Angiographic characteristics of infarct-related and non-infarct-related stenoses in patients in whom stable angina progressed to acute myocardial infarction

Differential associations of angiographic extent and severity of coronary artery disease with asymmetric dimethylarginine but not insulin resistance in non-diabetic men with stable angina: a cross-sectional study

Background

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthesis inhibitor, and insulin resistance (IR) have been implicated in atherogenesis. Our aim was to estimate relations between ADMA, the magnitude of IR and angiographic indices of extent and severity of coronary atherosclerosis in non-diabetic men with stable coronary artery disease (CAD).

Methods

We studied 151 non-diabetic men (mean age 57 ± 11 years) with stable angina, obstructive CAD (at least 1 luminal diameter stenosis of ≥70% in major coronary segments) and without heart failure, and 34 age-matched controls free of ≥50% coronary narrowings. The following CAD indices were computed: the number of major epicardial vessels with ≥70% stenosis, Sullivan extent score representing a proportion of the visible coronary tree with vessel wall irregularities, and Gensini score which reflects both CAD severity and extent, yet assigning a heavier weight to proximal segments and to the more severe narrowings by a non-linear point system. An estimate of IR was derived by homeostasis model assessment (HOMA-IR) from fasting insulin and glucose.

Results

Among the CAD patients, the proportions of subjects with 1-vessel, 2- vessel and 3-vessel CAD were 26%, 25% and 49%, respectively. ADMA levels were higher in patients with obstructive CAD compared to the controls (0.51 ± 0.10 vs. 0.46 ± 0.09 μmol/L [SD], P = 0.01), whereas HOMA-IR was similar (median, 3.2 [interquartile range: 2.4–4.9] vs. 2.9 [2.3–4.7], P = 0.2). Within the CAD group, ADMA increased across ascending quartiles of Sullivan score (Spearman’s rho = 0.23, P = 0.004), but not with Gensini score (rho = 0.12, P = 0.15) or the number of vessels involved (rho = 0.08, P = 0.3). ADMA correlated to log-transformed Sullivan score (Pearson's r = 0.21, P = 0.008), which was only slightly attenuated upon multivariate adjustment (β = 0.19 ± 0.08 [SEM], P = 0.015). HOMA-IR did not differ according to any measure of angiographic CAD (P ≥ 0.2). ADMA and log (HOMA-IR) were mutually unrelated (r = 0.07, P = 0.4).

Conclusions

ADMA is associated with diffuse but not focal coronary atherosclerosis in non-diabetic men with stable CAD irrespectively of the degree of IR. The independent relationship between ADMA and coronary atherosclerotic burden may contribute to the well-recognized prognostic effect of ADMA in CAD.

Acute myocardial infarction late following stent implantation: Incidence, mechanisms and clinical presentation

Acute myocardial infarction (AMI) can occur late following stent implantation with an incidence up to >6% at 3-4 years, with no difference between DES and BMS. AMI can originate either from the stented site or from disease progression at nonstented sites. Restenosis, against previous thoughts, can lead to AMI. Stent thrombosis occurs with similar overall frequency following DES and BMS implantations, although a higher very late stent thrombosis with DES has been observed. Dissimilar mechanisms between BMS and DES thrombosis are very likely, with impaired neointimal healing being the rule for DES but the exemption for BMS. The use of invasive imaging techniques is useful in elucidating the involved mechanism. Disease progression is a particularly important cause of AMI late post stenting. The angiographic study depicted stent failure and disease progression equally implicated in the AMI late post stenting. When the AMI underlying mechanism is stent thrombosis, it usually occurs earlier and more frequently presented as STEMI compared to the other causes of AMI. The AMI caused by restenosis is more often presented as nonSTEMI, while disease progression leads to AMI later than the other causes. Further research should address equally not only the stent related inadequacies but also disease progression as causes of the future AMI. Angiographic follow-up and intracoronary imaging seem the most appropriate methods to define the exact pathophysiologic mechanism responsible for the AMI post stenting.

Eccentric stenosis of the carotid artery associated with ipsilateral cerebrovascular events

BACKGROUND AND PURPOSE

Eccentric stenosis of the coronary artery is associated with plaque disruption and acute coronary syndrome. The purpose of the present study was to determine whether eccentric stenosis of the carotid artery contributes to cerebrovascular events.

MATERIALS AND METHODS

Of 6859 patients with vascular diseases who underwent duplex carotid ultrasonography, we studied 512 internal carotid arteries in 441 patients who had a maximum area stenosis at or more than 70%, which corresponds with approximately 50% or more by the NASCET method. The maximal (A) and minimal wall thicknesses (B) were measured on cross-sectional sonography images, and an eccentricity index was calculated using the following formula: (A - B)/A. Arteries in the lowest quartile of the eccentricity index (<0.69) were defined as having a concentric stenosis, whereas the others were defined as having eccentric stenosis. The underlying clinical characteristics and plaque morphologies, as well as the occurrence of ipsilateral ischemic stroke or transient ischemic attack in the preceding year, were compared between patients with eccentric and concentric stenosis.

RESULTS

Patient characteristics and plaque morphology were similar between the 2 groups. Cerebrovascular events occurred more frequently ipsilaterally to the artery with eccentric stenosis (13.5%) than to the artery with concentric stenosis (5.5%; P = .013); the difference was more evident when cerebrovascular events of presumed carotid arterial origin were assessed (P = .005). After adjusting for risk factors and plaque morphology, eccentric stenosis was independently related to the presence of recent cerebrovascular events (odds ratio = 2.76; 95% confidence interval = 1.19-6.40).

CONCLUSIONS

In patients with an area carotid stenosis of 70% or more, eccentric plaque was associated with a significantly increased incidence of ipsilateral cerebrovascular events compared with patients with concentric stenosis.

Prognostic and clinical correlates of angiographically diffuse non-obstructive coronary lesions

OBJECTIVE

To make a prospective assessment of the clinical and prognostic correlates of angiographically diffuse non-obstructive coronary lesions.

DESIGN

Angiographic vessel and extent scores were calculated in 228 clinically stable patients (mean (SD) age, 60 (11) years; 43 women, 185 men) undergoing prospective follow up for the composite end point of death and myocardial infarction. The effect on outcome of clinical variables (age, sex, previous myocardial infarction, diabetes mellitus, smoking habit, systemic hypertension, hypercholesterolaemia, ejection fraction) and angiographic variables (vessel and extent score) was evaluated by Cox's proportion hazard model.

RESULTS

The vessel score was 3 in 34 patients (15%), 2 in 78 (34%), 1 in 87 (38%), and 0 in 29 (13%). Median extent score was 60 (range 6-110; first quartile 40, third quartile 70). Forty one events (nine deaths and 32 myocardial infarcts) occurred over a median follow up period of 30 months. Age and extent score were the only multivariate predictors of outcome, but the latter provided 28% additional prognostic information after adjustment for the most predictive variables (gain in chi2 = 7, p < 0.01). A vessel score of 3 was associated with worse survival, while no significant discrimination was possible among the other groups. However, assignment of patients to two groups according to an ROC curve derived cut off value for the extent score made it possible to obtain significant discrimination of survival even in cases with vessel scores of 0 to 2. Age and diabetes were clinical markers of a higher extent score.

CONCLUSIONS

The angiographic extent score is a powerful marker of adverse outcome independent of severity and the number of flow limiting coronary lesions, and may reflect the link between clinical risk profile and diffusion of coronary atherosclerosis. Thus it should be of clinical value for targeting aggressive preventive measures.

Plaque rupture and consequent thromboses probably do not cause acute coronary syndromes

The objective of this communication is to provide evidence that the spasm of resistance vessel (S-RV) concept of ischemic heart disease (IHD) and other ischemic disorders provides a more consistent set of explanations for acute coronary syndromes than the accepted mechanism of plaque rupture and consequent thromboses. The concept avers that S-RV directly induces symptoms in the various syndromes of IHD, including acute coronary syndromes. The S-RV concept is considered to be an alternate paradigm to explain IHD, and interest only develops in such models when there is significant doubt about the validity of the accepted paradigm. This report is an update of a study reported in this Journal in 1999 and has 2 changes; evidence will be evaluated by formal verification/falsification (pass/fail) methods - the method used to evaluate paradigms, and this report focuses on the mechanism of acute coronary syndromes because of the importance of these syndromes. It is well accepted that acute coronary syndromes are due directly to plaque rupture/thromboses, and there is considerable evidence to support this obvious mechanism. In spite of the obviousness of this mechanism, the S-RV concept asserts that S-RV is a more rational mechanism to explain acute coronary syndromes. Consistent with this position, the results of the study favor the S-RV concept. The standard position was given 8 passes, 2 passes with associated possible limited failures, and 2 possible failures. In contrast, the S-RV concept was given 12 passes, and no failures. Hopefully, the results of this study, and other available information about the S-RV concept, will prompt interest in the concept - such as independent testing of its premises.

Vasomotor effects of L- and D-arginine in stenotic atheromatous coronary plaque

OBJECTIVE

To examine the effects of exogenous L- and D-arginine on coronary stenosis vasomotion in relation to stenosis morphology.

DESIGN

Intracoronary infusions of normal saline, L- and D-arginine (50 and 150 micromol/min), and glyceryl trinitrate (250 microg bolus) were given in 24 patients with coronary artery disease and stable angina. Coronary stenoses were classified as smooth or complex (irregular borders). The diameter of the coronary stenoses and their adjacent reference segments was measured by computed quantitative angiography.

RESULTS

During L-arginine infusion a larger proportion of complex stenoses than smooth stenoses dilated by >/= 10% (p < 0.01), and the magnitude of dilatation was greater at the site of complex stenoses (p < 0.05). Irrespective of the type of morphology there was a positive correlation (p < 0.01) between the severity of stenoses and the magnitude of vasodilatation to L-arginine. The response to glyceryl trinitrate was similar in the two groups. No significant change was found in either group in response to D-arginine.

CONCLUSIONS

In patients with coronary artery disease, coronary stenoses-particularly those of complex morphology-dilate in response to the administration of L-arginine but not D-arginine. This finding is consistent with partial deficiency of the substrate for nitric oxide synthesis, L-arginine, at the site of complex stenoses.

HMG-CoA reductase inhibitor stabilizes rabbit atheroma by increasing basal NO and decreasing superoxide

Male rabbits fed a 0.5% cholesterol diet for 8 wk were divided into three groups. Group 1 was hypercholesterolemic; group 2 was fed a regular diet for an additional 12 wk; and group 3 was fed a regular diet with simvastatin (5 mg x kg(-1) x day(-1)). Simvastatin treatment reduced the atherosclerotic area and total and esterified cholesterol concentrations in the thoracic aorta. Tone-related basal nitric oxide (NO) release was highest in group 3. Acetylcholine-induced, NO-dependent relaxation was improved in group 3 compared with group 2. Amount of endothelial nitric oxide synthase (eNOS) mRNA in vessels increased in group 1, compared with normal aorta, and decreased in group 2; however, it did not decrease in group 3. The amount of O released from vessels increased in group 1 and group 2 compared with normal rabbits; however, it decreased in group 3, especially in the endothelial cells. Peroxynitrite determined by nitrotyrosine staining decreased in group 3. Additionally, the arteries of rabbits fed a regular diet with or without simvastatin were investigated. The aorta from simvastatin-treated group showed increase of tone-related basal NO release and eNOS mRNA and decrease of O release. Taken together, upregulation of eNOS and decrease of O treatment were observed in vivo in the process of the sufficient stabilization of atheroma following simvastatin.

Complex stenosis morphology and vasomotor responses to inhibition of nitric oxide synthesis

OBJECTIVE

To assess the relation between coronary vasomotor effects of N(G)-monomethyl-L-arginine (LNMMA) administration and coronary stenosis morphology, length, and severity in patients with stable angina.

DESIGN

In 28 patients (24 male, four female) with coronary artery disease and chronic stable angina, intracoronary normal saline and 4 micromol/min LNMMA were infused for four minutes each, followed by an intracoronary bolus of 250 microg glyceryl trinitrate. Coronary stenoses were classified as concentric (smooth), eccentric (smooth), or complicated (irregular). The diameters of these stenoses and their adjacent reference proximal segments were measured by quantitative angiography.

RESULTS

During LNMMA infusion a significantly larger proportion of complicated stenoses than concentric and eccentric stenoses constricted by >/= 5% (p < 0.01) and the magnitude of vasoconstriction was greater in complicated than in concentric and eccentric stenoses (p < 0.05). For complicated stenoses the magnitude of constriction (in mm) with reference to normal saline was greater than that of the concentric and eccentric stenoses (p < 0.05), whereas concentric and eccentric stenoses constricted similarly. Irrespective of the type of morphology, there was a correlation (p < 0.05) between both the severity and the length of stenoses and the magnitude of vasoconstriction to LNMMA. A similar proportion of concentric, eccentric, and complicated stenoses showed >/= 5% increase in diameter with glyceryl trinitrate, and the magnitude of the response was similar in the three groups.

CONCLUSIONS

In patients with coronary artery disease, the response to LNMMA is greater when stenosis morphology is complex, indicating greater nitric oxide activity. This provides further evidence that plaques with complex morphology are in an active state.

50th anniversary historical article. Acute coronary syndromes: the degree and morphology of coronary stenoses

In 110 patients with either stable or unstable angina, the morphology of coronary artery lesions was qualitatively assessed at angiography. Each obstruction reducing the luminal diameter of the vessel by 50% or greater was categorized into one of the following morphologic groups: concentric (symmetric narrowing); type I eccentric (asymmetric narrowing with smooth borders and a broad neck); type II eccentric (asymmetric with a narrow neck or irregular borders, or both); and multiple irregular coronary narrowings in series. For the entire group, type II eccentric lesions were significantly more frequent in the 63 patients with unstable angina (p less than 0.001), whereas concentric and type I eccentric lesions were seen more frequently in the 47 patients with stable angina (p less than 0.05). Type II eccentric lesions were also present in 29 of 41 arteries in patients with unstable angina compared with 4 of 25 arteries in those with stable angina (p less than 0.0001) in whom an "angina-producing" artery could be identified. Therefore, type II eccentric lesions are frequent in patients with unstable angina and probably represent ruptured atherosclerotic plaques or partially occlusive thrombi, or both. A temporary decrease in coronary perfusion secondary to these plaques with or without superimposed transient platelet thrombi or altered vasomotor tone may be responsible for chest pain in some of these patients with unstable angina.