Endothelial and metabolic characteristics of patients with angina and angiographically normal coronary arteries: comparison with subjects with insulin resistance syndrome and normal controls.

OBJECTIVES: This study was performed to characterize the endothelial and metabolic alterations of patients with angina and angiographically normal coronary arteries ("cardiac" syndrome X [CSX]) compared with subjects with insulin resistance syndrome ("metabolic" syndrome X [MSX]) and normal controls. BACKGROUND: Previous studies have found high endothelin-1 levels, impaired endothelium-dependent vasodilation and insulin resistance in patients with angina pectoris and angiographically normal coronary arteries. On the other hand, subjects with insulin resistance syndrome have shown high endothelin-1 levels. METHODS: Thirty-five subjects were studied: 13 patients with angina pectoris and angiographically normal coronary arteries (CSX group); 9 subjects with insulin resistance syndrome (MSX group) and 13 normal controls. All subjects received an acute intravenous bolus of insulin (0.1 U/kg) combined with a euglycemic clamp and forearm indirect calorimetry. Endothelin-1 levels, nitrite/nitrate (NOx) levels, end products of nitric oxide metabolism, glucose infusion rates (index of insulin sensitivity) and their incremental areas (deltaAUCs [area under curves]) were measured during this period. RESULTS: Basal endothelin-1 levels were higher in CSX and MSX groups than in normal controls (8.19 +/- 0.46 and 6.97 +/- 0.88 vs. 3.67 +/- 0.99 pg/ml; p < 0.01), while basal NOx levels were significantly higher in MSX group than in CSX and normal controls (36.5 +/- 4.0 vs. 24.2 +/- 3.3 and 26.8 +/- 3.2 mol/liter, p < 0.05). After insulin administration, the deltaAUCs of NOx (p < 0.05) were lower in CSX group than in MSX and normal controls, and the deltaAUCs of endothelin-1 were lower in group CSX than in normal controls. Glucose infusion rate was significantly lower in CSX and MSx groups than in normal controls (p < 0.01), suggesting that in both CSX and MSX groups insulin resistance is present. A positive correlation was found between the deltaAUCs of nitric oxide and the AUCs of glucose infusion rate. CONCLUSIONS: Blunted nitric oxide and endothelin responsiveness to intravenously infused insulin is a typical feature of patients with angina pectoris and angiographically normal coronary arteries and may contribute to the microvascular dysfunction observed in these subjects.     

Brachial artery flow-mediated vasodilation in patients with cardiac syndrome X

Cardiac syndrome X (CSX) differs from coronary artery disease (CAD) and is characterized by angina, positive stress test, and patent coronary arteries. The probable mechanism is a microvascular disorder associated with endothelial dysfunction. In this study, brachial artery flow-mediated vasodilation was used as well as the endothelin-1 assay to assess endothelial function in patients with cardiac syndrome X (CSX), coronary artery disease (CAD), and healthy controls. All subjects underwent a 2-step brachial artery flow-related vasodilatation test. Serum endothelin-1, one of the most potent constricting factors, was measured for all participants. Patients with CSX had a lower brachial artery dilation ratio than controls but higher than that of CAD patients. Control subjects and CSX patients had higher endothelin-1 levels than CAD patients. CSX patients were found to have worse endothelial function than healthy volunteers, but patients with CAD had even worse endothelium function than CSX patients.     

Cardiac syndrome X in women: the role of oestrogen deficiency

Cardiac syndrome X (CSX), defined as typical exertional chest pain, a positive response to stress testing, and normal coronary arteriograms, encompasses different pathogenic subgroups. Both cardiac and non-cardiac mechanisms have been suggested to play a pathogenic role, and it has been shown that the syndrome is associated with myocardial ischaemia in at least a proportion of patients. Radionuclide myocardial perfusion defects, coronary sinus oxygen saturation abnormalities and pH changes, myocardial lactate production and stress-induced alterations of cardiac high energy phosphate have been reported in CSX patients, suggesting an ischaemic origin for their symptoms. Microvascular abnormalities often caused by endothelial dysfunction appear to be responsible for myocardial ischaemia in these patients. CSX is more prevalent in women than in men, and the majority of women with CSX are peri- or post-menopausal. Thus oestrogen deficiency has been suggested to have a pathogenic role in CSX. Additional factors such as abnormal pain perception may also contribute to the genesis of chest pain in patients with angina and normal coronary angiograms. The management of this syndrome is difficult because of the heterogeneity of pathogenic mechanisms and uncertainties as to its origin. This article discusses the problem of CSX in women, the potential pathogenic role of oestrogen deficiency, and practical clinical management.     

Cardiac syndrome X.

This article describes: 1) situations that can cause angina pectoris in the absence of formal atherosclerotic obstructive lesions: a) those that cause non-atherosclerotic coronary obstructions and b) those with normal coronary angiography, among them cardiac syndrome X (CSX); 2) the various definitions of CSX, particularly the definition of true CSX by Bertrand et al.: effort anginal pain plus positive exercise test, plus a second demonstration of myocardial ischemia (e.g. abnormal myocardial scintigraphy), plus normal coronary angiography; 3) the different pathogenic mechanisms that have been proposed for CSX, which suggest that the problem is mainly at the microvascular level; 4) the excellent survival prognosis of CSX; 5) the lack of any standard therapeutic protocol.     

14C尿素呼气试验检测幽门螺杆菌感染在老年人疾病诊断中的应用探讨

目的探讨14C尿素呼气试验(urea breath test,UBT)检测幽门螺杆菌(H.pylori)感染在老年人消化道疾病、急性冠脉综合征(ACS)诊断中的意义.方法用自身对照的方法比较30例消化道疾病患者内镜活检快速尿素酶试验H.pylori阳性与UBT阳性、血清学阳性情况,20例血清学H.pylori抗体阳性的ACS患者与UBT、内镜阳性情况.结果消化道疾病组内镜活检H.pylori阳性者做UBT的阳性率为93%,血清学阳性95%,血清学H.pylori阳性的ACS者做UBT的阳性率为50%,不稳定心绞痛者症状消失10 d后查内镜H.pylori阳性率为42%.结论用UBT诊断老年人与H.pylori感染有关的疾病安全可靠.     

Recovery-phase patterns of ST segment depression in the heart rate domain cannot distinguish between anginal patients with coronary artery disease and patients with syndrome X

Continuous plots of ST segment depression related to heart rate during exercise and recovery (heart rate recovery loops) can differentiate patients with coronary artery disease from clinically normal subjects. To assess whether this method can also distinguish patients with angina and coronary artery disease from those with syndrome X (angina, positive exercise tests, and normal coronary arteries), we studied 75 patients with coronary artery disease and 30 patients with syndrome X. The average heart rate recovery loops for coronary artery disease and syndrome X patients followed similar counterclockwise loop rotations. Individual data analysis, however, showed that in coronary artery disease patients the loop rotation was counterclockwise in 66 (88%) and intermediate in nine (12%), while none had a clockwise loop nine (30%), and intermediate in nine (30%). Thus heart rate recovery loops cannot distinguish patients with angina and coronary artery disease from those with syndrome X.     

Plasma asymmetric dimethylarginine and L-arginine levels in patients with cardiac syndrome X

BACKGROUND: Endothelial dysfunction and subsequently impaired microvascular circulation are the leading mechanisms in the development of cardiac syndrome X (CSX). The study evaluated the plasma asymmetric dimethylarginine (ADMA) and L-arginine levels of the patients with CSX and the control group and aimed to determine any relationship between these parameters and epicardial coronary blood flow and myocardial tissue perfusion. METHODS: The study group consisted of 32 patients (mean age: 52.6+/-9.4 years, 14 men) with typical exertional angina, positive exercise test, and normal coronary arteries diagnosed as CSX. Plasma ADMA, L-arginine levels, and L-arginine/ADMA ratio were compared with the values of the control group, which consisted of 17 age-matched and sex-matched individuals. Concentrations of L-arginine and ADMA were measured by high-performance liquid chromatography. In all the coronary territories, epicardial coronary flow was assessed by thrombolysis in myocardial infarction (TIMI) frame count (TFC) method, and tissue level perfusion, by myocardial blush grade (MBG) method. A MBG score less than 3 was considered an impaired myocardial perfusion, and a MBG score of '3' in all the coronary territories, a normal myocardial perfusion. RESULTS: The plasma ADMA levels of the study group were higher than those of the control group (0.83+/-0.38 vs. 0.55+/-0.44 micromol/l, P=0.03), whereas plasma L-arginine levels were similar in both groups (70.25+/-21.89 vs. 76.09+/-18.22 micromol/l, P=0.36), resulting in a diminished L-arginine/ADMA ratio in the patients with CSX [82.3 (60.2-128.8) vs. 242.2 (76.7-386.4), P=0.003]. In CSX group, the patients with abnormal myocardial tissue perfusion had increased plasma ADMA levels compared with those with normal tissue perfusion (0.99+/-0.37 vs. 0.69+/-0.34 micromol/l, P=0.02), whereas plasma L-arginine levels were similar in both groups. No correlations were observed between TFC values and plasma ADMA, L-arginine levels, and L-arginine/ADMA ratio. Plasma ADMA levels, however, were negatively correlated with MBG scores (r=-0.349, P=0.014). CONCLUSION: We have shown for the first time that in the patients with CSX, increased plasma ADMA levels might be associated with impaired myocardial tissue perfusion when assessed by MBG.     

Combination of Variant and Microvascular Angina

Prinzmetal's variant angina (VA) and cardiac syndrome X (CSX) are two distinct, usually easily recognizable, forms of angina syndromes, caused by epicardial spasm, usually responsible for transient transmural myocardial ischemia at rest and by coronary microvascular dysfunction (CMVD), usually responsible for effort induced subendocardial ischemia, respectively. In this article we report clinical evidence in three patients of the simultaneous occurrence of angina episodes typical of both VA and CSX, suggesting that common pathogenetic factors may be responsible for clinical manifestations both of functional macrovascular and microvascular coronary artery abnormalities in some angina patients. Copyright © 2009 Wiley Periodicals, Inc.     

Cardiac syndrome X: a critical overview and future perspectives

The classic definition of cardiac syndrome X (CSX) seems inadequate both for clinical and research purposes and should be replaced with one aimed at including a sufficiently homogeneous group of patients with the common plausible pathophysiological mechanism of coronary microvascular dysfunction. More specifically, CSX should be defined as a form of stable effort angina, which, according to careful diagnostic investigation, can reasonably be attributed to abnormalities in the coronary microvascular circulation.     

Cardiac syndrome X and endothelial dysfunction: new concepts in prognosis and treatment

Cardiac syndrome X (CSX), or angina with no flow-limiting stenosis on coronary angiogram, has been regarded as a condition with an excellent prognosis despite variable symptomatic improvement. Newer data show that patients with CSX with endothelial dysfunction have an increased risk for future adverse cardiac events. Current hypotheses of CSX pathophysiology emphasize a dysfunctional vascular endothelium that leads to microvascular ischemia. Treatments that target improving endothelial function, such as statins, angiotensin-converting enzyme inhibitors, estrogen, and lifestyle modification, are promising additions to treatment regimens for CSX. The goal of this article is to provide information for improved diagnosis, risk stratification, and therapy for the population with CSX.     

Cardiac syndrome X: Relation to microvascular angina and other conditions

Cardiac syndrome X (CSX) describes patients with angina-like chest pain, positive stress ischemia, and nonobstructive coronary angiograms. Microvascular angina (MVA) is an etiologic mechanism in women with cardiac symptoms and abnormal vascular dysfunction without obstructive coronary artery disease, although not all patients with MVA show detectable ischemia. CSX is more prevalent in women than men, with an average age in the mid-to-late 50s. Many additional cardiac and noncardiac mechanisms have been proposed for CSX over the past three decades. The uncertainty and inconsistency of data for determining diagnosis and causality along with the unusual response to traditional antianginal treatment hinder the development of effective treatment strategies. Many researchers believe that women with MVA do not have a benign prognosis and may be better classified as intermediate risk. Better understanding of the disease characteristics; its relation to traditional and novel risk factors, especially in women; identification of reliable, accurate diagnostic procedures; and a comprehensive preventive therapeutic approach are all important for optimizing management strategy for MVA and CSX.     

Sympathetic skin response and RR interval variation in patients with cardiac syndrome X

Sympathetic skin response (SSR) and R-R interval variation (RRIV) are noninvasive electrophysiological tests used in the assessment of sympathetic and parasympathetic nervous system function, respectively. Cardiac syndrome X (CSX) is usually diagnosed in the presence of typical angina pectoris, a positive response to exercise testing, and normal-appearing coronary angiograms without spasm induced by hyperventilation or ergonovine. Alterations of autonomic nervous system control of cardiac function have been described in CSX. The aim of the study was to investigate autonomic nervous system function in patients with CSX. Nine patients with CSX (2 men, 7 women) and healthy controls (11 men, 19 women) were included in the study. SSRs were recorded from palm of hands by stimulation of the median nerve. RRIV recordings were taken from precordium during both rest position (R%) and deep inspiration of 6 times per minute (D%). In addition D% - R% and D%/R% values were calculated. SSR amplitude of CSX was lower than in controls (3.64 +/-4.78 vs 6.36 +/-3.4 mV, p = 0.017). There was no difference between groups for SSR latency values (CSX: 1,366 +/-99; controls: 1,383 +/-85 msec). Also, R% (CSX: 13.04 +/-6.3; controls: 12.92 +/-3.91) and D% (CSX: 16.63 +/-8.88; controls: 21.43 +/-7.3) values were similar in the 2 groups. However, D% - R% (CSX: 3.59 +/-10.11; controls: 8.51 +/-7.01) and D%/R% (CSX: 1.45 +/-0.93; controls: 1.78 +/-0.69) values were slightly lower in patients with CSX but were not statistically significant. A linear correlation was found between SSR amplitude and D%/R% (r = 0.336, p = 0.036). The authors conclude that, among patients with CSX, there are alterations of autonomic nervous control of skin as well as of other organs (ie, heart). SSR and RRIV testing can be done easily in the neurophysiology laboratory to assess the sympathetic and parasympathetic system, respectively.     

Microcirculatory dysfunction in cardiac syndrome X: role of abnormal blood rheology

Objective: Cardiac syndrome X (CSX) is of clinical interest, yet the underlying pathophysiological mechanisms have not been fully elucidated. It is well known that elevated blood viscosity and red blood cell (RBC) aggregation can adversely affect microcirculatory blood flow. The present study was designed to explore whether CSX is associated with abnormalities of blood rheology. Methods: Blood samples were obtained from 152 adult angina patients undergoing diagnostic coronary angiography; geometric and flow‐velocity data were obtained. Rheologic measurements were performed in a blinded manner; 21 subjects were later identified with CSX. Hemorheologic and clinical laboratory data were compared to 21 age‐ and gender‐matched healthy controls. Results: CSX patients had markedly abnormal blood rheology: (1) higher RBC aggregation and aggregability as judged by erythrocyte sedimentation rate and Myrenne indices at stasis and low shear (p < 0.001) and (2) elevated hematocrit‐corrected blood viscosity, plasma viscosity (p < 0.001), and yield stress (p < 0.01). White blood cell counts and high‐sensitivity C‐reactive protein levels were significantly elevated in CSX; coronary‐flow velocities were below normal. Conclusions: Abnormal hemorheologic parameters exist in subjects with CSX and may contribute to the pathophysiology of the disease, presumably via adversely affecting blood flow in the coronary microcirculation. Therapeutic measures aimed at normalizing blood rheology and hence microcirculatory flow should be explored.     

Overview of gender aspects of cardiac syndrome X

Cardiac syndrome X, a condition defined by the presence of angina-like chest pain, a positive response to stress testing and normal coronary arteriograms, has been shown to occur in approximately 20--30% of angina patients undergoing coronary arteriography. The prevalence of syndrome X is significantly higher in women compared to men. In the majority of patients with chest pain and normal coronary arteriograms, symptoms are likely to be non-cardiac in origin. However, myocardial ischaemia may be the pathogenic mechanism in a proportion of syndrome X patients. Indeed, the clinical characteristics, the ischaemic electrocardiographic findings and the presence of myocardial perfusion defects during stress testing are similar in syndrome X and coronary artery disease patients. Moreover, coronary sinus oxygen saturation abnormalities and pH changes, as well as myocardial lactate production and alterations of cardiac high energy phosphate are seen during stress testing in patients with syndrome X and appear to endorse an ischaemic origin of symptoms in at least a proportion of these individuals. Patients with chest pain and normal coronary arteries have abnormal vasodilatory coronary blood flow responses and an increased sensitivity of the coronary microcirculation to vasoconstrictor stimuli (microvascular angina). Microvascular endothelial dysfunction appears to be responsible for these coronary microcirculation abnormalities. Given the high prevalence of peri- and post-menopausal women in cardiac syndrome X, it has been hypothesized that oestrogen deficiency may play a major role in the pathogenesis of this condition. Oestrogen vasoactive properties involve endothelium-dependent effects and, in postmenopausal women, forearm vasodilatation induced by acetylcholine is potentiated by the acute local administration of intravenous oestradiol. This suggests that endothelium-dependent responses in the peripheral circulation may be modulated by steroid hormones. Impairment of endothelial function in post-menopausal women with syndrome X has been reported by various groups and it could be hypothesized that oestrogen deficiency may contribute to the development of microvascular angina through endothelial dysfunction and that exogenous oestrogen administration may have a beneficial effect in syndrome X patients. This article reviews current knowledge regarding the role of oestrogen deficiency in the pathogenesis of syndrome X and the potential therapeutic role of oestrogen replacement therapy in women with chest pain and normal coronary arteriograms     

Effects of trimetazidine on clinical symptoms and tolerance of exercise of patients with syndrome X: a preliminary study

BACKGROUND: Trimetazidine diminishes angina and improves tolerance of exercise of patients with ischemic heart disease, and has no influence on blood pressure and heart rate. OBJECTIVE: To determine the effect of trimetazidine on angina symptoms and exercise tolerance in patients with syndrome X. METHODS: We investigated the effect of trimetazidine on the clinical symptoms and tolerance of exercise of 34 patients (20 women and 14 men, aged 32-60 years) with syndrome X (angina pectoris, positive result of exercise test, and normal coronary angiogram). The exercise test was performed before initiation of oral administration of trimetazidine therapy (20 mg three times a day) and 1 and 6 months thereafter. RESULTS: We obtained negative results of exercise treadmill tests for four patients (11.76%) after 1 month and five patients (14.71%) after 6 months of trimetazidine treatment. There was also a decrease in the incidence of effort angina after 6 months of treatment (26 patients or 76.47% before treatment versus 13 patients or 38.23% after 6 months of treatment). The drug had no significant influence on the heart rate and blood pressure. The duration for which patients could exercise was significantly prolonged by 1 month (652.9 +/- 206.2 versus 563.4 +/- 190.4 s, P = 0.0047) and 6 months (650.3 +/- 207.8 s, P = 0.0094) of treatment with trimetazidine. CONCLUSION: Treatment with trimetazidine decreases signs of angina during exercise and improves tolerance of exercise of patients with syndrome X.     

Haemorheologic studies in patients with reduced coronary vasodilator capacity but normal coronary angiogram (syndrome X)

The cause of syndrome X, i.e. typical angina, positive exercisetest, normal coronary angiogram, normal resting cardiac function,but reduced coronary vasodilator capacity is still unknown.The purpose of the study was to investigate blood fluidity asa possible cause of syndrome X. Haematocrit, plasma viscosity,erythrocyte aggregation, and erythrocyte deformability wereexamined in 14 patients with syndrome X (group 1), 24 patientswith typical angina, positive exercise test, but normal coronaryvasodilator capacity (group 2), and 37 patients with atypicalchest pain and normal coronary arteries (control group). Coronaryvasodilator capacity was determined by the argon method. Comparedwith normals, patients with syndrome X showed an elevated plasmaviscosity (1.31 ±0.05 mPas vs l.26±0.04 mPas,2P>001), an elevated erythrocyte photometric aggregationindex (141 ±27% vs 100 ±23%, 2?>001) and areduced erythrocyte filterability (0.51 ±0.12 vs 0.66± 0.09, 2P > 0.01). Significant differences in thehaemorheologic parameters between group 1, group 2 and the controlgroup, however, were not detected. Multiple regression analysisdid not reveal a significant relationship between coronary vasodilatorcapacity and the haemorheologic parameters tested. The datasuggest that the reduction in coronary vasodilator capacityin patients with syndrome X cannot be attributed to haemorheologicalterations.     

Dipyridamole body surface potential mapping: noninvasive differentiation of syndrome X from coronary artery disease

Up to 20% to 30% of patients with angina and abnormal stress test have normal coronary arteries at angiography or syndrome X (Sy X). We tested whether body surface potential mapping (BSPM) with intravenous dipyridamole could differentiate patients with Sy X from patients with coronary artery disease (CAD). We compared the effects of intravenous dipyridamole (0.28 mg/kg over 4 min) on BSPM in 17 healthy volunteers (controls) and in 2 groups of patients with angina and abnormal ergometric tests who were referred for angiography: 27 patients with obstructive disease (> or =70% diameter stenosis) in the CAD group, and 17 patients with Sy X. Control subjects were easily differentiated from patients with CAD or Sy X by markedly smaller baseline BSPM DeltaST-T < or = LSD departure areas (P <.001), but the Sy X and CAD groups had similar ST-T departure areas. The average potential integral difference after dipyridamole (APID) differentiated Sy X and CAD patients: the mean APID increased in patients with Sy X and trended negative in the CAD group. The APID(20%-40%) (integrated over 20% to 40% of the ST-T interval) mean value was 0.59 +/- 0.67 microVs in the Sy X group and -0.18 +/- 0.59 microVs in the CAD group (P <.01). At a threshold APID(20%-40%) > 0.17 microVs, the sensitivity and specificity for Sy X was 71% and 78%, respectively; the area under the receiver operating characteristic curve was 0.79 (95% CI 0.64, 0.93). Dipyridamole BSPM is a promising noninvasive diagnostic modality to differentiate patients with Sy X from those with CAD.     

幽门螺杆菌与冠心病的关系

目的：探讨幽门螺杆菌（HP）与冠心病（CHD）的关系。方法：268例冠心病不稳定型心绞痛患者均进行14C试验,根据检查结果分为HP阳性组（114例）和HP阴性组（159例）,每组患者均接受冠心病不稳定型心绞痛的标准治疗方案,分别观察两组患者3个月内心绞痛发生需要入院的情况与一年内心肌梗死发生率。结果：3个月内,两组因心绞痛再入院率无显著差异（χ2=0.76,P〉0.05）;一年内HP阳性组心肌梗塞发生率明显高于HP阴性组（5.3%比0.6%,P〈0.05）。结论：幽门螺杆菌与冠心病不稳定型心绞痛患者发生心肌梗死有一定关系,但是具体作用机制还需要进一步探讨。     

Helicobacter pylori reinfection rate 3 years after successful eradication

BACKGROUND AND AIM: Helicobacter pylori (HP) infection is one of the most prevalent human infections and has been implicated as a predisposing factor in gastric cancer, chronic active gastritis, duodenal ulcer, gastric ulcer and gastric lymphoma. Reinfection after successful eradication is quite uncommon in adults. In the only study carried out in Iran, a reinfection rate of 19.1% after 1 year has been reported. We studied the rate of reinfection 3 years after successful HP eradication. METHODS: All patients who had undergone HP eradication 3 years before the study and had successful eradication verified by a negative (14)C urea breath test (UBT) 1 year after eradication were invited to complete a questionnaire and undergo another UBT. In addition, spouses and the offspring of those testing positive were offered an UBT. RESULTS: Ninety-eight patients were enrolled (49% male). Mean age was 44 +/- 13 years (range: 18-75 years). Twenty patients (20.4%) had a positive UBT. Epigastric burning (25%vs 69%) and pyrosis (50%vs 67%) were seen less commonly in those who were HP free at 3 years compared to those who tested positive for HP. CONCLUSIONS: According to our data, in our region the HP reinfection rate is 20.4% 3 years after successful eradication.     

A combination of electrocardiographic methods represents a further step toward the noninvasive identification of patients with syndrome X.

Identification of patients with angina but normal coronary arteriograms (syndrome X) using noninvasive means would be desirable. The ability of four established exercise electrocardiographic methods to identify angina patients with and without coronary artery disease was compared with that of a method based on a combination of the above (combined method). A treadmill score, a multivariate method, the ST segment recovery loop, the ST/heart rate adjustment, and the combined method were applied to 112 patients who had typical exertional angina and positive exercise tests (greater than 1 mm ST segment depression); 90 had documented coronary artery disease and 22 had syndrome X. The combined method and the treadmill score had a significantly higher diagnostic accuracy (both 81%, as 91 of the 112 patients were correctly identified by both methods) than the multivariate (66%) and ST segment recovery loop (64%) methods (p less than 0.05). The ST/heart rate adjustment had a lower sensitivity for syndrome X than any other method (1 of 22). Thus methods that involve the assessment of both ST and non ST segment variables have greater accuracy in separating syndrome X and coronary artery disease patients than methods relying more heavily on ST segment changes.