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.     

Heart rate adjustment of exercise-induced ST segment depression. Improved risk stratification in the Framingham Offspring Study

BACKGROUND. Simple heart rate adjustment of ST segment depression during exercise (delta ST/HR index) and the pattern of ST depression as a function of heart rate during exercise and recovery (the rate-recovery loop) have been shown to improve the ability of the exercise electrocardiogram to detect the presence of coronary heart disease (CHD), but the performance of these methods for the prediction of future coronary events remains to be examined. METHODS AND RESULTS. We compared the delta ST/HR index and the rate-recovery loop with standard electrocardiographic criteria for prediction of CHD events in 3,168 asymptomatic men and women in the Framingham Offspring Study who underwent treadmill exercise electrocardiography and who, at entry, were free of clinical and electrocardiographic evidence of CHD. After a mean follow-up of 4.3 years, there were 65 new CHD events: four sudden deaths, 24 new myocardial infarctions, and 37 incident cases of angina pectoris. When a Cox proportional hazards model with adjustment for age and sex was used, a positive exercise electrocardiogram by standard criteria (greater than or equal to 0.1 mV horizontal or downsloping ST segment depression) was not predictive of new CHD events (chi 2 = 0.40, p = 0.52). In contrast, stratification according to the presence or absence of a positive delta ST/HR index (greater than or equal to 1.6 microV/beat/min) and a positive (counterclockwise) rate-recovery loop was associated with CHD event risk (chi 2 = 9.45, p less than 0.01) and separated subjects into three groups with varying risks of coronary events: high risk, when both tests were positive (relative risk 3.6; 95% confidence interval, 2.4-5.4); intermediate risk, when either the delta ST/HR index or the rate-recovery loop was positive (relative risk, 1.9; 95% confidence interval, 1.3-2.8); and low risk, when both tests were negative. After multivariate adjustment for age, sex, smoking, total cholesterol level, fasting glucose level, diastolic blood pressure, and electrocardiographic evidence of left ventricular hypertrophy, the combined delta ST/HR index and rate-recovery loop criteria remained predictive of coronary events (chi 2 = 5.45, p = 0.02). CONCLUSIONS. Heart rate adjustment of ST segment depression by the delta ST/HR index and the rate-recovery loop during exercise electrocardiography can improve prediction of future coronary events in asymptomatic men and women.     

踏板运动试验心率恢复环评估冠状动脉病变的价值

为探讨心电图运动试验心率恢复环评估冠状动脉病变的价值,分析74例患者(冠心病患者36例)的选择性冠状动脉造影及踏板运动试验资料。结果:(1)心率恢复环可分为A、B、C、D四种类型,其中A、B二型为异常;(2)心率恢复环诊断冠状动脉病变的敏感性、特异性和阳性预测价值分别为83.3％、81.6％和81.1％,与ST段压低标准无差异。(3)心率恢复环形态与冠状动脉病变支数相关性良好(P<0.001)。认为心率恢复环对诊断冠状动脉病变、特别是评判冠状动脉病变严重度有一定的实用价值。     

Effect of baseline ST segment elevation on test performance of standard and heart rate-adjusted ST segment depression criteria

Whether the ST segment shift used to evaluate the presence and severity of myocardial ischemia should include the additional deviation due to decreasing amounts of baseline ST segment elevation was examined in 100 clinically normal subjects and in 124 patients with coronary disease. Exercise ST segment depression was calculated in two ways: as the difference between exercise and resting ST segment depression, but excluding any resting ST elevation (STdep), and as the total ST segment difference or excursion, including any baseline resting ST elevation (STdiff). These values were also used for separate calculation of the maximal ST/heart rate slope and delta ST/heart rate index in each case. Given partition values with matched specificity of 95% in clinically normal subjects, 150 microV of STdep was significantly more sensitive for coronary disease than 220 microV of STdiff (61% [76 of 124] versus 50% [62 of 124], p less than 0.005). Comparison of receiver operating characteristic curves confirmed the superior test performance of STdep for the identification of coronary disease in this population (area under the curve 0.920 versus 0.869, p = 0.0019). In contrast, detection of three-vessel coronary obstruction by standard ST segment criteria was not affected by definition of ST segment excursion. Substitution of STdiff for STdep did not change the performance of the ST/heart rate slope of the delta ST/heart rate index for either the detection of coronary disease or for the identification of three-vessel coronary obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heart rate adjustment of ST segment depression for improved detection of coronary artery disease

Normal values for heart rate-adjusted indexes of ST segment depression during treadmill exercise electrocardiography (the ST segment/heart rate slope and the delta ST segment/heart rate index) were derived from evaluation of 150 subjects with a low likelihood of coronary artery disease, including 100 normal subjects and 50 subjects with nonanginal chest pain. Partitions chosen by the method of percentile estimation to include 95% of normal subjects remained highly specific in subjects with nonanginal pain syndromes. Sensitivities of the derived partitions for detection of myocardial ischemia were tested in an additional 150 patients with a high likelihood of coronary disease, including 100 patients with angiographically demonstrated coronary obstruction and 50 patients with stable angina. In contrast to the 68% (102 of 150 subjects) sensitivity of standard exercise electrocardiographic criteria for the detection of disease in this population, the sensitivity of an ST segment/heart rate slope partition of 2.4 muV/beats/min was 95% (142 of 150 subjects, p less than 0.001), and the sensitivity of a delta ST segment/heart rate index partition of 1.6 muV/beats/min was 91% (137 of 150 subjects, p less than 0.001). Analysis of receiver-operating curves confirmed the superior performance of the heart rate-adjusted indexes throughout a wide range of test specificities. These findings suggest that heart rate adjustment of ST segment depression can markedly improve the clinical usefulness of the treadmill exercise electrocardiogram.     

Heart rate adjustment of the time-voltage ST segment integral: identification of coronary disease and relation to standard and heart rate-adjusted ST segment depression criteria

To assess the effect of heart rate adjustment of the magnitude of the ST integral (ST-HR integral) on exercise test performance, the exercise electrocardiogram (ECG) of 50 clinically normal subjects and 100 patients with known or suspected coronary artery disease was analyzed. At matched specificity of 96% with standard ECG criteria (greater than or equal to 0.1 mV of additional horizontal or downsloping ST segment depression), an unadjusted ST integral partition of 16 microV-s identified coronary disease in the 100 patients with known or suspected disease with a sensitivity of only 41%, a value significantly lower than the 59% sensitivity of standard ECG criteria (p less than 0.01) and the 65% sensitivity of an ST depression partition of 130 microV (p less than 0.001). However, test performance of the ST integral was greatly improved by simple heart rate adjustment: at a matched specificity of 96%, an ST-HR integral partition of 0.154 microV-s/beat per min identified coronary disease in the 100 patients with a sensitivity of 90%, a value significantly greater than the 59% sensitivity of standard criteria and 65% sensitivity of ST depression criteria (each p less than 0.001) and similar to the 91% sensitivity of the ST-HR index and 93% sensitivity of the ST-HR slope (each p = NS). Comparison of receiver-operating characteristic curves confirmed the superior overall test performance of the ST-HR integral relative to the ST integral and ST segment depression, and demonstrated improved performance that was comparable with that of the ST-HR index and the ST-HR slope.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise Electrocardiography Testing in Patients with Aortic Stenosis

Background: Studies that have been conducted with exercise testing in patients with aortic stenosis (AS) have demonstrated that results of an exercise test can mimic coronary artery disease (CAD). The objective of our study was to investigate if there were any differential feature(s) of exercise testing in patients with AS compared to those with CAD. Methods: We prospectively studied 42 patients with AS (age 37 ± 23, range 8–75) with an averaged maximal gradient of 42 ± 19 mmHg (range 26–95). All patients had undergone a coronary angiography within 1 week of exercise testing and none had CAD. Another 100 patients with CAD, diagnosis proven with coronary angiography, comprised our second group for the comparison (CAD group). Cornell protocol was used in all patients. Results: ST segment depression was observed in all patients 160 ± 25 μV in AS group and 170 ± 20 μV in CAD group, P > 0.05). Thirty-four (81%) patients in the AS group and 88 (88%) patients in the CAD group exceeded the classical threshold for the test positivity (P > 0.05), ST/HR slopes derived from heart rate adjustment to ST segment level did not differ between the study groups (3.2 ± 2.3 and 3.7 ± 2.2 μV/beat/min in AS and CAD groups, respectively, P > 0.05). Recovery phase patterns of ST segment in heart rate domain were different between AS and CAD (clockwise loop: 86% vs 0%; counterclockwise loop: 9% vs 88% in AS group and CAD group, respectively, both P < 0.001) Percentage of the intermediate loop was 5% in the AS group and 12% in the CAD group. Conclusions: Our study demonstrated that patients with AS could be distinguished from those with CAD with the method of rate-recovery loop analysis. A.N.E. 1999;4(3):333–339     

Clinical significance of simple heart rate-adjusted ST segment depression in supine leg exercise in the diagnosis of coronary artery disease

To evaluate the clinical significance of simple heart rate-adjusted ST segment depression (delta ST/delta HR) in the diagnosis of coronary artery disease, 42 patients with stable exertional angina underwent supine leg exercise testing and cardiac catheterization. During exercise, heart rate, a multilead electrocardiogram, and pulmonary artery wedge pressure were recorded. The sensitivity and accuracy of the delta ST/delta HR criteria (greater than or equal to 3.0 microV/beat/min) were significantly greater than the conventional analysis of ST segment depression criteria (greater than or equal to 0.2 mV) for detecting three-vessel coronary artery disease at a matched specificity of 72% (100% versus 46%, 81% versus 64%, p less than 0.01). A significant linear correlation was found between maximum pulmonary artery wedge pressure increments during exercise (delta PAWP) or Gensini score and the delta ST/delta HR (delta PAWP: r = 0.51, p less than 0.001; Gensini score: r = 0.47, p less than 0.001). There were no statistically significant differences in the delta PAWP or Gensini score between patients with three-vessel disease who had delta ST/delta HR greater than or equal to 3.0 microV/beat/min and those with one- or two-vessel disease who had delta ST/delta HR greater than or equal to 3.0 microV/beat/min (delta PAWP: 18.1 +/- 2.0 versus 21.9 +/- 3.3, p = NS; Gensini score: 68.5 +/- 6.6 versus 66.3 +/- 11.3, p = NS). These findings demonstrate that delta ST/delta HR is more useful than a conventional analysis of ST segment depression for identifying not only anatomically severe coronary artery disease but also functionally severe coronary artery disease.     

Prognostic value of heart rate adjustment of exercise-induced ST segment depression in the multiple risk factor intervention trial

Objectives.We sought to assess the effect of heart rate adjustment of ST segment depression on risk stratification for the prediction of death from coronary artery disease.Background.Standard analysis of the ST segment response to exercise based on a fixed magnitude of horizontal or downsloping ST segment depression has demonstrated only limited diagnostic sensitivity for the detection of coronary artery disease and has variable test performance in predicting coronary artery disease mortality. Heart rate adjustment of the magnitude of ST segment depression has been proposed as an alternative approach to increase the diagnostic and prognostic accuracy of the exercise electrocardiogram (ECG).Methods.Exercise ECGs were performed in 5,940 men from the Usual Care Group of the Multiple Risk Factor Intervention Trial at entry into the study. An abnormal ST segment response to exercise was defined according to standard criteria as ≥ 100 μV of additional horizontal or downsloping ST segment depression at peak exercise. The ST segment/heart rate index was calculated by dividing the change in ST segment depression from rest to peak exercise by the exercise-induced change in heart rate. An abnormal ST segment/heart rate index was defined as >1.60 μV/beats per min.Results.After a mean follow-up of 7 years there were 109 coronary artery disease deaths. Using a Cox proportional hazards model, a positive exercise ECG by standard criteria was not predictive of coronary mortality (age-adjusted relative risk [RR] 1.5,95% condence interval [CI] 0.6 to 3.6, p = 0.39). In contrast, an abnormal ST segment/heart rate index significantly increased the risk of death from coronary artery disease (age-adjusted RR 4.1, 95% CI 2.7 to 6.0, p < 0.0001). Excess risk of death was confined to the highest quintile of ST segment/heart rate index values, and within this quintile, risk was directly related to the magnitude of test abnormality. After multivariate adjustment for age, diastolic blood pressure, serum cholesterol and cigarettes smoked per day, the ST segment/heart rate index remained a significant independent predictor of coronary death (RR 3.6, 95% CI 2.4 to 5.4, p < 0.001).Conclusions.Simple heart rate adjustment of the magnitude of ST segment depression improves the prediction of death from coronary artery disease in relatively high risk, asymptomatic men. These findings strongly support the use of heart rate-adjusted indexes of ST segment depression to improve the predictive value of the exercise ECG.     

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.     

Effect of ST segment measurement point on performance of standard and heart rate-adjusted ST segment criteria for the identification of coronary artery disease

BACKGROUND. Recent reports critical of the performance of heart rate-adjusted indexes of ST depression during exercise electrocardiography have used J-point rather than ST segment measurements. However, no standard exists for the optimal time after the J-point at which to measure ST segment deviation. METHODS AND RESULTS. To assess the effect of ST segment measurement position on performance of standard exercise electrocardiographic criteria, the delta ST segment/heart rate (delta ST/HR) index, and the ST segment/heart rate (ST/HR) slope for the detection of coronary artery disease, the exercise electrocardiograms of 50 clinically normal subjects and 80 patients with known or likely coronary disease were analyzed using ST depression measured at both the J-point and at 60 msec after the J-point (J + 60). A positive exercise electrocardiogram by standard criteria, defined as 0.1 mV or more of additional horizontal or downsloping ST depression at end exercise, had a specificity of 96% when ST depression was measured at either the J-point or J + 60. There was no difference in sensitivity of standard electrocardiographic criteria at J + 60 and J point (both 59%, p = NS). However, at matched specificity of 96%, the delta ST/HR index and ST/HR slope calculated using ST depression at J + 60 were significantly more sensitive (90% and 93%) than when calculated using J-point depression (64% and 61%, each p less than 0.001). Comparison of areas under respective receiver operating characteristic curves confirmed the superior performance of J + 60 as opposed to J-point measurements for both the delta ST/HR index (0.98 versus 0.89, p = 0.006) and the ST/HR slope (0.96 versus 0.87, p = 0.007) and also demonstrated modestly improved overall test performance for standard electrocardiographic criteria using J + 60 measurements (0.88 versus 0.82, p = 0.001). CONCLUSIONS. Use of J-point measurements significantly degrades performance of heart rate-adjusted indexes of ST depression but has less effect on standard criteria.     

U波异常有助诊断缺血性心脏病—冠脉造影与心电图对照

目的 探讨U波异常在诊断缺血性心脏病中的价值。方法 选择临床拟为冠心病的男性患者52例，排除电解质紊乱，应用常规心电图、运动负荷心电图及冠脉造影，分析ST段缺血性改变、U波异常在诊断缺血性心脏病中的敏感性和特异性。结果 52例临床拟诊冠心病患者，冠脉造影阳性者38例。冠脉造影阳性者中，常规心电图ST段呈缺血性改变者16例，U波异常者8例，其诊断缺血性心脏病的灵敏度分别为42．11％、21．11％(16/38、8/38)；运动试验阳性者26例，运动诱发U波异常者15例，其诊断缺血性心脏病的灵敏度分别为68．42％、39．47％(26/38、15／38)。冠脉造影阴性者(n＝14)中，常规心电图ST段无缺血性改变6例，U波正常13例，特异度分别为42．86％、92．86％(6／14、13／14)5运动负荷时，结果 阴性9例，U波正常14例，特异度分别为64．29％、100％(9／14、14／14)。运动负荷时尚见2例单独U波异常，其冠脉造影证实有病理性狭窄。结论 U波异常在诊断缺血性心脏病中敏感性虽不如ST段下移的高，但U波异常的特异性高，尤其是运动诱发的U波异常更具诊断价值；缺血性U波异常有助诊断冠心病。     

食道心房超速负荷试验中QT间期离散度诊断冠心病的价值

目的 :评价食道心房超速负荷试验的 QT间期离散度 （QTd）诊断冠心病的价值。方法 :对 32例冠心病患者 （冠心病组 ）及 34例正常者 （对照组 ）进行食道心房超速负荷试验 ,记录试验前后 12导联同步心电图 ,测量其 ST段、校正 QT间期 （QTc）及 QTd。根据 ROC曲线求出 QTc及 QTd的截断点 ,以冠脉造影为诊断冠心病的标准诊断方法 ,利用四格表法 ,分别计算各观测指标的特异度及敏感度。并与“并联试验”相互比较。结果 :ST段下移、QTc,QTd诊断冠心病的特异度分别为 10 0 % ,6 8% ,94% ;敏感度分别为 5 3% ,78%和 84%。 ST段下移和 QTd并联试验时敏感度可达 94%。结论 :食道心房超速负荷试验时 ,如以传统的诊断指标 ST段下移 ,结合 QTd,可明显提高其诊断的敏感度 ,可作一项重要参考指标     

Evaluation of coronary artery disease by an improved method of exercise electrocardiography: the ST segment/heart rate slope

Analysis of the rate-related change in exercise-induced ST segment depression, the ST/HR slope, has been shown to significantly improve the accuracy of the exercise ECG for the identification of patients with coronary artery disease and for the recognition of patients with stable angina pectoris who have anatomically or functionally severe coronary artery obstruction. This method, in effect, normalizes the extent of ST segment depression for heart rate, which serves as an index of exercise-induced augmentation of myocardial oxygen demand. While preserving the specificity of the exercise ECG at greater than 90%, an ST/HR slope value of 1.1 microV/bpm as an upper limit of normal improved exercise test sensitivity from 57% to 91% in patients with stable angina who were examined using standard Bruce protocols and three monitoring leads. In addition, an ST/HR slope value of 6.0 microV/bpm was found to partition patients with and without three-vessel coronary artery disease with a sensitivity of 78%, specificity of 97%, positive predictive value of 93%, and overall test accuracy of 90%. No other criteria based on standard ECG interpretation performed as well as the ST/HR slope for the recognition of three-vessel disease in these patients. Further, patients with high ST/HR slopes who did not have three-vessel coronary disease could be shown to have functionally severe two-vessel disease by radionuclide cineangiography. These data suggest that the ST/HR slope can improve the evaluation and management of patients with possible coronary disease. Additional improvement in ST/HR slope accuracy and applicability is likely to result from modification of exercise protocols to reduce heart rate increments between stages, an increase in monitoring leads to include CM5, and computer analysis of the ST segment depression.     

平板运动试验心率校正的ST段压低参数对冠心病诊断价值的探讨

探讨心率校正的ST段压低参数诊断冠状动脉 (简称冠脉 )病变的准确性 ,12 8例患者接受次极量平板运动试验和冠脉造影。观察各例患者运动中心率相关的ST段压低最大速度即最大ST段 /心率斜率 ,最大心率时ST段与静息时ST段压低值之差除以最大心率与静息心率之差即ΔST/HR指数 ,以及ST段压低 ,观察值与阳性判断标准比较。结果显示 ,最大ST/HR斜率诊断冠心病的敏感性、特异性及诊断符合率最高 ,分别为 94.1%、92 .3%、94.5 % ,ST段压低诊断冠心病的敏感性、特异性及诊断符合率最低 ,分别为 74.5 %、6 9.2 %、73.4%。最大ST/HR斜率在冠脉不同程度病变间无重叠 ,其它参数虽与冠脉病变程度有平行关系 ,但有较大程度的重叠。结论 :心率校正的ST段压低参数显著提高了对冠心病的诊断价值 ,其中最大ST/HR斜率对冠脉病变支数有定量诊断价值     

Can myocardial ischemia be recognized by the exercise electrocardiogram in coronary disease patients with abnormal resting Q waves?

This study was performed in order to determine whether exercise-induced myocardial ischemia demonstrated by thallium-201 imaging could be detected by ST segment shifts in patients with abnormal Q waves at rest. Fifty-four patients with coronary artery disease and exercise-induced thallium-201 defects were compared to 22 patients with similar Q wave patterns but without thallium-201 exercise defects and to 14 normal subjects. Exercise data were analyzed visually in the 12-lead ECG and for spatial ST vector shifts. Both ST segment depression observed on the 12-lead ECG and spatial criteria were reasonably sensitive and specific for ischemia when the resting ECG showed no Q waves or inferior Q waves (range 69% to 93%). However, when anterior Q waves were present, ST segment shifts could not distinguish patients with ischemia from those with normal perfusion as determined by thallium imaging.     

Morphology of ambulatory ST segment changes in patients with varying severity of coronary artery disease. Investigation of the frequency of nocturnal ischaemia and coronary spasm

The frequency and magnitude of objectively determined myocardial ischaemia during normal daily activities of patients with varying severity of coronary artery disease are unknown. Furthermore, the incidence of nocturnal resting myocardial ischaemia and frequency of coronary spasm in patients with normal coronary arteries and chest pain are also not known. One hundred consecutive patients with chest pain referred for coronary angiography were therefore investigated with exercise testing and ambulatory ST segment monitoring. Fifty two of 74 patients with significant coronary artery disease and six of 26 with no significant coronary narrowing had episodes of ST segment change during 48 hours of ambulatory monitoring. Two patients, one with normal coronary arteries and localised spasm and one with three vessel disease, had episodes of ST segment elevation, whereas all other patients had episodes of ST segment depression. The frequency, duration, and magnitude of ST segment changes were greater in patients with more severe types of coronary artery disease. Thus more than six episodes of ST segment change per day occurred in patients with two or three vessel disease or left main stem stenosis and in the only patient with coronary spasm and normal coronary arteries. Nocturnal ischaemia occurred in 15% of patients with coronary artery disease and was almost an invariable indicator of two or three vessel coronary artery disease or left main stem stenosis. Episodes of ST segment change occurred most commonly during the morning hours and least commonly during the night, in parallel with changes in basal hourly heart rates. The heart rate at the onset of ST segment change tended to be lower in patients with coronary artery disease than in those with normal coronary arteries. The duration of exercise to ST segment depression tended to be shorter in patients with more severe disease, but it could not predict patients with nocturnal myocardial ischaemia, left main stem stenosis, or coronary spasm, whereas ambulatory ST segment monitoring was able to identify most of these patients.     

Exercise Testing in the Detection of Severe Coronary Artery Disease

Summary: The clinical value of exercise testing in the detection of severe coronary artery disease remains undefined. This question was examined in 289 men and 45 women. The diagnosis of coronary artery disease could be reliably made without exercise testing in patients with angina pectoris which markedly restricted walking or which was accompanied by pathological Q waves on the ECG. Such patients usually had coronary artery disease involving two or three major vessels.
Exercise testing was an aid to diagnosis in patients with a normal standard ECG and chest pain suspicious of myocardial ischaemia, either mild angina or atypical. When exercise testing resulted in both angina and ST segment depression in men, coronary artery disease was present in 38 of 41 (93%) of cases. On the other hand, three vessel disease was found in only six of 100 (6%) of men whose exercise test did not evoke angina and ST segment change. A normal exercise test in a woman with suspicious chest pain and a normal ECG was associated with normal coronary arteries in 14 of 15 (93%) of cases. It may be concluded that exercise testing is of most diagnostic value in the assessment of patients with a normal standard ECG and a differential diagnosis of mild angina pectoris and atypical chest pain.     

Morphology of ambulatory ST segment changes in patients with varying severity of coronary artery disease. Investigation of the frequency of nocturnal ischaemia and coronary spasm.

The frequency and magnitude of objectively determined myocardial ischaemia during normal daily activities of patients with varying severity of coronary artery disease are unknown. Furthermore, the incidence of nocturnal resting myocardial ischaemia and frequency of coronary spasm in patients with normal coronary arteries and chest pain are also not known. One hundred consecutive patients with chest pain referred for coronary angiography were therefore investigated with exercise testing and ambulatory ST segment monitoring. Fifty two of 74 patients with significant coronary artery disease and six of 26 with no significant coronary narrowing had episodes of ST segment change during 48 hours of ambulatory monitoring. Two patients, one with normal coronary arteries and localised spasm and one with three vessel disease, had episodes of ST segment elevation, whereas all other patients had episodes of ST segment depression. The frequency, duration, and magnitude of ST segment changes were greater in patients with more severe types of coronary artery disease. Thus more than six episodes of ST segment change per day occurred in patients with two or three vessel disease or left main stem stenosis and in the only patient with coronary spasm and normal coronary arteries. Nocturnal ischaemia occurred in 15% of patients with coronary artery disease and was almost an invariable indicator of two or three vessel coronary artery disease or left main stem stenosis. Episodes of ST segment change occurred most commonly during the morning hours and least commonly during the night, in parallel with changes in basal hourly heart rates. The heart rate at the onset of ST segment change tended to be lower in patients with coronary artery disease than in those with normal coronary arteries. The duration of exercise to ST segment depression tended to be shorter in patients with more severe disease, but it could not predict patients with nocturnal myocardial ischaemia, left main stem stenosis, or coronary spasm, whereas ambulatory ST segment monitoring was able to identify most of these patients.     

平板运动试验的心率校正ST段下移指标对冠心病的预测价值

目的：探讨平板运动试验中ST段下移、△ST／△HR指数和最大ST／HR斜率预测冠心病的价值。方法：对已行冠脉造影检查并在造影前有平板运动试验资料的120例患者资料进行分析。研究ST段下移、△ST／△HR指数和最大ST／HR斜率诊断冠心病的敏感性、特异性。结果：120例患者冠脉造影阳性者66例。ST段下移、△ST／△HR指数和最大ST／HR斜率的（敏感性和特异性）分别为（69．7％、72．2％）、（92．4％、88．9％）和（93．9％、90．7％）。冠心病组△ST／△HR指数和最大ST／HR斜率敏感性、特异性均显著高于非冠心病组（P〈0．01）。结论：平板运动试验中采用心率校正的ST段指标能提高对冠心病的诊断价值。