Coronary arterial spasm and Prinzmetal's variant form of angina induced by hyperventilation and Tris-buffer infusion

Hyperventilation testing in the diagnosis of vasospastic angina: A clinical review and meta-analysis

BACKGROUND

Given the limited access to invasive vasospastic reactivity testing in Western Countries, there is a need to further develop alternative non-invasive diagnostic methods for vasospastic angina (VSA). Hyperventilation testing (HVT) is defined as a class IIa recommendation to diagnose VSA by the Japanese Society of Cardiology.

METHODS

In this systematic review and meta-analysis reported according to the PRISMA statement, we review the mechanisms, methods, modalities and diagnostic accuracy of non-invasive HVT for the diagnostic of VSA.

RESULTS

A total of 106 articles published between 1980 and 2022 about VSA and HVT were included in the systematic review, among which 16 were included in the meta-analysis for diagnostic accuracy. Twelve electrocardiogram-HVT studies including 804 patients showed a pooled sensitivity of 54% (95% confidence intervals [CI]; 30%-76%) and a pooled specificity of 99% (95% CI; 88%-100%). Four transthoracic echocardiography-HVT studies including 197 patients revealed a pooled sensitivity of 90% (95% CI; 82%-94%) and a pooled specificity of 98% (95% CI; 86%-100%). Six myocardial perfusion imaging-HVT studies including 112 patients yielded a pooled sensitivity of 95% (95% CI; 63%-100%) and a pooled specificity of 78% (95% CI; 19%-98%). Non-invasive HVT resulted in a low rate of adverse events, ventricular arrhythmias being the most frequently reported, and were resolved with the administration of nitroglycerin.

CONCLUSIONS

Non-invasive HVT offers a safe alternative with high diagnostic accuracy to diagnose VSA in patients with otherwise undiagnosed causes of chest pain.

Noninvasive evaluation of dynamic microvascular dysfunction in ischemia and no obstructive coronary artery disease patients with suspected vasospasm

INTRODUCTION

In patients with ischemia and no obstructive coronary artery disease (INOCA), a dynamic coronary microvascular dysfunction (CMD) is frequent but difficult to capture by noninvasive means.The aim of our study was to assess dynamic CMD in INOCA patients with stress echocardiography after vasoconstrictive and vasodilator stimuli.

METHODS

In this prospective single-center study, we have enrolled 40 INOCA patients (age 56.3 ± 13 years, 32 women). All participants underwent stress echocardiography with hyperventilation (HYP), followed by supine bicycle exercise (HYP+EXE) and adenosine (ADO). Stress echocardiography included an assessment of regional wall motion abnormality (RWMA) and coronary flow velocity (CFV) in the distal left anterior descending (LAD) coronary artery.

RESULTS

HYP induced a 30% increase in rate pressure product (rest = 10 244 ± 2353 vs. HYP = 13 214 ± 3266 mmHg x bpm, P  < 0.001) accompanied by a paradoxical reduction in CFV (HYP< rest) in 21 patients (52%). HYP alone was less effective than HYP+EXE in inducing anginal pain (6/40, 15% vs. 10/40, 25%, P  = 0.046), ST segment changes (6/40, 15% vs. 24/40, 60%, P  < 0.001), and RWMA (6/40, 15% vs. 13/40, 32.5%, P  = 0.008). ADO-induced vasodilation was preserved (≥2.0) in all patients.

CONCLUSION

In patients with INOCA, a coronary vasoconstriction after HYP is common, in absence of structural CMD detectable with ADO. HYP+EXE test represents a more powerful ischemia inducer than HYP alone. Stress echocardiography with LAD-CFV may allow the noninvasive assessment of dynamic and structural coronary microcirculation during stress.

Machine learning-based prediction model for myocardial ischemia under high altitude exposure: a cohort study

High altitude exposure increases the risk of myocardial ischemia (MI) and subsequent cardiovascular death. Machine learning techniques have been used to develop cardiovascular disease prediction models, but no reports exist for high altitude induced myocardial ischemia. Our objective was to establish a machine learning-based MI prediction model and identify key risk factors. Using a prospective cohort study, a predictive model was developed and validated for high-altitude MI. We consolidated the health examination and self-reported electronic questionnaire data (collected between January and June 2022 in 920th Joint Logistic Support Force Hospital of china) of soldiers undergoing high-altitude training, along with the health examination and second self-reported electronic questionnaire data (collected between December 2022 and January 2023) subsequent to their completion on the plateau, into a unified dataset. Participants were subsequently allocated to either the training or test dataset in a 3:1 ratio using random assignment. A predictive model based on clinical features, physical examination, and laboratory results was designed using the training dataset, and the model's performance was evaluated using the area under the receiver operating characteristic curve score (AUC) in the test dataset. Using the training dataset (n = 2141), we developed a myocardial ischemia prediction model with high accuracy (AUC = 0.86) when validated on the test dataset (n = 714). The model was based on five laboratory results: Eosinophils percentage (Eos.Per), Globulin (G), Ca, Glucose (GLU), and Aspartate aminotransferase (AST). Our concise and accurate high-altitude myocardial ischemia incidence prediction model, based on five laboratory results, may be used to identify risks in advance and help individuals and groups prepare before entering high-altitude areas. Further external validation, including female and different age groups, is necessary.

Life-threatening coronary vasospasm in patients with type 2 diabetes with SGLT2 inhibitor-induced euglycemic ketoacidosis: a report of two consecutive cases

Euglycemic diabetic ketoacidosis (eDKA) has emerged as an adverse event associated with sodium-glucose transporter-2 inhibitors (SGLT2i). We present two consecutive cases of SGLT2i-induced eDKA, both manifested as life-threatening coronary vasospastic angina (VSA). Case 1: A 64-year-old male overweight patient with type 2 diabetes (BMI 28.2 kg/m2), treated with dapagliflozin 5 mg daily for 6 months and a restricted diet for 2 months, experienced loss of consciousness following severe chest pain while driving, resulting in a traffic accident: plasma glucose, 163 mg/dL; urine ketones, (+++); bicarbonate (HCO3-), 13.2 mmol/L; and total ketone body, 1539 µmol/L. Coronary angiography (CAG) performed on day 5 revealed diffusely spastic coronary arteries with 90% stenosis in the right coronary artery, leading to the diagnosis of VSA in the presence of coronary atherosclerosis. Case 2: A 63-year-old male patient with type 2 diabetes (BMI 22.2 kg/m2) experienced severe chest discomfort and faintness following 2 months of chest pain while on dapagliflozin 10 mg daily for 1 year: plasma glucose, 112 mg/dL; urine ketones, (+++); HCO3-, 15.3 mmol/L; and total ketone body, 10,883 µmol/L. CAG performed on day 10 revealed no organic stenosis but diffusely spastic coronary arteries in response to coronary ergonovine infusion, confirming the diagnosis of VSA. SGLT2i has the potential to inhibit acetylcholine and butyrylcholine esterase activities, leading to reduced scavenging of acetylcholine and possible induction of coronary vasospasm. These cases highlight the association between life-threatening VSA and SGLT2i-induced eDKA.

A Practical Approach to Invasive Testing in Ischemia with No Obstructive Coronary Arteries (INOCA)

Up to 65% of women and approximately 30% of men have ischemia with no obstructive coronary artery disease (CAD; commonly known as INOCA) on invasive coronary angiography performed for stable angina. INOCA can be due to coronary microvascular dysfunction or coronary vasospasm. Despite the absence of obstructive CAD, those with INOCA have an increased risk of all-cause mortality and adverse outcomes, including recurrent angina and cardiovascular events. These patients often undergo repeat testing, including cardiac catheterization, resulting in lifetime healthcare costs that rival those for obstructive CAD. Patients with INOCA often remain undiagnosed and untreated. This review discusses the symptoms and prognosis of INOCA, offers a systematic approach to the diagnostic evaluation of these patients, and summarizes therapeutic management, including tailored therapy according to underlying pathophysiological mechanisms.

Role of acetylcholine spasm provocation test as a pathophysiological assessment in nonobstructive coronary artery disease

Coronary angiography (CAG) sometimes shows nonobstructive coronary arteries in patients with suspected angina or acute coronary syndrome (ACS). The high prevalence of nonobstructive coronary artery disease (CAD) in those patients has recently been reported not only in Japan but also in Western countries, and is clinically attracting attention. Coronary spasm is considered to be one of the leading causes of both suspected stable angina and ACS with nonobstructive coronary arteries. Coronary spasm could also be associated with left ventricular dysfunction leading to heart failure, which could be improved following the administration of calcium channel blockers. Because we rarely capture spontaneous attacks of coronary spasm with electrocardiograms or Holter recordings, an invasive diagnostic modality, acetylcholine (ACh) provocation test, can be useful in detecting coronary spasm during CAG. Furthermore, we can use the ACh-provocation test to identify high-risk patients with coronary spasm complicated with organic coronary stenosis, and then treat with intensive care. Nonobstructive CAD includes not only epicardial coronary spasm but also microvascular spasm or dysfunction that can be associated with recurrent anginal attacks and poor quality of life. ACh-provocation test could also be helpful for the assessment of microvascular spasm or dysfunction. We hope that cardiologists will increasingly perform ACh-provocation test to assess the pathophysiology of nonobstructive CAD.

A comprehensive clinical diagnostic score system for prediction of coronary artery spasm in patients with acute chest pain

Background

Currently, there is no validated multivariate model to predict probability of coronary artery spasm (CAS) in patients with acute chest pain.

Methods

A total of 976 consecutive patients with acute chest pain were enrolled. Patients were divided into two groups based on the presence of significant CAS. To adjust potential confounders, a multivariable analysis was performed and a clinical diagnostic score system for CAS was utilized for score derivation.

Results

Multivariable analysis model selected 6 predictors for CAS. The integer score was assigned to each predictors: angina at rest alone (10 points), positive of hyperventilation test (8 points), allergies (3 points), asthma, ST-segment elevation and myocardial bridge (2 points each). We showed that the clinical diagnostic score system had accuracy in predicting CAS, as measured by the area under the curve (AUC), which was 0.952–0.966. The cut-off baseline value for the clinical diagnostic score system was set to 11–12 points with specificity of 91.0–93.3% and sensitivity of 90.7–92.9%, respectively.

Conclusion

A clinical diagnostic score system was derived and validated as an accurate tool for estimating the pretest probability of CAS in patients with acute chest pain.

Coronary artery spasm - Clinical features, pathogenesis and treatment

Coronary artery spasm (CAS) plays an important role in the pathogenesis of ischemic heart disease, including angina pectoris, myocardial infarction, and sudden death, occurring most often from midnight to early morning. CAS is prevalent among East Asians and is associated with an aldehyde dehydrogenase 2 (ALDH2)-deficient genotype (ALDH2*2) and alcohol flushing, which is prevalent among East Asians but is virtually non-existent in other populations. ALDH2 eliminates not only acetaldehyde but also other toxic aldehydes from lipid peroxidation and tobacco smoking, thereby protecting tissues and cells from oxidative damage. Risk factors for CAS include smoking and genetic polymorphisms including those of ALDH2*2, endothelial NO synthase, paraoxonase I, and interleukin-6. Accordingly, oxidative stress, endothelial dysfunction, and low-grade chronic inflammation play an important role in the pathogenesis of CAS, leading to increased coronary smooth muscle Ca²⁺ sensitivity through RhoA/ROCK activation and resultant hypercontraction. Ca-channel blockers blocking the intracellular entry of Ca²⁺ are specifically effective for treatment for CAS.

Coronary spasm: It’s common, but it’s still unsolved

Coronary spasm is caused by a transient coronary narrowing due to the constriction of epicardial coronary artery, which leads to myocardial ischemia. More than 50 years have passed since the first recognition of coronary spasm, and many findings on coronary spasm have been reported. Coronary spasm has been considered as having pivotal roles in the cause of not only rest angina but also exertional angina, acute coronary syndrome, and heart failure. In addition, several new findings of the mechanism of coronary spasm have emerged recently. The diagnosis based mainly on coronary angiography and spasm provocation test and the mainstream treatment with a focus on a calcium-channel blocker have been established. At a glance, coronary spasm or vasospastic angina (VSA) has become a common disease. On the contrary, there are several uncertain or unsolved problems regarding coronary spasm, including the presence of medically refractory coronary spasm (intractable VSA), or an appropriate use of implantable cardioverter defibrillator in patients with cardiac arrest who have been confirmed as having coronary spasm. This editorial focused on coronary spasm, including recent topics and unsolved problems.

Coronary Artery Vasospasm

Coronary artery vasospasm (CVS) is an important mechanism of myocardial ischemia and produces any of the manifestations of coronary artery disease from silent myocardial ischemia, to effort-induced angina and variant angina, to acute coronary syndrome including myocardial infarction or sudden cardiac death. The pathogenesis, characteristic clinical features, diagnosis, and treatment of CVS are summarized. Emphasis is placed on correct diagnosis of CVS using pharmacological spasm provocation test, either during coronary angiography or with echocardiographic monitoring of ventricular wall motion. Current underutilization of pharmacologic provocative test at the time of coronary angiography cannot be justified, as there is no evidence supporting that the incidence of CVS is declining. Physicians' vigilance for objective documentation of CVS is necessary for appropriate management of patients with various clinical presentations of ischemic heart disease.

Clinical Applications of Breathing Regulation

Breathing training is widely used as an aid in reducing anxiety states, but several other applications also show promise. This article reviews evidence that normalizing breathing patterns may offer help in some cases of essential hypertension, angina, functional chest disorder, chronic obstructive pulmonary disease (COPD), and cardiac rehabilitation. Hyperventilation and hypo-ventilation, inhibited breathing, and breath suspension are all deviations from an optimal breathing pattern in which breathing volume is closely matched to metabolic needs. Such disordered breathing has varying effects on acid/base balance, arterial diameter, and sodium retention by the kidneys. Therefore, a chronic breathing imbalance can contribute to pathophysiology, which may be remediable to an extent by altering habitual breathing patterns.

Approximately half of patients with coronary spastic angina had pathologic exercise tests

OBJECTIVES

We examined the clinical usefulness of treadmill exercise tests (TETs) in diagnosing coronary spastic angina (CSA).

METHODS

We performed the TETs and 24-h Holter monitoring in 300 CSA patients consisting of 152 patients with rest angina, 77 patients with effort angina, and 71 patients with rest and effort angina. Organic stenosis (>75%) was observed in 44 patients. Multiple spasms were recognized in 204 patients (68%).

RESULTS

Positive TETs were recognized in 113 patients (38%) and borderline was observed in 30 patients (10%). Positive response was significantly higher in patients with organic stenosis than those without fixed stenosis (63.6% vs. 33.2%, p<0.001). Moreover, ST elevation was more frequent in patients with organic stenosis than those without fixed stenosis (27.3% vs. 1.2%, p<0.001). Positive response in patients with effort angina (46.8%) was higher than those in patients with rest angina (33.6%) and rest and effort angina (36.6%), but not significant. Positive response was not different between single spasm and multiple spasms. In all 300 patients, ST segment elevation was observed in only four patients (1.3%) on the 24-h Holter monitoring.

CONCLUSIONS

TET was useful in documenting ischemia in patients with CSA. More than a third of patients with CSA had positive TETs. Moreover, we obtained the pathologic TET response in approximately half of patients with CSA.

Coronary artery spasm following off-pump coronary artery bypass surgery

Coronary artery spasm after coronary artery bypass surgery may result in life-threatening arrhythmias, circulatory collapse, or death. We report two cases of coronary artery spasm after coronary artery bypass surgery, one of which developed ventricular fibrillation requiring extracorporeal membrane oxygenation support. Both patients were discharged in good condition and are currently followed as outpatients. Unexpected sudden hemodynamic compromise could be due to coronary vasospasm, and this should be considered as one of the possible differential diagnoses. We were able to prevent the lethal consequences seen with coronary artery spasm by early diagnosis and management.

Spasm provocation tests performed under medical therapy: a new approach for treating patients with refractory coronary spastic angina on emergency admission

Objective There are no objective methods for evaluating the severity of vasospasms in patients with refractory coronary spastic angina (R-CSA) under adequate medical therapy. We examined whether spasm provocation tests performed under adequate medication are useful for evaluating the severity of disease in R-CSA patients on emergency admission. Methods and Results We performed spasm provocation tests before and after the administration of medical therapy in eight R-CSA patients, including one ventricular fibrillation survivor (VF-S) and seven patients with unstable angina (UAP) on emergency readmission. We also performed these tests only after medical therapy on urgent admission in four R-CSA patients, including two patients with UAP, one patient with VF-S and one patient with acute coronary syndrome. All 12 R-CSA patients had been medicated with ≥ 2 vasodilator drugs. Positive coronary spasms were defined as >99% transient narrowing. The coronary artery spasms disappeared in three patients under medication, and mitigation of vasospasticity was observed in three patients. In these six cases we continued the same medications. Meanwhile in two patients, we recommended a consultation for psychosomatic medicine. In contrast, the remaining six R-CSA patients exhibited higher levels of vasospasticity, irrespective of the administration of aggressive medical therapy, in which the doses of vasoactive drugs were increased in order to suppress coronary artery spasms. Conclusion In some R-CSA patients on emergency admission, performing spasm provocation tests under medical therapy is useful for determining the subsequent treatment strategy. Therefore, this test may become a new tool in the treatment of R-CSA.

Evaluation and treatment of respiratory alkalosis

Respiratory alkalosis is the most frequent acid-base disturbance encountered in clinical practice. This is particularly true in critically ill patients, for whom the degree of hypocapnia directly correlates with adverse outcomes. Although this acid-base disturbance often is considered benign, evidence suggests that the alkalemia of primary hypocapnia can cause clinically significant decreases in tissue oxygen delivery. Mild respiratory alkalosis often serves as a marker of an underlying disease and may not require therapeutic intervention. In contrast, severe respiratory alkalosis should be approached with a sense of urgency and be aggressively corrected.

Role of calcium-activated potassium channels in the genesis of 3,4-diaminopyridine-induced periodic contractions in isolated canine coronary artery smooth muscles

We found that 3,4-diaminopyridine (3,4-DAP), a voltage-gated potassium channel (K(V)) inhibitor, elicits pH-sensitive periodic contractions (PCs) of coronary smooth muscles. Underlying mechanisms of PCs, however, remained to be elucidated. The present study was performed to examine the roles of ion channels in the genesis of PCs. To determine the electromechanical changes of smooth muscles, isolated coronary arterial rings from beagles were suspended in organ chambers filled with Krebs-Henseleit solution, and 10(-2) M 3,4-DAP was added to elicit PCs. 3,4-DAP caused periodic spike-and-plateau depolarization accompanied by contraction. PCs were not produced when the CaCl(2) concentration in the chamber was ≤ 0.3 × 10(-3) or ≥ 10(-2) M. PCs were eliminated by a CaCl(2) concentration ≥ 5 × 10(-3) M or by lowering pH below 7.20 with HCl and recovered by the addition of iberiotoxin or charybdotoxin, which inhibit large-conductance calcium-activated potassium channels (K(Ca)), or by elevating pH above 7.35 with NaOH. PCs, as well as the spike-and-plateau depolarization, were eliminated by nifedipine, which inhibits L-type voltage-gated calcium channels (Ca(V)). Influx of Ca(2+) through L-type Ca(V), which was opened because closing of K(Ca), secondary to 3,4-DAP-induced closing of K(V), resulted in contraction; the intracellular Ca(2+) increased by this influx opened K(Ca), leading to closure of Ca(V) and consequent cessation of Ca(2+) influx with resultant relaxation. These processes were repeated spontaneously to cause PCs. H(+) and OH(-) were considered to act as the opener and closer of K(Ca), respectively.

Disruption of coronary vasomotor function: the coronary spasm syndrome

Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically as a coronary syndrome and plays an important role in the genesis of myocardial ischemia. Over the past half century, coronary angiography allowed the in vivo demonstration of spasm in patients who fit the initial clinical description of the condition as reported by Prinzmetal et al. Several clinical, basic, and more recently, genetic studies have provided insight into the pathogenesis, manifestations, and therapy of this condition. It is not uncommonly encountered in patients with coronary syndromes and absence of clearly pathologic lesions on angiography. Provocation tests utilizing pharmacologic and nonpharmacologic stimuli combined with imaging (echocardiography or coronary angiography) can help make the correct diagnosis. The use of calcium channel blockers and long-acting nitrates is currently considered standard of care and the overall prognosis appears to be good. The recent discovery of genetic abnormalities predisposing to abnormal spasm of the coronaries has stimulated interest in the development of targeted therapies for the management of this condition.

Exercised-Induced Coronary Spasm in Near Normal Coronary Arteries

In contrast to effort-induced symptoms in obstructive coronary disease, spasm in normal coronary arteries is characterized by angina at rest. We describe a 44-year-old patient with minor coronary plaques and pure exercised-induced coronary spasm. The case questions the differential pathogenic considerations of variant of the variant as opposed to Prinzmetal's variant angina.

Vasospastic angina: control of disease activity and efficacy of drug treatment using the prolonged hyperventilation test

Sixteen consecutive patients with vasospastic angina underwent a control provocation test in the coronary care unit or the cardiac catheterization laboratory in order to evaluate the disease activity and the efficacy of long-term calcium antagonist treatment. In patients without angina at rest, the prolonged hyperventilation test was negative in 10/10 patients on calcium antagonist treatment (group A + B) and in 4/5 patients without medication (group C). The test was positive in 1/1 patient with angina at rest without medication (group D). However, the test provoked vasospastic angina in 1/5 patients who were asymptomatic without medication. In both the latter patients the prolonged hyperventilation test became negative after the restart of calcium antagonist treatment. During a mean follow-up period of 18 months (range 16-19) after the control hyperventilation test, no relapse of angina at rest, arrhythmias, syncopes, deaths or myocardial infarctions were registered. Thus, a negative test is compatible with low disease activity and/or efficacy of calcium antagonist treatment. Further, the test may reveal a subclinical tendency to coronary artery spasm.

Prinzmetal's variant angina)(PVA). Circadian variation in response to hyperventilation

The study reports on the outcome of hyperventilation tests in a 57-year-old male with Prinzmetal's variant angina, formerly often complicated by ventricular fibrillation. It was found that hyperventilation for a period of 6 min after a delay of 4 to 6 min was followed by the development of ST-elevation and pain, but only when the test was performed in the morning, whereas the outcome of tests performed later in the day were negative. Pretreatment with calcium blockers, nifedipine or verapamil proved effective in preventing the anginal response to the test, also when it was performed in the morning. It is concluded that hyperventilation performed in the early morning, but not later in the day, may prove to be an effective and safe procedure for provoking Prinzmetal's variant angina, and that hyperventilation may be useful in the evaluation of the efficacy of drug therapy.

Vasospastic ischaemia induced by the hyperventilation test in patients with a negative response to ergometrine

We present the case histories of two patients with angina pectoris who developed coronary artery spasm in response to provocation with prolonged hyperventilation (verified by ST segment elevation in both and coronary angiography in one) despite a negative ECG response to intravenous injection of 0.4 mg ergometrine. This new observation, which is in conflict with recent publications stating that ergot provocation is more sensitive than hyperventilation, suggests that in some patients diagnostic provocation with hyperventilation may be an alternative to the widely used ergot provocation.

Exercise stress testing in angina patients with positive response to hyperventilation testing: influence of the coronary artery tone

We studied the exercise stress test and the coronary artery tone in two groups of angina patients with comparable coronary atherosclerosis. Group I (20 males and 5 females, mean age 53.5 years) with a positive, and group II (22 males and 3 females, mean age 52.5 years) with a negative response to the hyperventilation test (HVT). A positive exercise stress test (ST depression greater than or equal to 1 mm) was found in 24 patients in group I vs. 15 in group II (p less than 0.01), despite a lower maximal rate pressure product (198 +/- 11.2 vs. 236 +/- 10.1, p less than 0.05) and maximal work load (110 W +/- 7.1 vs. 136 +/- 7.4 W, p less than 0.02) in group I. A high coronary artery tone (dilatation (DIL%) of the coronary arteries after nitroglycerin greater than or equal to 10%) was found in 18 patients in group I and in 4 in group II (p less than 0.01). DIL% was 22.6 +/- 3.8 vs. 5.8 +/- 1.4 in groups I and II, respectively (p less than 0.005). DIL% was significantly related to persistence of ST depression after exercise (r = 0.36, p less than 0.05), and 21 of 22 patients with high tone had a positive exercise stress test vs. 18 of 28 with low tone (p less than 0.05). These findings suggest that the coronary artery tone influences the response to exercise in some patients with angina. Since the patients in group I were identified by HVT, our results underline the clinical relevance of this test.

Pathogenetic mechanisms of coronary vasospasm

Coronary vasospasm plays a role in several manifestations of coronary heart disease, though its causes still remain to be established. Among suggestions made to account for it are normal increases in vasomotor tone, particularly in stenosed arteries, and local vascular hypersensitivity reactions. Stimuli known to precipitate spasm are discussed, particularly the role of the sympathetic nervous system and the possible involvement of platelet aggregation. Coronary vasospasm is stimulated by a number of different triggering mechanisms which vary between patients and even within patients at different times. However, it is concluded that vasospasm is the result of an interaction between hypersensitive vascular smooth muscle and a number of specific constrictor stimuli.

Role of coronary vasoconstriction in ischemic heart disease and search for novel therapeutic targets

Atherothrombosis has long been recognized as an important mechanism of cardiac events in ischemic heart disease, and large multicenter clinical studies have shown the benefit of antiplatelet agents, statins, beta-blockers and angiotensin converting enzyme inhibitors in preventing these events. However, more recent studies have been less successful at showing incremental gains in targeting these mechanisms, suggesting that the limits of this strategy have been exploited. Coronary vasoconstriction is another important mechanism in ischemic heart disease but has received little attention and yet is a potential therapeutic target. In the current review, the reasons why coronary vasconstriction has received insufficient consideration are explored. In particular, we need to change our approach from lumping heterogeneous clinical entities together to focusing on clinically-discrete homogeneous groups with a common mechanism and thus therapeutic target. The role of coronary vasoconstriction is examined in the various ischemic syndromes (variant angina, chronic stable angina, acute coronary syndromes and syndrome X) and the underlying mechanisms discussed. Finally, in order to advance studies in this field, an innovative research strategy is proposed, including: (1) selection of paradigmatic cases for the various ischemic syndromes; (2) candidate therapeutic targets; and (3) approaches in assessing the clinical efficacy of these potential therapies.

Myocardial ischemia due to vasospasm of small coronary arteries detected by methylergometrine maleate stress myocardial scintigraphy

BACKGROUND

Recently, several case reports have implicated vasospasm of small coronary arteries in vasospastic angina pectoris. Vasospasm of small coronary arteries was also considered from angiographic findings in patients with atypical chest pain. In Syrian hamster, vasospasm in small coronary arteries was considered to be the cause of dilated cardiomyopathy.

HYPOTHESIS

This study was undertaken to determine whether vasospasm in small coronary arteries can be induced by methylergometrine maleate stress thallium-201 (201Tl) myocardial scintigraphy.

METHODS

Twenty-five patients with chest pain, all of whom had intact coronary arteries, were studied. After intracoronary methylergometrine maleate injection, coronary arteriograms also looked normal in all cases. Thallium-201 myocardial scintigraphy was carried out immediately after intracoronary methylergometrine maleate injection in four patients with chest pain. In the remaining 21 patients with chest pain, methylergometrine maleate was given intravenously within up to 2 weeks before 201Tl myocardial scintigraphy.

RESULTS

In the intracoronary injection study, one patient had chest discomfort after methylergometrine maleate injection, and ST-segment elevation was observed on electrocardiogram (ECG). Of the 21 patients with chest pain, 11 patients felt angina-like chest pain after intravenous injection of methylergometrine maleate, but their ECGs showed no ischemic changes. Stress 201Tl myocardial scintigrams showed methylergometrine maleate-induced perfusion defects with complete redistribution in 3 of 4 patients in the intracoronary injection study and in 12 of 21 patients in the intravenous injection study. These findings suggest that vasospasm in small coronary arteries caused myocardial ischemia in 15 of 25 patients (60%) with chest pain.

CONCLUSION

Vasospasm in small coronary arteries may be involved in the myocardial ischemia of some patients with chest pain who do not show any large coronary artery vasospasm.

Coronary artery spasm--clinical features, diagnosis, pathogenesis, and treatment

Coronary (artery) spasm plays an important role in the pathogenesis of ischemic heart disease, including stable angina, unstable angina, myocardial infarction, and sudden death. The prevalence of coronary spasm differs among populations, is higher in Japan and Korea than in the Western countries probably due to genetic as well as environmental factors. Coronary spasm occurs most often from midnight to early morning and is usually not induced by exercise in the daytime. The attacks of coronary spasm are associated with either ST segment elevation or depression, or negative U wave on ECG. Patients with multi-vessel coronary spasm may suffer from lethal arrhythmia, including advanced AV block, ventricular tachycardia or fibrillation, or even sudden death, and they are often resistant to conventional medical therapy including Ca-channel blockers (CCBs). Endothelial nitric oxide (NO) activity is reduced and markers of oxidative stress are elevated in patients with coronary spasm. Thrombogenesis is enhanced and plasma levels of hsCRP and P-selection are elevated in patients with coronary spasm. Thus, patients with coronary spasm have endothelial dysfunction and are suffering from a low-grade chronic inflammation. Polymorphisms of endothelial NO synthase, smoking, and low-grade inflammation are the most important risk factors for coronary spasm. Coronary spasm is a hyper-contraction of coronary smooth muscle triggered by an increase of intracellular Ca2+ in the presence of an increased Ca2+ sensitivity. It has been shown that RhoA/ROCK pathway is involved in Ca2+ sensitivity and that the reduced endothelial NO activity results in increased Ca2+ sensitivity through enhanced RhoA/ROCK pathway. Accordingly, it is possible that in addition to CCBs, RhoA/ROCK pathway blockers may prove to be useful for the treatment of coronary spasm.

Airway hyperresponsiveness in patients with coronary spastic angina: relationship between coronary spasticity and airway responsiveness

BACKGROUND

Several reports have suggested a possible link between bronchial asthma and coronary spasm, but the possibility of a relationship in coronary spastic angina (CSA) has not been clarified.

METHODS AND RESULTS

Airway responsiveness to methacholine and coronary spasticity to acetylcholine were examined in 42 patients with CSA and 36 patients with chest pain syndrome (CP). Furthermore, 18 control subjects were examined and their airway responsiveness compared with that of the CSA and CP patients. The incidence of airway hyperresponsiveness was significantly higher in the CSA group (74%) than in the CP (19%) and control (17%) groups (p<0.0001). The geometric mean of the log minimum dose (Dmin), defined as the cumulative dose at the point at which respiratory conductance began to decrease, was significantly lower in the CSA group (0.75 log units) than in the CP (1.20 log units) and control (1.38 log units) groups (p=0.004).

CONCLUSION

These results demonstrate that acetylcholine-induced coronary spasticity is significantly related to methacholine-induced airway responsiveness in patients with CSA. A generalized hyperresponsiveness of the vascular and nonvascular smooth muscles, including that through cholinergic mechanisms, may exist in patients with CSA.

Need for documentation of guidelines for coronary artery spasm: an investigation by questionnaire in Japan

BACKGROUND

Because there are no guidelines concerning coronary spasm in Japan, the present study examined the current status of the spasm provocation test.

METHODS AND RESULTS

Questionnaires concerning the number of cases of coronary angiography, percutaneous coronary intervention, and invasive/non-invasive spasm provocation tests over 3 years (2001-2003) and the status of spasm provocation tests were sent to members of the Japanese Circulation Society in 120 cardiology hospitals in the Chugoku and Shikoku areas. Completed surveys were returned from 45 hospitals, giving a collection rate of 38%. As a spasm provocation agent, acetylcholine tests were performed in 29 hospitals, and ergonovine tests in 18 hospitals. Non-invasive spasm provocation tests were performed in only 9 hospitals (20%). In total, 5,267 patients underwent acetylcholine spasm provocation test (2,387 patients) or ergonovine spasm provocation test (2,880 patients) and vasospastic angina was diagnosed in 1,663 (2.4%) patients. Invasive spasm provocation tests were performed in 7.8% of patients with diagnostic catheterization and the spasm-positive rate was 31.6%. The difference among hospitals concerning the number of invasive spasm provocation tests was remarkable, and the angiographic spasm-positive standard and acetylcholine/ergonovine dose varied among the hospitals.

CONCLUSIONS

Guidelines on coronary spasm in Japan are essential to overcome the current differences between institutions.

Does panic disorder increase the risk of coronary heart disease? A cohort study of a national managed care database

OBJECTIVE

The association between panic disorder (PD) and coronary heart disease (CHD) was examined in a large national managed care database.

METHODS

The Integrated Health Care Information Services managed care database is a fully de-identified, Health Insurance Portability and Accountability Act-compliant database and includes complete medical history for more than 17 million managed care lives; data from more than 30 United States health plans covering 7 census regions and from patient demographics, including morbidity, age, and gender. A cohort study was designed with a total of 39,920 PD patients and an equal number of patients without PD. The Cox proportional hazards regression models were used to assess the risk of CHD adjusted for age at entry into the cohort, tobacco use, obesity, depression, and use of medications including angiotensin converting enzyme inhibitors, beta blockers, and statins.

RESULTS

Patients with PD were observed to have nearly a 2-fold increased risk for CHD (HR = 1.87, 95% CI = 1.80-1.91) after adjusting for these factors. There was some evidence of a possible trend toward increased risk in a subgroup of patients diagnosed with depression. After controlling for the aforementioned covariates and comparing these patients with those who did not have a diagnosis of depression, it was noted that patients with a comorbid diagnosis of depression were almost 3 times more likely to develop CHD (HR = 2.60, 95% CI = 2.30-3.01).

CONCLUSIONS

The risk of CHD associated with a diagnosis of PD suggests the need for cardiologists and internists to monitor panic disorder to ensure a reduction in the risk of CHD.

Recurrent ST-segment elevations in a patient without significant coronary disease

We report a case of recurrent ST-segment elevations totaling 7 times over 3 hours during subtotal gastrectomy and the early postoperative period in a patient with no history of coronary artery disease. Possible contributing factors include cold stimulus, epidural anesthesia, and inadequate depth of anesthesia. The first episode almost resulted in cardiac arrest and was treated with intravenous epinephrine. The second episode was associated with ventricular fibrillation, which was treated with defibrillation and intravenous verapamil. The third to the seventh episodes were successfully treated with intravenous nitrate. The electrocardiographic changes and postoperative coronary angiography were consistent with a clinical diagnosis of coronary artery spasm. This case suggests that coronary artery spasm is capable of occurring repeatedly in a cyclic pattern during perioperative periods.

Clinical impact of selective spasm provocation tests: comparisons between acetylcholine and ergonovine in 1508 examinations

BACKGROUND

There are few reports regarding the concordance of coronary arterial response between acetylcholine (ACh) and ergonovine (ER) spasm provocation tests.

OBJECTIVES

We attempted to perform selective spasm provocation tests to examine the incidence of provoked spasm in patients who had undergone first coronary angiography as much as possible and we compared the coronary arterial response and clinical usefulness between selective intracoronary injection of ACh and intracoronary administration of ER.

METHODS

We performed 1508 selective spasm provocation tests, consisting of 873 ACh tests and 635 ER tests, from 1991 to 2002. We examined the frequency of provoked spasms of each agent retrospectively. ACh was injected in incremental doses of 20, 50 and 80 microg into the right coronary artery and 20, 50 and 100 microg into the left coronary artery. ER was administered as 10 microg/min over 4 min for a maximal dose of 40 microg in the right coronary artery and as 16 microg/min over 4 min for a total dose of 64 microg in the left coronary artery. Coronary spasm was defined as transient >99% luminal narrowing.

RESULTS

Intracoronary ACh provoked spasms in 36.0% of patients and intracoronary ER induced spasms in 29.8% of patients. In patients with ischemic heart disease, the incidence of provoked spasms was not different between ACh tests (50.9%) and ER tests (43.8%). In contrast, the frequency of provoked spasms with ACh tests was significantly higher than that with ER tests (11.0% compared with 6.4%, P<0.05) in patients without ischemic heart disease. Moreover, ACh provoked more spasms in patients without fixed stenosis than ER (36.2% compared with 25.5%, P<0.01) and multiple spasms were frequently observed when performing ACh tests (40.0% compared with 27.0%, P<0.01). Major complications were observed in 1.4% of patients with ACh tests and in 0.2% of patients with ER tests. The need for intracoronary administration of isosorbide dinitrate to relieve coronary spasms during ER testing before performing another coronary artery test was more frequently observed in ACh tests (5.04% compared with 1.49%, P<0.01). However, no serious irreversible complications, such as death or acute myocardial infarction, were observed in this study. There was a significant difference in sex, history of smoking and hyperlipidemia between patients with and without spasms for both tests, whereas no difference in age or hypertension was observed in either test.

CONCLUSION

Thus, both selective ACh and ER tests were useful as spasm provocation tests.

Is there a role for provocation testing to diagnose coronary artery spasm?

Spontaneous coronary artery spasm is an important cause of morbidity both in patients with coronary artery disease and in those with variant angina. A number of pharmacological agents have been identified which can provoke coronary artery spasm in susceptible patients. The role of provocation testing in the clinical diagnosis of coronary spasm is controversial. This is reflected by variations in the clinical use of provocation testing between specialist cardiac centres. Provocation testing appears to be a sensitive method of identifying patients with variant angina and active disease but such patients can often be diagnosed clinically. The specificity is less clear. There is little evidence that altering patient therapy on the basis of a positive test modifies prognosis. There may be a role for provocation testing in rare patients with refractory disease to identify a target site for coronary stenting. A more widespread use of these tests in patients with undiagnosed chest pain syndromes would not currently be recommended.

Efficacy of Calcium Channel Blocker in the Secondary Prevention of Myocardial Infarction-Retrospective Analysis of the 10-Year Prognosis of Coronary Thrombolysis-Treated Patients-

BACKGROUND

Calcium channel blockers (CCBs) may have a positive influence on the long-term prognosis of Japanese patients with ischemic heart disease.

METHODS AND RESULTS

The effect of nifedipine-retard (NR) (n=202) compared with that of non-CCB treatment (n=92) on the secondary prevention of myocardial infarction (MI) was retrospectively investigated in patients who had survived acute MI between 1987 and 1996. The primary endpoint was the occurrence of cardiac death or non-fatal MI. The median follow-up was 6.3+/-2.4 years. The incidence of cardiac events was 8.9% in the NR group and 14.1% in the non-CCBs group (p=0.14, odds ratio (OR): 0.584, 95% confidence interval (CI): 0.286-1,193). However, subanalysis revealed that NR significantly reduced the incidence of cardiac events in patients aged less than 55 years (4.2 vs 18.2%, p=0.016, OR: 0.180, 95%CI: 0.045-0.721) and those who did not smoke (8.6 vs 16.4%, p=0.048, OR: 0.462, 95%CI: 0.203-0.999).

CONCLUSION

Although this was a retrospective analysis, it showed that NR did not cause an increase in the incidence of cardiac events in post-MI patients; it even prevented cardiac events, especially in those who were less than 55 years of age and in non-smokers, suggesting the potential usefulness of CCBs in the secondary prevention of MI in Japan.

New protocol to detect coronary spastic angina without fixed stenosis

A new combined test, accelerated exercise following mild hyperventilation (HV), was examined to determine whether it is effective at detecting a positive response in patients with pharmacologically-induced coronary vasospasm and near normal coronary arteries. Fifty-eight consecutive patients who underwent both triple non-invasive spasm provocation tests and diagnostic coronary angiography were enrolled. They all had pharmacologically-induced coronary vasospasms and no significant organic stenosis. In these patients, an HV test was performed first, followed by a treadmill exercise test (TET), and finally the new combined test under no medication within 3 days. Of the 58 patients, positive responses were observed in 9 patients to the HV, in 15 to the TET, and in 35 to the newly combined test. The remaining 21 patients had negative responses although the triple sequential tests were perfomed. Thus, the sensitivities of the HV test, TET, and newly combined test were 16% (9/58), 26% (15/58), and 63% (35/56), respectively. Forty-six subjects with near normal coronary arteries and no ACh-provoked spasm served as controls. None of these subjects had positive responses to any of these three tests, and thus their specificity was all 100%. No serious or irreversible complications were seen in this study. We recommend this newly-combined protocol for the induction of coronary artery spasm in patients with vasospastic angina pectoris and without significant stenosis as a diagnostic tool.