Intravascular ultrasound findings of negative arterial remodeling at sites of focal coronary spasm in patients with vasospastic angina

Ultrastructural changes of vascular smooth muscle cells and resistance to vasospasm treatment in femoral arteries of an arteriosclerotic rat model

The objective of this study was to establish an animal model of arteriosclerosis for assessing vasospasm and to investigate the relationship between arteriosclerosis and vasospasm. Twelve-week-old male Sprague-Dawley rats were fed a diet supplemented with adenine and vitamin D (adenine/vitD). Body weight, blood, and femoral artery histopathology were assessed at 2, 4, and 6 weeks. Change in the femoral artery was examined by transmission electron microscope (TEM). Vasospasm was induced by administering epinephrine extravascularly into the femoral artery and released by the treatment with lidocaine as a vasodilator. During this period, the extravascular diameter and blood flow were measured. The rats in the adenine/vitD group developed renal dysfunction, uremia, hyperphosphatemia, and elevated serum alkaline phosphatase. Histological and TEM analyses of the femoral arteries in the treated rats revealed the degeneration of elastic fibers and extensive calcification of the tunica media and intima. Vascular smooth muscles were degenerated and osteoblasts were developed, resulting in calcified arteriosclerosis. Vasospasm in arteriosclerotic arteries was detected; however, vasodilation as well as an increase in the blood flow was not observed. This study revealed the development of vasospasm in the femoral arteries of the arteriosclerotic rats and, a conventional vasodilator did not release the vasospasm.

Catheter-induced vasospasm of the anatomically normal right coronary artery in a patient with Non-ST Elevation Myocardial Infarction and obstructive disease in the left anterior descending artery; A challenging case report and review of the literature: Running title: Catheter-induced RCA occlusion

This case report illustrates the clinical course and management strategy of severe catheter-induced vasospasm of the right coronary artery (RCA) resulting in brief cardiac arrest in a male patient in his 60s presenting with Non-ST elevation myocardial infarction and obstructive disease in the left anterior descending artery (LAD). The patient was successfully resuscitated and further stay was uneventful. Optical coherence tomography imaging following administration of intracoronary isosorbide dinitrate confirmed normal coronary anatomy and flow restoration in the RCA, suggesting that the index episode was probably a vasospasm of the RCA. After establishing coronary flow in the RCA, the stenosis in the LAD was treated with a drug-eluting stent. Invasive cardiologists should be aware of the catheter-induced coronary artery spasm, which may have important clinical implications particularly in the presence of concomitant atherosclerotic disease in other coronary arteries (in our case the LAD). This approach helps to avoid unnecessary coronary stenting.

Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making: an expert consensus document of the European Association of Percutaneous Cardiovascular Interventions

This consensus document is the second of two reports summarizing the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI) on the clinical use of intracoronary imaging including intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near infrared spectroscopy (NIRS)-IVUS. Beyond guidance of stent selection and optimization of deployment, invasive imaging facilitates angiographic interpretation and may guide treatment in acute coronary syndrome. Intravascular imaging can provide additional important diagnostic information when confronted with angiographically ambiguous lesions and allows assessment of plaque morphology enabling identification of vulnerability characteristics. This second document focuses on useful imaging features to identify culprit and vulnerable coronary plaque, which offers the interventional cardiologist guidance on when to adopt an intracoronary imaging-guided approach to the treatment of coronary artery disease and provides an appraisal of intravascular imaging-derived metrics to define the haemodynamic significance of coronary lesions.

Coronary Computed Tomography Angiography for the Diagnosis of Vasospastic Angina: Comparison with Invasive Coronary Angiography and Ergonovine Provocation Test

OBJECTIVE

To investigate the diagnostic validity of coronary computed tomography angiography (cCTA) in vasospastic angina (VA) and factors associated with discrepant results between invasive coronary angiography with the ergonovine provocation test (iCAG-EPT) and cCTA.

MATERIALS AND METHODS

Of the 1397 patients diagnosed with VA from 2006 to 2016, 33 patients (75 lesions) with available cCTA data from within 6 months before iCAG-EPT were included. The severity of spasm (% diameter stenosis [%DS]) on iCAG-EPT and cCTA was assessed, and the difference in %DS (Δ%DS) was calculated. Δ%DS was compared after classifying the lesions according to pre-cCTA-administered sublingual nitroglycerin (SL-NG) or beta-blockers. The lesions were further categorized with %DS ≥ 50% on iCAG-EPT or cCTA defined as a significant spasm, and the diagnostic performance of cCTA on identifying significant spasm relative to iCAG-EPT was assessed.

RESULTS

Compared to lesions without SL-NG treatment, those with SL-NG treatment showed a higher Δ%DS (39.2% vs. 22.1%, p = 0.002). However, there was no difference in Δ%DS with or without beta-blocker treatment (35.1% vs. 32.6%, p = 0.643). The significant difference in Δ%DS associated with SL-NG was more prominent in patients who were aged < 60 years, were male, had body mass index < 25 kg/m², and had no history of hypertension, diabetes, or dyslipidemia. Based on iCAG-EPT as the reference, the per-lesion-based sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of cCTA for VA diagnosis were 7.5%, 94.0%, 60.0%, 47.1%, and 48.0%, respectively.

CONCLUSION

For patients with clinically suspected VA, confirmation with iCAG-EPT needs to be considered without completely excluding the diagnosis of VA simply based on cCTA results, although further prospective studies are required for confirmation.

Intravascular ultrasound findings and stent implantation for a patient with coronary spastic angina at site of progressive atherosclerotic plaque and responded poorly to medical treatment: a case report

BACKGROUND

Most coronary spastic angina patients are responsive to coronary vasodilators therapy, and stent implantation is not recommended for regular use. We reported the angiographic and intravascular ultrasound (IVUS) images of a rare case who responded poorly to medical treatment due to progressive atherosclerotic plaque at the spastic site.

CASE PRESENTATION

A 60-year-old man complaining of 1-month history of episodic chest pain at rest was admitted to our hospital. The diagnosis of coronary spastic angina was made based on the angiographic evidence of vasospasm at the right coronary artery (RCA). The patient responded poorly to conventional medical treatment during the 1-year follow-up. The repeated angiography revealed totally occlusion of the proximal segment of the RCA at the same location as 1 year before, and IVUS demonstrated there was vulnerable plaque and thrombus at the site of spasm. Episodic chest pain ceased completely in the follow up period after stenting.

CONCLUSION

Coronary spasm might present at the vessel site with advanced atherosclerotic plaque. For patients with refractory vasospastic angina and significant occlusion, stenting might be a viable and valuable treatment strategy under the guidance of intracoronary imaging.

[Prinzmetal angina. Questions of pathogenesis, clinic, diagnosis and treatment]

Current problems of Prinzmetal angina (vasospastic angina, variant angina) considers in this review. Attention is drawn to early diagnosis, which should be comprehensive, taking into account possible atypical courses and the development of complications. The important role of electrocardiographic monitoring (including using implantable recorders) is highlighted. It is emphasized that patients with cardiac arrhythmias, syncope are at high risk of developing sudden cardiac death. In this category of patients, it is recommended to timely determine the indications for implantation of a cardioverter - defibrillator. Authors consider the prospects of using new methods of treatment of angina pectoris.

Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making: an expert consensus document of the European Association of Percutaneous Cardiovascular Interventions

This consensus document is the second of two reports summarizing the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI) on the clinical use of intracoronary imaging including intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near infrared spectroscopy (NIRS)-IVUS. Beyond guidance of stent selection and optimization of deployment, invasive imaging facilitates angiographic interpretation and may guide treatment in acute coronary syndrome. Intravascular imaging can provide additional important diagnostic information when confronted with angiographically ambiguous lesions and allows assessment of plaque morphology enabling identification of vulnerability characteristics. This second document focuses on useful imaging features to identify culprit and vulnerable coronary plaque, which offers the interventional cardiologist guidance on when to adopt an intracoronary imaging-guided approach to the treatment of coronary artery disease and provides an appraisal of intravascular imaging-derived metrics to define the haemodynamic significance of coronary lesions.

Catastrophic catheter-induced coronary artery vasospasm successfully rescued using intravascular ultrasound imaging guidance

A 46-year-old man underwent coronary angiography for stable angina. He developed inferior ST-segment myocardial infarction during the angiography. Intravascular ultrasound (IVUS) findings suggested coronary vasospasm. Intracoronary administration of isosorbide dinitrate restored the coronary flow. This case illustrates the essential role IVUS imaging played in establishing the diagnosis of catheter-induced coronary vasospasm.

Intravascular imaging in coronary artery disease

Although it is the method used by most interventional cardiologists to assess the severity of coronary artery disease and guide treatment, coronary angiography has many known limitations, particularly the fact that it is a lumenogram depicting foreshortened, shadowgraph, planar projections of the contrast-filled lumen rather than imaging the diseased vessel itself. Intravascular imaging-intravascular ultrasound and more recently optical coherence tomography-provide a tomographical or cross-sectional image of the coronary arteries. These techniques are clinically useful to answer questions such as whether the stenosis is clinically relevant; the identification of the culprit lesion; or whether the plaque (or patient) is at high risk of future adverse events. They can also be used to optimise stent implantation to minimise stent-related adverse events, provide answers to the likelihood of distal embolisation or peri-procedural myocardial infarction during stent implantation, and provide reasons for stent thrombosis or restenosis. This review considers the usefulness of intravascular imaging in day-to-day practice.

Effect of hypertension on coronary remodeling patterns in angiographically normal or minimally atherosclerotic coronary arteries: an intravascular ultrasound study

Whether there is any particular role of hypertension in remodeling process has not been completely understood yet. The aim of this study was to assess the association between hypertension and remodeling patterns in normal or minimally atherosclerotic coronary arteries. Seventy-nine patients who were free of significant coronary atherosclerosis were divided into two groups according to the absence (n = 39) or presence (n = 40) of hypertension; and standard intravascular ultrasound examination was performed in 145 segments. To determine the remodeling pattern in early atherosclerotic process, patients were also analyzed according to the level of plaque burden at the lesion site after the analysis of remodeling patterns. Positive remodeling was more prevalent in the hypertensive group (52.5% vs. 12.8%; P < .001) whereas negative remodeling was more common in diabetic patients (53.6% vs. 27.4%; P = .03). Mean remodeling index was 1.04 for hypertensives and 0.96 for normotensives (P = .03). There were no correlations between remodeling patterns and other risk factors such as age, family history, and hypercholesterolemia. Early atherosclerotic lesions (< 30%) exhibited more negative remodeling characteristics while intermediate pattern was observed more frequently in patients with high plaque burden (P = .006 and .02, respectively). Positive remodeling showed no association in this context (P = .07). This study demonstrated that minimal atherosclerotic lesions in hypertensives had a tendency for compensatory arterial enlargement. Positive remodeling may result from local adaptive processes within vessel wall or hemodynamic effects of blood pressure itself.

Coronary vasospastic angina: assessment by multidetector CT coronary angiography

Objective

We aimed to describe the imaging findings of multidetector CT coronary angiography (MDCTA) in cases of vasospastic angina (VA) and to determine the accuracy of MDCTA in the identification of VA as compared with invasive coronary angiography with an ergonovine provocation test (CAG with an EG test).

Materials and Methods

Fifty-three patients with clinically suspected VA were enrolled in this study. Two radiologists analyzed the stenosis degree, presence or absence of plaque, plaque composition, and a remodeling index of the related-segment in CAG with an EG test, which were used as a gold standard. We evaluated the diagnostic performances of MDCTA by comparing the MDCTA findings with those of CAG with an EG test.

Results

Among the 25 patients with positive CAG with an EG test, all 12 patients with significant stenosis showed no definite plaque with the negative arterial remodeling. Of the six patients with insignificant stenosis, three (50%) had non-calcified plaque (NCP), two (33%) had mixed plaque, and one (17%) had calcified plaque. When the criteria for significant stenosis with negative remodeling but no definite evidence of plaque as a characteristic finding of MDCTA were used, results showed sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) of 48%, 100%, 100%, and 68%, respectively.

Conclusion

Significant stenosis with negative remodeling, but no definite evidence of plaque, is the characteristic finding on MDCTA of VA. Cardiac MDCTA shows good diagnostic performance with high specificity and PPV as compared with CAG with an EG test.

Accelerated coronary atherosclerosis revealed by arrhythmogenic coronary spasm

Coronary artery spasm is sometimes associated with life-threatening ventricular arrhythmias. Based on intravascular ultrasound findings, it appears that coronary artery spasm promotes negative arterial remodeling, suggesting that patients with coronary artery spasm might be at higher risk of accelerated coronary atherosclerosis. We report the cases of 3 patients with ventricular arrhythmia secondary to coronary artery spasm complicated by accelerated coronary atherosclerosis. Consequently, coronary disease progression should be considered in the case of angina pectoris recurrence in patients with coronary artery spasm, especially in those with coronary artery spasm complicated by ventricular arrhythmia.

Functional medial thickening and folding of the internal elastic lamina in coronary spasm

Although there are a number of studies on vasospastic angina, the structural changes at the cellular level that occur in the coronary arterial wall during spasm are not well known. Coronary spasm was induced by brushing the coronary adventitia in nine anesthetized beagles, and structural changes in the spastic coronary segments were examined by light and electron microscopy, making comparisons with the adjacent nonspastic segments. The % diameter stenosis of the spastic segments as measured angiographically was 79.4±12% (mean±SD). Light microscopic changes in the spastic and nonspastic segments were as follows: medial thickness 1,512 vs. 392 μm (P<0.0001) and % diameter and % area stenoses of spastic segment 81.0% and 96.5%, respectively, indicating that spasm was induced by medial thickening. Circular smooth muscle cells (SMCs) in the media were arranged in parallel with the internal (IEL) and external (EEL) elastic lamina in nonspastic segments but radially rearranged in spastic segments. SMCs were classified by their patterns of connection to IEL into six types by electron microscopy. Of these, three contracted and pulled the IEL toward the EEL, causing folding of the IEL and waving of EEL resulting in thickening of the media and narrowing of the lumen. We conclude that coronary spasm was elicited by radial rearrangement of the medial SMCs due to their own contraction and resultant medial thickening and folding of IEL, creating a piston effect to narrow the lumen, i.e., spasm.

Morphological features of coronary arteries in patients with coronary spastic angina: assessment with intracoronary optical coherence tomography

BACKGROUND

Coronary spasm (CS) plays an important role in the pathogenesis of many types of ischemic heart disease, but morphological appearance of non-stenotic coronary segments with CS is not fully understood. We evaluate the morphological characteristics of coronary arteries in patients with coronary spastic angina (CSA) using intravascular optical coherence tomography (OCT).

METHODS

We evaluated 37 patients with resting chest pain whose coronary angiograms did not reveal significant stenosis. These patients underwent an acetylcholine (ACh) provocation test. OCT was performed after complete dilatation of coronary arteries, and additionally during ACh-induced CS in four patients.

RESULTS

Based on the ACh test, 23 patients were diagnosed as having CSA, and the remaining 14 patients without CS were referred to as CS-negative. OCT study revealed that coronary segments with ACh-induced CS had homogeneous intimal thickening, and quantitative analysis showed that CS-positive segments had a significantly greater intima area as compared with corresponding CS-negative segments without lipid or calcium content. By contrast, CS-positive segments had a significantly smaller intima area as compared with CS-negative segments with lipid or calcium deposit. During ACh-induced CS, lumen and total vascular areas were significantly decreased, whereas intima area did not change in comparison with complete vasodilatation. The luminal surface of the intima formed a markedly wavy configuration during CS.

CONCLUSIONS

Coronary artery segments involved in CS are characterized by diffuse intimal thickening without lipid or calcium content. High-resolution coronary OCT imaging could make it possible to analyze the vascular pathophysiology in patients with CS.

Plaque components at coronary sites with focal spasm in patients with variant angina: virtual histology-intravascular ultrasound analysis

BACKGROUND

We compared the plaque components at coronary sites with focal spasm after ergonovine provocation test in 30 variant angina (VA) patients with those at culprit coronary sites in 32 unstable angina (UA) patients using virtual histology-intravascular ultrasound (VH-IVUS).

METHODS

VH-IVUS classified and color-coded tissue into four major components: fibrotic; fibro-fatty; dense calcium (DC); and necrotic core (NC). Thin-cap fibroatheroma (TCFA) was defined as a NC≥10% of plaque area in at least 3 consecutive frames without overlying fibrous tissue in the presence of ≥40% plaque burden.

RESULTS

The lesion site plaque burden was significantly smaller (44.5±10.8% vs. 70.5±13.1%, p<0.001), the plaque volume was significantly smaller (135±118 mm³ vs. 223±160 mm³, p=0.020), the remodeling index was significantly lower (0.90±0.14 vs. 0.97±0.23, p=0.023), and more plaque was hypoechoic with less calcium (87% vs. 56% and 0% vs. 19%, respectively, p=0.033) in VA patients compared with UA patients. The % NC and DC areas were significantly smaller at the minimum lumen site within spasm/culprit lesion (12.9±12.9% vs. 22.3±11.7%, p=0.004, and 6.5±8.0% vs. 12.8±10.8%, p=0.011, respectively), and the % NC and DC volumes were significantly smaller in VA patients compared with UA patients (12.2±10.3% vs. 17.7±8.1%, p=0.025, and 6.4±6.0% vs. 11.8±8.5%, p=0.007, respectively). The TCFA within lesion segments was less frequently observed in VA patients compared with UA patients (13% vs. 53%, p=0.001).

CONCLUSIONS

VA patients have less plaque, more negative remodeling behavior, more hypoechoic plaque with less calcification, and less NC- and DC-containing lesions and less TCFA lesions compared with UA patients.

Noninvasive detection of coronary atherosclerotic plaque by multidetector row computed tomography

BACKGROUND

Coronary artery disease continues to be one of the leading causes of death and disability around the globe, challenging the efficacy of currently applied schemes to predict the risk for future coronary events. In fact, algorithms such as the Framingham risk score that are based on traditional risk factors like hypertension and dyslipidemia are not very sensitive, leaving a majority of the population at intermediate risk.

METHODS

Advances in multidetector computed tomography (MDCT) technology with submillimeter slice collimation (approximately 0.6 mm) and high temporal resolution now permit contrast-enhanced imaging of the coronary artery lumen and wall in a single breath hold. The current generation of MDCT provided in-plane resolution of 0.5 mm and a temporal resolution of 210 ms. The simultaneous acquisition of 16/64 parallel cross-sections reduces image acquisition time to about 10-20s using 60-80 ml of contrast agents to opacify the coronary artery lumen. CT imaging for coronary calcification is an established method with low radiation exposure. The amount of calcification is expressed as an Agatston Score (AS).

RESULTS

The presence and amount of coronary calcification significantly increases the relative risk for future coronary events, independent from traditional risk factors (risk ratio 8.7 [95% Cl, 2.7-28.1]). Especially, individuals with a high AS (>400) who are at intermediate 10-y Framingham event risk may benefit from this additional risk stratification. However, calcification is rarely present in children and adolescents. However, there is a growing body of evidence suggesting that contrast-enhanced MDCT can detect both calcified and noncalcified plaques with high sensitivity and specificity for the detection of plaques > 0.5 mm when compared to intravascular ultrasound. Moreover, initial data suggest that plaque characteristics such as plaque area, volume, quantify and coronary plaque remodeling index can be quantified in good agreement with IVUS. The composition of noncalcified plaque may be further stratified into predominantly fibrous or lipid-rich plaque. Noncalcified plaque may be present already in children and adolescents with multiple risk factors.

CONCLUSION

The available data indicate that high resolution MDCT can reliably detect, quantify and characterize calcified and noncalcified coronary atherosclerotic plaque. With MDCT, we now have a unique opportunity to study the natural history and response to therapy of noncalcified coronary plaques, which may be already present in obese children or children with multiple risk factors.

An increased monocyte count predicts coronary artery spasm in patients with resting chest pain and insignificant coronary artery stenosis

BACKGROUND

Coronary atherosclerosis with inflammation gives rise to coronary vasospasm in the patients with coronary vasospastic angina. We have postulated that the peripheral leukocyte count and the differential count are associated with vasospastic angina.

METHODS

144 patients who underwent intracoronary ergonovine provocation testing between January 2002 and December 2004 were divided into two groups: Group I (72 patients with provoked spasm, mean age: 54.8 +/- 10.7 years, males: 75%) and Group II (72 without spasm, mean age: 55.3 +/- 10.2 years, males: 35%). Blood sampling was done to measure the lipid profiles and inflammatory markers, including the high sensitive C-reactive protein (hsCRP) levels and the monocyte counts. We compared the angiographic findings and laboratory data between the two groups.

RESULTS

There were no significant differences in the levels of serum lipid and hsCRP between the two groups. The white blood cell count and the monocyte count were higher in Group I than with Group II (7496.4 +/- 2622.28 vs. 6703.2 +/- 1768.37/mm3, respectively, p = 0.035; 627.5 +/- 270.70 vs. 426.9 +/- 205.76/mm3, respectively, p < 0.001). Gensini's score was higher in Group I than in Group II (2.2 +/- 2.88 vs. 0.5 +/- 1.03, respectively, p < 0.001). Multivariate analysis showed that the monocyte count and Gensini's score were independent factors affecting coronary spasm (p = 0.047 and p = 0.018, respectively). According to a receiver operating characteristics curve analysis, the area under the curve of the monocyte count was 0.738, that of the neutrophil count was 0.577 and that of the WBC count was 0.572. The cut-off value of the monocyte count was 530/mm3; the sensitivity and specificity of this cut-off value were 64% and 76%, respectively.

CONCLUSIONS

The peripheral monocyte count is an independent marker for predicting vasospastic angina in the patients with resting chest pain and insignificant coronary artery stenosis.

Common adrenergic receptor polymorphisms as novel risk factors for vasospastic angina

BACKGROUND

Sympathetic activity mediated by adrenergic receptors (ARs) appears to play an important role in controlling the vasomotor tone and, thus, may be associated with vasospastic angina (VA). We investigated the association of the common functional polymorphisms of the AR gene and VA. The candidates were alpha2CDel322-325, beta1Gly389Arg, beta2Arg16Gly, and beta2Gln27Glu polymorphisms.

METHODS

Eighty-two patients with VA, confirmed by coronary angiography with or without ergonovine provocation test, and 114 apparently healthy control subjects were investigated for genotype of 4 AR polymorphisms and established risk factors of ischemic heart disease.

RESULTS

The minor alleles were alpha2CDel322-325, beta1Gly389, beta2Gly16, and beta2Glu27 and their frequencies were 7%, 18%, 42%, and 29%, respectively, in the control subjects of this Korean population, which were different from those of other ethnic groups. On univariate analysis, age, smoking, male sex, alpha2CDel322-325 allele carrier state, and beta2Gln27 homozygote state were significant risk factors for VA. After multivariate analysis using multiple logistic regression model, age (odds ratio [OR] 1.809, CI 1.046-1.135, P < .0001), smoking (OR 4.902, CI 2.105-11.416, P = .0002), alpha2CDel322-325 allele carrier state (OR 5.132, CI 2.094-12.578, P = .0003), and beta2Gln27 allele homozygosity (OR 3.152, CI 1.364-7.285, P = .0072) remained as independent risk factors. In the combined genotype analysis, the effect of beta2Gln27 allele was evident only when the alpha2CDel322-325 allele was absent.

CONCLUSIONS

The alpha2CDel322-325 allele carrier state and beta2Gln27 allele homozygote state were identified as novel risk factors of VA in this Korean population. This result suggests the importance of the adrenergic stimuli and the genetic background in the pathogenesis of the VA.

Normal angiogram in acute coronary syndrome-preangiographic risk stratification, angiographic findings and follow-up

BACKGROUND

Coronary angiographies performed during acute coronary syndrome show different coronary morphologies-vessel occlusions, thrombi and various types of stenoses. In a few cases of acute coronary syndrome, angiography reveals normal coronary arteries. It is the purpose of this study to analyze this specific subset of patients who presented with an acute coronary syndrome but had a normal coronary angiogram with respect to the preangiographic diagnostics, risk stratification and clinical follow-up.

METHODS AND RESULTS

A total of 897 coronary angiographies were performed as an emergency procedure in our institution. The majority of patients (n = 821) presented with coronary artery disease and the majority was treated by mechanical revascularization (86.3%). In 76 patients (8.5%), no coronary artery stenosis was documented. However, according to the preangiographic risk stratification, coronary artery disease was expected in these patients. Observations documented angiographically included coronary spasms (6.6%) and muscle bridges (5.3%). During a mean follow-up of 11.2 +/- 6.4 months, one patient developed an acute myocardial infarction requiring coronary intervention. All other patients were free of any cardiac event.

CONCLUSIONS

In summary, we have to consider that coronary angiography may not always detect the cause of myocardial ischemia in every patient. There is a small group of patients with normal coronary angiograms during acute coronary syndrome. Additional diagnostic procedures like intravascular ultrasound (IVUS) or the assessment of intracoronary physiological parameters may increase the diagnostic value of angiography.

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.

Small Artery Remodeling Depends on Tissue-Type Transglutaminase

Remodeling of small arteries is essential in the long-term regulation of blood pressure and blood flow to specific organs or tissues. A large part of the change in vessel diameter may occur through non-growth-related reorganization of vessel wall components. The hypothesis was tested that tissue-type transglutaminase (tTG), a cross-linking enzyme, contributes to the inward remodeling of small arteries. The in vivo inward remodeling of rat mesenteric arteries, induced by low blood flow, was attenuated by inhibition of tTG. Rat skeletal muscle arteries expressed tTG, as identified by Western blot and immunostaining. In vitro, activation of these arteries with endothelin-1 resulted in inward remodeling, which was blocked by tTG inhibitors. Small arteries obtained from rats and pigs both showed inward remodeling after exposure to exogenous transglutaminase, which was inhibited by addition of a nitric oxide donor. Enhanced expression of tTG, induced by retinoic acid, increased inward remodeling of porcine coronary arteries kept in organ culture for 3 days. The activity of tTG was dependent on pressure. Inhibition of tTG reversed remodeling, causing a substantial increase in vessel diameter. In a collagen gel contraction assay, tTG determined the compaction of collagen by smooth muscle cells. Collectively, these data show that small artery remodeling associated with chronic vasoconstriction depends on tissue-type transglutaminase. This mechanism may reveal a novel therapeutic target for pathologies associated with inward remodeling of the resistance arteries.

Remodeling of coronary arteries in diabetic patients-an intravascular ultrasound study

BACKGROUND

Coronary artery remodeling is a structural change in the vessel wall and typically in response to atherosclerotic plaque. The nature of coronary remodeling has been described in different clinical situations. However, remodeling characteristics of coronary arteries of diabetic patients have never been studied.

HYPOTHESIS

We tested the hypothesis that positive remodeling of coronary artery in response to atherosclerotic plaque in diabetic patients would be less compared to nondiabetic patients.

METHODS

Coronary intravascular ultrasound analysis of data in 26 consecutive patients (12 diabetic and 14 nondiabetic) was performed. Linear regression analyses of vessel area versus plaque area were carried out to establish a relation between the degree of plaque and the extent of remodeling in diabetic and nondiabetic groups.

RESULTS

The positive remodeling quantified as the slope of the regression line was similar in both the groups (diabetic group 1.32 and nondiabetic group 0.80) when all segments with different plaque areas were considered (P > 0.05). However, the diabetic group had greater positive remodeling in segments with plaque area less than 55%, as the slope for diabetic group was 2.01 and nondiabetic group was 1.40 (P < 0.05).

CONCLUSIONS

Both the diabetic and nondiabetic patients had positive remodeling in response to atherosclerotic plaque formation. Diabetics had greater positive remodeling in the early stages of atherosclerosis compared to nondiabetics, thus providing evidence against our hypothesis. The adverse clinical outcomes in diabetics may not be due to inadequate positive remodeling of coronary arteries as previously thought.

Intravascular ultrasound assessment of atherosclerosis

Atherosclerosis imaging has taken on increasing importance in the understanding of the natural history of coronary artery disease and the processes leading to luminal narrowing, as well as the assessment of disease burden and therapy efficacy. Intravascular ultrasound (IVUS) has emerged as the new gold standard for atherosclerosis imaging because it provides cross-sectional images of both the arterial wall and lumen with excellent resolution, reveals the diffuse nature of atherosclerosis and the involvement of reference segments, and takes into account vessel wall remodeling. In addition to its clinical indications, IVUS is now widely used as the primary efficacy assessment measure of several antiatherosclerotic approaches in randomized clinical trials. Advantages of IVUS include its ability to reveal antiatherosclerotic effects within a relatively short period of time and with a reasonable sample size, which is in contrast to trials assessing angiographic changes or clinical events. IVUS can also help to determine dose-response relationships in the development of novel pharmacologic agents. IVUS is currently the ideal imaging modality for clinical trials of atherosclerosis progression/regression.

Intravascular ultrasound assessment of patterns of arterial remodeling in the absence of significant reference segment plaque burden in patients with coronary artery disease

OBJECTIVES

We evaluated the impact of reference vessel segment plaque burden on lesion remodeling. Intravascular ultrasound (IVUS) assessment of lesion remodeling compares lesions to reference segments. However, reference segments are rarely disease-free and, therefore, have also undergone remodeling changes.

METHODS

Pre-intervention IVUS was obtained in 274 patients with right coronary artery lesions selected because the right coronary artery has less tapering and fewer side branches than the left anterior descending or left circumflex artery. Standard IVUS definitions were used. Patients were divided according to reference vessel segment plaque burden: group A (minimal reference disease, n = 91), both proximal and distal reference plaque burden <20%; group B (n = 91), either proximal or distal reference plaque burden 20% to 40% but both < or =40%; and group C (n = 92), either proximal or distal reference plaque burden >40%.

RESULTS

The remodeling index measured 0.98 +/- 0.16 in group A (range, 0.68 to 1.47), 1.04 +/- 0.18 in group B (range, 0.67 to 1.91), and 1.04 +/- 0.15 in group C (range, 0.74 to 1.70), analysis of variance p = 0.0208 (p = 0.0234 group A vs. group B and p = 0.0012 group A vs. group C, but p = 0.8 group B vs. group C). Positive, intermediate, and negative remodeling were observed in 24 (26%), 24 (26%), and 43 lesions (48%) in group A; 36 (40%), 28 (30%), and 27 lesions (30%) in group B; and 34 (37%), 39 (42%), and 19 lesions (21%) in group C, respectively (p = 0.0022).

CONCLUSIONS

Negative remodeling occurs commonly in coronary lesions with minimal reference segment disease. Negative remodeling is not just an "artifact" introduced by comparing lesions to diseased reference segments.

Coronary flow reserve in patients with vasospastic angina: correlation between coronary flow reserve and age or duration of angina

OBJECTIVES

This study sought to assess the coronary flow reserve (CFR) in patients with pure vasospastic angina (VSA).

METHODS AND RESULTS

The phasic flow velocities of both spasm-positive and spasm-negative coronary arteries of the left anterior descending artery (LAD) were recorded at rest and during hyperaemia (50 microg of adenosine triphosphate infusion intracoronary) using a 0.014 inch, 15 MHz Doppler guide wire in 42 patients with pure VSA and acetylcholine (ACh)-induced coronary artery spasms (20-100 microg), and 23 controls with normal coronary arteries without ACh-induced vasospasm. These 42 patients had 16 vessels with focal spasms (>99%), 17 vessels with diffuse spasms (>90%) in the LAD, and nine vessels with ACh-induced spasms in the right coronary artery, but not the LAD. Coronary flow reserve was obtained from the ratio of the hyperaemic/baseline time-averaged peak velocity. Coronary flow reserve did not differ between patients with VSA and the controls (2.9+/-0.8 versus 3.2+/-0.7, NS). Moreover, CFR did not differ among the four cases (focal: 2.8+/-0.7; diffuse: 3.0+/-0.9; non spasm: 2.9+/-0.7 versus controls: 3.2+/-0.7, respectively, NS). Coronary flow reserve in vessels with proximal spasms was significantly higher than that in vessels with mid or distal spasms (3.4+/-0.8 versus 2.6+/-0.6, 2.6+/-0.9, p<0.05). The only significant correlation was between CFR and age (p=0.0275) or the duration of angina before admission (p=0.0405).

CONCLUSIONS

There was no difference in CFR in patients with ACh-induced spasms between the spasm-positive and spasm-negative vessels. Moreover, CFR was maintained normally in vessels with diffuse spasms, as in those with focal spasms. The most important determinant factors for CFR in patients with VSA were age and the duration of angina before admission.

The Glu298Asp polymorphism in the endothelial nitric oxide synthase gene is strongly associated with coronary spasm

BACKGROUND

Coronary spasm seems to be associated with coronary nitric oxide deficiency.

OBJECTIVES

We investigated whether the Glu298Asp polymorphism in the endothelial nitric oxide synthase (eNOS) gene is a definite risk factor for coronary spasm and whether diffuse spasm involving normal-looking coronary artery correlates significantly with the Glu298Asp polymorphism, in contrast with focal spasm superimposed on an atherosclerotic plaque.

METHODS

A polymerase chain reaction followed by restriction fragment length polymorphism analysis was performed in 118 control participants and in 102 patients with variant angina and a similar degree of atherosclerotic burden. Patients with coronary spasm were divided into diffuse spasm and focal spasm subgroups according to morphological criteria.

RESULTS

There was a significantly higher incidence of the Glu298Asp polymorphism in the coronary spasm group than in the control group (21.5% compared with 8.5%, P=0.006). Multiple logistic regression analysis using risk factors and the Glu298Asp polymorphism showed that the most important predictive factor for coronary spasm was the Glu298Asp polymorphism (odds ratio 2.83, 95% confidence interval 1.25-6.41, P=0.009). The diffuse spasm subgroup had a significantly higher frequency of the Glu298Asp polymorphism than the control group (25.9% compared with 8.5%, P=0.002). However, the focal spasm subgroup did not differ from the control group in the frequency of Glu298Asp polymorphism.

CONCLUSION

The Glu298Asp polymorphism in the eNOS gene is a definite risk factor for coronary spasm, especially for diffuse coronary spasm. This result supports the notion that diffuse coronary spasm is significantly associated with endothelial dysfunction, in contrast to focal spasm.

Early constriction or expansion of the external elastic membrane area determines the late remodeling response and cumulative lumen loss in transplant vasculopathy: an intravascular ultrasound study with 4-year follow-up

BACKGROUND

Early constriction of the external elastic membrane (EEM) area has been observed after cardiac transplantation. The aim of this study was to compare the late disease process of transplant vasculopathy between coronary segments with early constrictive and expansive remodeling.

METHODS

Serial intravascular ultrasound data obtained annually for 4 years after transplantation in 38 transplant recipients was available. In 135 matched segments from 59 coronary arteries ultrasound images were digitized at 1-mm intervals. Mean values of the external elastic membrane (EEM), lumen and intimal areas were calculated. On the basis of a decrease or increase in EEM area within the first year after transplantation, we defined segments with early constrictive remodeling (CR, n = 71) or early expansive remodeling (ER, n = 64).

RESULTS

Annual changes in intimal area were similar between segments with early CR and ER throughout the follow-up period. However, during the second and third year, annual increases in EEM area were greater in segments with early CR than in segments with early ER (second year: 1.5 +/- 2.7 vs 0.6 +/- 2.8 mm(2), p = 0.052; third year: 1.3 +/- 2.5 vs -0.03 +/- 2.6 mm(2), p = 0.003). Despite this late expansion, segments with early CR showed a cumulative decrease in the EEM area and a greater lumen loss than segments with early ER (-2.5 +/- 3.4 vs -0.6 +/- 2.6 mm(2), p < 0.001).

CONCLUSIONS

In transplant vasculopathy, the late remodeling response was different between segments with early constrictive and expansive remodeling, despite similar intimal thickening. Early constriction caused an overall decrease in EEM area and greater loss of lumen during follow-up.

What has intravascular ultrasound taught us about plaque biology?

Intravascular ultrasound (IVUS) has a defined role in the cardiac catheterization laboratory to assess lesion severity and the procedural success of vascular interventions. However, IVUS has also contributed to our understanding of the biology of atherosclerosis and restenosis. In acute coronary syndromes, IVUS has revealed varying degrees of stenosis, thrombosis, and plaque derangement typical of the plaque disruption seen in many pathologic studies of patients who have died of this condition. IVUS has demonstrated that the culprit lesions of patients surviving acute coronary syndromes also tend to be softer, with less calcium, and tend to have more plaque with positive arterial remodeling (compensatory enlargement) than lesions causing stable coronary syndromes. Arterial remodeling is also an important component of restenosis after coronary interventions. IVUS has suggested that interventions that reduce restenosis tend to have a greater impact on preventing negative remodeling (constriction) rather than reducing neointimal proliferation. Oxidant stress may be an important contributor to negative remodeling, as IVUS has demonstrated this anatomy at sites of coronary artery spasm. Positive remodeling seen by IVUS is also associated with impaired endothelial vasomotor dysfunction, and IVUS studies have demonstrated the contribution of vasomotor tone to arterial elasticity. Future directions include integrating IVUS with other imaging modalities, such as angiography, to study the interaction of anatomic and physiologic factors in atherosclerosis progression, and using the raw ultrasound signal to distinguish plaque components and differences in wall strain that may identify vulnerable plaques.