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.     

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     

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.     

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.     

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.     

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.     

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.     

Assessment of aortocoronary bypass grafting using exercise ST segment/heart rate relation.

The maximal rate of progression of ST segment depression relative to increases in heart rate (maximal ST/HR slope) has recently been shown to be an accurate index of the presence and the severity of coronary heart disease in patients with angina. The value of this new exercise test was assessed in patients undergoing aortocoronary bypass. The maximal ST/HR slope and the results of coronary angiography were obtained in each of 46 patients before aortocoronary bypass surgery and in 26 of the 46 patients six months after the operation. At each stage of the investigation the maximal ST/HR slope detected without false results the absence and the number of significantly diseased vessels as shown by angiocardiography. As in previous findings the ranges of the maximal ST/HR slope showed no overlap between the four groups of patients: those with no significant disease and those with single, double, or triple vessel disease. In each of the 46 patients in whom the maximal ST/HR slope was determined before operation and three months afterwards the slope was lower after operation than before, indicating improvement. Follow up examinations showed that the maximal ST/HR slopes accurately detected the number of patent grafts used to bypass significantly diseased coronary arteries. Furthermore, the development of a significant narrowing or occlusion in any vein graft caused an increase in the maximal ST/HR slope which was equivalent to the value of single vessel disease. It is suggested that the maximal ST/HR slope may be used reliably in individual patients to indicate restoration of adequate blood supply to the myocardium after successfully aortorcoronary bypass surgery and the to detect in the period of six months after the operation the degree of severity of coronary heart disease whether it is caused by occlusion of the graft of significant disease of the coronary arteries.     

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.     

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.     

Assessment of aortocoronary bypass grafting using exercise ST segment/heart rate relation

The maximal rate of progression of ST segment depression relative to increases in heart rate (maximal ST/HR slope) has recently been shown to be an accurate index of the presence and the severity of coronary heart disease in patients with angina. The value of this new exercise test was assessed in patients undergoing aortocoronary bypass. The maximal ST/HR slope and the results of coronary angiography were obtained in each of 46 patients before aortocoronary bypass surgery and in 26 of the 46 patients six months after the operation. At each stage of the investigation the maximal ST/HR slope detected without false results the absence and the number of significantly diseased vessels as shown by angiocardiography. As in previous findings the ranges of the maximal ST/HR slope showed no overlap between the four groups of patients: those with no significant disease and those with single, double, or triple vessel disease. In each of the 46 patients in whom the maximal ST/HR slope was determined before operation and three months afterwards the slope was lower after operation than before, indicating improvement. Follow up examinations showed that the maximal ST/HR slopes accurately detected the number of patent grafts used to bypass significantly diseased coronary arteries. Furthermore, the development of a significant narrowing or occlusion in any vein graft caused an increase in the maximal ST/HR slope which was equivalent to the value of single vessel disease. It is suggested that the maximal ST/HR slope may be used reliably in individual patients to indicate restoration of adequate blood supply to the myocardium after successfully aortorcoronary bypass surgery and the to detect in the period of six months after the operation the degree of severity of coronary heart disease whether it is caused by occlusion of the graft of significant disease of the coronary arteries.     

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.     

Comparison of ST segment/heart rate index to standard ST criteria for analysis of exercise electrocardiogram

The objective of our study was to compare the discriminating power of a proposed ST segment/heart rate index with that of a standard method of assessing exercise-induced ST segment depression for diagnosing coronary artery disease. We used a cross-sectional retrospective analysis of exercise test and coronary angiographic data. The study took place in a 1,200-bed Veterans Affairs Medical Center; participants were 328 male patients who had undergone both a sign and symptom-limited treadmill test and coronary angiography. The sensitivity of the ST segment/heart rate index was 54% at a cut point of 0.021 mm/(beats/min), corresponding to a specificity of 73%. The standard visual ST segment analysis had a sensitivity of 58% at this same specificity, which corresponded to an ST segment cut point of 1-mm depression relative to rest (p = NS). Similarly, for diagnosing three-vessel or left main coronary disease, no significant difference was found between the sensitivities or the two measurements at cut points of equivalent specificity. In this consecutive series of patients presenting for routine clinical testing, the ST segment/heart rate index did not improve the diagnostic accuracy of the exercise test for identifying the presence or severity of coronary artery disease relative to standard visual criteria.