Correlation between the ST/heart rate slope and the severity of coronary disease in inferior infarcts. A new criterion of positivity of the ergometric test

We reviewed a group of 80 patients who had bicycle exercise stress testing and cardiac catheterization: 60 patients with known coronary artery disease (CAD) had a remote myocardial infarction, anterior, inferior, Q and no Q wave (post MI), 20 patients evaluated for suspected CAD resulted to have normal coronary arteries or lesions less than 50%. Patients were divided into three groups according to the extent of CAD. Group I with anatomically or functionally high risk CAD: left main (LM) stenosis greater than or equal to 50%, 3 vessels CAD greater than or equal to 70%, proximal left anterior descending stenosis (PLAD) greater than or equal to 90% with another vessel CAD; group II with one or two vessels CAD greater than or equal to 70%; group III with no or insignificant CAD. Linear regression analysis of the heart rate (HR)--related change in ST segment depression (ST/HR slope) was compared with six conventional electrocardiographic exercise test criteria to evaluate whether ST/HR slope can identify with improved accuracy group I. When all 80 patients are assessed together, ST/HR slope greater than or equal to 60 mm/beat/min 10(3) compared with standard electrocardiographic criteria failed to discriminate significantly between high-risk CAD (group I) and less extensive (group II) or insignificant CAD (group III). When only Q wave inferior post MI are considered, ST/HR slope greater than or equal to 60 mm/beat/min. 10(3) compared with ST segment depression greater than or equal to 1 mm identifies group I with 90% +/- 4 versus 75% +/- 6 overall predictive accuracy (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Diagnostic value of Q wave changes during the exercise test. Review of the literature and personal experience

To test if a low Q wave voltage and its faulty increase after exercise is an additional sign of myocardial ischemia, 64 pts with no previous myocardial infarction, bundle branch block or left ventricular hypertrophy were studied by a treadmill test and coronary angiography. Nineteen had single vessel disease (SVD), 21 double vessel disease (DVD), 4 triple vessel disease (TVD) and 20 normal coronary arteries. Sensitivity (SENS), specificity (SPEC) and predictive value (P) of Q wave changes have resulted as follows: 84%, 55%, 80.4%, respectively, compared to 79.5%, 75%, 87.5% of ST modifications associated or not with angina. The SENS of Q wave changes was 72% in SVD and 92% in multivessel disease (p less than 0.05). In 68% of our pts ST and Q wave changes gave concordant results and their combination increased SENS, SPEC, PV to 90.1%, 80%, 90.3%. In conclusion: Q wave analysis can provide further evidence of myocardial ischemia and can increase SENS, SPEC of stress test. In our experience Q wave is a more sensitive finding than ST depression in multivessel disease.     

Post-infarction exercise testing in patients under 55 years. Relation between ischaemic abnormalities and the extent of coronary artery disease.

Previous studies have suggested that the early post-infarction exercise test is useful in predicting the extent of coronary artery disease. The results of a heart rate limited exercise test three weeks after infarction and a symptom limited exercise test six weeks after infarction obtained by both standard lead electrocardiograms and 16 lead precordial maps were compared in 100 consecutive survivors of acute myocardial infarction under 55 years of age. Exercise tests were defined as being positive on the basis of angina, ST segment depression greater than or equal to 1 mm in any electrocardiogram lead, or exertional hypotension. Multivessel disease, that is two or three vessel disease, was present in 60 patients, and three vessel disease in 22 patients. The sensitivity, specificity, and predictive value for multivessel disease of the three week test were 38%, 83%, and 76% respectively; and results for the six week test were 55%, 75%, and 77% respectively. Only 32% of patients with three vessel disease were identified at the three week test, and 59% at the six week test. Significantly more patients with multivessel and three vessel disease were identified by the symptom limited six week test. Precordial mapping offered no advantages over the standard 12 lead electrocardiogram in either the identification of patients with multivessel disease or the prediction of the distribution of coronary artery disease. Angina pectoris during the exercise test at six weeks was the single most useful predictor of multivessel disease. Multivessel disease was found in 27 (87%) of the 31 patients with angina with or without ST depression during the test at six weeks compared with 33 (48%) of the 69 patients who did not have angina during the test at six weeks. Exercise testing in the early post-infarction period in patients under 55 years of age is of limited value in predicting the extent of coronary artery disease. It is, therefore, unreasonable to use such exercise tests to select patients for coronary arteriography after myocardial infarction. None the less angina pectoris occurring during a symptom limited exercise test six weeks after infarction is a strong predictor of multivessel disease, and coronary arteriography is recommended in these patients.     

Post-infarction exercise testing in patients under 55 years. Relation between ischaemic abnormalities and the extent of coronary artery disease

Previous studies have suggested that the early post-infarction exercise test is useful in predicting the extent of coronary artery disease. The results of a heart rate limited exercise test three weeks after infarction and a symptom limited exercise test six weeks after infarction obtained by both standard lead electrocardiograms and 16 lead precordial maps were compared in 100 consecutive survivors of acute myocardial infarction under 55 years of age. Exercise tests were defined as being positive on the basis of angina, ST segment depression greater than or equal to 1 mm in any electrocardiogram lead, or exertional hypotension. Multivessel disease, that is two or three vessel disease, was present in 60 patients, and three vessel disease in 22 patients. The sensitivity, specificity, and predictive value for multivessel disease of the three week test were 38%, 83%, and 76% respectively; and results for the six week test were 55%, 75%, and 77% respectively. Only 32% of patients with three vessel disease were identified at the three week test, and 59% at the six week test. Significantly more patients with multivessel and three vessel disease were identified by the symptom limited six week test. Precordial mapping offered no advantages over the standard 12 lead electrocardiogram in either the identification of patients with multivessel disease or the prediction of the distribution of coronary artery disease. Angina pectoris during the exercise test at six weeks was the single most useful predictor of multivessel disease. Multivessel disease was found in 27 (87%) of the 31 patients with angina with or without ST depression during the test at six weeks compared with 33 (48%) of the 69 patients who did not have angina during the test at six weeks. Exercise testing in the early post-infarction period in patients under 55 years of age is of limited value in predicting the extent of coronary artery disease. It is, therefore, unreasonable to use such exercise tests to select patients for coronary arteriography after myocardial infarction. None the less angina pectoris occurring during a symptom limited exercise test six weeks after infarction is a strong predictor of multivessel disease, and coronary arteriography is recommended in these patients.     

Electrocardiographic findings in acute right ventricular infarction: sensitivity and specificity of electrocardiographic alterations in right precordial leads V4R, V3R, V1, V2, and V3

To determine the sensitivity, specificity, predictive value and diagnostic efficiency of electrocardiographic alterations in the diagnosis of acute right ventricular infarction, 43 autopsy patients with acute myocardial infarction and an electrocardiogram including 12 leads plus leads V3R and V4R were studied. Group A included 21 patients with right ventricular infarction, of whom 14 (group AI) had posterior and 7 (group AII) had anterior right ventricular infarction. Group B included 22 patients without right ventricular infarction. Excluding group AII patients, the sensitivity of the presence of a Q wave reached 78.6% in lead V4R and decreased in leads V1 to V3; its specificity was low in all the leads. The sensitivity of ST segment elevation reached 100% in lead V4R and decreased in leads V1 to V3; its specificity was highest (68.2%) in leads V4R and V3R, its negative predictive value was 100% and its diagnostic efficiency was 80.6%. The criterion of ST segment elevation in lead V4R being higher than that in leads V1 to V3 was less sensitive (78.6%) than ST segment elevation in lead V4R alone, but its specificity reached 100%, its positive predictive value 100% and its diagnostic efficiency 91.7%. In conclusion, there are no electrocardiographic criteria to identify anterior right ventricular necrosis, but posterior right ventricular necrosis may be identified by the presence of a Q wave or ST segment elevation in the right precordial leads, reaching the highest sensitivity and specificity in lead V4R. The criterion of ST segment elevation in lead V4R being higher than that in leads V1 to V3 offers the highest specificity and efficiency in the diagnosis.     

Value of the Corrected QT Interval Dispersion Obtained Exercise Electrocardiography in Determining Remote Vessel Disease in Patients with Healed Q‐Wave Myocardial Infarction

Background: QT and corrected QT dispersion (QTD, QTcD) obtained by using the standard 12‐lead ECG is a marker of nonhomogenous ventricular repolarization. QTD obtained from exercise ECG increases the diagnostic reliability of ST‐segment changes. The aim of this study was to investigate the diagnostic accuracy of the QTD and QTcD obtained by a 12‐lead ECG during the peak exercise in determining remote vessel disease in patients with healed Q‐wave MI. Methods: Eighty patients with healed Q‐wave Ml (mean age 54 ± 8 years; 71 men, 9 women; 29 anterior; 51 inferior Ml) who underwent exercise stress testing and coronary angiography were included in this study. Patients were divided into two groups, with (group I) and without (group II) remote vessel coronary artery disease. During peak exercise, sensitivity, specificity, negative and positive predictive value of the ST‐segment depression, and QTcD were compared between both groups. Moreover, the resting and peak exercise ECG parameters were compared between group I and group II. Results: In coronary angiography, remote vessel disease was detected in 48 patients (group I). In determining remote vessel disease, the sensitivity, specificity, and the negative and positive predictive values of the peak exercise QTcD ≧ 70 ms were significantly higher than those of the peak exercise ST‐segment depression (81%, 63%, 69%, and 76% vs 71%, 53%, 55%, and 69%, respectively; P < 0.01 for all comparisons). In group I, QTD and QTcD were significantly higher in patients with anterior wall Ml than those with inferior wall Ml both during the resting and peak exercise ECG. In group II, the resting QTD and QTcD were significantly higher in patients with anterior wall MI than those with inferior wall MI. In patients with anterior wall MI and inferior wall Ml, QTD and QTcD significantly increased with exercise in group I. Conclusion: In patients with healed Q‐wave Ml, the value of QTcD ≧ 70 ms increases the diagnostic: accuracy of the exercise stress testing in determining remote vessel disease. A.N.E. 2002;7(3):228–233     

急性ST段抬高型心肌梗死直接冠脉成形术ST段变化的临床价值

目的探讨急性ST段抬高型心肌梗死患者行直接冠脉成形术,术前和术后ST段变化对远期心血管事件的临床预测价值。方法对54例ST段抬高型心肌梗死患者行直接冠脉成形术,观察术前和术后1h心电图ST段变化,计算ST段回落指数。对所有患者随访12个月,观察12个月内心血管事件（猝死、心肌梗死、再狭窄、再次血管重建、慢性心衰）发生情况。对ST段回落指数和随访心血管事件行ROC分析,并通过COX比例风险模型多因素回归分析ST段回落指数对12个月终点事件的独立预测价值。结果在12个月的随访中,发生心源性死亡2例,再发心绞痛4例,慢性心衰7例。ST段回落指数临界点取63％时,对目标心脏事件预测的ROC曲线下面积0．843,灵敏度76．9％,特异度78．0％。COX比例风险模型多因素回归分析显示ST段回落指数对目标终点事件具有独立预测价值。结论急性ST段抬高型心肌梗死患者行直接PCI术,术前和术后ST段的变化即ST段回落指数对术后12个月预后具有独立预测价值。     

Diagnostic value of changes in the Q wave induced by exertion

In order to evaluate the diagnostic value of exercise-induced Q wave changes and its relationship with the extent of coronary involvement and presence and location of a previous myocardial infarction, we examined the stress electrocardiograms of 188 consecutive patients with chest pain. Coronary arteriography shoved single vessel disease (SV) in 28 patients and multivessel disease (MV) in 130 patients; a previous myocardial infarction was present in 64 patients. The Q wave amplitude was measured as average of ten values in CM5 at rest and at peak exercise; a Delta-Q less than 0, i.e. reduction or no change of Q wave at peak exercise, was considered a positive response for coronary artery disease. The Delta-Q criterion shoved a significantly better sensitivity than ST depression, as a whole, but this improvement was nullified when patients with anterior myocardial infarction were excluded; as well specificity of Delta-Q although better than ST, did not allow a significant improvement for the diagnostic value of stress test. We also evaluated the diagnostic accuracy for multivessel coronary artery disease of both criteria positive was 78% whereas the negative predictive value of both criteria negative was 91%. We concluded that the exercise-induced Delta-Q less than 0 is a good indicator of coronary artery disease, although not superior to ST depression; the negativity of both criteria seems to be highly reliable for the exclusion of multivessel coronary artery disease.     

Electrocardiographic differentiation between right coronary and left circumflex coronary arterial occlusion in isolated inferior wall myocardial infarction

The presence of atrioventricular block and ST segment elevation in lead V4R accurately predicts right coronary artery occlusion in patients with inferior wall myocardial infarction. However, these electrocardiographic signs are absent in the majority of patients with inferior myocardial infarction. We studied ST segment elevation in leads II and III, ST segment in lead I and T wave polarity in lead V4R in order to differentiate between right coronary artery and left circumflex coronary artery occlusions in 104 patients with inferior myocardial infarction who subsequently underwent coronary angiography. The ST segment elevation was greater in lead III than in lead II when the right coronary artery was the culprit vessel and vice versa when the left circumflex was the culprit vessel (p < 0.001). An upright T wave in lead V4R and ST segment depression in lead I was common when the right coronary artery was the culprit vessel and not seen with left circumflex occlusion (p < 0.001). ST segment elevation in lead III was higher than in lead II with a sensitivity of 99 percent and a specificity of 100 percent for diagnosing right coronary artery as the culprit vessel. ST segment elevation in lead II was higher than in lead III with a sensitivity of 93 percent and a specificity of 100 percent in identifying the left circumflex as the culprit vessel. Thus, these signs are very useful in identifying the culprit vessel in inferior myocardial infarction.     

Predictive value and limitations of the ST/HR slope

To assess the value and predictive limitations of the exercise ST/HR slope, exercise test results were compared in 50 patients with stable angina and in 17 normal subjects with those in two groups known to have a high prevalence of inaccurate electrocardiographic responses to exercise. The last two groups included 51 patients tested within three weeks of acute myocardial infarction and 17 with important aortic regurgitation but no coronary disease. Of the normal subjects, 16 (94%) had ST/HR values less than or equal to 1 X 1 microV/beat/min. Of those with stable angina pectoris, 42 of 46 (91%) patients with coronary artery disease had ST/HR slopes ranging from 1 X 2 to 20 X 0 microV/beat/min, with false negative findings (slopes less than or equal to 1 X 1 microV/beat/min) in only four (9%). In contrast, of those with recent myocardial infarction, 15 of 42 (36%) with coronary disease had false negative slopes, including 12 of 20 (60%) with anterior wall injury. Of those with aortic regurgitation, conversely, 14 of 16 (88%) patients with calculable ST/HR slopes had values greater than 1 X 1 microV/beat/min despite the absence of coronary disease. Despite the accuracy of the test in patients with stable angina, false negative results are common in those after recent myocardial infarction, and false positive results occur often in those with abnormal volume loading due to aortic regurgitation.     

Predictive value and limitations of the ST/HR slope.

To assess the value and predictive limitations of the exercise ST/HR slope, exercise test results were compared in 50 patients with stable angina and in 17 normal subjects with those in two groups known to have a high prevalence of inaccurate electrocardiographic responses to exercise. The last two groups included 51 patients tested within three weeks of acute myocardial infarction and 17 with important aortic regurgitation but no coronary disease. Of the normal subjects, 16 (94%) had ST/HR values less than or equal to 1 X 1 microV/beat/min. Of those with stable angina pectoris, 42 of 46 (91%) patients with coronary artery disease had ST/HR slopes ranging from 1 X 2 to 20 X 0 microV/beat/min, with false negative findings (slopes less than or equal to 1 X 1 microV/beat/min) in only four (9%). In contrast, of those with recent myocardial infarction, 15 of 42 (36%) with coronary disease had false negative slopes, including 12 of 20 (60%) with anterior wall injury. Of those with aortic regurgitation, conversely, 14 of 16 (88%) patients with calculable ST/HR slopes had values greater than 1 X 1 microV/beat/min despite the absence of coronary disease. Despite the accuracy of the test in patients with stable angina, false negative results are common in those after recent myocardial infarction, and false positive results occur often in those with abnormal volume loading due to aortic regurgitation.     

Diagnostic value of changes in Q wave amplitude in left thoracic leads during physical loading

The informative value of stress-induced changes in Q wave amplitude and ST segment for the diagnosis of coronary heart disease was compared in records from left chest leads. Bicycle ergometry was conducted in 74 patients with coronary angiographically documented stenosis (more than 70% of the lumen) of one or more coronary arteries, and 28 subjects showing no apparent coronary arterial changes. The lack of increment in Q wave amplitude was shown to be a fairly sensitive sign of myocardial ischemia. Yet, its specificity is relatively low, much inferior to that of ST changes. The predictive value of changes in ST segment is significantly higher, as compared to that of changes in Q wave amplitude during exercise. Simultaneous assessment of ST and Q wave changes in response to stress failed to improve the predictive accuracy, as compared to the interpretation of ST changes alone.     

Exercise four hour redistribution thallium-201 single photon emission computed tomography and exercise induced ST segment elevation in detecting the viable myocardium in patients with acute myocardial infarction

OBJECTIVE: To investigate the specificity and sensitivity of the combination of redistribution in exercise thallium-201 single photon emission computed tomography (SPECT) and exercise induced ST elevation for detecting the viable myocardium in patients with acute myocardial infarction. DESIGN: 37 patients were studied within seven weeks of onset of Q wave myocardial infarction (anterior in 22, inferior in 15). All patients underwent exercise four hour redistribution thallium-201 SPECT and positron emission tomography using fluorine-18-fluorodeoxyglucose (FDG) and nitrogen-13 ammonia under fasting conditions. RESULTS: Sixteen patients showed exercise induced ST elevation >/= 1.5 mm, and 15 of these had increased FDG uptake in the infarct region. Eleven of 16 patients (10 of 11 patients with anterior infarctions) with irreversible thallium-201 defects and increased FDG uptake showed exercise induced ST elevation. The sensitivity, specificity, and predictive accuracy of redistribution, exercise induced ST segment elevation, or both for detecting increased FDG uptake were 82%, 75%, and 67% (94%, 75%, and 91% for anterior infarctions), respectively. CONCLUSIONS: In patients with acute Q wave myocardial infarction, the combination of redistribution in exercise thallium-201 SPECT and exercise induced ST elevation can detect the viable myocardium in the infarct region with high sensitivity and specificity, especially in patients with anterior infarctions.     

Accurate detection of triple vessel disease in patients with exercise induced ST segment depression after infarction

The severity of coronary artery disease is an important determinant of prognosis after acute myocardial infarction. The ability of a symptom limited exercise test to predict the presence of triple vessel disease was assessed in 221 patients three weeks after infarction. Coronary angiography was performed in patients with exercise induced ST segment depression. The presence of ST segment depression alone was poorly indicative of triple vessel disease; however, some specific features of ST segment changes on exercise were of predictive value. Downsloping ST segment configuration alone or horizontal ST segment depression associated with an early onset and a late recovery time after exercise correctly identified 30 (90%) of 33 patients with triple vessel disease whereas it incorrectly identified only 6 (15%) of 39 patients with single and double vessel disease. An abnormal blood pressure response was also predictive. In patients with ST segment depression after infarction triple vessel disease can be detected accurately by a combination of the electrocardiographic and haemodynamic variables attained on exercise.     

Accurate detection of triple vessel disease in patients with exercise induced ST segment depression after infarction.

The severity of coronary artery disease is an important determinant of prognosis after acute myocardial infarction. The ability of a symptom limited exercise test to predict the presence of triple vessel disease was assessed in 221 patients three weeks after infarction. Coronary angiography was performed in patients with exercise induced ST segment depression. The presence of ST segment depression alone was poorly indicative of triple vessel disease; however, some specific features of ST segment changes on exercise were of predictive value. Downsloping ST segment configuration alone or horizontal ST segment depression associated with an early onset and a late recovery time after exercise correctly identified 30 (90%) of 33 patients with triple vessel disease whereas it incorrectly identified only 6 (15%) of 39 patients with single and double vessel disease. An abnormal blood pressure response was also predictive. In patients with ST segment depression after infarction triple vessel disease can be detected accurately by a combination of the electrocardiographic and haemodynamic variables attained on exercise.     

Relationship of prior myocardial infarction to false-positive electrocardiographic diagnosis of acute injury in patients with chest pain

Prompt management of patients suffering acute myocardial infarction requires accurate early diagnosis based on the electrocardiogram. To assess the predictive value of ST segment elevation and ST segment depression (both greater than or equal to 0.1 mV) for the diagnosis of evolving myocardial infarction, we studied 100 consecutive patients admitted to the coronary care unit of The New York Hospital with at least 30 minutes of chest pain. Of 31 patients with ST segment elevation, 26 patients (84%) evolved myocardial infarction (positive test results for serum creatine phosphokinase-MB isoenzyme fraction), while only 13 (48%) of 27 patients with ST segment depression had myocardial infarctions. Among patients with ST segment elevations with a history of prior myocardial infarction, only five (50%) of ten evolved myocardial infarction, compared with 21 of 21 with no prior infarction. False-positive diagnoses of acute injury were due to ST elevation in the area of prior Q wave infarction. Prior myocardial infarction did not alter the lower predictive value of ST segment depression for evolving infarction. We conclude that patients presenting with chest pain and ST segment elevation have approximately twice the likelihood of myocardial infarction than patients with ST segment depression; incorporation of historic information regarding prior myocardial infarction can improve the predictive value of ST segment elevations to 100% but does not improve prediction with ST segment depressions.     

Intracoronary electrocardiogram and angina pectoris during percutaneous coronary interventions as an assessment of myocardial viability: comparison with low-dose dobutamine echocardiography.

The aims of this study were to evaluate the diagnostic value of intracoronary electrocardiogram (ECG) and presence of angina pectoris during percutaneous coronary interventions in the prediction of myocardial viability assessed by low-dose dobutamine echocardiography (LDDE). Seventy-one patients (60 men; mean age, 54 +/- 11 years) with recent Q-wave MI and angiographically documented regional wall motion abnormality in the presence of a significant (>/= 70%) nonocclusive stenosis of the infarct-related vessel who were referred for angioplasty were prospectively included in the study. The intracoronary ECG was recorded using coronary angioplasty guidewire. Significant ST segment elevation was defined as a new or worsening ST segment elevation of >/= 0.1 mV at 80 msec after the J-point. Angina pectoris was noted as present or absent during balloon inflation. All patients underwent LDDE for viability assessment. Significant ST segment elevation in the intracoronary ECG and chest pain were observed in 56 (78.9%) and 49 (69%) of the 71 patients. Viability was present on LDDE in 52 (92.9%) of 56 patients with and 3 (20%) of 15 without ST segment elevation. Viability was detected in 45 (91.8%) of 49 patients with and 10 (45.4%) of 22 without angina pectoris during balloon occlusion. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ST segment elevation for viability were 94.5%, 75%, 92.9%, 80%, and 90.1%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of angina pectoris for viability were 81.8%, 75%, 91.8%, 54.5%, and 80.3%, respectively. The present study demonstrated that a simple assessment of ST segment elevation in the intracoronary ECG or angina pectoris during coronary angioplasty can be used to assess myocardial viability identified by LDDE in patients with previous MI.     

Pathogenesis, treatment and prognosis of impending myocardial infarction and early post-infarction angina--relation between ST-segment shift during myocardial ischemia and the pathogenesis.

We studied 141 patients to evaluate the pathogenesis and clinical picture of high-risk unstable angina (UA), designated as impending myocardial infarction (IMI) in this study, or severe early post-infarction angina (PIA). IMI and PIA were diagnosed when chest pain appeared at rest and lasted 15 min or more despite extensive pharmacological therapy during hospital stay among consecutive 510 patients with UA. All patients underwent coronary angiography urgently within 72 h after chest pain, and were divided into 2 subgroups according to ST segment shifts during chest pain. In IMI, 42 patients with ST depression had higher incidences of prior myocardial infarction (MI), worsening UA, multivessel disease and complex lesions such as eccentric irregular lesion or ulceration. On the contrary, in 44 with ST elevation, new onset UA, single vessel disease and coronary thrombus (CT) were dominant. In PIA, 32 patients with ST elevation revealed higher incidences in Q wave MI, ST elevation at the MI onset, single vessel disease and CT, compared to 23 with ST depression who showed a high proportion of complex lesions. Thus, it was evident that there was a common link between the pathogenesis of IMI and PIA. The therapeutic options were also different in the groups according to ST segment shift. We conclude that ST segment shifts during chest pain may be useful for determining the pathogenesis and clinical features of high-risk UA.     

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.