Electrocardiography cannot reliably differentiate transient left ventricular apical ballooning syndrome from anterior ST-segment elevation myocardial infarction

Objective

The presentation and electrocardiographic (ECG) characteristics of transient left ventricular apical ballooning syndrome (TLVABS) can be similar to that of anterior ST-segment elevation myocardial infarction (STEMI). We tested the hypothesis that the ECG on presentation could reliably differentiate these syndromes.

Subjects and Methods

Between January 1, 2002 and July 31, 2004, we identified 18 consecutive patients with TLVABS who were matched with 36 subjects presenting with acute anterior STEMI due to atherothrombotic left anterior descending coronary artery occlusion.

Results

All patients with TLVABS were women (mean age, 72.0 ± 13.1 years). The heart rate, PR interval, QRS duration, and corrected QT interval were similar between groups. Distribution of ST elevation was similar, but patients with anterior STEMI exhibited greater ST elevation. Regressive partitioning analysis indicated that the combination of ST elevation in lead V₂ of less than 1.75 mm and ST-segment elevation in lead V₃ of less than 2.5 mm was a suggestive predictor of TLVABS (sensitivity, 67%; specificity, 94%). Conditional logistic regression indicated that the formula: (3 × ST-elevation lead V₂) + (ST-elevation V₃) + (2 × ST-elevation V₅) allowed possible discrimination between TLVABS and anterior STEMI with an optimal cutoff level of less than 11.5 mm for TLVABS (sensitivity, 94%; specificity, 72%). Patients with TLVABS were less likely to have concurrent ST-segment depression (6% vs 44%; P = .003).

Conclusions

Women presenting with TLVABS have similar ECG findings to patients with anterior infarct but with less-prominent ST-segment elevation in the anterior precordial ECG leads. These ECG findings are relatively subtle and do not have sufficient predictive value to allow reliable emergency differentiation of these syndromes.     

Addition of right-sided and posterior precordial leads during stress testing

Background

Exercise treadmill testing has limited sensitivity for the detection of coronary artery disease, frequently requiring the addition of imaging modalities to enhance the predictive value of the test. Recently, there has been interest in using nonstandard electrocardiographic (ECG) leads during exercise testing.

Methods

We consecutively enrolled all patients undergoing exercise myocardial imaging with four additional leads recorded (V₄R, V₇, V₈, and V₉). The test characteristics of the 12-lead, the 15-lead (12-lead, V₇, V₈, V₉), and the 16-lead (12-lead, V₄R, V₇, V₈, V₉) ECGs were compared with stress imaging in all patients. In the subset of patients who underwent angiography within 60 days of stress testing, these lead arrays were compared with the catheterization findings.

Results

There were 727 subjects who met entry criteria. The mean age was 58.5 ± 12.3 years, and 366 (50.3%) were women. Pretest probability for disease was high in 241 (33.1%), intermediate in 347 (47.7%), and low in 139 (19.1%). A total of 166 subjects had an abnormal 12-lead ECG during exercise. The addition of 3 posterior leads to the standard 12-lead ECG resulted in 7 additional subjects having an abnormal electrocardiographic response to exercise. The addition of V₄R resulted in only 1 additional patient having an abnormal ECG during exercise. The sensitivity of the ECG for detecting ischemia as determined by stress imaging was 36.6%, 39.2%, and 40.0% (P = NS) for the 12-lead, 15-lead, and 16-lead ECGs, respectively. In those with catheterization data (n = 123), the sensitivity for determining obstructive coronary artery disease was 43.5%, 45.2%, and 45.2% (P = NS) for the 12-lead, 15-lead, and 16-lead ECGs, respectively. The sensitivity of imaging modalities was 77.4% when compared with catheterization.

Conclusions

In patients undergoing stress imaging studies, the addition of right-sided and posterior leads did not significantly increase the sensitivity of the ECG for the detection of myocardial ischemia. Additional leads should not be used to replace imaging modalities for the detection of coronary artery disease.     

Diagnostic Accuracy of Electrocardiographic ST-Segment Depression in Patients With Rapid Atrial Fibrillation for the Prediction of Coronary Artery Disease

Background

We aimed to examine the diagnostic value of ST-segment depression in patients with rapid atrial fibrillation (AF) for the prediction of coronary artery disease (CAD).

Methods

Hemodynamically stable patients with AF, and a heart rate > 80% of their maximum predicted according to their age, were allocated to 2 groups according to their electrocardiographic findings on admission: group A included patients without any ST-segment abnormalities and group B, patients with downward or horizontal ST-segment depression ≥ 1 mm in 2 or more contiguous leads. Group A patients were subjected to a dobutamine stress echo or Tl-201 myocardial single-photon emission computed tomography, followed by coronary angiography in case of abnormal results and Group B patients to coronary angiography. CAD was defined angiographically as stenosis of ≥ 50% in any major epicardial coronary vessel.

Results

Out of 115 consecutive patients, with a mean age of 65.9 ± 10.2 years, 42.6% were male, 18.3% smokers, 68.7% hypertensive, 21.7% had diabetes, and 40% had hyperlipidemia. We enrolled 71 and 44 patients in group A and B, respectively. Prevalence of significant CAD among studied patients was 21.7%, 3/71 (4.2%) and 22/44 (50.0%) in group A and B, respectively. Overall ST-segment depression during rapid AF had 88.0% sensitivity (95% confidence interval [CI], 67.7%-96.8%) and 75.6% specificity (95% CI, 65.2%-83.7%) in predicting presence of CAD, and positive and negative predictive value was 50.0% (95% CI, 34.8%-65.2%) and 95.8% (95% CI, 87.3%-98.7%), respectively.

Conclusions

In consecutive patients with rapid AF, the absence of ST-segment depression might indicate absence of CAD.     

Electrocardiographic differentiation between occlusion of the first diagonal branch and occlusion of the left anterior descending coronary artery

Purpose

We sought to electrocardiographically distinguish ST-segment elevation (STE)-acute myocardial infarction (AMI) caused by occlusion of the first diagonal branch (D1) from STE-AMI caused by occlusion of the left anterior descending coronary artery (LAD).

Methods

We examined 28 patients with STE-AMI caused by D1 occlusion (G-D) and 342 with STE-AMI caused by LAD occlusion (G-L).

Results

G-D had a higher prevalence of STE ≥0.5 mm in each of leads I and aVL and a lower prevalence of STE ≥1 mm in each of leads V₁ through V₆ than G-L. The prevalence of STE ≥0.5 mm in lead aVL without STE ≥1 mm in lead V₁ was higher in G-D (82.1%) than in G-L (9.4%, P < .01).

Conclusion

ST-segment elevation ≥0.5 mm in lead aVL without STE ≥1 mm in lead V₁ may be useful to distinguish STE-AMI caused by occlusion of the D1 from STE-AMI caused by occlusion of the LAD.     

A quantitative evaluation of ST-segment changes on the 18-lead electrocardiogram during acute coronary occlusions

This study determined quantitative ST segment changes on the 18-lead electrocardiogram (ECG) during occlusions in each of the coronary arteries.

Methods

Continuous 18-lead ECGs, including standard 12 leads, posterior (V_7-9), and right ventricular (RV) leads (V_3-5R) were recorded for 155 subjects undergoing percutaneous coronary occlusions, the maximum intervention.

Results

During 58 left anterior descending (LAD) coronary occlusions, the maximum ST elevation and depression were in V₃ (4.2mm) and III (−0.9mm), respectively. During 44 right coronary artery (RCA) occlusions, the maximum ST elevation and depression were in III (2.2mm) and aVL (−1.4mm), respectively. During 53 left circumflex (LCX) occlusions, the maximum ST elevation and depression were in V₇ (0.8mm) and V₂ (−1.6mm), respectively.

Conclusions

ST elevation often occurred in the anteroapical (V₁-V₆), lateral (I, aVL), and RV lead V_3R during LAD occlusions; in the inferior, RV, and posterior leads during RCA occlusions; and in the posterior, inferior, and apical leads (V₅-V₆) during LCX occlusions.     

Clinical and angiographic characteristics of patients with combined anterior and inferior ST-segment elevation on the initial electrocardiogram during acute myocardial infarction

Objective

We evaluated the significance of combined anterior and inferior ST-segment elevation on the initial electrocardiogram (EKG) in patients with acute myocardial infarction (AMI) and correlated it with AMI size and left ventricular (LV) function.

Methods

We analyzed admission EKGs of 2996 patients with AMI from the GUSTO-I angiographic substudy and the GUSTO-IIb angioplasty substudy who underwent immediate angiography. In all, we identified 1046 patients with anterior ST elevation (ST-segment elevation in ≥2 of leads V₁-V₄) and divided them into 3 groups: Group 1, anterior + inferior ST elevation (ST elevation in ≥2 of leads II, III, aVF, n =179); Group 2, anterior ST elevation only (<2 of leads II, III, aVF with ST elevation or depression, n = 447); Group 3, anterior ST elevation + superior ST elevation (ST depression in ≥2 of leads II, III, aVF, n = 420).

Results

Cardiac risk factors, prior AMI, prior percutaneous transluminal coronary angioplasty or coronary artery bypass graft, Killip class, and thrombolytic therapy assignment did not differ among the 3 groups. Group 1 patients had greater number of leads with ST elevation compared to Groups 2 and 3 (ST elevation in ≥6 leads 83% vs 22% vs 49%, P = .001). Despite greater ST-segment elevation, Group 1 patients had a lower peak CK level (median baseline peak CK 1370 vs 1670 vs 2381 IU, P = .0001) and less LV dysfunction (median ejection fraction 0.53 vs 0.49 vs 0.45, P = .0001; median number of abnormal chords 21 vs 32 vs 40, P = .0001). Angiographically, Group 1 had 2 distinct subsets of patients with either right coronary artery (RCA) (59%) or left anterior descending coronary artery (LAD) (36%) occlusion. In contrast, the infarct-related artery (IRA) was almost entirely the LAD in Groups 2 and 3 (97%). Further, the site of IRA occlusion in Group 1 was mostly proximal RCA (67%) in the RCA subgroup and mid or distal LAD (70%) in the LAD subgroup. ST-segment elevation in lead V₁ ≥ V₃ and absence of progression of ST elevation from lead V₁ to V₃ on the EKG differentiated IRA-RCA from IRA-LAD in patients with combined anterior and inferior ST elevation.

Conclusions

The AMI size and LV dysfunction in patients with anterior ST elevation is directly related to the direction of ST segment deviation in the leads II, III, aVF; least with inferior ST elevation, intermediate with no ST deviation, and maximal with superior ST elevation (inferior ST depression). Despite greater ST-segment elevation, patients with combined anterior and inferior ST elevation have limited AMI size and preserved LV function. Angiographically, they comprise 2 distinct subsets with either proximal RCA or mid to distal LAD occlusion. A predominant right ventricular and limited inferior LV AMI from a proximal RCA occlusion, or a smaller anterior AMI from a more distal occlusion of LAD may explain their limited AMI size despite greater ST elevation.     

Predictors of exercise capacity and the impact of angiographic coronary artery disease in heart transplant recipients

Background

Maximal exercise capacity is limited in patients after heart transplantation. The extent to which transplant coronary artery disease contributes to exercise intolerance in these patients has not been well defined.

Methods

This prospective study examined exercise capacity among 174 heart transplant recipients who underwent 358 exercise tests 0.3 to 13 years after surgery. Data were collected as part of routine posttransplantation treatment that each year consist of clinical and hemodynamic measurements (including ejection fraction, cardiac index, pulmonary capillary wedge pressure, and the presence of coronary artery disease) and cardiopulmonary exercise test (including measures of peak Vo₂). The mean follow-up was 3.5 ± 0.2 years after transplantation. Serial exercise test data were available in 102 patients

Results

Peak Vo₂ was 19.4 ± 0.4 mL/kg per minute, representing 70% ± 1.3% of the age-predicted value. Exercise capacity increased significantly after transplantation and then remained stable throughout long-term follow-up. Only age, maximal systolic blood pressure, pulmonary vascular resistance, and body mass index were independent determinants of exercise capacity (R² = 0.51), whereas specific transplant factors such as denervation, hemodynamic variables, donor characteristics, immunosuppressive drugs, biochemical parameters, and transplant coronary artery disease (TxCAD) did not contribute to the explanation of reduced exercise capacity. Although TxCAD was not related to exercise capacity in the multivariate analysis, exercise capacity declined by 17.1% (P < .05) among those in whom CAD developed during follow-up.

Conclusions

Exercise capacity is reduced among heart transplant recipients, and age is the strongest determinant of aerobic performance. Specific transplant-related factors, including TxCAD, do not contribute significantly to the explanation of exercise capacity. However, the occurrence of TxCAD may contribute to reduced exercise capacity during follow-up, since peak Vo₂ appears to decline only among those who have TxCAD.     

Determinants of ST-segment level in lead aVR in anterior wall acute myocardial infarction with ST-segment elevation

Background

This study aimed to clarify the determinants of ST-segment level in lead aVR in anterior wall acute myocardial infarction (AAMI).

Methods

We analyzed ST-segment levels in all 12 leads on admission and emergency coronary angiographic findings in 261 patients with a first AAMI with ST-segment elevation. The length of the left anterior descending coronary artery (LAD) was classified as follows: short = not reaching the apex; medium = perfusing less than 25% of the inferior wall; long = perfusing 25% or more of the inferior wall.

Results

The ST-segment level in lead aVR correlated significantly with the ST-segment levels in leads I, II, III, aVF, V₁, and V_3-6, especially with those in leads II and V₆ (r = −0.63, P < .001; r = −0.61, P < .001; respectively). Patients with a proximal LAD occlusion had a greater ST-segment level in lead aVR than those with a distal LAD occlusion (P < .001). Patients with a long LAD had a lower ST-segment level than those with a short or medium LAD (P < .05).

Conclusions

The ST-segment levels, especially in leads II and V₆, the site of the LAD occlusion, and the length of the LAD affect the ST-segment level in lead aVR in ST-segment elevation AAMI.     

Optimization of the precordial leads of the 12-lead electrocardiogram may improve detection of ST-segment elevation myocardial infarction

Background

For the assessment of patients with chest pain, the 12-lead electrocardiogram (ECG) is the initial investigation. Major management decisions are based on the ECG findings, both for attempted coronary artery revascularization and risk stratification. The aim of this study was to determine if the current 6 precordial leads (V₁-V₆) are optimally located for the detection of ST-segment elevation in ST-segment elevation myocardial infarction (STEMI).

Methods

We analyzed 528 (38% anterior [200], 44% inferior [233], and 18% lateral [95]) patients with STEMI with both a 12-lead ECG and an 80-lead body surface map (BSM) ECG (Prime ECG, Heartscape Technologies, Bangor, Northern Ireland). Body surface map was recorded within 15 minutes of the 12-lead ECG during the acute event and before revascularization. ST-segment elevation of each lead on the BSM was compared with the corresponding 12-lead precordial leads (V₁-V₆) for anterior STEMI. In addition, for lateral STEMI, leads I and aVL of the BSM were also compared; and limb leads II, III, aVF of the BSM were compared with inferior unipolar BSM leads for inferior STEMI. Leads with the greatest mean ST-segment elevation were selected, and significance was determined by analysis of variance of the mean ST segment.

Results

For anterior STEMI, leads V₁, V₂, 32, 42, 51, and 57 had the greatest mean ST elevation. These leads are located in the same horizontal plane as that of V₁ and V₂. Lead 32 had a significantly greater mean ST elevation than the corresponding precordial lead V₃ (P = .012); and leads 42, 51, and 57 were also significantly greater than corresponding leads V₄, V₅, V₆, respectively (P < .001). Similar findings were also found for lateral STEMI. For inferior STEMI, the limb leads of the BSM (II, III, and aVF) had the greatest mean ST-segment elevation; and lead III was significantly superior to the inferior unipolar leads (7, 17, 27, 37, 47, 55, and 61) of the BSM (P < .001).

Conclusion

Leads placed on a horizontal strip, in line with leads V₁ and V₂, provided the optimal placement for the diagnosis of anterior and lateral STEMI and appear superior to leads V₃, V₄, V₅, and V₆. This is of significant clinical interest, not only for ease and replication of lead placement but also may lead to increased recruitment of patients eligible for revascularization with none or borderline ST-segment elevation on the initial 12-lead ECG.     

Electrocardiographic predictors of culprit artery in acute inferior ST elevation myocardial infarction

Background

In acute inferior ST-segment elevation myocardial infarction (STEMI), multiple electrocardiographic algorithms have been proposed to predict the culprit artery. Our purpose is to review these and compare them to ST depression in lead aVR to predict culprit artery in inferior STEMI.

Methods

In 106 patients with acute inferior STEMI who underwent emergent coronary angiography, we correlated electrocardiographic and angiographic findings pertaining to the culprit artery. We then reviewed the algorithms proposed by Fiol et al and Tierala et al, and applied them and our own from Kanei et al using ST depression in aVR for predicting the left circumflex artery (LCx) as the culprit, to the population. Finally, we compared the sensitivities and specificities of the respective algorithms for predicting the culprit artery.

Results

The sensitivity and specificity of ST depression in lead aVR to predict LCx as the culprit were 53% and 86%, respectively, and 86% and 55%, respectively for predicting the right coronary artery (RCA) as the culprit. When their algorithms were applied to our population, the sensitivities and specificities of Fiol et al and Tierala et al were slightly higher.

Conclusion

Compared to other proposed algorithms, ST depression in aVR is a simple method with satisfactory sensitivity and specificity to predict the culprit artery in inferior STEMI.     

Acute anterior wall myocardial infarction entailing ST-segment elevation in lead V3R, V1 or aVR: electrocardiographic and angiographic correlations

Background

The correlation between ST-segment elevation (ST↑) in lead V₃R (ST↑_V3R), lead V₁ (ST↑_V1), and lead aVR (ST↑_aVR) during anterior wall acute myocardial infarction (AMI) and the culprit lesion site in the left anterior descending (LAD) coronary artery and the nature of the conal branch of the right coronary artery has not been throughly described.

Methods

One hundred forty-two patients with first anterior wall AMI were included. The 15-lead electrocardiogram with the standard 12 leads plus leads V₃R through V₅R showing the most pronounced ST-segment deviation before initiation of reperfusion therapy was evaluated and correlated with the exact LAD occlusion site in relation to the first septal perforator (S1) and the nature of the conal branch of the right coronary artery as determined by coronary angiography.

Results

ST-segment elevation in lead aVR, ST↑_V1 of at least 2 mm, and ST↑_V3R of at least 1 mm were more prevalent among patients with occlusions proximal to S1 than patients with occlusions distal to S1 (41.7% vs 4.9%, P < .01; 30.0% vs 7.3%, P < .01; and 91.7% vs 4.9%, P < .01, respectively). Of the 60 patients with occlusions proximal to S1, 20 patients had a small conal branch (18 patients with ST↑_aVR and 15 patients with ST↑_V1 ≥2 mm), and 24 patients had a large conal branch (all patients with non-ST↑_aVR and ST↑_V1 <2 mm; P < .01). The sensitivity of ST↑_V1 of more than 1 mm, of at least 2 mm, ST↑_V3R of at least 1.5 mm, and ST↑_aVR for detecting a small conal branch was 65.1%, 81.8%, 84.0%, and 90%, respectively; the specificity was 68.5%, 64%, 66.7%, and 64.9%, respectively.

Conclusions

In patients with anterior wall AMI, ST↑_V3R of at least 1 mm combined with ST↑ in leads V₂ through V₄ were strongly predictive of LAD occlusion proximal to S1; furthermore, ST↑_aVR and ST↑_V1 of at least 2 mm were found to be useful in identifying LAD occlusion proximal to S1. ST↑_aVR, ST↑_V3R of at least 1.5 mm, and ST↑_V1 of at least 2.0 mm were also associated with the presence of a small conal branch not reaching the intraventricular septum during anterior wall AMI.     

Enhanced recognition of ischemia by three variable analysis of the exercise stress test

Background

ECG ST-segment deviations have been the standard measure of coronary artery disease (CAD) during the exercise stress test (EST). Our past research has shown other ECG variables to be significant in EST. This study evaluates the benefit of routinely combining these variables in the detection of CAD.

Methods

Sequential patients (n = 439) with suspected CAD referred for EST had their cases reviewed. Clinical and ECG variables were associated with myocardial perfusion imaging (MPI) scintigrams used to detect ischemia during maximum EST.

Results

An increase in P-wave duration was the most sensitive predictor of ischemia with a sensitivity of 64.3%, a specificity of 86.5%, and a positive predictive power (PPP) of 57.8%. ST elevation ≥ 1 mm in lead AVR had a sensitivity of 53.1%, a specificity of 78.3%, and a PPP of 41.3%. ST depression ≥ 1 mm in leads V₄–V₆ had a sensitivity of 11.2%, a specificity of 94.7%, and a PPP of 37.9%. When these variables were combined, specificity and PPP increased to 100% (p < 0.001).

Conclusions

EST evaluation solely by ST deviation fails to identify a significant portion of ischemic cases. Combinations of ΔPWD, ST elevation in AVR, and ST depression improved the identification of ischemia.     

The relationship between initial ST-segment deviation and final QRS complex changes related to the posterolateral wall in acute inferior myocardial infarction

Objectives

The aim of this study was to assess the relationship between initial ST-segment deviation and final QRS complex changes related to the posterolateral left ventricular wall in patients with acute inferior myocardial infarction receiving reperfusion therapy. The secondary aim was to determine if this relationship is stronger for patients who present early in the ischemia/infarction process in comparison with patients who present late.

Methods

The ST-segment depression in the leads V₁, V2, and −V6 were measured in the electrocardiograph (ECG) just before initiation of myocardial reperfusion. These leads were chosen because they represent the posterolateral wall in the Selvester score. In addition, the Anderson-Wilkins acuteness score was calculated in the admission ECG. Selvester criteria related to the posterolateral wall were identified in the ECG performed before hospital discharge to assess final infarct size.

Results

Fifty-six patients were included in this study. No significant relationship was found between the sum of initial ST-segment depression in the leads V₁, V₂, and −V₆, and final infarct size in the posterolateral left ventricular wall for the total study population (r = 0.19, P = .16). Patients were subgrouped by Anderson-Wilkins acuteness score of less than 3 vs 3 or more. In those with a low acuteness score, the amount of ST-segment depression had no relationship with final infarct size (r = −0.16, P = .41). However, the correlation was statistically significant for those with a high acuteness score (r = 0.42, P = .04).

Conclusion

The initial ST-segment depression in leads V₁, V₂, and −V₆ can predict ECG-estimated amount of infarction in the posterolateral left ventricular wall in patients with acute inferior myocardial infarction receiving reperfusion therapy, but only in those who present early in the ischemia/infarction process.     

The diagnostic utility of heart rate-corrected ST-segment depression during adenosine nuclear stress testing

Background

Vasodilator stress testing relies heavily on the imaging portion so that clinically useful information from the electrocardiogram may be overlooked. Stress-induced ST-segment depression, although uncommon, is highly predictive of severe disease. We investigated whether minor ST depressions during adenosine nuclear stress testing corrected for the modest heart rate increases (ST/HR slope and ST/HR index) might be clinically relevant.

Methods

The study included 74 consecutive patients with electrocardiograms interpretable for ischemia who underwent coronary angiography within the following 6 months.

Results

Abnormal responses using conventional thresholds for ischemic ST depression, the ST/HR slope, and ST/HR index were present in 8%, 20%, and 27%, respectively. The sensitivity for conventional ST depression was 11% and, when corrected for heart rate, increased to 27% and 36%, (P = .012), without adversely affecting the high positive predictive accuracy (83%, 80%, and 80%). Even with a normal perfusion scan, heart rate correction was highly predictive of multivessel coronary artery disease (4/5 patients).

Summary

Heart rate correction of ST depression during adenosine nuclear stress improves on conventional ST depression and may compliment perfusion imaging in detecting multivessel disease.     

Electrocardiographic prediction of short-term prognosis in patients with acute myocardial infarction associated with the left main coronary artery

Purpose

The purpose of this study was to assess the usefulness of electrocardiogram on admission to predict short-term prognosis in patients with acute myocardial infarction (AMI) associated with left main coronary artery (LMCA).

Methods

Electrocardiogram was obtained on admission in 41 patients with AMI associated with LMCA who underwent reperfusion therapy. Electrocardiographic findings were compared between nonsurvivors and survivors.

Results

There were 24 nonsurvivors and 17 survivors during 30-day follow-up. Nonsurvivors had ST-segment elevation in both leads aVR and aVL (54% vs 18%, P < .05), left anterior fascicular block (83% vs 41%, P < .05), and right bundle-branch block (54% vs 18%, P < .05) more frequently, and ST-segment depression in lead V₅ (17% vs 59%, P < .05) less frequently than survivors among patients with AMI associated with LMCA.

Conclusions

Our data suggested that electrocardiogram on admission might be useful to predict short-term prognosis in patients with AMI associated with LMCA.     

Stress-induced ST-segment elevation in patients without prior Q-wave myocardial infarction

Background

Stress-induced ST-segment elevation is an uncommon finding that usually occurs in patients with prior myocardial infarction (MI). Our purpose was to assess the angiographic and clinical significance of this finding in patients without prior MI.

Methods

Of the 29 002 consecutive ambulatory patients who underwent stress myocardial perfusion imaging over a 5-year period, 205 (0.7%) developed stress-induced ST-segment elevation, of whom 39 (19%) had no Q-wave MI in leads showing ST-segment elevation during either exercise (n = 31) or dipyridamole (n = 8) stress myocardial perfusion imaging. All 39 patients were hospitalized and underwent coronary angiography.

Results

Significant coronary artery disease was found in all 39 patients: 87% had critical (≥90%) stenosis, and 59% had multiple vessel disease. During hospitalization, 37 patients (95%) underwent revascularization.

Conclusions

In patients without prior Q-wave MI, stress-induced ST-segment elevation is associated with critical coronary artery disease. Therefore, these patients should be considered for early coronary investigation.     

ST-segment depression in aVR as a predictor of culprit artery and infarct size in acute inferior wall ST-segment elevation myocardial infarction

Background

ST-segment depression in lead aVR in acute inferior wall ST-segment elevation myocardial infarction (STEMI) has recently been suggested as a predictor of left circumflex (LCx) artery involvement. The purpose of this study is to evaluate the clinical significance of aVR depression during inferior wall STEMI.

Methods

This study included 106 consecutive patients who presented with inferior wall STEMI and underwent urgent coronary angiogram. Clinical and angiographic findings were compared between patients with and without aVR depression ≥0.1 mV.

Results

The sensitivity and specificity of aVR depression as a predictor of LCx infarction were 53% and 86%, respectively. In patients with right coronary artery infarction, aVR depression was associated with increased cardiac enzymes and the involvement of a large posterolateral branch, which may explain the larger infarction.

Conclusions

ST-segment depression in lead aVR in inferior wall STEMI predicts LCx infarction or larger RCA infarction involving a large posterolateral branch.     

Application of body surface mapping to exercise testing: S-T80 isoarea maps in patients with coronary artery disease

Body surface electrocardiographic maps were recorded before and after exercise in 25 men with angiographically documented coronary disease. Torso potential distributions at 192 locations were derived from a 32 lead electrode array using methods previously described in our laboratory. The S-T segment was characterized by the spatial distribution of the integral of S-T segment voltage over 80 ms (S-T₈₀). Body surface regions where the S-T₈₀ areas were —8 mV·ms or greater were identified in 18 of 25 patients. The most negative S-T₈₀ site on the map was called the “S-T₈₀ minimum.” The S-T₈₀ minima were located 1 or 2 electrode rows away from the standard V₄–V₆ electrode positions in 6 of 10 patients who developed S-T₈₀ areas of —8 mV·ms or greater. Our data suggest that standard electrocardiographic leads may not be optimal for identifying S-T segment depression in all patients with coronary disease. Furthermore, body surface mapping during exercise provides a more quantitative and qualitative method for characterizing the ischémic response to exercise.     

Electrocardiographic characteristics in angiographically documented occlusion of the dominant left circumflex artery with acute inferior myocardial infarction: limitations of ST elevation III/II ratio and ST deviation in lateral limb leads

Background

The prognosis of dominant left circumflex artery (LCx) occlusion-related inferior acute myocardial infarction (AMI) patients is poor, but the electrocardiographic (ECG) characteristics of this AMI entity have not been described.

Methods

One hundred thirty-five patients with first dominant right coronary artery (RCA) or dominant LCx-related inferior AMI were included. The characteristics of ECG obtained on admission for 55 patients with culprit lesions proximal to the first major right ventricular (RV) branch of dominant RCA (group proximal dominant RCA), 62 patients with culprit lesions distal to the first major RV branch of dominant RCA (group distal dominant RCA), and 18 patients with culprit lesions in dominant LCx (group dominant LCx) were compared.

Results

There were no significant differences among the 3 groups in the prevalence regarding an S/R ratio greater than 1:3 in aVL, ST elevation in aVR (ST↑_aVR), ST depression in aVR (ST↓_aVR) of 1 mm or more, and atrioventricular block. Greater ST elevation in lead III than in II and greater ST depression in aVL than I showed specificity of 17% and 44% to identify dominant RCA as culprit lesion, respectively. All 3 groups could be distinguished on the basis of ST↑_V4R, ST↓_V4R, ST↓_V3/ST↑_III of 1.2 or less, and ST↓_V3/ST↑_III of more than 1.2.

Conclusions

Greater ST elevation in lead III than in II, greater ST depression in aVL than I, and an S/R ratio of greater than 1:3 in aVL were not useful to discriminate between dominant RCA and dominant LCx occlusion-related inferior AMI. ST-segment deviation in lead V₄R and the ratio of ST↓_V3/ST↑_III were useful in predicting the dominant artery occlusion-related inferior AMI.     

Is application of electrocardiographic exercise test always usefull in the diagnosis of coronary artery disease? Advantages and limitations of this method

To determine the diagnostic value of the electrocardiographic exercise testing (EET) in 551 patients with chest pain regarded as definite or probable stable angina pectoris (CAD), results of performed EET were compared with coronary angiography. All patients underwent exercise testing according to the Bruce protocol. The criterion for a positive exercise ST-segment response was > or = 1 mm of horizontal or down sloping depression 80 msec after J-point. The indications for cardiac catheterization in each patient were determined at the discretion of the attending physician. Clinically important coronary artery disease was defined as > 50 per cent narrowing of the diameter of at least one major vessel or > or = 50 per cent of the left main coronary artery. RESULTS: The sensitivity and specificity of EET for detection of CAD were for the entire group, in women and men respectively: 93%, 91%, 94% and 21%, 16%, 27%. CONCLUSION: 1. Indications for EET should be based on prior probability of coronary artery disease. 2. Application of higher than conventional ST depression criteria (> or = 2 mm) lowers sensitivity but increases specificity of EET. 3. Variables determining false positive results are as follows: age, sex (female), low probability of CAD, ST-segment depression in leads: II, III, aVF and mitral valve prolapse. 4. Variables determining false negative results are as follows: high probability of CAD, sex (male) and one vessel disease.