n = 2), Holland (n = 2), and Poland (n = 1). In total, 1,483 participants were enrolled into the registry of whom 1,047 were randomized and 386 were not randomized (registry-only). CONCLUSION: This international, registry-based clinical trial will provide novel evidence on the natural history of angina and stratified therapy for angina with no obstructive coronary arteries. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/study/NCT04674449. UNIQUE IDENTIFIER: NCT04674449.

Humans↗

Primary amyloidosis as a cause of microvascular angina and intermittent claudication.

Primary systemic amyloidosis or AL amyloidosis is a rare condition characterized by extracellular deposits of fibrils composed of fragments of immunoglobulin light chains. Widespread deposition of this amyloid in tissues interferes with their normal function and leads to multiple organ failure. Clinical manifestations are highly variable due to the wide range of organs involved. The heart is affected in 90% of cases; in 30% of these, cardiac dysfunction is the form of presentation and in 50% it is the cause of death. The commonest form of cardiovascular manifestation is congestive heart failure due to restrictive cardiomyopathy caused by extensive interstitial infiltration of amyloid into the myocardium. Occasionally, it can present as angina, due to infiltration of amyloid into the walls of small vessels. The authors describe the case of a patient in whom the disease presented simultaneously with heart failure and effort angina, as well as intermittent claudication.

Aged↗

[Syndrome X and microvascular angina].

The term X syndrome is used to indicate a group of patients who present anginous symptoms and ischemic-type electrocardiographic alterations which appear during exercise tolerance tests, dipiridamol tests or Holter's dynamic monitoring where coronary ultrasonography reveals no evident coronary lesions, vasospastic angina, arterial hypertension and/or diabetes mellitus, block of the left branch when resting or exercising, cardiomyopathy or valvulopathy. The highest incidence is in females with a mean age of around 50. A reduced reserve of coronary flow, highlighted both in response to vasodilatators or rapid stimulation and by positron emission tomography (PET), underlies this syndrome. It is thought to be caused by a dysfunction of the coronary microcirculation which consists in a deficit of the endothelium-dependent vasodilatory mechanisms, probably also owing to the accumulation of vasoconstrictive type substances, like endothelin-1. In addition to a dysfunction of the coronary microcirculation, one widely backed hypothesis concerns the existence of an altered perception of painful symptoms in patients with X syndrome: the anomalous constriction of prearteries might cause an increased release of adenosine, able to provoke angina despite the scarce signs of myocardial ischemia in terms of the metabolic or functional profile. From a therapeutic point of view, treatment of these patients is often ineffective: treatment should be based on the use of nitrates, calcium-antagonists or beta-blockers, if necessary moving on to other forms of therapy (aceinhibitors, xanthine methylate, estrogens, alphablockers, imipramine); the simultaneous use of tranquillizers may be useful in view of the anxious personality often characteristic of these patients.

Female↗

Small artery structural alterations of patients with microvascular angina (syndrome X).

1. There is increasing evidence that a substantial number of patients who suffer from angina have normal epicardial arteries (Syndrome X), and it has been suggested that these individuals have a generalized disorder of small vessels not confined to the intramyocardial vasculature. 2. Small arteries were therefore obtained from biopsies of skin and subcutaneous fat from nine normotensive patients with Syndrome X and nine matched control subjects. Vessels were dissected and mounted as ring preparations in a myograph for morphological and functional assessment. 3. Morphological measurements revealed a significant increase in media thickness/lumen diameter ratio in arteries from patients with Syndrome X. Contractile responses to U46619 were similar in arteries from patients and control subjects. Endothelium-dependent relaxation induced with acetylcholine and bradykinin was greater in arteries from patients although differences were not statistically significant. Endothelium-independent relaxation induced by forskolin and sodium nitroprusside was not different. 4. In conclusion, these data demonstrate that subcutaneous small arteries from patients with Syndrome X are characterized by increased media thickness/lumen diameter ratios, although contractile responses were normal. Additionally, endothelium-dependent relaxation was not impaired in arteries from these patients. Thus, no significant functional abnormalities were associated with the observed structural differences.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

Syndrome of diminished vasodilator reserve of the coronary microcirculation (microvascular angina or syndrome X): diagnosis by combined atrial pacing and thallium 201 imaging--a case report.

Patients with angina-like chest pain without evidence of epicardial coronary artery disease or coronary arterial vasospasm are becoming increasingly recognized. These are often related to noncardiac causes including esophageal, musculoskeletal, and hyperventilatory or panic states. However, recently a subgroup of such patients are being recognized as having true myocardial ischemia and chest pain on the basis of diminished coronary microvascular vasodilatory reserve (microvascular ischemia or Syndrome X). The authors describe such a patient who was found to have replication of anginal pain associated with a reversible ischemic defect on thallium 201 imaging during atrial pacing, suggesting ischemia in this myocardial segment. Resolution of angina and ST segment electrocardiographic changes of ischemia occurred with cessation of pacing. We believe this is the first report of a patient with this form of myocardial ischemia diagnosed by this method and should be considered in patients with anginal chest pain after significant coronary artery disease and coronary vasospasm have been excluded.

Angina Pectoris↗