Indications for coronary artery bypass graft surgery

ACBGS is indicated in patients with stable angina who have left main coronary artery disease; three-vessel disease; three or four of the clinical variables set forth in the Veterans Administration Cooperative Study; obstruction in proximal third of left anterior descending coronary artery as part of two- or three-vessel disease; and two- or three-vessel disease and exercise-induced ischemic ST-segment depression greater than or equal to 1.5 mm. ACBGS may increase survival in patients with limited exercise capacity. Finally, ACBGS may be indicated to increase the quality of life in patients with disabling angina that is refractory to medical treatment. Patients with unstable angina who have an inadequate response to intensive medical therapy should have emergency ACBGS. Indications for elective ACBGS in patients with unstable angina who respond adequately to medical therapy are the same as those for stable angina. Patients with rupture of the ventricular septum, acute severe mitral regurgitation, and cardiogenic shock with vessels suitable for ACBGS should have urgent ACBGS after acute myocardial infarction. Patients with postinfarction angina after the first few days following acute myocardial infarction, especially non-Q-wave infarction, should be considered for ACBGS. Indications for elective ACBGS in postinfarction patients are the same as those in stable angina. Patients with coronary artery disease, especially those with a significant amount of ischemic myocardium, who must undergo cardiac surgery for valvular heart disease or for congenital heart disease should probably have ACBGS performed at the time of surgery.     

A defective angina pectoris pain warning system: experimental findings of ischemic and electrical pain test

Ischemic pain threshold and tolerance levels using the tourniquet pain technique and electrical cutaneous pain thresholds were measured in patients with asymptomatic ischemic heart disease. Thirty asymptomatic patients, who repeatedly exhibited no angina pectoris pain during the occurrence of exercise-induced coronary ischemia (greater than or equal to 0.1 mV ST segment depression in exercise ECG) were compared to 30 randomly selected symptomatic control patients. In a smaller patient group (6 symptomatic, 6 asymptomatic) the degree of forearm ischemia during the tourniquet test was determined non-invasively by monitoring transcutaneous pO2. Results indicated that asymptomatic patients needed significantly more time to reach pain threshold following occlusion of forearm blood flow and exhibited significantly lower tcpO2 values at threshold than symptomatic patients. Electrical pain thresholds were also elevated in the asymptomatic group. These findings indicate that the phenomenon of asymptomatic myocardial ischemia can be explained by an extracardiac pain modifying mechanism.     

Angina and ST-segment depression during treadmill and arm ergometer testing in patients with coronary artery disease

The clinical use of exercise rehabilitation programs has increased for patients with coronary artery disease. Exercise testing in these programs typically is conducted on a treadmill or cycle ergometer, although many patients' vocations require upper extremity activities and some patients cannot perform lower extremity exercises. To compare the hemodynamic responses and the incidence of angina and ST-segment depression during upper and lower extremity exercise in patients with coronary artery disease, we administered symptom-limited arm ergometer and submaximal or maximal symptom-limited treadmill tests to 95 cardiac rehabilitation patients who had completed an eight-week exercise training program. Treadmill testing resulted in significantly higher heart rates, systolic blood pressures, and double products than arm ergometer testing. The incidence of ST-segment depression was significantly greater with treadmill testing than with arm ergometer testing, but the incidence of angina was not different between tests. Ten patients had ST-segment depression during both arm ergometer and treadmill testing, and the double products at the onset of ST-segment depression were not different. Our data suggest that arm ergometer testing is less likely to result in ST-segment depression than treadmill testing in patients with coronary artery disease, possibly because of the lower hemodynamic responses during arm ergometer testing.     

Absence of severe exercise-induced ischemia does not identify low-risk patients with three-vessel coronary artery disease.

The purpose of this study was to determine the prognosis of medically treated patients with three-vessel coronary artery disease and normal left ventricular function who do not have severe ischemia on exercise radionuclide angiography. The absence of severe ischemia was defined prospectively (in accordance with previously published criteria) as the presence of at least one of the following: (1) workload more than 600 kg-m/min, (2) ST-segment depression of less than 1 mm, or (3) unchanged or increased left ventricular ejection fraction during exercise. Of 42 patients (33% in functional class III or IV) followed up for a median duration of 53 months (range, 1 to 84 months), 22 had initial cardiac events during follow-up, including 6 cardiac deaths, 5 nonfatal myocardial infarctions, and 11 late (a median of 29 months after the exercise study) coronary revascularization procedures. At 4 years of follow-up, the overall survival was 83%. Survival free of cardiac death or myocardial infarction was 77%, and survival free of all cardiac events was 59%. Even in the absence of severe exercise-induced ischemia, medically treated patients with three-vessel coronary artery disease and normal left ventricular function still have a poor long-term outcome.     

The prevalence of silent ischemia in Turkish patients with type 2 diabetes mellitus

Cardiovascular disease (CVD) is the major cause of death in patients with type 2 diabetes mellitus. However, the diagnosis of CVD is delayed due to concealment of antecedent symptoms by factors such as autonomic neuropathy. In this study, we aimed to investigate the frequency of silent ischemia by using exercise electrocardiogram (ECG). The present study included 500 Turkish patients with type 2 diabetes (male/female: 222/278), who showed no evidence of CAD and angina pectoris or no sign(s) of ischemic changes in resting ECGs. All patients underwent treadmill exercise test according to Bruce protocol, and 62 cases (12.4%) exhibited abnormal changes. These patients identified by exercise ECG consisted of 28 males (28/222, [12.6%]) and 34 females (34/278, [12.2%]) and were then examined by coronary angiography. CAD was diagnosed in 53 individuals by coronary angiography. The abnormalities of exercise test are associated with the age of the patients or the duration of diabetes (p < 0.05). There is no significant difference in the severity of coronary disease or in the prevalence of silent ischemia between male and female patients. However, among the patients identified by exercise ECG females have higher body mass index than males, suggesting that obesity may represent the risk factor of CAD in women with type 2 diabetes.     

Exercise testing in suspected coronary artery disease

The interpretation and selection of exercise tests depends on the pretest probability of CAD. Imperfect tests (like exercise tests) provide probability estimates, not definite statements (such as "the patient has CAD" or "the patient does not have CAD"). In patients with a low pretest probability of CAD (asymptomatic persons or men and women with nonanginal chest pain), abnormal exercise test results provide probability estimates that are much too low to conclude that the patient has CAD. In patients with anginal pain and normal exercise tests, the probability of CAD is too high to conclude that the patient has a normal coronary circulation. Exercise tests are not useful for trying to rule out CAD in patients with anginal pain. In patients with an intermediate pretest probability of CAD (men and women with atypical angina and women with typical angina), abnormal exercise tests (particularly the myocardial scintiscan) provide probability estimates that are high enough to justify starting treatment for CAD. Exercise tests are most useful in this group, a conclusion that has been reached by other methods of analysis. The myocardial scintiscan is much more useful than the exercise ECG in women. When CAD is strongly suspected, exercise tests have relatively little diagnostic value but may be useful for prognosis. However, clinical evidence of poor ventricular function may alone suffice to select patients with angina pectoris for coronary arteriography. Conversely, when clinical indicators of congestive heart failure are absent, the prognosis in chronic stable angina is so favorable that any further testing may be unnecessary. Screening asymptomatic persons for CAD is a very low yield practice. Patients who have no cardiac risk factors (hypercholesterolemia, family history of CAD, cigarette smoking, and hypertension) are at especially low risk of a primary cardiac event. Older men with stable typical angina are particularly likely to have left main coronary artery stenosis or three-vessel disease with poor ventricular function. The exercise ECG can identify groups of older men with a relatively high risk of having left main coronary artery stenosis. Physicians should be cautious when applying these recommendations to a primary care practice. The foregoing analysis is based on data obtained from patients who had been selected for coronary arteriography. There are two principal effects of biased selection of study patients: The pretest probability of CAD in clinical subgroups is probably lower than as shown here.(ABSTRACT TRUNCATED AT 400 WORDS)     

The effect of single doses of antianginal preparations on the correlation of the time of the onset of typical pain and the electrocardiographic signs of myocardial ischemia in patients with stenocardia of effort

Altogether 359 paired bicycle ergometries coupled with administration of single doses of antianginal drugs were carried out in 62 men suffering from angina pectoris of effort, functional classes II and III. A study was made of the indicator characterizing the time that elapsed since the onset of a typical angina pectoris attack till the appearance of the signs of ischemia on the ECG. Administration of effective single doses of antianginal drugs raised the time elapsed since the pain onset till the appearance of the ST segment greater than or equal to 1.0 mm fall during the exercise. Administration of ineffective doses of nitrates, calcium antagonists and placebo entailed a decline of that indicator, a rise of the number of cases where the segment ST greater than or equal to 1.0 mm fall was recordable before the onset of painful sensations. Administration of propranolol in ineffective single doses failed to provoke a decrease of the time elapsed since the typical pain onset till the appearance of the ST segment greater than or equal to 1.0 mm fall. Intake of ineffective single doses of nitrates, calcium antagonists and placebo may deprive certain patients of early signalization and appearance of the ECG signs of myocardial ischemia.     

Ambulatory monitoring of silent myocardial ischemia: what is its utility?

In patients with angina pectoris, ambulatory ST segment monitoring has documented that asymptomatic myocardial ischemic episodes occur with greater frequency than previously suspected. During such episodes, ischemia has been verified by nuclear, echocardiographic, and biochemical techniques. Painless ST segment depression is consistent with severe coronary artery disease when detected by ambulatory monitoring in patients with angina and portends a worsened prognosis in patients about to have vascular surgical procedures. On the other hand, ST depression without angina has a better prognosis than ST depression with angina during treadmill exercise testing. Silent ischemia of prolonged duration per 24-hour period suggests a poor prognosis in patients with a history of unstable angina or myocardial infarction.     

Effects of nicardipine on chronic stable effort angina: a non-invasive assessment

The effects of 60 mg/day nicardipine hydrochloride were evaluated in a 4-week single-blind study on 12 patients with chronic stable effort angina. All patients completed the treatment with few reports of adverse effects. Nicardipine hydrochloride was effective in reducing the incidence of anginal attacks and consumption of glyceryl trinitrate. Treadmill exercise time, angina onset time and the time to 1 mm ST-segment depression were increased. The extent of ST-segment depression was reduced at maximum comparable exercise, with a reduced rate-pressure product and, at maximum exercise, with an increased rate-pressure product. Myocardial stress 201Tl scintillography was carried out in eight of the patients and showed improved washout in antero-septal, infero-apical and postero-lateral segments. Echocardiographic measures of left ventricular function were enhanced because of reduction of afterload. Systemic vascular resistance and end-systolic stress were also decreased and a significant correlation was found between the increase in ejection fraction and reduction of systolic blood pressure. It is concluded that nicardipine hydrochloride is effective in the control of stable effort angina by reducing myocardial oxygen consumption and enhancing coronary blood flow thereby improving left ventricular function.     

Predictive accuracy of ST depression during rapid atrial fibrillation on the presence of obstructive coronary artery disease

Background

Rapid atrial fibrillation (AF) is commonly associated with ST-segment depressions. ST-segment depression during a chest pain episode or exercise stress testing in sinus rhythm is predictive of obstructive coronary artery disease (CAD), but it is unclear if the presence or magnitude of ST-segment depression during rapid AF has similar predictive accuracy.

Methods

One hundred twenty-seven patients with rapid AF (heart rate ≥120 beats per minute) who had cardiac catheterization performed during the same hospital admission were retrospectively reviewed. Variables to compute thrombolysis in myocardial infarction (TIMI) risk score, demographic profiles, ST-segment deviation, cardiac catheterization results, and cardiac interventions were collected.

Results

Thirty-five patients had ST-segment depression of 1 mm or more, and 92 had no or less than 1 mm ST depression. Thirty-one patients were found to have obstructive CAD. In the group with ST-segment depression, 11 (31%) patients had obstructive CAD and 24 (69%) did not. In the group with less than 1 mm ST-segment depression, 20 (22%) had obstructive CAD and 72 (78%) did not (P = .25). Sensitivity, specificity, and positive and negative predictive values for presence of obstructive CAD were 35%, 75%, 31%, and 78%, respectively. The presence of ST-segment depression of 1 mm or more was not associated with presence of obstructive CAD before or after adjustment of TIMI variables. The relationship between increasing grades of ST-segment depression and obstructive CAD showed a trend toward significance (P = .09), which did not persist after adjusting for TIMI risk variables (P = .36).

Conclusion

ST-segment depression during rapid AF is not predictive for the presence of obstructive CAD.     

康复训练对冠心病患者介入治疗后的运动耐量的影响

目的 察康复训练对冠心病经皮冠状动脉介入治疗（PCI）后患者运动耐量的影响。方法 确诊为冠心病并成功进行了首次PCI的患者57例，随机分为运动康复组（26例）和对照组（31例）．2组患者除行PCI治疗外，均采用相似的常规疗法（口服肠溶阿司匹林、硝酸酯类、转换酶抑制剂或他汀类药物等）。运动康复组于PCI术后第3天开始进行不同阶段、不同运动强度的康复训练，运动分为热身期，锻炼期、恢复期。3个月后，行心电图活动平板运动试验。观察活动平板运动试验运动前、运动中的心率、血压、心电图改变及心绞痛发作情况。结果 运动康复治疗3个月后，运动康复组与对照组静息及运动时心率、收缩压、舒张压、心率-血压双乘积差异无统计学意义（P〉0．05），其总运动时间、运动至出现S段压低1mm时间、运动至心绞痛出现时间与对照组相比明显延长（P〈0．05或P〈0．01），最大运动耐量明显增加（P〈0．05或P〈0．01）。结论 照运动处方进行的运动训练能明显缓解冠心病介入治疗后患者心绞痛症状及改善心电图缺血性S—T变化，提高冠心病介入治疗后患者的运动耐量，延长运动时间。     

Stratification of single-vessel coronary stenosis by ischemic threshold at the onset of wall motion abnormality during continuous monitoring of left ventricular function by semisupine exercise echocardiography.

We studied the relation between the ischemic threshold at the onset of wall motion abnormality on exercise echocardiography (EE) and the severity of coronary stenosis in patients with 1-vessel coronary artery disease (CAD). We screened 216 consecutive patients who underwent coronary angiography and EE for suspected CAD. Ninety-five (74 men; age, 56 +/- 12 years) satisfied the study criteria, that is, the presence of 1-vessel disease or no evidence of CAD on angiography and a normal baseline echocardiogram. Eighty-seven patients had 1-vessel CAD on angiography, and exercise-induced wall motion abnormality occurred in 73 (77%). Optimal cutoff values of percent diameter stenosis and minimal lumen diameter for predicting a positive EE were 61% (sensitivity and specificity of 76%) and 1.12 mm (sensitivity and specificity of 74%). Among patients with positive EE, heart rate-blood pressure product at ischemic threshold was correlated with quantitative coronary stenosis (r = -0.72, P <.001). The ischemic threshold from continuous monitoring of left ventricular function during semisupine EE is correlated with the severity of coronary stenosis among patients with 1-vessel disease and a normal resting echocardiogram.     

Prognostic endpoint yield of high-level versus low-level graded exercise testing

The prognostic endpoint yield (PEY) of a low-level (less than or equal to 4.6 METS) vs a high-level graded exercise test administered soon after myocardial infarction was evaluated with 184 patients. Test endpoints considered prognostically significant for future cardiac events were (1) ST segment depression greater than or equal to 1mm, (2) angina pectoris, and (3) complex ventricular beats. Test endpoints were assigned to both low-level and high-level tests if they occurred less than or equal to 4.6 METS; test endpoints greater than 4.6 METS were assigned to the high-level test only. Allowing the 145 patients who were asymptomatic during the low-level test to continue into the high-level protocol revealed a 2.5 times greater occurrence of angina pectoris (38 vs 15), a 3.4 times greater occurrence of ST segment depression (27 vs 8), and twice the occurrences of ventricular beats (4 vs 2). This substantial increase in prognostic endpoint yield was demonstrated in the presence of a significantly longer exercise time with the high-level test (9.0 vs 5.1 min), with no significant difference between protocols for peak heart rate or systolic blood pressure. Therefore, a high-level graded exercise test appears to increase the yield of test endpoints with known prognostic importance.     

Diagnosis of right ventricle hypertrophy during pulmonary heart disease in patients with chronic bronchitis]

The comparison of ECG, VCG and ECHO data performed in 78 patients with chronic bronchitis allowed us to distinguish 4 grades of right ventricular hypertrophy (RVH): 1) absence of RVH (QRS loop occupies up to 70% of the area in horizontal plane, right ventricular wall thickness (RVWT) up to 5 mm, ECG changes); 2) slightly marked RVH (QRS-loop area 70-89%, RVWT 6-9 mm, electric axis deviation to the right on ECG, and P.100/R + S greater than 20 in lead II); 3) marked RVH (QRS-loop area 90-100%, RVWT 6-10 mm, right ventricular end-diastolic dimension 2-1-3.0 cm, on ECG--the above changes plus R/SV1 greater than 1.0, RV1 greater than or equal to 5 mm, RV1 greater than or equal to 7 mm, and P-pulmonale); 4) marked RVH with significant dilatation and repolarization abnormalities (VCG and ECHO data as above plus right ventricular end-diastolic dimension on ECG more than 3.0 cm, S-T depression, and negative T-wave in leads aVF and V1-3). Apparent ECG signs of RVH in chronic bronchitis develop much later, after the development of secondary pulmonary hypertension.     

Acute Coronary Syndromes: Diagnosis and Management, Part I

The term acute coronary syndrome (ACS) refers to any group of clinical symptoms compatible with acute myocardial ischemia and includes unstable angina (UA), non—ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). These high-risk manifestations of coronary atherosclerosis are important causes of the use of emergency medical care and hospitalization in the United States. A quick but thorough assessment of the patient''s history and findings on physical examination, electrocardiography, radiologic studies, and cardiac biomarker tests permit accurate diagnosis and aid in early risk stratification, which is essential for guiding treatment. High-risk patients with UA/NSTEMI are often treated with an early invasive strategy involving cardiac catheterization and prompt revascularization of viable myocardium at risk. Clinical outcomes can be optimized by revascularization coupled with aggressive medical therapy that includes anti-ischemic, antiplatelet, anticoagulant, and lipid-lowering drugs. Evidence-based guidelines provide recommendations for the management of ACS; however, therapeutic approaches to the management of ACS continue to evolve at a rapid pace driven by a multitude of large-scale randomized controlled trials. Thus, clinicians are frequently faced with the problem of determining which drug or therapeutic strategy will achieve the best results. This article summarizes the evidence and provides the clinician with the latest information about the pathophysiology, clinical presentation, and risk stratification of ACS and the management of UA/NSTEMI.ACC = American College of Cardiology; ACE = angiotensin-converting enzyme; ACS = acute coronary syndrome; ADP = adenosine diphosphate; AHA = American Heart Association; BNP = B-type natriuretic peptide; CABG = coronary artery bypass grafting; CAD = coronary artery disease; CHF = congestive heart failure; CI = confidence interval; CK-MB = muscle and brain fraction of creatine kinase; CRP = C-reactive protein; CURE = Clopidogrel in Unstable Angina to Prevent Recurrent Events; ECG = electrocardiography; ED = emergency department; GP = glycoprotein; HR = hazard ratio; IV = intravenous; LDL = low-density lipoprotein; LMWH = low—molecular-weight heparin; LV = left ventricular; MI = myocardial infarction; NSTEMI = non—ST-segment elevation MI; PCI = percutaneous coronary intervention; STEMI = ST-segment elevation MI; TIMI = Thrombolysis in Myocardial Infarction; UA = unstable angina; UFH = unfractionated heparinThe term acute coronary syndrome (ACS) refers to any group of clinical symptoms compatible with acute myocardial ischemia and covers the spectrum of clinical conditions ranging from unstable angina (UA) to non—ST-segment elevation myocardial infarction (NSTEMI) to ST-segment elevation myocardial infarction (STEMI). Unstable angina and NSTEMI are closely related conditions: their pathophysiologic origins and clinical presentations are similar, but they differ in severity. A diagnosis of NSTEMI can be made when the ischemia is sufficiently severe to cause myocardial damage that results in the release of a biomarker of myocardial necrosis into the circulation (cardiac-specific troponins T or I, or muscle and brain fraction of creatine kinase [CK-MB]). In contrast, the patient is considered to have experienced UA if no such biomarker can be detected in the bloodstream hours after the initial onset of ischemic chest pain. Unstable angina exhibits 1 or more of 3 principal presentations: (1) rest angina (usually lasting >20 minutes), (2) new-onset (<2 months previously) severe angina, and (3) a crescendo pattern of occurrence (increasing in intensity, duration, frequency, or any combination of these factors). Each year in the United States, approximately 1.36 million hospitalizations are required for ACS (listed either as a primary or a secondary discharge diagnosis), of which 0.81 million are for myocardial infarction (MI) and the remainder are for UA. Roughly two-thirds of patients with MI have NSTEMI; the rest have STEMI.¹     

Early exercise thallium-201 single photon emission computed tomography in unstable angina: a prospective study

Summary. To evaluate the safety and diagnostic value of early symptom-limited exercise electrocardiography (ECG) and exercise thallium-201 single photon emission computed tomography (SPECT) in unstable angina (UA), 39 patients were studied prospectively soon after stabilization on medical treatment. No patient had a history of myocardial infarction (MI) or revascularization and patients with left bundle branch block were excluded. Exercise ECG and exercise thallium-201 SPECT were performed 8 plusmn; 4 days and 11 plusmn; 6 days respectively after admission to hospital. Seventeen out of 39 patients (44%) had positive exercise ECGs and 22 (56%) negative or inconclusive ones. Exercise thallium-201 SPECT was positive in 26 patients (67%) and negative in 13 patients (33%). Thirty-one patients underwent coronary arteriography and 24 of them proved to have significant coronary artery disease (CAD). The sensitivity, specificity and positive predictive value of exercise ECG in detecting CAD are 62%, 86%, and 94% respectively while the corresponding results are 96%, 100%, and 100% for exercise thallium-201 SPECT. Therefore, it is concluded that the early symptom-limited exercise test is safe in medically stabilized patients with UA. Early exercise thallium-201 SPECT is highly sensitive and predictive of the presence of significant CAD among patients in the early recovery phase of UA and can be used in selecting this group of patients for coronary angiography and other therapeutic strategies.     

A new electrocardiographic criteria for emergent reperfusion therapy

The benefit of emergency reperfusion therapy with fibrinolytics or primary percutaneous coronary intervention in patients with ST-segment elevation (STE) acute myocardial infarction (MI) is well known. However, what is not well known are which subgroups of MI patients with ST-segment depression (STD) on the 12-lead electrocardiogram (ECG) may benefit from emergent reperfusion therapy. Current clinical guidelines recommend against administering emergent reperfusion therapy to MI patients with STD on the ECG unless a true posterior MI is suspected. Overlooked subgroups of patients with STD on the initial ECG who may potentially benefit from emergent reperfusion therapy are patients with multilead STD with coexistent STE in lead aVR. This finding has been reported in MI patients with occlusion of the left main artery, occlusion of the proximal left anterior descending artery, and MI in the presence of severe multivessel coronary artery disease. Because these patients have a higher mortality in the setting of MI, we believe that this ECG finding be considered a STEMI equivalent and that patients with this finding receive consideration for emergent reperfusion therapy preferably at a center with both primary percutaneous coronary intervention and coronary artery bypass grafting capability. In this report, we present 3 such patients to heighten the awareness of the emergency physician to this phenomenon.     

Spatial distribution of repolarization times in patients with coronary artery disease

The potential clinical value of QT dispersion (QTd), a measure of the interlead range of QT interval duration in the surface 12-lead ECG, remains ambiguous. The aim of the study was the temporal and spatial analysis of the QT interval in healthy subjects and in patients with coronary artery disease (CAD) using magnetocardiography (MCG) and surface ECG. Standard 12-lead ECG and 37-channel MCG were performed in 20 healthy subjects, 23 patients with CAD without prior myocardial infarction (MI), 31 MI patients and 11 MI patients with ventricular tachycardia (VT). QTd was increased in CAD without MI compared to normals (ECG 46.1 +/- 6.0 vs 42.8 +/- 5.0, P < 0.05; MCG 66.8 +/- 20.3 vs 49.7 +/- 10.8, P < 0.01) and in VT compared to MI (ECG 66.8 +/- 16.5 vs 51.9 +/- 16.6, P < 0.05; MCG 93.6 +/- 29.6 vs 66.8 +/- 20.8, P < 0.005). In MCG, spatial distribution of QT intervals in patient groups differed from those in healthy subjects in three ways: (1) greater dispersion, (2) greater local variability, and (3) a change in overall pattern. This was quantified on the basis of smoothness indexes (SI). Normalized SI was higher in CAD without MI compared to normals (3.8 +/- 1.1 vs 2.7 +/- 0.6, P < 0.001) and in VT compared to MI (6.4 +/- 1.6 vs 4.2 +/- 1.4, P < 0.0005). For the normal-CAD comparison a sensitivity of 74% and a specificity of 80% was obtained, for MI-VT, 100% and 77%, respectively. The results suggest that examining the spatial interlead variability in multichannel MCG may aid in the initial identification of CAD patients with unimpaired left ventricular function and the identification of post-MI patients with augmented risk for VT.     

The Diagnostic Significance of Reciprocal ST Segment Depression in Acute Myocardial Infarction

The relationship between reciprocal ST-segment depression, theresult of an early submaximal exercise ECG, and the anatomyof coronary artery disease was explored in 142 patients withacute myocardial infarction. Reciprocal ST-segment depression was observed in 65 per centof 79 patients with inferior infarction and 57 per cent of 63with anterior infarction. Thirty-three of the 52 patients withreciprocal ST-segment depression had a significant stenosisof the coronary artery supplying the reciprocal ST-segment territory(63 per cent), and 31 of the 46 patients with a positive exercisetest had a significant stenosis of the coronary artery supplyingthe ischaemic territory (67 per cent). Forty-one of the patientswith reciprocal ST-segment depression (79 per cent) and 35 ofthe patients with positive exercise tests (76 per cent) werefound to have multivessel coronary artery disease. The study showed that reciprocal ST-segment depression was associatedwith stenosis of the coronary artery supplying the territoryopposite the infarct in nearly two-thirds of the patients andwith multivessel coronary artery disease in almost four-fifthsof them. Reciprocal ST-segment depression after infarction wasas accurate as a positive submaximal exercise test at predictingthe presence of multivessel coronary artery disease.     

The diagnostic significance of reciprocal ST segment depression in acute myocardial infarction

The relationship between reciprocal ST-segment depression, the result of an early submaximal exercise ECG, and the anatomy of coronary artery disease was explored in 142 patients with acute myocardial infarction. Reciprocal ST-segment depression was observed in 65 per cent of 79 patients with inferior infarction and 57 per cent of 63 with anterior infarction. Thirty-three of the 52 patients with reciprocal ST-segment depression had a significant stenosis of the coronary artery supplying the reciprocal ST-segment territory (63 per cent), and 31 of the 46 patients with a positive exercise test had a significant stenosis of the coronary artery supplying the ischaemic territory (67 per cent). Forty-one of the patients with reciprocal ST-segment depression (79 per cent) and 35 of the patients with positive exercise tests (76 per cent) were found to have multivessel coronary artery disease. The study showed that reciprocal ST-segment depression was associated with stenosis of the coronary artery supplying the territory opposite the infarct in nearly two-thirds of the patients and with multivessel coronary artery disease in almost four-fifths of them. Reciprocal ST-segment depression after infarction was as accurate as a positive submaximal exercise test at predicting the presence of multivessel coronary artery disease.