Identification of anatomically extensive coronary artery disease by the exercise ECG ST segment/heart rate slope

To assess the ability of the ST segment/heart rate (ST/HR) slope to identify three-vessel coronary disease and the relationship between the ST/HR slope and the anatomic extent of disease as determined by the Gensini and Duke jeopardy scores, the exercise ECGs of 128 patients with stable angina were compared with findings at coronary cineangiography. A ST/HR slope greater than or equal to 6 microV/beat/min identified three-vessel coronary disease with a sensitivity of 93% compared with sensitivities of only 50% for early positive standard test responses (p less than 0.001) and 66% for markedly positive standard test responses (p less than 0.01). The negative predictive value of this ST/HR slope partition for three-vessel disease was 94%. Patients with ST/HR slopes greater than or equal to 6 who did not have three-vessel disease had anatomically more extensive obstruction than did patients with lower test values (mean Gensini score 43 +/- 5 vs 22 +/- 3, p less than 0.002 and mean jeopardy score 4.8 +/- 0.4 vs 3.0 +/- 0.3, p less than 0.01). Test performance of the calculated ST/HR slope exceeded that of a simplified index derived by dividing the total change in ST segment depression by the total change in heart rate. These findings demonstrate that a ST/HR slope greater than or equal to 6 is highly sensitive for the identification of three-vessel coronary disease and also identifies patients with anatomically severe obstruction. A ST/HR slope less than 6 makes three-vessel coronary disease or otherwise anatomically extensive coronary obstruction unlikely.     

The slope of ST segment/heart rate relationship during exercise in the prediction of severity of coronary artery disease

The results of a new excercise electrocardiography test werecompared with those of coronary arteriography in 120 patients.Thirty patients were under beta-blocker therapy and 90 patientswere not. In each patient the rate of progression of ST segmentdepression with respect to increases in heart rate was measuredin 13 electrocardiographic leads; the steepest slope of regressionlines relating ST segment depression to heart rate (maximalST/HR slope) was used as an index of myocardial ischaemia. Theresults of coronary angiography revealed 105 patients with significantcoronary artery disease (> 75% luminal narrowing); 32 patientshad single-vessel disease, 43 patients had double-vessel diseaseand 30 patients had triple-vessel disease. Significant coronaryartery disease could not be demonstrated in 15 patients. Theranges of the maximal ST/HR slope were different in the fourgroups of patients and the differences between the means werestatistically significant (P<0.0005); these differences weremaintained irrespective of beta-blocker therapy and there wereno false results or indeterminate test results. In contrastusing usual exercise criteria a definitive test result couldnot be obtained in 20 patients and there was an overlap betweenthe four groups. It is concluded that the maximal ST/HR slope can be used reliablyto predict the presence or absence and the severity of coronaryartery disease in individual patients with anginal pain, whetherthey are on beta-blocker therapy or not.     

心率校正的ST段改变诊断冠心病的准确性探讨

目的评价运动心电图ＳＴ段压低的几个变量对诊断冠心病价值。方法９７例冠心病病人和５０例健康人作对照组进行Ｂｒｕｃｅ方案的活动平板试验，受试对象计算运动末ＳＴ段（ＳＴｅｎｄ）压低，恢复期ＳＴ段（ＳＴｒｅｃ）压低，ＳＴ／ＨＲＩｎｄｅｘ和ＳＴ／ＨＲｈｙｓｔｅｒｅｓｉｓ，其中ａＶＲ导联不计其内。结果冠心病组和健康对照组的ＳＴ／ＨＲｈｙｓｔｅｒｅｓｉｓ指标的敏感性和特异性均高于其它三个指标的任何一个（Ｐ均＜００５）。结论ＳＴ／ＨＲｈｙｓｔｅｒｅｓｉｓ反映了心率校正后的运动期与恢复期的ＳＴ段差值的平均值，因而比ＳＴｅｎｄ、ＳＴｒｅｃ和ＳＴ／ＨＲＩｎｄｅｘ三个指标均准确，值得临床推广。     

Inability of the ST segment/heart rate slope to predict accurately the severity of coronary artery disease.

Analysis of the ST segment/heart rate slope during exercise testing has been suggested as a method of accurately predicting the presence and severity of coronary artery disease. Exercise tests were performed in 78 patients presenting with the chest pain to determine the maximum ST segment/heart rate slope. In 21 (27%) patients the ST segment/heart rate slope could not be calculated in any electrocardiographic lead. In the remaining 57 (73%) patients the maximum ST segment/heart rate slope accurately predicted the presence or absence of coronary disease in 44 patients (sensitivity 90%, specificity 40%). In addition, the extent of coronary disease was accurately predicted in 24 patients (sensitivity 42%). Thus the maximum ST segment/heart rate slope did not perfectly predict either the presence or the severity of significant coronary artery disease.     

The ST segment/heart rate slope as a predictor of coronary artery disease: comparison with quantitative thallium imaging and conventional ST segment criteria

The ST segment shift relative to exercise-induced increments in heart rate, the ST/heart rate slope (ST/HR slope), has been proposed as a more accurate ECG criterion for diagnosing significant coronary artery disease (CAD). Its clinical utility, with the use of a standard treadmill protocol, was compared with quantitative stress thallium (TI) and standard treadmill criteria in 64 unselected patients who underwent coronary angiography. The overall diagnostic accuracy of the ST/HR slope was an improvement over TI and conventional ST criteria (81%, 67%, and 69%). For patients failing to reach 85% of their age-predicted maximal heart rate, its diagnostic accuracy was comparable with TI (77% and 74%). Its sensitivity in patients without prior myocardial infarctions was equivalent to that of thallium (91% and 95%). The ST/HR slope was directly related to the angiographic severity (Gensini score) of CAD in patients without a prior infarction (r = 0.61, p less than 0.001). The ST/HR slope was an improved ECG criterion for diagnosing CAD and compared favorably with TI imaging.     

Use of the exercise maximal ST segment/heart rate slope in assessing the results of coronary angioplasty

A new exercise test was used to assess the effects of coronary angioplasty in 22 patients. Twenty five angioplasty procedures were performed and the exercise maximal ST segment/heart rate slope was measured before and after operation on 23 occasions; in two patients treated for unstable angina the slope was measured only after the two procedures. Successful angioplasty (23 of the 25 procedures) resulted in a significant reduction of the maximal ST/HR slope, usually falling by the equivalent of single vessel disease according to previously published criteria. When angioplasty produced little angiographic change (two of the 25 procedures) the maximal ST/HR slope was not significantly altered. A second, and successful, angioplasty for these two patients led to a significant reduction of the maximal ST/HR slope. Twelve patients were restudied by coronary angiography and exercise testing approximately six months after angioplasty. Of these, six had experienced recurrent chest pain, and the exercise test successfully identified the three who had restenoses and the three who did not. Thus the maximal ST/HR slope was useful as a non-invasive and accurate method for following the progress of individual patients after coronary angioplasty.     

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。     

Use of the exercise maximal ST segment/heart rate slope in assessing the results of coronary angioplasty.

A new exercise test was used to assess the effects of coronary angioplasty in 22 patients. Twenty five angioplasty procedures were performed and the exercise maximal ST segment/heart rate slope was measured before and after operation on 23 occasions; in two patients treated for unstable angina the slope was measured only after the two procedures. Successful angioplasty (23 of the 25 procedures) resulted in a significant reduction of the maximal ST/HR slope, usually falling by the equivalent of single vessel disease according to previously published criteria. When angioplasty produced little angiographic change (two of the 25 procedures) the maximal ST/HR slope was not significantly altered. A second, and successful, angioplasty for these two patients led to a significant reduction of the maximal ST/HR slope. Twelve patients were restudied by coronary angiography and exercise testing approximately six months after angioplasty. Of these, six had experienced recurrent chest pain, and the exercise test successfully identified the three who had restenoses and the three who did not. Thus the maximal ST/HR slope was useful as a non-invasive and accurate method for following the progress of individual patients after coronary angioplasty.     

Comparison of the ST/heart rate slope with the modified Bruce exercise test in the detection of coronary artery disease

The rate of depression of the ST segment with increasing heart rate (HR) during exercise has been claimed to predict the extent of coronary artery disease (CAD). To determine whether the maximal ST/HR slope is better than the Bruce treadmill exercise test for predicting the presence of CAD, the maximal ST segment/HR slope was calculated in 81 patients and compared with the results of a standard 12-lead exercise test. In 21 patients (26%), the ST/HR slope could not be calculated. In 60 patients with ST/HR slope values, the extent of CAD was predicted in 24 patients (40%). The sensitivity and specificity of the ST/HR slope in predicting the presence of CAD in the 60 patients with slope values were 91% and 27%, respectively. The sensitivity and specificity of the modified Bruce treadmill exercise test in the 81 patients were 81% and 64%, respectively. Thus, the use of the ST/HR slope does not provide additional information that cannot be obtained using the standard Bruce exercise test.     

心电图最大ST／HR斜率法在老年人冠心病临床诊断中的价值

目的　探讨心电图最大ＳＴ／ＨＲ斜率对老年人冠心病的诊断价值。　方法　采用踏车运动试验测定３０例老年冠心病患者和３０ 例健康老年对照者的最大ＳＴ／ＨＲ斜率及ＳＴ段压低值。　结果　老年冠心病组的心电图最大ＳＴ／ＨＲ斜率值明显高于对照组〔分别为（３．０±１．３）及（０．９±０．９）μＶ·ｂｐ－ １·ｍ ｉｎ－ １,Ｐ＜ ０．０１〕,最大ＳＴ／ＨＲ斜率法诊断老年人冠心病的敏感性和特异性高于ＳＴ段压低法（分别为９０．０％ 、８６．６％ 和６０．０％ 、７３．３％ ,均为Ｐ＜ ０．０５）。随冠状动脉病变数目增多其最大ＳＴ／ＨＲ斜率值呈增大趋势。　结论　最大ＳＴ／ＨＲ斜率法对老年人冠心病的临床诊断有较高的敏感性和特异性,优于单纯ＳＴ段压低法,并对预示冠状动脉病变数目有一定的价值     

ST/HR slope during prostacyclin treatment: an improved method to identify patients with advanced coronary artery disease

Constriction of atherosclerotic coronary segments during exercise may further reduce coronary flow reserve in patients with coronary artery disease. This could influence the linear regression analysis of the heart rate-related changes in ST-segment depression (ST/HR slope) thereby limiting the accuracy of this method in identifying the severity of the disease. To test this hypothesis, the exercise related ST/HR slopes on placebo were compared with those obtained during coronary vasodilation induced by a prostacyclin analogue (iloprost 6 ng kg-1 min-1) in 42 anginal patients with documented coronary artery disease. In seven of these, the same protocol was repeated during right heart catheterization. The overall diagnostic accuracy of the ST/HR slope on iloprost was better than on placebo in patients with advanced coronary artery disease. This was due mainly to a consistent rightward shift of the ST/HR slope in patients with one- and two-vessel, but not three-vessel disease or left main stem disease. The reason for the greater effects of iloprost on ST/HR slopes in patients with a lesser degree of atherosclerosis remains unclear. However, coronary blood flow was higher during drug infusion, which suggests that iloprost may prevent the occurrence of dynamic coronary events able to reduce the maximum coronary flow reserve during exertion. This mechanism may be predominant in patients with minor coronary artery disease.     

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.     

Localization of coronary artery disease with exercise induced ST segment depression: coronary angiographic correlation

Abnormalities of the 12 lead electrocardiogram (ECG) are often used to localize the anatomic site of myocardial ischemia and vessel involvement in patients (pts) with coronary artery disease. This study is to determine if ischemia of specific vascular segments can be identified by exercise induced ST segment depression (STD) on 12-lead ECG. One hundred and forty three pts with a positive treadmill stress testing (TST) who had coronary arteriography within one month of TST were reviewed. There were 114 men and 29 women, aged 34-74 years (mean 55 years). The Bruce protocol was used for TST. Significant coronary stenosis was defined as obstruction of 70% or greater of the luminal diameter. The pattern of STD on 12 lead ECG during exercise was similar in pts with single vessel disease involving the left anterior descending artery (LAD), right coronary artery (RCA) or circumflex artery (Cx). This pattern of STD in single vessel disease was also comparable to 2-vessel, 3-vessel or left main stem disease. Twenty-two percent of pts with LAD disease had isolated STD in inferior leads. Twenty-five and 29% of pts with RCA and Cx disease respectively had STD in the anterior leads alone during exercise testing. It is concluded that exercise induced STD in 12 lead ECG can not predict ischemia of specific vascular segments or specific vessel involvement.     

ST/HR slope and improved exercise ECG detection of myocardial ischemia in patients with suspected coronary artery disease.

Predictive values of ST/HR slope and ST-segment displacement during symptom-limited exercise were determined in 85 patients who underwent coronary angiography for suspected coronary artery disease, using perfusional and functional radionuclide images with 99mTc-2-methoxy-isobutil-isonitrile as an index of stress-induced myocardial ischemia. ST/HR slope showed a better sensitivity than conventional stress-induced changes of ST-segment displacement (96% vs. 73%, respectively). In patients with clinical suspicion of coronary artery disease, the main result was the negative predictive value of ST/HR slope when compared with conventional ST-segment displacement (98% vs. 41%). ST/HR slope was unable to perfectly separate patients with different degrees of ischemia, however, subjects without scintigraphic signs of stress-induced ischemia and patients with ischemic impairment in three myocardial regions were correctly identified as distinct populations. In patients with a previous myocardial infarction, no difference was found between the two criteria and a wide overlap of ST/HR slope values was present. The authors conclude that ST/HR slope is useful to detect the rate of change in electric parameters during exercise and might therefore more adequately be used to separate normal from definitely abnormal responses to exercise.     

A modified treadmill exercise protocol for computer-assisted analysis of the ST segment/heart rate slope: methods and reproducibility

A new treadmill exercise protocol, modified from the standard Bruce method, was designed to improve ST segment/heart rate slope accuracy and applicability by reducing heart rate increments between exercise stages. In 150 patients exercised according to the new protocol and in 150 patients exercised according to the Bruce protocol, similar exercise tolerance and similar overall heart rate, systolic blood pressure and double product responses to exercise were observed. The mean increment in heart rate between exercise stages of the new protocol was ten beats/minute, which was significantly lower than the 27 beats/minute/stage found with the Bruce protocol. The accuracy of computer-measured ST segment depression was validated by comparison with physician measurement in a separate subgroup of patients with angina pectoris, and serial testing demonstrated stronger interest reproducibility for the ST segment/heart rate slope than for either measured ST segment depression, peak heart rate achieved or duration of exercise.     

Correlation of heart rate/ST slope and coronary angiographic findings

The heart rate/ST slope was evaluated in 49 patients undergoing routine investigation for possible coronary artery disease. The slope correctly predicted the absence of any 75% stenoses in the seven patients to whom this applied; it was, however, correct for only four of 30 with one stenosis, one of 10 with two, and neither of the patients with three. Distinct slope ranges were not found, and the previously published ranges said to be specific for no significant stenosis and one, two, and three vessel disease were not.