Improved accuracy of the exercise electrocardiogram in detection of coronary artery and three-vessel coronary disease

The study objective was to assess the widespread applicability of ST/HR slope for the modified Bruce exercise test using a computerized electrocardiogram (ECG); compare the usefulness of the ST/HR slope with standard ECG criteria in detection of coronary artery disease (CAD) and identification of three-vessel or left main CAD; and then develop a new, modified ST/HR score (MSHS) for improving the diagnostic accuracy of ST/HR slope. The studies were retrospective and prospective in design, conducted in referral-based cardiology clinics at a national cardiovascular center. A selected sample of 142 patients underwent exercise ECG and coronary angiography, as did a normal control group of 402 patients who were apparently free from CAD. Sixty three other patients who underwent coronary angiography were also studied prospectively. No limitations of medical treatment were exacted for the test except digitalis treatment. Linear regression analysis, from which ST/HR slope was derived, was done with seven measurements of HR and ST displacement at 60 ms from J point in leads a VF and V5 during 6 min before the end of exercise. MSHS was derived from a multiple regression model with peak HR (% maximum HR), ST index (ST depression + ST slope), and ST/HR slope. Although the usual ST criteria (sensitivity = 63 percent, specificity = 73 percent), ST index (71 percent, 80 percent), and ST/HR slope (70 percent, 97 percent) were equally accurate in detection of CAD, MSHS showed significantly improved sensitivity (88 percent) with similar specificity (81 percent). In identification of three-vessel or left main CAD, when compared with other criteria, ST/HR slope and MSHS provided improved diagnostic accuracy: sensitivity (74 and 78 percent, respectively), specificity (88 and 93 percent) and overall test accuracy (85 and 89 percent). The improved accuracy of ST/HR slope and MSHS was prospectively validated in 63 other patients. ST/HR slope was applicable to computerized ECG data for the standard treadmill test, and showed improved accuracy in detection of three-vessel or left main CAD. The new, modified ST/HR score more accurately predicted not only the presence but also the severity of CAD.     

Improved exercise performance in persons with stable angina pectoris receiving diltiazem

The effects of diltiazem, a calcium antagonist drug, were compared with those of placebo on exercise performance during a series of symptom-limited upright exercise tests. Ten patients with chronic stable angina were studied over a period of 7 weeks. The drug was administered in a random double-blind fashion and was evaluated at increasing dose levels of 120, 180 and 240 mg/day. Diltiazem was effective in increasing the total duration of exercise (p <0.001) and the time to the first onset of angina (p <0.02) and to the first appearance of 1 mm of S-T depression (p <0.02). These effects were most marked at the highest dose level of diltiazem. The heart rate was reduced at rest (p <0.05) and during submaximal exercise (p <0.001). There was a reduction in diastolic blood pressure during submaximal exercise (p <0.04) but no change in systolic pressure. Pressure-rate product was significantly reduced at submaximal (p <0.001) but not maximal exercise. The reduction in pressure-rate product is postulated as the mechanism by which diltiazem enhances duration of exercise. There was no reduction in electrocardiographic evidence of myocardial ischemia at peak exercise by either clinical observation or computer analysis of spatial electrocardiographic variables. Five of the six patients who continued to take the drug maintained or improved their exercise performance on follow-up study 8 to 10 months later.     

ST segment analysis in 24-hour long-term ECG in patients with stable angina pectoris and angiographically detected coronary sclerosis

ST-segment analysis on 24-hour Holter ECG was performed in 64 patients with angiographically proven coronary artery disease, a positive exercise test and chronic stable angina. During 125 days of recording, 494 episodes of transient ST-segment depression were observed, at an average of 4.0 +/- 3.7 episodes (1-13 episodes, median: 3 episodes) per day. The duration of ST depression per episode was 13.2 +/- 14.4 min (1-90 min; median: 8 min). No episodes of ST-elevation were observed. Only 27 (5.5%) ischemic episodes occurred during the night, between midnight and 6:00 a.m., but they were frequently observed during the morning hours between 7:00 and 12:00 a.m. Nearly all episodes of ischemia were preceded by an increase in heart rate. However, heart rate at the onset of significant ST-segment depression was significantly lower during Holter monitoring than during exercise test (p less than 0.001); this indicates that factors additional to the increase in myocardial demand might be relevant for transient myocardial ischemia during daily life. 382 of the 494 episodes (77.3%) of ischemia were asymptomatic; heart rate at the onset of ST-segment depression was similar in symptomatic and asymptomatic episodes; however, in asymptomatic episodes, maximal heart rate was significantly lower (p less than 0.001) and the duration of the episodes significantly longer (p less than 0.001). The percentage of asymptomatic episodes was very high in patients with one-vessel disease, whereas the duration and amount of ST-segment depression, as well as heart rate, at the onset of ischemia, were not dependent on the extent of coronary artery disease.     

Reactivity of proximal and distal angiographically normal and stenotic coronary segments in chronic stable angina pectoris

To assess whether vasoreactivity of significant coronary stenosis (greater than 50% intraluminal diameter reduction) and that of angiographically normal coronary segments differs in proximal and distal locations, 53 patients (40 men, 13 women, mean +/- standard deviation age 55 +/- 11 years) with chronic stable angina and angiographically documented coronary artery disease were studied. While abstaining from antianginal therapy, all 53 patients underwent coronary arteriography before and after 1 mg of intracoronary isosorbide dinitrate and 21 of the 53 also before and after 20 to 30 micrograms intracoronary ergonovine. Computerized quantitative angiography was used to assess changes in the intraluminal diameter of 126 normal coronary segments (63 proximal, 63 distal) and 43 significant coronary stenoses. Nitrates dilated proximal normal coronary segments by 7.4 +/- 1.2% and distal normal coronary segments by 15 +/- 1.7% (p less than 0.01). Significant proximal coronary stenoses dilated by 11 +/- 2.5% and distal stenoses by 23 +/- 2.8% (p less than 0.01) after nitrates. Ergonovine reduced the diameter of proximal normal coronary segments by 9.3 +/- 1.7% and that of normal distal segments by 15.5 +/- 1.4% (p less than 0.01). Proximal stenoses constricted by 11 +/- 2.2% and distal stenoses by 18.4 +/- 2.8% (p = 0.06). Analysis of segments showed that nitrates dilated 19 of 63 (30%) proximal normal segments by (greater than or equal to 10%), 31 of 63 (49%) distal (p less than 0.05) and 21 of 43 (49%) stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Correlation of the exercise ST/HR slope with anatomic and radionuclide cineangiographic findings in stable angina pectoris

A rate-related change in ST-segment depression with exercise (ST/HR slope) of 6.0 microV/beat/min or more has been proposed as an accurate predictor of 3-vessel coronary artery disease (CAD). To further assess the accuracy and functional correlates of this method, exercise electrocardiograms were compared with radionuclide rest and exercise left ventricular (LV) ejection fraction (EF) and angiography in 35 patients with stable angina. The ST/HR slope was significantly increased in patients with 3-vessel CAD. An ST/HR slope of 6.0 or more identified 3-vessel CAD with a sensitivity of 89% and specificity of 88%. The predictive value for 3-vessel CAD was 73% owing to the presence of 3 false-positive slopes. The patients from whom these slopes were derived had functionally severe 2-vessel CAD, with an average decrease in exercise LVEF of 13%. Two of these 3 had additional left main CAD and the third has unsuspected additional aortic regurgitation. For the entire group, the exercise ST/HR slope was linearly related to the exercise change in LVEF (r = -0.55, p less than 0.001). Mean exercise change in LVEF for stable angina patients with ST/HR slopes of 4.5 or more was significantly different from that for patients with lower ST/HR slopes (-12 +/- 1% vs + 2 +/- 2%, p less than 0.0001). Thus, the ST/HR slope is both sensitive and specific for the identification of 3-vessel CAD, and high ST/HR slopes in patients with less extensive anatomic disease may predict functionally severe ischemia.     

不稳定型心绞痛患者肌钙蛋白I与心电图ST段变化及冠脉造影的关系探讨

目的探讨不稳定型心绞痛(UAP)患者肌钙蛋白I(cTnI)与心电图ST段移位及冠状动脉病变性质之间的关系.方法对57例UAP患者于心绞痛发作时,发作6、24小时取静脉血2ml,用酶联免疫分析法测血清cTnI浓度,同时做12～18导联心电图,计算ST段缺血性下移或上移情况.57例患者按Judkins法行冠状动脉造影术,按2001年ACC/AHA PCI标准将冠状动脉解剖病变分低危险、中危险、高危险病变,按传统Proudilit狭窄分级法将冠脉狭窄分为Ⅰ～Ⅵ级,分析cTnI与心电图ST段移位及冠状动脉危险病变之间的关系.结果 UAP患者心绞痛发作后6、24小时cTnI明显增高,且24小时cTnI浓度与心电图ST段移位相关(r=0.59,P＜0.05),病变愈复杂(中、高危险病变)狭窄程度愈重(＞50%以上狭窄),cTnI愈高.结论 cTnI可预测UAP患者的预后,cTnI愈高,心电图ST段移位愈大,冠脉危险病变愈重.     

Lipid markers, coronary score and coronary artery disease of stable angina pectoris type

In 120 middle aged male patients with stable angina pectoris and coronarographically documented CAD all examined serum lipid markers differed significantly in comparison with 30 male subjects with vertebro-cardial syndrome and negative coronaro-angiogram (p less than 0.001). The low mean overall coronary score values (4.017 +/- 2.376) reflect the low extent of the coronary atherosclerosis. The coronary score values were significantly positively correlated to the serum levels of cholesterol, triglyceride, LDL-cholesterol, VLDL-cholesterol and negatively correlated to the serum concentration of HDL-cholesterol and HDL-cholesterol/total cholesterol ratios in all examined subjects (CAD and n-CAD groups) (p less than 0.001). In contrast, no significant correlation between coronary score and the examined lipid markers was exhibited in the CAD group of patients when comparing subjects with low and middle coronary score values. According to our results the ratio HDL-cholesterol/total cholesterol represents the best single indicator of the presence and also discriminator of the severity of the coronary athero-sclerosis in the patients with stable angina pectoris.     

Body surface distributions of ST segment changes after exercise in effort angina pectoris without myocardial infarction

To investigate the sites of exercise-induced ST segment changes on the body surface in effort angina pectoris without myocardial infarction, we performed 87-lead ECG mapping in 61 patients before and 1.5 and 5 minutes after treadmill exercise. ST segment depression most often occurred in the left anterior chest leads and ST segment elevation developed mainly in the right upper chest leads. There was a good correlation between the number of lead points that showed ST segment depression (nSTd) and the number of those that showed ST segment elevation (nSTe) 1.5 minutes after exercise (r = 0.92). From 1.5 to 5 minutes after exercise, changes in nSTd for individual patients correlated well with changes in nSTe (r = 0.89). It was suggested that the ST segment elevation observed in this study directly reflected the subendocardial ischemia of the left ventricle. In patients with one-vessel disease (n = 32), there was wide overlap in the sites of ST segment changes among patients with left anterior descending artery disease (n = 19), those with left circumflex artery disease (n = 6), and those with right coronary artery disease (n = 7). These findings should lead to a better understanding of exercise-induced ST segment changes for the diagnosis of coronary artery disease.     

不稳定型心绞痛患者肌钙蛋白Ⅰ与心电图ST段变化及冠脉造影的关系探讨

目的　探讨不稳定型心绞痛 (UAP)患者肌钙蛋白 I(c Tn I)与心电图 ST段移位及冠状动脉病变性质之间的关系。方法　对 5 7例 U AP患者于心绞痛发作时 ,发作 6、2 4小时取静脉血 2 ml,用酶联免疫分析法测血清 c Tn I浓度 ,同时做 12～ 18导联心电图 ,计算 ST段缺血性下移或上移情况。5 7例患者按 Judkins法行冠状动脉造影术 ,按 2 0 0 1年 ACC/AHA PCI标准将冠状动脉解剖病变分低危险、中危险、高危险病变 ,按传统 Proudilit狭窄分级法将冠脉狭窄分为 ～ 级 ,分析 c Tn I与心电图 ST段移位及冠状动脉危险病变之间的关系。结果　UAP患者心绞痛发作后 6、2 4小时 c Tn I明显增高 ,且 2 4小时 c Tn I浓度与心电图 ST段移位相关 (r =0 .5 9,P<0 .0 5 ) ,病变愈复杂 (中、高危险病变 )狭窄程度愈重 (>5 0 %以上狭窄 ) ,c Tn I愈高。结论　 c Tn I可预测 U AP患者的预后 ,c Tn I愈高 ,心电图 ST段移位愈大 ,冠脉危险病变愈重     

A three-vessel virtual histology intravascular ultrasound analysis of frequency and distribution of thin-cap fibroatheromas in patients with acute coronary syndrome or stable angina pectoris

The frequency and distribution of thin-cap fibroatheromas (TCFA) have important clinical implications. We evaluated the frequency and distribution of TCFA identified by virtual histology intravascular ultrasound (VH-IVUS) in acute coronary syndrome (ACS) and stable angina pectoris (SAP). Preintervention 3-vessel VH-IVUS was performed in 105 patients with ACS and 107 with SAP. The length of left anterior descending artery imaged was 72 +/- 16 mm-54 +/- 12 mm in the left circumflex and 92 +/- 19 mm in the right coronary. VH-IVUS-derived TCFA (VH-TCFA) had a necrotic core > or =10% of plaque area without overlying fibrous tissue in a plaque burden > or =40%. There were 76 ruptured plaques (55 in ACS and 21 in SAP) and 439 VH-TCFA (262 in ACS and 177 in SAP, 2.5 +/- 1.5 vs 1.7 +/- 1.1 TCFA per patient with ACS and with SAP, respectively; p <0.001). Twelve patients with ACS and 1 with SAP had multiple ruptured plaques (p <0.001); 76 patients with ACS and 58 with SAP had multiple VH-TCFA (p = 0.009). Presentation of ACS was the only independent predictor for multiple ruptured plaques (p = 0.013) or multiple VH-TCFA (p = 0.011). Eighty-three percent of VH-TCFA were located within 40 mm of the coronary: 111 < or =10 (25%), 110 from 11 to 20 (25%), 83 from 21 to 30 (19%), and 61 from 31 to 40 mm (14%). The axial distribution of VH-TCFA was similar in patients with ACS and those with SAP and was similar to the axial distribution of ruptured plaques. In conclusion, 3-vessel VH-IVUS imaging showed a higher frequency of VH-TCFA in primary and secondary lesions in patients with ACS compared with those with SAP, but showed a similar clustering of VH-TCFA in the proximal 40 mm of each coronary artery.     

Frequency of ST-segment depression produced by mental stress in stable angina pectoris from coronary artery disease

Physical exertion is a well-documented trigger of transient myocardial ischemia in patients with coronary disease. More recently, studies have shown that mental stress may also be a cause of myocardial ischemia. The purpose of this study was to examine the relationship of physical activities and perceived mental states to myocardial ischemia while patients were going about their normal daily activities. Twenty-eight patients with documented coronary artery disease underwent ambulatory monitoring of the electrocardiogram. Physical activity and perceived mental status were recorded by patients in a diary which was then graded according to intensity of the activity. Analyses of the continuous electrocardiographic recordings were done separately from the analysis of the diaries. The time of each episode of ischemia, the duration of each episode in minutes and the number of episodes in each 24-hour period were calculated. A total of 372 episodes of ST-segment depression occurred in 912 hours of monitoring. Ischemic events occurring during usual physical and usual mental activities were most frequent (36%). Twenty-six percent of ischemic episodes occurred during increased physical activity, but usual mental activities. Interestingly, 22% of the ischemic events occurred at high levels of mental stress, but low physical activity. Ten percent of episodes occurred during sleep. Although the majority of events occurred during usual daily activities, when duration of ischemia was normalized for time spent in each category, increasing physical or mental activity was associated with an increasing duration of ischemia per unit (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Importance of coronary collateral circulation for increased treadmill exercise capacity by nitrates in patients with stable effort angina pectoris

The purpose of this study was to elucidate the mechanism that induces an improvement in exercise capacity by nitrates in patients with stable effort angina pectoris. The study population was composed of 19 patients: group A, 10 patients with chronic stable effort angina who had a well-developed coronary collateral circulation to the potentially ischemic region; group B, 9 patients with chronic stable effort angina who had no collateral circulation to the jeopardized myocardium. Treadmill exercise was performed according to the standard Bruce protocol with and without pretreatment with orally administered 10 mg isosorbide dinitrate. Percent increases (mean +/- SE) in exercise duration were not significantly different between groups A and B (25 +/- 6 vs. 14 +/- 6%). Percent increases in the maximal rate-pressure product tended to be greater in group A than in group B (27 +/- 6 vs. 10 +/- 6%). Percent increases in the rate-pressure product at the onset of angina pectoris were significantly greater in group A than in group B (37 +/- 7 vs. 7 +/- 6%; p less than 0.01). Percent increases in the rate-pressure product at 0.1 mV S-T segment depression were also significantly greater in group A than in group B (26 +/- 6 vs. 1 +/- 5%; p less than 0.01). These results suggest that isosorbide dinitrate dilates epicardial collateral vessels with smooth muscle layers, but fails to dilate the coronary arteries with significant organic stenoses.     

Relation of C-reactive protein to coronary collaterals in patients with stable angina pectoris and coronary artery disease

The heterogeneity in the degree of collateralization among patients with coronary artery disease (CAD) is poorly understood. We sought to determine whether chronic subclinical inflammation is related to coronary collateral development in patients with chronic stable angina pectoris and obstructive CAD. High-sensitivity C-reactive protein (CRP) levels were measured in 177 patients with stable angina pectoris before coronary angiography. Multivariable logistic regression revealed an inverse graded association between CRP and the presence of coronary collaterals (Rentrop grade 1 to 3). Compared with patients in the first CRP tertile, the adjusted odds ratio for the presence of coronary collaterals was 0.70 (95% confidence interval, 0.33 to 1.52; p = 0.45) for patients in the second CRP tertile and 0.33 (95% confidence interval, 0.15 to 0.75; p = 0.008) for patients in the third CRP tertile (p for trend = 0.008). In conclusion, an inverse graded association exists between CRP and the presence of coronary collaterals in patients with stable angina pectoris.     

Silent myocardial ischemia: hemodynamic changes during dynamic exercise in patients with proven coronary artery disease despite absence of angina pectoris

The hemodynamic changes during exercise occurring in 36 patients with proven coronary artery disease (10 without and 26 with previous myocardial infarction) who tolerated the stress test without angina were analyzed and compared with changes observed in a control group of 36 carefully matched patients whose exercise was limited by angina. All patients were exercised to the same extent, reaching a similar rate-pressure product at the end of the stress test (19,508 +/- 4,828 [SD] versus 19,247 +/- 4,117 beats/min X mm Hg [NS] in the study and control groups without prior infarction, and 19,665 +/- 3,950 versus 17,701 +/- 4,600 beats/min X mm Hg [NS] in the respective groups with infarction). In all groups left ventricular end-diastolic pressure increased from rest to exercise (from 18 +/- 4 to 36 +/- 11 and from 13 +/- 5 to 29 +/- 9 mm Hg, respectively, in the study and control groups without prior infarction and from 17 +/- 7 to 32 +/- 13 and from 19 +/- 7 to 36 +/- 9 mm Hg in the respective groups with prior infarction). Left ventricular ejection fraction decreased (from 59 +/- 7 to 50 +/- 15 and from 60 +/- 4 to 52 +/- 9% in the study and control groups without prior infarction and from 54 +/- 9 to 47 +/- 10 and 55 +/- 9 to 50 +/- 4% in the respective groups with prior infarction). Whereas the changes from rest to exercise were highly significant within each group, no significant differences were noted between the corresponding groups. Regional de novo hypokinesia appeared in all patients without prior infarction and in 25 and 22 patients, respectively, of the groups with prior infarction. Thus, under similar physical stress conditions, comparable hemodynamic changes indicative of ischemia are observed in patients with significant coronary artery lesions with or without previous myocardial infarction irrespective of the occurrence of angina. Therefore, angina pectoris cannot be considered a prerequisite for hemodynamically significant ischemia during exertion.     

运动训练对老年稳定型心绞痛患者运动耐量的影响

目的 探讨运动训练对老年稳定型心绞痛患者运动耐量的影响. 方法 60例老年稳定型心绞痛患者随机分为运动训练组(n=30)和常规治疗组(n=30),同时接受12周相同的冠心病药物治疗,运动训练组同时给予运动训练.用平板运动试验和6 min步行试验评估运动耐量. 结果 6 min步行距离与平板运动代谢当量显著相关(r＝0.816,P＜0.01);运动训练组和常规治疗组6 min步行距离较治疗前明显延长(P＜0.01或P＜0.05),运动训练组较常规治疗组延长更明显,差异有显著性(P＜0.05). 结论 运动训练能显著提高稳定型心绞痛患者的运动耐量,6 min步行试验可用来评估稳定型心绞痛患者的运动耐量.     

Outcome of percutaneous coronary intervention in unstable angina pectoris versus stable angina pectoris in two different time periods

Percutaneous coronary intervention (PCI) for unstable angina pectoris (UAP) has traditionally been associated with a higher risk of ischemic complications than that for stable angina pectoris (SAP). However, PCI procedures have evolved, so this study was designed to determine whether PCI for UAP is still associated with less favorable outcomes. In-hospital and 1-year outcomes in Dynamic Registry patients who presented for PCI with UAP (n = 2,994) or SAP (n = 1,457) between 1997 and 2002 were compared. One-year results were also compared with consecutive patients who underwent angioplasty (n = 2,431) from the 1985 to 1986 Percutaneous Transluminal Coronary Angioplasty Registry. Although Dynamic Registry patients with UAP were older and more likely to smoke (p < 0.05), have diabetes mellitus (p = 0.03), or a previous myocardial infarction (p < 0.001), procedural success was higher than in patients with SAP. By 1 year, there was greater risk of death (4.4% vs 2.6%, p < 0.01), death/myocardial infarction (9.9% vs 6.6%, p < 0.001), and death, myocardial infarction, and coronary artery bypass grafting (15.1% vs 11.6%, p < 0.01) in patients with UAP. In patients with UAP, there was no significant difference in adjusted 1-year death and death/myocardial infarction rates when comparing the waves of the Dynamic Registry with those of the Percutaneous Transluminal Coronary Angioplasty Registry, although death/myocardial infarction rates among Dynamic Registry patients were lower. However, in patients with SAP, the adjusted rate for death/myocardial infarction was lower in wave 3, and for death, myocardial infarction, and revascularization, there was a significant decrease in event rates with each successive recruitment period (p < 0.05 for all comparisons). In conclusion, in contradistinction to patients with SAP, death and death/myocardial infarction rates in patients who have undergone PCI for UAP have not significantly decreased over the past 16 years and patients with UAP remain at a greater risk of ischemic events at 1 year compared with patients with SAP.     

Effects of the platelet inhibitor ticlopidine on exercise tolerance in stable angina pectoris

Coronary blood flow might be reduced by platelet aggregatesor by vasospasm induced by platelet-produced thromboxane A2.Therefore the effects of the platelet inhibitor ticlopidine(500 mg daily) on platelet function and on exercise tolerancewere investigated in a double-blind placebo-controlled studyin 38 middle-aged men with stable incapacitating angina pectoris.Before and after 4 and 8 weeks of treatment, exercise testswere performed in warm and cold environments. The in vitro plateletreactivity to ADP was determined at rest and the plasma levelsof beta-thromboglobulin (BTG) and platelet factor 4 (PF4) weremeasured before and immediately after exercise. There were nosigns of increased platelet activity at rest or after exerciseas judged by the levels of BTG and PF4. Despite a potent inhibitionof platelet reactivity to ADP in vitro during ticlopidine treatment,the exercise tolerance was reduced in exercise tests in bothwarm and cold environments and in daily life. Therefore plateletactivity does not seem to play any significant role in exercisetolerance in the stable phase of angina pectoris.