Comparison of epicardial coronary artery tone and reactivity in Prinzmetal's variant angina and chronic stable angina pectoris

MINOCA: One Size Fits All? Probably Not—A Review of Etiology, Investigation, and Treatment

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of conditions that include both atherosclerotic (coronary plaque disruption) and non-atherosclerotic (spontaneous coronary artery dissection, coronary artery spasm, coronary artery embolism, coronary microvascular dysfunction, and supply–demand mismatch) causes resulting in myocardial damage that is not due to obstructive coronary artery disease. Failure to identify the underlying cause may result in inadequate and inappropriate therapy in these patients. The cornerstone of managing MINOCA patients is to identify the underlying mechanism to achieve the target treatment. Intravascular imaging is able to identify different morphologic features of coronary plaques, while cardiac magnetic resonance is the gold standard for detection of myocardial infarction in the setting of MINOCA. In this review, we summarize the relevant clinical issues, contemporary diagnosis, and treatment options of MINOCA.

Assessment of Vascular Dysfunction in Patients Without Obstructive Coronary Artery Disease: Why, How, and When

Ischemic heart disease secondary to coronary vascular dysfunction causes angina and impairs quality of life and prognosis. About one-half of patients with symptoms and signs of ischemia turn out not to have obstructive coronary artery disease, and coronary vascular dysfunction may be relevant. Adjunctive tests of coronary vasomotion include guidewire-based techniques with adenosine and reactivity testing, typically by intracoronary infusion of acetylcholine. The CorMicA (Coronary Microvascular Angina) trial provided evidence that routine management guided by an interventional diagnostic procedure and stratified therapy improves angina and quality of life in patients with angina but no obstructive coronary artery disease. In this paper, the COVADIS study group provide a comprehensive review of why, how, and when coronary vascular dysfunction should be assessed invasively. They discuss the rationale through a shared understanding of vascular pathophysiology and clinical evidence. They propose a consensus approach to how an interventional diagnostic procedure is performed with focus on practical aspects. Finally, the authors discuss the clinical scenarios in patients with stable and acute coronary syndromes in which measurement of coronary vascular function may be helpful for patient care.

Overview of the pharmacological spasm provocation test: Comparisons between acetylcholine and ergonovine

The spasm provocation tests of ergonovine and acetylcholine have been employed in the cardiac catheterization laboratory. Ergonovine acts through the serotogenic receptors, while acetylcholine acts through the muscarinic cholinergic receptors. Different mediators may have the potential to cause different coronary responses. However, there are few reports concerning the coronary response between ergonovine and acetylcholine in the same patients. Acetylcholine is supersensitive for females; spasm provoked by ergonovine is focal and proximal, whereas provoked spasm by acetylcholine is diffuse and distal. We should use both tests as supplementary in the clinic because ergonovine and acetylcholine have self-limitations to induce coronary spasms during daily life. The maximal pharmacological doses, administration methods, and the angiographical positive definition are remarkably different for each institution in the world. We recommend the pharmacological spasm provocation tests as Class I in the guidelines in patients with vasospastic angina throughout the world.

Coronary artery spasm: Current knowledge and residual uncertainties

Myocardial ischaemia results from a direct mismatch between oxygen supply and demand, commonly arising as a result of coronary atherosclerosis, microvascular dysfunction or acute thrombosis and luminal obstruction. However, transient ischaemia may also occur due to coronary spasm leading to acute and unexpected myocardial ischaemia without obvious visible coronary pathology. Aside from symptoms of chest pain, coronary spasm can cause infarction, LV impairment, promote life threatening arrhythmias and ultimately sudden cardiac death. While therapeutic options are available, controversies exist around diagnosis, pathology, management and prognosis. This review summarises some of the common questions in this area. In particular we explore and discuss the available evidence for the pharmacological treatment of coronary spasm, and strategies for identification and management of very high risk patients to try and reduce the incidence of sudden premature death.

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Myocardial ischaemia results from a mismatch between oxygen supply and demand.

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Spasm might lead to myocardial ischaemia without visible coronary pathology.

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Coronary spasm can cause infarction, LV impairment and sudden cardiac death.

Conformational change in coronary artery structure assessed by optical coherence tomography in patients with vasospastic angina

OBJECTIVES

The aim of this study was to investigate the conformational change of arterial structure in the vasospastic lesion with optical coherence tomography.

BACKGROUND

Coronary artery spasm plays an important role in the pathogenesis of ischemic heart diseases. The conformational change of each arterial layer during vasospasm has not been studied in detail.

METHODS

We assessed 19 coronary arteries (10 spasm and 9 nonspasm lesions) with optical coherence tomography during the provocation test for coronary spasm. An intimal bump was defined as 1 or more intimal projections into the lumen that disappeared after the administration of nitroglycerine (NTG). Intimal gathering was defined as a folding/gathering of the intima, resulting in multiple kinks in the luminal contour that resolved after the administration of NTG.

RESULTS

The spasm lesion more frequently showed an intimal bump at baseline and intimal gathering during spasm compared with the nonspasm lesion (spasm 80% vs. nonspasm 0%, p < 0.01, spasm 100% vs. nonspasm 0%, p < 0.01, respectively). The spasm lesion demonstrated a thicker maximum media thickness (spasm 0.24 ± 0.04 mm vs. nonspasm 0.12 ± 0.03 mm, p < 0.01) at baseline, whereas no differences were observed after the administration of NTG (spasm 0.13 ± 0.03 mm vs. nonspasm 0.13 ± 0.02 mm, p = 0.65).

CONCLUSIONS

Our results suggest that medial contraction occurs even in an asymptomatic state and facilitates the formation of an intimal bump in patients with vasospastic angina. Luminal narrowing during spasm is associated with intimal gathering without alteration of intimal area.

Variant angina associated with coronary artery endothelial dysfunction and myocardial bridge: a case report and review of the literature

The association of variant angina (VA) and myocardial bridges is a rare finding. We describe a case of VA with recurrent coronary spasm triggered by different stimuli at the site of a myocardial bridge. The interplay of endothelial dysfunction, coronary vasoconstriction and myocardial bridging was detected by intracoronary acetylcholine test and IVUS. We speculate that mechanical stimulation at the bridge site caused endothelial dysfunction and enhanced local susceptibility to vasoconstrictor stimuli. Variant angina should always be suspected in cases of ST-elevation acute coronary syndrome without any significant angiographic coronary stenosis.

A comparative study of eccentric and concentric coronary stenosis vasomotion in patients with Prinzmental's variant angina and patients with stable angina pectoris

BACKGROUND AND HYPOTHESIS

In patients with stable angina pectoris, eccentric stenoses have a greater potential for dynamic changes of caliber in response to vasoactive stimuli than concentric lesions. It is not known whether in patients with coronary artery spasm the degree of coronary vasoconstriction differs in eccentric versus concentric stenoses. Therefore, we examined the relationship between coronary stenosis morphology and the vasomotor response to vasoactive stimuli in patients with variant angina.

METHODS

Computerized quantitative angiography was used to measure minimum luminal diameter of eccentric and concentric stenoses before and after the administration of ergonovine and isosorbide dinitrate in 22 patients with Prinzmetal's variant angina and in 20 patients with chronic stable angina.

RESULTS

In patients with variant angina, mean stenosis diameter reduction with ergonovine was -0.85 +/- 0.38 and -1.12 +/- 0.69 mm in eccentric and concentric stenoses, respectively (p = NS). Isosorbide dinitrate promptly relieved spasm in all patients and increased the diameter of eccentric stenoses by 0.26 +/- 0.34 mm and that of concentric stenoses by 0.24 +/- 0.32 mm (p = NS). In patients with chronic stable angina, mean diameter reduction with ergonovine was -0.23 +/- 0.12 and -0.12 +/- 0.10 mm for eccentric and concentric stenoses, respectively (p < 0.05). Isosorbide dinitrate increased coronary diameter by 10% from baseline in 70% of eccentric and 38% of concentric stenoses (p < 0.01).

CONCLUSION

In patients with variant angina pectoris, eccentric and concentric spastic stenoses react similarly in response to vasoactive stimuli. In patients with chronic stable angina, eccentric stenoses are more likely to show vasomotor responses than concentric stenoses.

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.

Statin therapy in acute coronary syndromes: mechanistic insight into clinical benefit

Randomized trials have established that statin treatment reduces coronary events in primary prevention and in patients with stable coronary artery disease. In unstable coronary artery disease, however, the pathophysiological background is distinct, and the potential benefits of statin therapy have not been evaluated until recently. Data from animal models and clinical studies indicate that statin treatment can influence a spectrum of molecular and cellular mechanisms that are intimately related to the pathogenesis of acute coronary syndromes; these include the reduction of circulating levels of atherogenic lipoproteins (very low density lipoprotein, very low density lipoprotein remnants, intermediate density lipoprotein, and low density lipoprotein) and thus of arterial lipid deposition and the attenuation of inflammation, modulation of thrombogenesis and thrombolysis, improvement of endothelial dysfunction, and reduction of ischemia/reperfusion injury. Indeed, findings from prospective and observational studies have demonstrated that statin treatment significantly improves clinical outcome after acute coronary syndromes. Therefore, early initiation of statin therapy after an acute coronary event not only enhances adherence to treatment but also preempts the occurrence of new events. In this review, we discuss recent important developments in our knowledge of the clinical evidence of the beneficial effects of early statin therapy in acute coronary syndromes and the biological mechanisms that underlie them.

Evidence of partially preserved endothelial dilator function in diseased coronary arteries

OBJECTIVE

To examine the effects of substance P (endothelium dependent vasodilator) and glyceryl trinitrate (endothelium independent vasodilator) on epicardial coronary arteries in patients with normal coronary angiograms and patients with coronary artery disease.

DESIGN

Intracoronary infusions of normal saline, the receptor mediated nitric oxide stimulant substance P (5.6 and 27.8 pmol/min each for five minutes), and glyceryl trinitrate (250 microg bolus) were given in 24 patients with coronary artery disease and stable angina, and in nine patients with normal angiograms. The diameter of proximal and distal coronary segments was measured by computerised quantitative angiography

RESULTS

Proximal segments of patients with coronary artery disease dilated less than those of patients with normal angiograms in response to 27.8 pmol/min substance P (mean (SEM): 7.9 (1.3)% v 15 (2.3)% respectively, p < 0. 01). The proximal segments of diseased arteries also dilated less than those of "normal" arteries in response to glyceryl trinitrate (10.2 (1.6)% v 18.4 (2.9)%, respectively, p < 0.01). The responses of distal segments to substance P and glyceryl trinitrate were similar in the two patient groups. There were correlations (all p < 0.001) between the coronary diameter after substance P and after glyceryl trinitrate in normal proximal segments (r = 0.94) and normal distal segments (r = 0.64), in diseased proximal segments (r = 0.95) and diseased distal segments (r = 0.89), and for coronary stenoses (r = 0.93).

CONCLUSIONS

Proximal segments of patients with coronary disease dilated less than the proximal segments of "normal" patients in response to substance P and glyceryl trinitrate. The response to substance P is substantial and closely correlated with the response to glyceryl trinitrate in both "normal" patients and those with coronary disease. This suggests that although the proximal segments of diseased coronary arteries have a reduced capacity to dilate in response to direct stimulation of smooth muscle cell relaxation, they retain much of their endothelium dependent vasodilator function.

Racial heterogeneity in coronary artery vasomotor reactivity: differences between Japanese and Caucasian patients

Japanese investigators have provided a substantial contribution in the understanding of coronary vasomotor reactivity. On occasions, their findings have been at variance with those undertaken on caucasian patients, raising speculation that vasomotor differences between races may exist. In a comparative review of the published literature, we evaluated the vasoreactive differences among Japanese and caucasian patients with variant angina or myocardial infarction. In variant angina, Japanese patients appear to have diffusely hyperreactive coronary arteries compared with caucasian people, manifested by their segmental rather than focal spasm, hyperreactive nonspastic vessels and multivessel spasm. These differences may reflect the increased basal tone among Japanese variant angina patients and may relate to controversial differences in endothelial nitric oxide production or autonomic nervous system activity. Provocative vasomotor studies of Japanese patients with a recent myocardial infarction report a higher incidence of inducible spasm than caucasian studies, an observation recently supported by a controlled study. Furthermore, the hyperreactivity was diffuse, occurring in both non-infarct- and infarct-related vessels. These observations support the existence of racial coronary vasomotor reactivity differences but require confirmation in further prospectively conducted studies.

Plasma protein acute-phase response in unstable angina is not induced by ischemic injury

BACKGROUND

Elevated levels of C-reactive protein (CRP) are associated with an unfavorable clinical outcome in patients with unstable angina. To determine whether ischemia-reperfusion injury causes this acute-phase response, we studied the temporal relation between plasma levels of CRP and ischemic episodes in 48 patients with unstable angina and 20 control patients with active variant angina, in which severe myocardial ischemia is caused by occlusive coronary artery spasm.

METHODS AND RESULTS

Blood samples were taken on admission and subsequently at 24, 48, 72, and 96 hours. All patients underwent Holter monitoring for the first 24 hours and remained in the coronary care unit under ECG monitoring until completion of the study. On admission, CRP was significantly higher in unstable angina than in variant angina patients (P < .001). In unstable angina, 70 ischemic episodes (1.5 +/- 2 per patient) and in variant angina 192 ischemic episodes (9.6 +/- 10.7 per patient) were observed during Holter monitoring (P < .001), for a total ischemic burden of 14.8 +/- 30.2 and 44.4 +/- 57.2 minutes per patient, respectively (P < .001). The plasma concentration of CRP did not increase in either group during the 96 hours of study, even in patients who had episodes of ischemia lasting > 10 minutes.

CONCLUSIONS

The normal levels of CRP in variant angina, despite a significantly larger number of ischemic episodes and greater total ischemic burden, and the failure of CRP values to increase in unstable angina indicate that transient myocardial ischemia, within the range of duration observed, does not itself stimulate an appreciable acute-phase response.

Relation of basal coronary tone and vasospastic activity in patients with variant angina

OBJECTIVE

To examine the vasoconstrictor response to ergonovine and the vasodilator response to isosorbide dinitrate in spastic and non-spastic coronary segments from 31 patients undergoing serial angiographic follow up of variant angina.

METHODS

Coronary angiograms and ergonovine provocation tests were repeated at an interval of 45 (SD 15) months apart. While all 31 patients showed a positive response to ergonovine initially, vasospastic responsiveness persisted in only 16 patients at follow up (group 1) and not in the other 15 patients in whom symptoms of variant angina had resolved (group 2). Mean luminal diameter of 170 normal or near normal entire coronary segments (American Heart Association classification) were measured (a) at baseline, (b) after the administration of ergonovine, and (c) after the administration of isosorbide dinitrate, during both the initial and follow up angiograms using a computer based quantitative angiography analysis system (CAAS II).

RESULTS

In vasospastic patients (initial and follow up angiograms in group 1, and initial angiogram in group 2), basal tone was significantly higher in spastic segments compared to adjacent segments or segments in non-spastic vessels. The diagnostic sensitivity and specificity at 20% increase in basal coronary tone for the prediction of vasospasm were 77% and 73%, respectively.

CONCLUSIONS

Coronary artery tone may change in proportion to the activity of variant angina over several years. Contrary to some previous reports, the estimation of basal coronary tone may be useful in the assessment of vasospastic activity in patients with variant angina.

Rapid angiographic progression of coronary artery disease in patients with angina pectoris. The role of complex stenosis morphology

BACKGROUND

Rapid disease progression commonly underlies acute coronary events, and "complex" stenosis morphology may play a role in this phenomenon.

METHODS AND RESULTS

We studied the role of complex stenosis morphology in rapid disease progression in 94 consecutive patients awaiting routine coronary angioplasty. Coronary arteriography was repeated at 8 +/- 3 months' follow-up, immediately preceding angioplasty (68 patients) or after an acute coronary event (26 patients). Disease progression of 217 stenoses, of which 79 (36%) were "complex" and 138 (64%) were "smooth," was assessed by computerized angiography. At presentation, 63 patients had stable angina pectoris and 31 had unstable angina that settled rapidly with medical therapy. At follow-up, 23 patients (24%) had progression of preexisting stenoses and 71 (76%) had no progression. Patients with progression were younger (55 +/- 12 years) than those without (58 +/- 9 years) but did not differ with regard to risk factors, previous myocardial infarction, or severity and extent of coronary disease. Twenty-three lesions (11%) progressed, 15 to total occlusion (11 complex and 4 smooth; 65%). Progression occurred in 17 of the 79 complex stenoses (22%) and in 6 of the 138 smooth lesions (4%) (P = .002). Mean stenosis diameter reduction was also significantly greater in complex than in smooth lesions (11.6% versus 3.9% change; P < .001). Acute coronary events occurred in 57% of patients with progression compared with 18% of those without progression (P < .001) and were more frequent in patients who presented with unstable angina (P = .002).

CONCLUSIONS

Rapid stenosis progression is not uncommon, and complex stenoses are at risk more than smooth lesions.

Clinical factors and angiographic features associated with premature coronary artery disease

BACKGROUND

Clinical, angiographic, and biochemical features may differ in young patients with coronary heart disease compared with older patients.

METHODS

We compared clinical and angiographic characteristics in 100 male patients with clinical onset of disease at age < or = 45 years (group 1) with those of 100 older male patients (clinical onset of disease at > or = 60 years) (group 2). All patients had documented coronary artery disease. The two patient groups were compared in terms of the pattern of angina at disease onset, angiographic features, and coronary risk factors.

RESULTS

Seventy-six patients in group 1 and 49 patients in group 2 presented with acute coronary syndromes (unstable angina or myocardial infarction) at clinical disease onset (p < 0.001). Compared with patients in group 2, younger patients (group 1) showed a preponderance of single-vessel disease (54 vs 36%; p < 0.001) and complex stenosis morphologic features (59 vs 36%; p < 0.01). Family history of coronary artery disease (39 vs 11%; p < 0.001) and smoking (73 vs 46%; p < 0.001) were also more prevalent in younger patients. Mean plasma total cholesterol level was 6.4 +/- 1.3 mmol/L in group 1 and 6.1 +/- 1.2 mmol/L in group 2 (p = NS). Younger patients, however, had lower high-density lipoprotein (HDL) cholesterol (0.9 +/- 0.2 mmol/L and 1.1 +/- 0.4 mmol/L; p < 0.01) and higher plasma triglyceride levels compared with patients of group 2 (2.7 +/- 1.3 mmol/L vs 2.1 +/- 1.1 mmol/L; p < 0.001).

CONCLUSIONS

Patients with premature coronary disease referred to coronary angiography commonly have unheralded acute onset of symptoms, angiographically complex stenosis morphologic features, and less extensive coronary artery disease. In addition to previously identified risk factors such as family history and smoking, we observed that high plasma triglyceride and low HDL cholesterol levels are associated with premature coronary artery disease.

Evidence in support of the spasm of resistance vessel concept of ischemic heart disease: an update in 1993

The goal of this communication is to provide more evidence for the ischemic heart disease (IHD) component of the spasm of resistance vessel (S-RV) concept of IHD and other ischemic diseases. The S-RV concept of IHD is considered to be an alternate paradigm which challenges the accepted understanding of this disorder. The theory asserts that primary S-RV directly induces symptoms in IHD, and this position is in opposition to the accepted view that symptoms are induced directly by primary occlusions of epicardial arteries by coronary artery disease, spasm, and thromboses. The theory, if valid, should be useful in reducing the impact of IHD, as it generally is accepted that the correct appreciation of basic pathophysiological mechanisms helps ensure the most appropriate prevention and treatment of disease.

Correlation of basal coronary artery tone with constrictive response to ergonovine in patients with variant angina

OBJECTIVES

This study was conducted to examine whether basal coronary artery tone is elevated at the spastic site in patients with variant angina and to determine the significance of basal artery tone in predicting provocation of coronary artery spasm.

BACKGROUND

Previous data have been conflicting on whether basal coronary artery tone is elevated in patients with variant angina.

METHODS

We assessed basal coronary artery tone by obtaining the percent increase in coronary artery diameter induced by nitroglycerin in 20 patients with variant angina and 24 control subjects. We also examined the correlation between basal coronary artery tone and the constrictive response to ergonovine.

RESULTS

In the patients with variant angina in whom spasm was provoked by the lower doses (1 or 5 micrograms) of ergonovine, basal coronary artery tone was greater (p < 0.05) at the spastic site (54 +/- 15% or 36 +/- 16%, respectively) than at the nonspastic site (40 +/- 25% or 25 +/- 15%, respectively). Basal coronary tone at the nonspastic site in these patients was greater (p < 0.01) than that in control subjects (15 +/- 6%). In the patients with variant angina in whom spasm was provoked only by the higher doses (15 or 50 micrograms) of ergonovine, basal coronary artery tone was comparable at the spastic and nonspastic sites and was not different from that in control subjects. The diagnostic sensitivity and specificity of elevated basal coronary artery tone (> or = 40%) in predicting provocation of spasm were 26% and 98%, respectively.

CONCLUSIONS

These results indicate that elevated basal coronary artery tone may be useful in predicting provocation of coronary spasm, but the normal level of basal coronary artery tone does not exclude such provocation.

Comparison of coronary responses to intracoronary and intraaortic ergonovine and isosorbide dinitrate in patients with atypical chest pain

Fifty patients with atypical chest pain were studied to compare coronary responses to intracoronary and intraaortic ergonovine. The diameters of the proximal, middle (1) and (2) (proximal segments of segments 2 and 3 [AHA classification], respectively), and distal segments of the right coronary artery were measured before and after intracoronary ergonovine (4 micrograms/minute over 4 minutes) and isosorbide dinitrate (ISDN) (2 mg) in 24 patients, and before and after intraaortic ergonovine (0.2 mg) and ISDN (5 mg) in 26. Mean vasoconstriction by intracoronary and intraaortic ergonovine were 13 +/- 1.5% and 9 +/- 0.8%, respectively (p < 0.02). Irrespective of the methods of administration, the responses to ergonovine were similar in the 4 segments. Mean vasodilation by intracoronary and intraaortic ISDN, which were used to quantify the degree of basal coronary tone, were 25 +/- 2.2% and 27 +/- 1.5%, respectively (p = not significant [NS]). There were significant negative linear correlations between the responses to ergonovine and ISDN in the middle (2) (r = -0.51; p < 0.05) and distal (r = -0.53; p < 0.01) segments in patients with intracoronary injection, and the proximal (r = -0.41; p < 0.05), middle (1) (r = -0.66; p < 0.01) and middle (2) (r = -0.69; p < 0.01) segments in patients with intraaortic injection. These observations indicate that low-dose administration of intracoronary ergonovine produces sufficient coronary vasoconstriction, similar to or slightly greater than that of intraaortic ergonovine in patients with atypical chest pain, but basal coronary tone may influence the vasoreactivity to ergonovine.