Precordial ST-segment depression during acute inferior myocardial infarction: clinical, scintigraphic and angiographic correlations

ST-segment depression in left precordial leads in electrocardiogram of patients with acute inferior myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

The early identification of patients with acute inferior ST-segment elevation myocardial infarction (STEMI) with high risk features is particularly important. Acute inferior STEMI may be associated with ST-segment depression in the left precordial leads (V4-V6). This study assessed prognostic value of ST-segment depression in these left precordial leads during the admission of patients with acute inferior STEMI treated with primary percutaneous coronary intervention.

METHODS

This retrospective study enrolled 1,374 patients with acute inferior STEMI who underwent primary percutaneous coronary angioplasty between March 2011 and June 2014. The patients were divided into two groups: one group (n = 687) with left precordial ST-segment depression and the other (n = 687) without such ST-segment changes.

RESULTS

The patients with left precordial ST-segment depression were older and had higher incidence of hypertension, diabetes mellitus, and higher levels of troponin. In-hospital mortality was higher in patients with left precordial ST-segment depression. Advanced coronary artery disease was more observed in these patients.

CONCLUSION

In patients with acute inferior STEMI treated with primary coronary intervention, left precordial ST-segment depression during admission of ECG is associated with more advanced coronary artery disease, and worse in-hospital clinical outcomes.

Clinical Significance of Reciprocal ST-segment Changes in Patients With STEMI: A Cardiac Magnetic Resonance Imaging Study

INTRODUCTION AND OBJECTIVES

We sought to determine the association of reciprocal change in the ST-segment with myocardial injury assessed by cardiac magnetic resonance (CMR) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

METHODS

We performed CMR imaging in 244 patients who underwent primary PCI for their first STEMI; CMR was performed a median 3 days after primary PCI. The first electrocardiogram was analyzed, and patients were stratified according to the presence of reciprocal change. The primary outcome was infarct size measured by CMR. Secondary outcomes were area at risk and myocardial salvage index.

RESULTS

Patients with reciprocal change (n=133, 54.5%) had a lower incidence of anterior infarction (27.8% vs 71.2%, P < .001) and shorter symptom onset to balloon time (221.5±169.8 vs 289.7±337.3min, P=.042). Using a multiple linear regression model, we found that patients with reciprocal change had a larger area at risk (P=.002) and a greater myocardial salvage index (P=.04) than patients without reciprocal change. Consequently, myocardial infarct size was not significantly different between the 2 groups (P=.14). The rate of major adverse cardiovascular events, including all-cause death, myocardial infarction, and repeat coronary revascularization, was similar between the 2 groups after 2 years of follow-up (P=.92).

CONCLUSIONS

Reciprocal ST-segment change was associated with larger extent of ischemic myocardium at risk and more myocardial salvage but not with final infarct size or adverse clinical outcomes in STEMI patients undergoing primary PCI.

What is the predictive value of ST segment depression in inferior leads in first acute anterior myocardial infarction?

BACKGROUND

Electrical phenomenon and remote myocardial ischemia are the main factors of ST segment depression in inferior leads in acute anterior myocardial infarction (AAMI). We investigated the prognostic value of the sum of ST segment depression amplitudes in inferior leads in patients with first AAMI treated with primary percutaneous coronary intervention. (PPCI).

METHODS

In this prospective analysis, we evaluated the in-hospital prognostic impact of the sum of ST segment depression in inferior leads on 206 patients with first AAMI. Patients were stratified by tertiles of the sum of admission ST segment depression in inferior leads. Clinical outcomes were compared between those tertiles.

RESULTS

Univariate analysis revealed higher rate of in-hospital death for patients with ST segment depression in inferior leads in tertile 3, as compared to patients in tertile 1 (OR 9.8, 95% CI 1.5-78.2, p<0.001). After adjustment for baseline variables, ST segment depression in inferior leads in tertile 3 was associated with 5.7-fold hazard of in-hospital death (OR: 5.7, 95% CI 1.2-35.1, p<0.001). Spearman rank correlation test revealed correlation between the sum of ST segment depression amplitude in inferior leads and the sum of ST segment elevation amplitude in V1-6, L1 and aVL. Multivessel disease and additional RCA stenosis were also detected more often in tertile 3.

CONCLUSION

The sum of ST segment depression amplitude in inferior leads of admission ECG in patients with first AAMI treated with PPCI provide an independent prognostic marker of in-hospital outcomes. Our data suggest the sum of ST segment depression amplitude to be a simple, feasible and clinically applicable tool for rapid risk stratification in patients with first AAMI.

Prognostic Predictive Values of the Initial Electrocardiogram with St-Segment Elevation Acute Myocardial Infarction in Chinese Patients

Objective

To study the electrocardiogram (ECG) features that predict 30-day mortality of ST-segment elevation acute myocardial infarction (STEMI) in Chinese patients.

Method

This was a retrospective study. Patients presenting within twelve hours after the onset of chest pain with ECG features compatible with STEMI and the diagnosis confirmed after admission were included in the study. Data taken into account included age, sex and thrombolytic therapy in the emergency department. The hospital records of the patients were later retrieved from the computer. The initial ECG performed in the emergency department were reviewed.

Results

A total of 98 patients were included in the study. There was no statistically significant relationship between 30-day mortality and the type of myocardial infarction or the magnitude of the ST segment changes. Distortion of the terminal portion of the QRS complex and prior evidence of myocardial infarction (in another location different from the presenting one) showed statistically significant relationship with 30-day mortality, with odds ratio 10.364 (95% CI 1.715–62.620) and 12.731 (95% CI 2.317–69.962) respectively.

Conclusion

In newly diagnosed STEMI patients, if there is evidence of terminal distortion of the QRS complex or prior ECG changes of myocardial infarction, the 30-day mortality will be significantly higher.

Prognostic value of standard electrocardiographic parameters for predicting major adverse cardiac events after acute myocardial infarction

BACKGROUND

The prognostic value of electrocardiographic (ECG) variables in predicting major adverse cardiac events (MACEs) after acute myocardial infarction (AMI) in the era of modern therapy is unclear. This study was conducted to evaluate the prognostic significance of ECG parameters in predicting 1-year MACEs for AMI patients.

METHODS

Between January 2006 and January 2008, 529 AMI patients were included. ECG variables were analyzed from the ECG taken on discharge day. The 1-year MACEs were defined as death, nonfatal MI, and revascularization including repeat percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Mean follow-up duration was 360 ± 119 days.

RESULTS

Of these patients, 497 (94%) patients provided complete follow-up data (355 males; 67 ± 12 years old). The rate of 1-year MACEs was 16%. In univariate analysis, heart rate, corrected QT interval, left ventricular (LV) hypertrophy, voltage (SV(1) + RV(5) ), lateral ST-depression (V(5-6) or I, aVL), pathologic Q wave (V(1-4) , V(5-6) ), ST-elevation (V(1-4) , V(5-6) or I, aVL), and T-wave inversion (V(1-4) , V(5-6) , or I, aVL) had a significant association with 1-year MACEs. In the Cox regression hazard model, lateral ST-depression (hazard ratio [HR] 2.260, 95% confidence interval [CI] 1.204 to 4.241, P = 0.011) and corrected QT interval (HR 1.007, 95% CI 1.002 to 1.011, P = 0.004) were independent predictors of 1-year MACEs. After adjustment for all risk variables, lateral ST-depression (HR 3.781, 95% CI 1.047 to 13.656, P = 0.042) was the only ECG variable that independently predicted 1-year MACEs.

CONCLUSION

Lateral ST-depression on discharge day ECG is an independent predictor of 1-year MACEs after AMI.

Value of T-wave direction with lead III ST-segment depression in acute anterior wall myocardial infarction: electrocardiographic prediction of a "wrapped" left anterior descending artery

BACKGROUND

Lead III ST-segment depression during acute anterior wall myocardial infarction (AMI) has been attributed to reciprocal changes. However, the value of the T-wave direction (positive or negative) in predicting the site of obstruction and type of the left anterior descending (LAD) artery is not clear and has not been studied before.

HYPOTHESIS

The aim of the study was to assess retrospectively the correlation between two patterns of lead III ST-segment depression, and type of LAD artery and its level of obstruction during first AMI.

METHODS

The study group consisted of 48 consecutive patients, admitted to the coronary care unit for first AMI, who showed ST-segment elevation in lead a VL and ST-segment depression in lead III on admission 12-lead electrocardiogram. The patients were divided by T-wave direction into Group 1 (n = 31), negative T wave, and Group 2 (n = 17), positive T wave. The coronary angiogram was evaluated for type of LAD ("wrapped", i.e., surrounding the apex or not), site of obstruction (pre- or postdiagonal branch), and other significant coronary artery obstructions.

RESULTS

Mean lead III ST-segment depression was 1.99 +/- 1.32 mm in Group 1 and 1.13 +/- 0.74 mm in Group 2 (p = 0.004); mean ST-segment elevation in a VL was 1.35 +/- 0.84 mm and 1.23 +/- 0.5 mm, respectively (p = 0.5). A wrapped LAD was found in 12 patients (38.7%) in Group 1 and in 13 in Group 2 (76.4%) (p = 0.02). The sensitivity of lead III ST-segment depression with positive T wave to predict a wrapped LAD was 52%, and the specificity was 82% with a positive predictive value of 76%. On angiography, 25 patients (80%) in Group 1 and 13 (76%) in Group 2 had prediagonal occlusion of the LAD (p = 0.77). No significant difference between groups was found for right and circumflex coronary artery involvement or incidence of multivessel disease.

CONCLUSIONS

The presence of lead III ST-segment depression with positive T wave associated with ST-segment elevation in a VL in the early course of AMI can serve as an early electrocardiographic marker of prediagonal occlusion of a "wrapped" LAD.

Clinical implications of precordial ST-segment elevation in acute inferoposterior myocardial infarction caused by proximal right coronary artery occlusion

BACKGROUND

The clinical significance of inferior wall acute myocardial infarction (MI) with combined ST-segment elevation in both anterior and inferior leads, compared with inferior leads alone, is unknown.

HYPOTHESIS

Despite having more leads with precordial ST-segment elevation, these patients may have a better outcome due to less posterior involvement, which tends to drag down the precordial ST-segment.

METHODS

A total of 158 postinferior MI patients with documented proximal right coronary artery occlusion were retrospectively studied. They were divided into three subgroups according to the magnitude of concurrent ST-segment deviation in lead V2: Group A (n = 19) had ST-segment elevation >/= 2.0 mm; Group B (n = 74) had ST-segment lay between + 2.0 mm and - 2.0 mm; and Group C (n = 65) had ST-segment depression >/= 2.0 mm. The clinical and electrocardiographic characteristics were then compared among these threes subgroups.

RESULTS

The baseline demography, prevalence of risk factors, and treatment received were of no difference among the subgroups. However, Group A patients had significantly lower peak creatinine phosphokinase level and more preserved left ventricular function than Group B and C. Moreover, they had lower total sum of inferior ST-segment magnitude, less ST-segment depression in V4-6, and more ST-segment elevation in V(4R) than Group C. Group C patients had highest in-hospital and one-year mortality although it did not reach statistical significance.

CONCLUSIONS

Precordial ST-segment elevation in inferior wall acute MI was associated with smaller infarct size and better left ventricular function, probably secondary to occlusion of a less dominant RCA, which did not result in a significant posterior infarction.

Electrocardiographic Diagnosis of ST-elevation Myocardial Infarction

The ECG is an essential part of the initial evaluation of patients who have chest pain, especially in the immediate decision-making process in patients who have ST-elevation myocardial infarction. This article reviews and summarizes the current information that can be obtained from the admission ECG in patients who have ST-elevation acute myocardial infarction, with an emphasis on: (1) prediction of final infarct size, (2) estimation of prognosis, and (3) the correlations between various ECG patterns and the localization of the infarct and the underlying coronary anatomy.

The electrocardiogram in ST elevation acute myocardial infarction: correlation with coronary anatomy and prognosis

The electrocardiogram is considered an essential part of the diagnosis and initial evaluation of patients with chest pain. This review summarises the information that can be obtained from the admission electrocardiogram in patients with ST elevation acute myocardial infarction, with emphasis on: (1) prediction of infarct size, (2) estimation of prognosis, and (3) the correlations between various electrocardiographic patterns and the localisation of the infarct and the underlying coronary anatomy.

Are reciprocal changes a consequence of "ischemia at a distance" or merely a benign electrical phenomenon? A pulsed-wave tissue Doppler echocardiographic study

OBJECTIVES

The aim of the present study was to investigate whether ST segment depression in precordial leads at the time of acute inferior myocardial infarction represents a reciprocal change rather than concurrent anterior wall ischemia on the surface electrocardiography.

BACKGROUND

The mechanism of reciprocal ST segment depression during acute myocardial infarction is controversial. "Ischemia at a distance" or a benign electrical phenomenon has been implicated in numerous reports. Pulsed-wave tissue Doppler (PWTD) echocardiography can be used to examine the regional diastolic motion of the left ventricular myocardial wall and may allow the detection of ischemic segments.

METHODS

We evaluated regional myocardial ischemia using PWTD echocardiography in 48 patients with a first inferior wall myocardial infarction. The left ventricle was divided into 16 segments. PWTD echocardiographic velocities were obtained from each left ventricular segments.

RESULTS

Reciprocal ST segment depression was present in 35 patients (Group 1) but not in the remaining 13 patients (Group 2). There were no significant differences between groups 1 and 2 with respect to systolic (S) (7.4 +/- 1.1 vs 6.8 +/- 0.9 cm/s; P > 0.05), early (E) (10.5 +/- 2 vs 9.4 +/- 1.2 cm/s; P > 0.05), and late (A) (9.5 +/- 3.2 vs 8.5 +/- 2.3 cm/s; P > 0.05) diastolic waves peak velocities, E/A ratio 1.1 +/- 0.2 vs 1.1 +/- 0.1; P > 0.05), Ewave deceleration time (DT) (92 +/- 17 vs 101 +/- 16 ms; P > 0.05) and regional relaxation time (RT) (82 +/- 19 vs 93 +/- 21 ms; P > 0.05) in anterior wall (basal levels), which correspond to reciprocal ST segment depression on electrocardiography. According to E/A ratio detected by PWTD echocardiography in anterior wall and anterior septum, patients with reciprocal ST segment depression were also divided into two groups: Group A, with E/A ratio > 1; Group B, with E/A ratio < 1. Among the 35 patients with reciprocal ST segment depression, anterior wall ischemia was present in 10 patients and absent in 25 patients, whereas anterior septal ischemia was present 12 patients and absent in 23 patients.

CONCLUSIONS

Reciprocal ST segment depression during the early phases of inferior infarction is an electrical reflection of primary ST segment elevation in the area of infarction.

Precordial ST-segment depression in inferior myocardial infarction is associated with slow flow in the non-culprit left anterior descending artery

BACKGROUND

Anterior precordial ST-segment depression (APSTD) is common in the setting of inferior myocardial infarction (IMI). The presence of APSTD correlates with increased risk of adverse outcomes in patients with acute IMI as well as more myocardium at risk as assessed by sestamibi, larger infarcts, lower ejection fractions, and more severe wall motion abnormalities in the infarct region. The ECG leads associated with APSTD (V1-V3) are generally thought to represent electrical activity subtended by the anterior myocardium, which is perfused by the left anterior descending artery (LAD). To determine whether APSTD is associated with abnormal blood flow in the uninvolved or non-culprit LAD, we assessed TIMI flow grades and corrected TIMI frame counts (CTFC) in both the culprit and non-culprit arteries of IMI patients.

METHODS

Data were drawn from the TIMI 10B trial of tenecteplase versus front-loaded tissue plasminogen activator in acute MI. Baseline ECGs were obtained within 12 hours of symptom onset, and angiography was performed 90 minutes following thrombolytic administration. A patient was considered to have precordial ST-segment depression if any ST-segment depression was present in any of leads V1-V3.

RESULTS

The majority of IMI's were due to right coronary artery occlusions, both in patients with APSTD (79.6%) and without APSTD (77.9%). In patients in whom the LAD was not the culprit artery but with APSTD were significantly less likely to have TIMI 3 flow at 90 minutes and more likely to have TIMI 2 flow. There was a trend toward slower CTFC in APSTD patients (27.2 +/- 13.4 vs. 22.6 +/- 8.5 frames/sec, p = 0.07).

CONCLUSIONS

Among patients with acute IMI associated with precordial ST-segment depression, flow in the non-culprit left anterior descending artery was slower than that in patients without APSTD. This finding may partially explain the occurrence of APSTD in IMI.

Q-wave evolution of a first acute myocardial infarction without significant ST segment elevation

BACKGROUND

Some patients with acute myocardial infarction presenting without significant ST segment elevation develop a Q-wave infarction. It is unclear whether these patients can be identified from the admission electrocardiogram (ECG) and whether they differ in their in-hospital prognosis from those who retain a non-Q-wave myocardial infarction.

METHODS

In 432 consecutive patients admitted to our centre with a first acute myocardial infarction without Q waves and with ST segment amplitudes < or =0.1 mV on admission, we assessed the frequency, the electrocardiographic predictors and the short-term implications of a Q-wave evolution.

RESULTS

In 94 patients (22%), a Q-wave myocardial infarction evolved before hospital discharge (14 anterior, 26 inferior, six lateral, and 48 posterior). Minor anterior ST segment elevation was 36% sensitive and 95% specific in predicting anterior Q waves; minor inferior ST segment elevation, 42% and 89%, respectively, for inferior Q waves; and a maximal ST segment depression > or =0.2 mV in leads V2-V3 with upright T waves and without remote ST segment depression, 38% and 97%, respectively, for posterior R waves. Although patients with a Q-wave evolution had a greater creatinkinase MB peak than those retaining a non-Q-wave pattern (191+/-113 vs. 105+/-77 IU/l, respectively, P<0.001), they experienced a benign in-hospital course, with similar risk of severe complications after adjustment for the baseline clinical predictors than non-Q-wave patients.

CONCLUSIONS

About one fifth of patients with a first acute myocardial infarction without a significant ST segment elevation develop a Q-wave infarction and the admission ECG can help identify them. This evolution, however, is not associated with a worse in-hospital outcome.

Value of the initial electrocardiogram in patients with inferior-wall acute myocardial infarction for prediction of multivessel coronary artery disease

BACKGROUND

Patients with inferior-wall acute myocardial infarction (AMI) who have ST-segment depression in the left precordial leads (LSTD+) on the initial electrocardiogram were reported to have more diffuse coronary artery disease (CAD) than had those without this finding (LSTD-). This suggests that LSTD+ patients may need extensive revascularization interventions more often than do LSTD- patients. However, this has not yet been confirmed.

OBJECTIVE

To compare the coronary angiographic findings and treatment strategies for patients with inferior-wall AMI according to the LSTD pattern.

METHODS

The clinical outcomes and the angiographic findings for 238 consecutive patients aged < or = 75 years who had been admitted to our hospital between 1 February 1995 and 1 February 1997 with inferior-wall AMI were retrospectively analyzed. The patients were divided into two groups according to the pattern of precordial ST-segment depression: LSTD+, ST-segment depression in leads V4-V6; and LSTD-, absence of this finding. All patients were treated according to current practice guidelines including with thrombolysis and revascularization interventions.

RESULTS

The final study population included 217 patients; 83 were LSTD+ and 134 were LSTD-. All underwent coronary angiography within 30 days of the infarction. Compared with LSTD- patients, LSTD+ patients tended to be older (mean age 62.7 +/- 11.7 versus 58.3 +/- 9.6 years, P = 0.004), and had higher incidences of hypertension (39.8 versus 24.6%, P = 0.019) previous myocardial infarction (45.8 versus 20.1%, P = 0.0001) and congestive heart failure (21.7 versus 3.7%, P = 0.00008). Three-vessel CAD was much more common, and single-vessel CAD much less common, in the LSTD+ than in LSTD- group (62.7 versus 13.4% and 8.4 versus 50.7%, P < 0.00001 for both). Coronary-artery-bypass surgery and multivessel percutaneous coronary interventions (PCI) were used in treating 65.1% of the LSTD+ versus only 6.0% of the LSTD- patients (P < 0.00001), whereas single-vessel PCI was used in treating 71.6% of the LSTD- patients versus only 24.1% of the LSTD+ patients (P < 0.00001). Thus, the LSTD- pattern predicted single-vessel disease and single-vessel PCI only, whereas the LSTD+ pattern was predictive of multivessel CAD and of use of coronary-artery-bypass surgery or multivessel PCI (predictive values of 94.0 and 65.1%, respectively).

CONCLUSIONS

Among patients with inferior-wall AMI, left precordial ST-segment depression predicts a very high prevalence of multivessel CAD and use of extensive revascularization interventions. The absence of this finding predicts nondiffuse CAD and lack of a need for extensive revascularization.

Clinical Utility of Electrocardiographic ST-Segment Area for Predicting Unsatisfactory Outcomes Following Thrombolytic Therapy

The bedside surface 12-lead electrocardiogram is a mainstay in the early diagnostic evaluation of patients with suspected acute myocardial infarction. The presence of ST-segment elevation exceeding 1.0 mm in two or more anatomically associated leads is a reliable marker of myocardial injury and, when considered along with concomitant ST-segment depression, reflects the extent of myocardial injury. Mounting evidence also suggests that prolonged repolarization is a marker of injury and predicts the likelihood of malignant ventricular arrhythmias. We questioned whether a measure of both ST-segment duration and deviation (ST-deviation area) would offer additional prognostic information. Methods/Results: Admission electrocardiograms from 200 consecutive patients with ischemic chest pain accompanied by ST-segment elevation in whom thrombolytic therapy was given within 6 hours from symptom onset were analyzed. The sum of ST-segment elevation (Sigma ST elevation) and ST-segment deviation (Sigma ST deviation) were calculated, as was the sum of ST-segment deviation area (Sigma ST deviation area). All ST measurements were performed 60 msec after the J point. Computerized planimetry was used to calculate ST-segment area. Sigma ST deviation and Sigma ST deviation area remained constant over time. Patients with large deviations (Sigma ST elevation > 20 mm (odds ratio 2.14, p = 0.02) and Sigma ST deviation area > 150 (odds ratio 1.92, p = 0.02) had a higher incidence of in-hospital unsatisfactory clinical outcome (defined as death, congestive heart failure, cardiogenic shock, recurrent myocardial infarction, or the need for coronary revascularization). These relationships were present for both inferior and anterior infarctions. Sigma ST deviation area correlated closely with Sigma ST elevation (r = 0.92; p = 0.0001) and significantly but much less strongly with the sum of Q waves (r = 0.18; p = 0.01). By univariate analysis, only site of infarction (p = 0.01), Sigma ST deviation area (p = 0.04), and the sum of Q waves (p = 0.005) were identified as predictors of a poor clinical outcome. The sum of Q waves was identified by multivariate analysis as the best independent predictor of an unsatisfactory clinical outcome. Conclusions: A clinician's ability to provide optimal care is influenced strongly by the availability of diagnostic and prognostic information. In the evaluation of patients with acute myocardial infarction, ST-segment deviation area derived from the admission surface electrocardiogram can be used to risk-stratify patients. The full clinical potential of this measure is unknown and will require further evaluation.

Improved detection of posterior myocardial wall ischemia with the 15-lead electrocardiogram

BACKGROUND

A routine 12-lead electrocardiogram is commonly obtained to evaluate for possible acute myocardial infarction during the initial screening of patients with chest discomfort. Posterior myocardial infarction is commonly missed because it is not usually visible in the standard leads. In this study, we compared the sensitivity and specificity of posterior chest leads (V(7), V(8), and V(9)) and 12-lead electrocardiography in detecting posterior injury pattern during single-vessel percutaneous transluminal coronary angioplasty.

METHODS AND RESULTS

Three posterior chest leads in addition to the routine 12-lead electrocardiogram were monitored simultaneously during single-vessel percutaneous transluminal coronary angioplasty of the right, circumflex, and left anterior descending coronary arteries in a total of 223 patients. Posterior injury patterns (95%) were detected mostly during circumflex coronary occlusion. Posterior leads were able to detect injury pattern in 49% (36 of 74) of patients, whereas the 12-lead electrocardiogram was able to detect only 32% (P <.04). When all 15 leads were used to detect all ST elevations, sensitivity increased to 57%, with a specificity of 98% for the circumflex coronary artery. If maximal ST depressions in leads V(2) to V(3) are considered to be from posterior myocardial injury, then the overall sensitivity is increased to 69%.

CONCLUSIONS

Posterior leads significantly increased the detection of posterior injury pattern compared with the standard 12-lead electrocardiogram. Using all 15 leads significantly further improved the detection of circumflex coronary-related injury pattern over the standard 12-lead electrocardiogram.

Acute myocardial infarction with isolated ST-segment elevation in posterior chest leads V7-9: "hidden" ST-segment elevations revealing acute posterior infarction

OBJECTIVES

This study was done to determine whether electrocardiographic (ECG) isolated ST-segment elevation (ST) in posterior chest leads can establish the diagnosis of acute posterior infarction in patients with ischemic chest pain and to describe the clinical and echocardiographic characteristics of these patients.

BACKGROUND

The absence of ST on the standard 12-lead ECG in many patients with acute posterior infarction hampers the early diagnosis of these infarcts and thus may result in inadequate triage and treatment. Although 4% of all acute myocardial infarction (AMI) patients reveal the presence of isolated ST in posterior chest leads, the significance of this finding has not yet been determined.

METHODS

We studied 33 consecutive patients with ischemic chest pain suggestive of AMI without ST in the standard ECG who had isolated ST in posterior chest leads V7 through V9. All patients had echocardiographic imaging within 48 h of admission, and 20 patients underwent coronary angiography.

RESULTS

Acute myocardial infarction was confirmed enzymatically in all patients and on discharge ECG pathologic Q-waves appeared in leads V7 through V9 in 75% of the patients. On echocardiography, posterior wall-motion abnormality was visible in 97% of the patients, and 69% had evidence of mitral regurgitation (MR), which was moderate or severe in one-third of the patients. Four patients (12%), all with significant MR, had heart failure, and one died from free-wall rupture. The circumflex coronary artery was the infarct related artery in all catheterized patients.

CONCLUSIONS

Isolated ST in leads V7 through V9 identify patients with acute posterior wall myocardial infarction. Early identification of those patients is important for adequate triage and treatment of patients with ischemic chest pain without ST on standard 12-lead ECG.

Influence of thrombolytic therapy on inferior acute myocardial infarction with concomitant anterior ST segment depression

The purposes of this study were to analyze the prognostic significance of precordial ST segment depression and to determine whether thrombolytic therapy is effective for all patients with inferior acute myocardial infarction (AMI) or whether there is a different effectiveness for patients with concomitant anterior ST segment depression persisting for 24 hours or longer. Medical charts of 176 patients were studied. On the basis of ECG the patients were subclassified into three groups according to the presence, persistence, or absence of significant ST segment depression: Group 1: anterior ST segment depression persisting for less than 24 hours (45.4%); Group 2: anterior ST segment depression persisting for more than 24 hours (17.6%); Group 3: no anterior ST segment depression (37%). Age, Killip class, peak creatine kinase, hospital deaths, left ventricular ejection fraction, regional wall motion score, postinfarction angina, and ventricular/supraventricular arrhythmia of all patients were studied. Parameters of the three groups were compared: worse results were found in group 1 and the worst in group 2. This result is independent of thrombolytic therapy. Finally, the same parameters of thrombolyzed and nonthrombolyzed groups were compared: no statistically significant difference was observed. Among thrombolyzed patients the number of those with ST depression lasting more than 24 hours is lower than in nonthrombolyzed patients. It can be assumed that thrombolytic therapy in inferior AMI determines a shifting of patients from a worse prognosis group (ST segment depression persisting for more than 24 hours) to a better prognosis group (ST segment depression persisting for less than 24 hours).

Correlation of angiographic findings and right (V1 to V3) versus left (V4 to V6) precordial ST-segment depression in inferior wall acute myocardial infarction

This study assessed whether differences in the underlying mechanisms for various patterns of precordial ST-segment depression with inferior acute myocardial infarction (AMI) are associated with poorer prognoses. We studied 1,155 patients with inferior AMI who underwent thrombolysis in the Global Utilization of Streptokinase and TPA for Occluded arteries (GUSTO-I) angiographic substudy: those without precordial ST depression (n = 412; 35.7%), those with maximum ST depression in leads V1 to V3 (n = 547; 47.4%), and those with maximum ST depression in leads V4 to V6 (n = 196; 17.0%) on admission electrocardiogram. We compared the infarct-related artery, presence of left anterior descending or multivessel coronary artery disease, and left ventricular function among groups. Patients with maximum ST depression in leads V4 to V6 more often had 3-vessel disease (26.0%) than those without precordial ST depression (13.5%) or those with ST depression in leads V1 to V3 (15.7%; p = 0.002), and they had a lower ejection fraction (median 54% vs 60% and 55%, respectively; p <0.001). Patients with maximum ST depression in leads V1 to V3 less often had AMIs due to proximal right coronary artery obstruction (23.9%) than patients without precordial ST depression (35.2%) or those with ST depression in leads V4 to V6 (40.0%; p = 0.001) and had larger AMIs as estimated by peak creatine kinase. Different patterns of precordial ST depression are associated with distinctive coronary anatomy. ST depression in leads V4 to V6, but not V1 to V3, confers a greater likelihood of multivessel coronary artery disease.

Electrocardiographic patterns in acute inferior myocardial infarction with and without right ventricle involvement: classification, diagnostic and prognostic value, masking effect

BACKGROUND

In acute inferior myocardial infarction (AIMI), the ST depression from V1 to V4 has been the subject of many papers, while the ST changes in other leads, their association, and the right ventricular (RV) involvement have been studied less.

HYPOTHESIS

This study was performed to contribute to the meaning of the ST changes and RV involvement in AIMI.

METHODS

Seventy-one patients, admitted within 6 h from symptom onset, all thrombolysed, were enrolled. We classified them according to ST patterns and RV involvement. We divided the right coronary artery into three segments, considering the origin of RV branch and the crux as dividing points. We established a coronary score attributing 2 points to each terminal branch. Comparisons were performed between the electrocardiographic (ECG) findings at onset, the creatine phosphokinase (CPK) peaks, the radionuclide ejection fractions, and the coronary angiographies.

RESULTS

We found that the ST changes give indications regarding the site, extension, and extent of AIMI; RV involvement can mask posterior extension, points to the right coronary as the culprit vessel (100%), and, with high probability, indicates the proximal segment as the site of the lesion; the ECG signs of isolated AIMI indicate a peripheral obstruction; and a collateral circulation may appear relatively early.

CONCLUSIONS

Our findings prove the diagnostic and prognostic value of the ST changes and RV involvement at the onset of AIMI and suggest that the higher in-hospital mortality and complication rates found with RV involvement and reported in the literature are related more to posterior extension, masked by RV involvement than to this involvement per se. Furthermore, these findings prove the clinical value of our classification of the AIMIs and distinction in segments of the right coronary artery.

New electrocardiographic criteria for predicting the site of coronary artery occlusion in inferior wall acute myocardial infarction

In patients with inferior wall acute myocardial infarction (AMI), the site of the culprit lesion is an important determinant of outcome. Patients with right ventricular infarction have a poor prognosis, whereas those with occlusion of the left circumflex coronary artery (LCx) have a good prognosis. Therefore, we assessed whether standard 12-lead electrocardiograms obtained on admission could identify the site of coronary artery occlusion, (i.e., a site proximal to the origin of the right ventricular branch of the right coronary artery [RCA], a site distal to the origin of the right ventricular branch of the RCA, or a site in the LCx). The ratio of ST depression in lead V3 to ST elevation in lead III (V3/III ratio) was evaluated immediately before coronary angiography in 152 patients with a first inferior wall AMI confirmed by coronary angiography within 12 hours after the onset of symptoms. For occlusion of the proximal RCA, distal RCA, and LCx, V3/III ratio was 0.2+/-0.3, 0.8+/-0.5, and 2.5+/-2.5 (p = 0.0001), respectively. The V3/III ratio <0.5 identified proximal RCA occlusion, 0.5 <V3/III ratio < or = 1.2 identified distal RCA occlusion, and 1.2 <V3/III ratio identified LCx occlusion with sensitivities of 91%, 84%, and 84%, and specificities of 91%, 93%, and 95%, respectively. We conclude that the V3/III ratio is useful in predicting the site of coronary artery occlusion in patients with inferior wall AMI.

Diagnostic approach in exercise testing to detect a significant narrowing of the left anterior descending coronary artery in inferior vs posterior myocardial infarction

To detect a significant narrowing of the left anterior descending artery in patients with inferior/posterior myocardial infarction, 200 patients underwent standard exercise testing. Age, gender, and grade of stenosis of the left anterior descending artery were similar in 138 patients with inferior myocardial infarction and 62 with posterior myocardial infarction. In patients with left anterior descending artery stenosis, there were more lateral leads with ST-segment depression (1.8+/-1.0 vs 1.1+/-1.1; p<0.01) and fewer anterior leads with ST-segment depression (2.1+/-1.4 vs 2.9+/-1.4; p=0.02) in those with inferior myocardial infarction than in those with posterior myocardial infarction. Applying the criterion of exercise-induced ST-segment depression > or = 0.1 mV, sensitivities and specificities in detecting left anterior descending artery stenosis were 98% and 21% respectively in inferior myocardial infarction and 94% and 26% respectively in posterior myocardial infarction. In contrast, discriminant analysis revealed sensitivities and specificities of 77% and 91% respectively in inferior myocardial infarction and 71% and 81% respectively in posterior myocardial infarction using the variables related to severity of inducible ischemia and lateral and anterior lead ST-segment depression. These results indicate that a multivariate approach underscoring the site of myocardial infarction can help in identifying stenosis of the left anterior descending artery in patients with inferior/posterior myocardial infarction.

Significance of ST segment elevations in posterior chest leads (V7 to V9) in patients with acute inferior myocardial infarction: application for thrombolytic therapy

OBJECTIVES

This study was designed to examine whether ST segment elevation in posterior chest leads (V7 to V9) during acute inferior myocardial infarction (MI) identifies patients with a concomitant posterior infarction and whether these patients might benefit more from thrombolysis.

BACKGROUND

Because the posterior wall is faced by none of the 12 standard electrocardiographic (ECG) leads, the ECG diagnosis of posterior infarction is problematic and has often remained undiagnosed, especially in the acute phase.

METHODS

Eighty-seven patients with a first inferior infarction who were treated with recombinant tissue-type plasminogen activator were stratified according to the presence (Group A [46 patients]) or absence (Group B [41 patients]) of concomitant ST segment elevation in posterior chest leads V7 to V9.

RESULTS

Patients in Group A had a higher incidence of posterolateral wall motion abnormalities (p < 0.001) on radionuclide ventriculography, a larger infarct area (as evidenced by higher peak creatine kinase levels) (p < 0.02) and a lower left ventricular ejection fraction (LVEF) at hospital discharge (p < 0.008) than those in Group B. ST segment elevation in leads V7 to V9 was associated with a higher incidence of at least one of the following adverse clinical events: reinfarction, heart failure or death (p = 0.05). Although patency of the infarct-related artery (IRA) in Group A resulted in an improved LVEF at discharge (p < 0.012), LVEF was unchanged in Group B, regardless of the patency status of the IRA.

CONCLUSIONS

ST segment elevation in leads V7 to V9 identifies patients with a larger inferior MI because of concomitant posterolateral involvement. Such patients might benefit more from thrombolytic therapy.

Effects of propanolol in patients entered in the Beta-Blocker Heart Attack Trial with their first myocardial infarction and persistent electrocardiographic ST-segment depression

OBJECTIVE/BACKGROUND

It has been shown that patients with an acute myocardial infarction and persistent electrocardiographic ST-segment depression are at high risk for subsequent cardiac events. The purpose of this retrospective analysis was to examine the long-term effects of propranolol therapy in patients with their first acute myocardial infarction and persistent electrocardiographic ST-segment depression.

METHODS

The outcomes of 2877 patients enrolled in the Beta-Blocker Heart Attack Trial (BHAT) with their first myocardial infarction (75% of patients in BHAT) were reviewed. Patients were divided into three groups on the basis of presence or absence of > or =1 mm ST-segment depression in two contiguous leads of the 12-lead electrocardiogram obtained soon after admission or at the time of randomization, which occurred 10.1+/-3.5 days after the index myocardial infarction. Group 1 included 774 patients (392 randomly assigned to placebo and 382 to propranolol) with no ST-segment depression; group 2 included 1447 patients (713 placebo, 734 propranolol) with ST-segment depression at admission or at the time of randomization (labeled as transient); and group 3 included 656 patients (339 placebo and 317 propranolol) who had electrocardiographic ST-segment depression from the time of admission to the time of randomization (labeled as persistent).

RESULTS

In group 3, patients with persistent electrocardiographic ST depression, the mortality rate in patients randomly assigned to placebo was 13.6% compared with 7.6% in patients with propranolol (p = 0.012; log rank test). Sudden death in the placebo arm was 9.7% compared with 4.7% in the propranolol group (p = 0.012, log rank test). The results of the Cox regression analysis, adjusting for all baseline variables with p values <0.25, showed the relative risk of overall mortality rate and the relative risk of sudden death were 2.13 ( 1.22, 3.70) and 2.56 (1.27, 5.26), respectively, for the placebo group compared with the propranolol group. Patients with persistent ST-segment depression had the greatest benefit from propranolol (47.2 fewer events [deaths/reinfarctions] per 1000 person-years compared with 78 and 2.1 fewer events in patients with transient and no ST-segment depression, respectively).

CONCLUSIONS

It appears that the greatest benefit for beta-blocker therapy in patients after myocardial infarction is observed in patients with persistent ST-segment depression who are at greatest risk for death and reinfarction. Definitive conclusions regarding therapy with beta-adrenergic blocking agents in patients with persistent ST-segment depression cannot be made because our analysis, given its retrospective nature, is only hypothesis generating.

Association between anterior ST depression and increased myocardial salvage following reperfusion therapy in patients with inferior myocardial infarction

PURPOSE

To determine electrocardiographic features associated with myocardial salvage following reperfusion therapy in patients with inferior myocardial infarction.

PATIENTS AND METHODS

Ninety-two consecutive patients with acute inferior myocardial infarction were treated with reperfusion therapy in a tertiary care center. Several features were measured on the presenting electrocardiogram, including the presence or absence of ST depression in the chest leads and the total magnitudes of ST elevation or depression, and were then evaluated for their association with myocardial salvage. Myocardial salvage (% of left ventricle) was the difference between myocardium at risk and final infarct size. Tomographic myocardial perfusion imaging with technetium-99m sestamibi was performed acutely to measure myocardium at risk and repeated prior to hospital discharge to measure final infarct size.

RESULTS

The amount of myocardium at risk of infarction in the 92 patients was 19.1%+/-11.3% (range 1% to 68%), and the final infarct size was 10.6%+/-10.0% (range 0% to 45%). Thus, myocardial salvage in the 92 patients was 8.5%+/-8.4% (range -11% to 35%) of the left ventricle, or 0.51+/-0.38 (range 0.0 to 1.0) when expressed as a fraction of the myocardium at risk (salvage index). The presence or absence of anterior ST depression was the only one of seven electrocardiographic variables that was associated with myocardial salvage. Myocardial salvage was significantly greater in patients with anterior ST depression compared with those without it (10.6%+/-9.0% versus 5.9%+/-6.7%, P=0.025). Myocardium at risk was significantly greater in patients with anterior ST depression compared with those without the depression (22.8%+/-12.2% versus 14.6%+/-8.3%, P=0.0006), and infarct size tended to be larger (12.1%+/-10.4% versus 8.7%+/-9.4%, P=0.10). Myocardial salvage as a fraction of the myocardium at risk (salvage index) was similar between the two patient groups (0.52+/-0.37 versus 0.50+/-0.39, P=NS).

CONCLUSION

The presence of anterior ST depression during inferior myocardial infarction identifies a group of patients with the potential for greater myocardial salvage with reperfusion therapy. Such patients derive greater absolute benefit from reperfusion therapy because they have a larger amount of myocardium at risk, although their response to therapy (salvage index) is not intrinsically different.

Maximal precordial ST-segment depression in leads V4-V6 in patients with inferior wall acute myocardial infarction indicates coronary artery disease involving the left anterior descending coronary artery system

BACKGROUND

In inferior wall acute myocardial infarction, maximal ST-segment depression in left precordial leads (V4-V6) has been shown to be associated with increased in-hospital mortality, presumably due to coronary artery disease involving the left anterior descending coronary artery system.

METHODS

We measured ST-segment deviation from baseline in the initial electrocardiogram of patients with inferior wall acute myocardial infarction, who subsequently underwent coronary angiography during their in-hospital stay. Patients were divided into three groups: (I) No precordial ST-segment depression (n = 34). (II) Maximal precordial ST-segment depression in leads V1-V3 (n = 44). (III) Maximal precordial ST-segment depression in leads V4-V6 (n = 14).

RESULTS

The left anterior descending coronary artery or its diagonal branch were stenosed (> 50%) in 32%, 41%, and 71% of patients in groups I, II, and III, respectively (p = 0.04), and severely stenosed (> 70%) in 18%, 18% and 57% of patients in the respective groups (p = 0.007).

CONCLUSION

In patients with inferior wall acute myocardial infarction, maximal precordial ST-segment depression in leads V4-V6 is suggestive of severe coronary artery disease involving the left anterior descending coronary artery or its diagonal branch.

Usefulness of the admission electrocardiogram for identifying the infarct-related artery in inferior wall acute myocardial infarction

We analyzed the admission electrocardiogram in 109 patients with inferior wall acute myocardial infarction in an attempt to determine the infarct-related artery (IRA). The presence of ST depression in leads V1 or V2 had a high sensitivity for predicting the left circumflex artery as the IRA. The lack of ST depression in V1 or V2 had a high negative predictive value for excluding the left circumflex artery as the IRA.

Prognostic significance of precordial ST segment depression on admission electrocardiogram in patients with inferior wall myocardial infarction

OBJECTIVES

This study assessed retrospectively the correlation between the pattern of precordial ST segment depression on the admission electrocardiogram (ECG) and hospital mortality in patients with an inferior myocardial infarction treated with intravenous thrombolytic therapy.

BACKGROUND

Previous studies have shown that in acute inferior myocardial infarction, ST segment depression in the precordial leads is associated with increased hospital mortality. However, the significance of the different patterns of precordial ST segment depression has been evaluated in only two previous studies.

METHODS

The study included 1,321 patients (1,020 men) who enrolled in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) trial in Israel and received intravenous thrombolytic therapy. Patients with an ST segment elevation > or = 0.1 mV in at least two of the inferior leads were included. Patients were classified into four groups on the basis of their admission ECG: group I = patients with no precordial ST segment depression (n = 346); group II = those for whom the sum of ST segment depression in leads V1 to V3 was greater than that in leads V4 to V6 (n = 700); group III = those for whom the sum of ST depression in leads V1 to V3 was equal to that in leads V4 to V6 (n = 162); group IV = those with maximal ST depression in leads V4 to V6 (n = 113).

RESULTS

The overall hospital mortality rate was 3.6% (48 patients): for groups I, II, III and IV it was 2.9%, 2.8%, 4.3% and 9.7%, respectively. Multivariable logistic regression analysis confirmed that hospital mortality was independently associated with the pattern of precordial ST segment depression. The odd ratios in group IV relative to group I was 2.78 (95% confidence interval 1.26 to 6.13, p = 0.007).

CONCLUSIONS

The risk of mortality is higher in patients with an inferior myocardial infarction and maximal ST segment depression in precordial leads V4 to V6 versus precordial leads V1 to V3 on the admission ECG.

Prognostic significance of precordial ST segment depression during inferior myocardial infarction in the thrombolytic era: results in 16,521 patients

OBJECTIVES

We examined the prognostic significance of precordial ST segment depression among patients with an acute inferior myocardial infarction.

BACKGROUND

Although precordial ST segment depression has been associated with a poor prognosis, this correlation has not been adequately quantified, partly because of small sample sizes and methodologic limitations in previous studies.

METHODS

We examined the clinical and angiographic outcomes of 16,521 patients with an acute inferior myocardial infarction who underwent thrombolysis in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) study. Patients were classified into those without precordial ST segment depression (n = 6,422 [38.9%]), those with ST segment depression in leads V1 to V3 only (n = 5,850 [35.4%]), those with ST segment depression in leads V4 to V6 only (n = 876 [5.3%]) and those with ST segment depression in both leads V1 to V3 and leads V4 to V6 (n = 3,373 [20.4%]) on initial electrocardiography. Outcome measures included postinfarction complications (second- or third-degree heart block, congestive heart failure or shock) and 30-day and 1-year mortality.

RESULTS

Patients with precordial ST segment depression had larger infarctions, more postinfarction complications and a higher mortality rate than those without precordial ST segment depression (4.7% vs. 3.2% at 30 days; 5.0% vs. 3.4% at 1 year; both p < 0.001), regardless of whether ST segment depression was noted in leads V1 to V6 or in leads V4 to V6. The magnitude of precordial ST segment depression (sum of leads V1 to V6) added significant independent prognostic information after adjustment for clinical risk factors; the risk of 30-day mortality increased by 36% for every 0.5 mV of precordial ST segment depression.

CONCLUSIONS

Assessment of the magnitude of precordial ST segment depression is useful for acute risk stratification in patients with an inferior myocardial infarction.

Acute infarction of the left ventricular papillary muscle: electrocardiographic pattern and recognition of its location

BACKGROUND AND HYPOTHESIS

ST-segment depression during acute myocardial infarction (AMI) is known to herald serious hemodynamic complications. Since the mechanism of this dependence is not clear, we reinvestigated the old concept of papillary muscle infarction (PMI) as a cause of marked ST depression.

METHODS

Autopsies and morpho-electrocardiographic cor-relations were performed in 53 patients with AMI involving one or both left ventricular papillary muscles, and in 10 patients with AMI, but without acute PMI.

RESULTS

ST-segment depression > or = 1 mm in at least two leads (mean 3.6 +/- 2.2 mm) was found in 46 (86.8%) patients with, and in one without acute PMI. Thus, the sensitivity and specificity in selecting patients with acute PMI from among those with AMI were 86.8 and 90%, respectively, with an overall accuracy of diagnosis of acute PMI in the course of AMI of 87.3%. Among 26 patients with ST elevation consistent with diagnosis of AMI, ST depression, recorded in 22 patients, was insignificantly greater than in 24 of 27 patients without ST elevation: 4.1 +/- 2.9 versus 3.1 +/- 1.2 mm. Localization of ST depression in the limb leads allowed recognition of which papillary muscle suffered from acute infarction: ST depression in the inferior leads was seen only in patients with anterolateral PMI, whereas in leads I and/or a VL it was seen only in cases with posteromedial PMI. This rule was also valid in patients without concomitant ST elevation.

CONCLUSION

Patients with acute PMI show marked ST-segment depression. Its location in the limb leads allows recognition of which papillary muscle has undergone necrosis. This cause of marked ST depression in patients with AMI may explain the high mortality in this particular group.

A computer heart model incorporating anisotropic propagation. IV. Simulation of regional myocardial ischemia

The main goal of this study was to simulate clinical body surface potential maps, recorded during percutaneous transluminal coronary angioplasty protocols, using a realistic geometry computer heart model. Other objectives were to address the question of reciprocal ST-segment changes observed in the 12-lead electrocardiogram during ischemia and to verify the hypothesis that the shortening of the QRS duration observed in left anterior descending (LAD) coronary artery occlusion may be explained by conduction delay in the septal His-Purkinje system. Simulation was achieved by first introducing into the heart model three transmural zones of mild, moderate, and severe ischemia for assumed occlusions in the LAD, left circumflex, and right coronary arteries. The heart model was then excited, in turn, with these three zones present for assumed occlusions in the LAD, left circumflex, and right coronary arteries. Myocardial conduction velocities in the regions of moderate and severe ischemia were assumed to be reduced to 75 and 50% of normal, respectively. Model action potentials in the mild, moderate, and severely ischemic zones were also altered to reflect known ischemic changes in these action potentials. Body surface potential maps and electrocardiograms were computed by placing the heart inside a numerical torso model. Simulated map patterns during both ST-segment and QRS were qualitatively similar to clinical maps. Reciprocal ST-segment depression was observed for all three occlusions in remote leads that did not overlie the ischemic zones. QRS shortening due to septal His-Purkinje conduction delay was verified. The simulation results attest to the model's ability to reproduce body surface potential distributions recorded following percutaneous transluminal coronary angioplasty protocols. The simulations also showed that reciprocal ST-segment changes occur as a natural consequence of the primary ischemic region and that there is no need to invoke a second region of ischemia. Finally, the model demonstrated that QRS shortening can occur in LAD occlusion despite a slowing of conduction down the septal His-Purkinje system.

Usefulness of the 12-lead electrocardiogram in detection of myocardial infarction: electrocardiographic-anatomic correlations--Part II

Part II of this two-part series on electrocardiographic-necropsy correlation of infarct location focuses on lateral and posterior ("inferior") infarctions. The value of infarct location regarding complications and prognosis is also discussed.

Prognostic significance of the initial electrocardiographic pattern in patients with inferior wall acute myocardial infarction

The purpose of the study was to determine whether the initial electrocardiographic pattern is predictive of in-hospital mortality in inferior wall acute myocardial infarction. It is commonly perceived that patients with acute myocardial infarction presenting with greater ST elevation have a worse prognosis. The initial electrocardiogram of patients (n = 213) with inferior wall myocardial infarction was categorized based on the pattern of ST-segment elevation in inferior leads: (A) ST <1 mm with tall T waves, (B) ST > or = 1 mm with normal terminal QRS, and (C) ST > or = 1 mm with distortion of terminal QRS. ST deviation from baseline was calculated for all leads. Patients with maximal precordial ST depression in V4-V6 and pattern A had an in-hospital mortality rate of 68.8% compared with 16.9% for the entire study group. By univariate analysis, only pattern A was significantly predictive of in-hospital mortality [odds ratio = 2.91, 95% confidence interval (CI) 1.22-6.93], but by multivariate analysis adjusted for (1) age, (2) diabetes mellitus, (3) previous myocardial infarction, (4) thrombolytic therapy, (5) precordial ST-depression pattern, and (6) patterns of ST elevation, maximal ST depression in V4-V6 was significantly predictive (odds ratio = 4.93, 95% CI 1.79-13.56), whereas pattern A was not (odds ratio = 1.12, 95% CI 0.36-3.52). Contrary to popular perception, patients with inferior wall myocardial infarction presenting with minimal ST-segment elevation are at highest risk for in-hospital mortality, especially if accompanied by maximal precordial ST depression in V4-V6.

Usefulness of the 12-lead electrocardiogram in detection of myocardial infarction: electrocardiographic-anatomic correlations--part I

This two-part review evaluates a 56-year period (1938-1994) of electrocardiographic-necropsy correlation studies. Part I focuses on definitions of infarct location and evaluates anterior infarctions. Part II will focus on lateral and posterior infarcts.

Clinical applications of body surface potential mapping

Accumulated evidence suggests that the electrocardiographic information provided by the standard 12-lead electrocardiogram can be improved by use of multilead electrocardiograms. The clinical utility of body surface potential mapping is related to the selective regional information provided by the increased number of leads. That clinical utility includes such things as improved localization of accessory pathways in preexcitation syndromes, improved localization of pacing sites within the ventricles, localization of late potentials, and improved recognition of acute myocardial ischemia. Recording equipment and interpretation schemes are available to make possible more widespread application of potential mapping.

Early versus late congestive heart failure after initially uncomplicated anterior wall acute myocardial infarction

We determined the incidence and clinical, noninvasive, and angiographic variables contributing to postdischarge early (< or = 3 months) and late (> 3 months) congestive heart failure (CHF) after anterior wall acute myocardial infarction. The patient cohort consisted of 94 consecutive patients < 65 years of age who underwent predischarge exercise thallium-201 planar scintigraphy, rest radionuclide angiography, and coronary arteriography. At a mean of 49 months of follow-up, 10 of the 68 medically managed patients developed early CHF, and 10 had late CHF. The 10 patients with early CHF had significantly higher peak creatine kinase values (2,494 vs 1,032 IU/L, p = 0.01), and at discharge, a lower left ventricular (LV) ejection fraction (28 +/- 11% vs 41 +/- 11%, p < 0.02), more persistent thallium-201 defects (3.4 +/- 1.2 vs 2.1 +/- 1.2, p < 0.02), and fewer stress-induced redistribution defects (1.4 +/- 1.1 vs 0.4 +/- 1.1, p < or = 0.05) than those with late CHF. The early group had less multivessel disease (40% vs 90%, p < or = 0.03). Fifty percent (5 of 10) of patients who developed late CHF did so after a recurrent infarction compared with 10% (1 of 10) in the early CHF group (p < 0.07) and 8% in the group without CHF (p < 0.003). The 26 patients who underwent bypass surgery within 3 months had an LV ejection fraction and extent of ischemia and extent of angiographic stenoses comparable to patients with late CHF. None required hospitalization for CHF or had sustained a recurrent infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Body surface ECG potential maps in acute myocardial infarction

An algorithm for the early detection of acute myocardial infarction (MI) using body surface electrocardiographic potential mapping has been developed. The mapping system consists of a 64-hydrogel electrode harness applied rapidly to the anterior chest, from which electrocardiographic signals are stored on a memory card and processed by computer. At each of the 64 points, QRS and ST-T isointegrals and 10 other features of the QRST segment are measured. Using these measurements, new variables are derived that express the shape of the three-dimensional geometric surface of the map. The isointegrals, features, and shape variables are used in a variety of techniques to discriminate between MI and control subjects. Maps were recorded from 69 patients at initial presentation of chest pain suggestive of acute MI and from 80 healthy control subjects. Using a multiple logistic regression technique, 14 variables were identified that correctly classified 79 of the 80 control subjects (specificity, 98.8%) and 65 of the 69 MI patients (sensitivity, 94.2%). The algorithm based on these 14 variables was applied prospectively to maps recorded on a further 48 control subjects and 59 patients with acute MI. Of the MI patients, 31 had inferior, 13 inferoposterior, 10 anterior, 2 posterior, 1 lateral, 1 inferior with right bundle branch block, and 1 anterior non Q wave MI. The algorithm correctly classified all 48 control subjects (specificity, 100%) and 57 of the 59 MI patients (sensitivity, 96.6%). Marked differences in the three-dimensional geometric map surfaces between the control subjects and MI patients were demonstrated. Variables derived from these surfaces form the basis of an algorithm with a high sensitivity and specificity for the automated detection of acute MI. The design of adaptive algorithms and their application to patients with chest pain and atypical electrocardiographic changes, particularly ST depression, may lead to the earlier detection of MI and greater numbers of patients receiving thrombolytic therapy.

Prognostic significance of maximal precordial ST-segment depression in right (V1 to V3) versus left (V4 to V6) leads in patients with inferior wall acute myocardial infarction

This study examines whether patients with inferior wall acute myocardial infarction (AMI) and maximal ST-segment depression in left precordial leads are at higher risk for in-hospital mortality. The charts of patients (n = 213) with inferior wall AMI and an initial electrocardiogram that displayed peaked, tall T waves or ST-segment elevation with upright T waves in inferior leads were reviewed, after excluding patients with inverted T waves in inferior leads (n = 75). ST-segment deviation from baseline was measured for all leads. Patients were classified into 3 types: I = no precordial ST-segment depression; II = sum of ST-segment depression in leads V1 to V3 equal to or more than the sum of ST-segment depression in leads V4 to V6; and III = maximal precordial ST-segment depression in leads V4 to V6. Thirty-six patients (17%) died in the hospital. In-hospital mortality rates for patients with types I and II were 12% and 10%, respectively, compared with 41% for those with type III (p < 0.0001). Mortality rates in surviving patients were similar for all types up to 1 year after infarction. Multivariate logistic regression models for in-hospital mortality by ST-segment depression type adjusted for age, previous AMI, diabetes mellitus, and thrombolytic therapy revealed that type III pattern was a strong predictive factor for in-hospital mortality (odds ratio = 4.9, p = 0.0008, 95% confidence interval 1.93 to 12.26). Thus, patients with inferior wall AMI and maximal precordial ST-segment depression in leads V4 to V6 are at high risk for in-hospital mortality.

Eligibility for and benefit of thrombolytic therapy in inferior myocardial infarction: focus on the prognostic importance of right ventricular infarction

OBJECTIVES

This study was undertaken to determine eligibility for and benefit of thrombolytic therapy in patients with acute inferior myocardial infarction with or without right ventricular involvement.

BACKGROUND

Right ventricular involvement commonly complicates acute inferior myocardial infarction and is considered to have prognostic relevance. We hypothesized that the presence of right ventricular infarction, diagnosed early by ST segment elevation in the right precordial lead (V4R), may be of clinical importance in identifying patients who will benefit most from thrombolytic therapy.

METHODS

We studied 200 consecutive patients with acute inferior myocardial infarction to assess the prognostic impact of right ventricular infarction in those considered eligible or ineligible for reperfusion therapy. Prognostic analyses were based on the in-hospital period and a 1- to 6-year follow-up (mean [+/- SD] 37 +/- 12 months).

RESULTS

ST segment elevation in lead V4R was a reliable marker of right ventricular infarction (sensitivity 88%, specificity 78%, diagnostic efficiency 83%) in 107 patients (54%) with inferior myocardial infarction. Seventy-one eligible patients (36%) received thrombolytic therapy and had a lower mortality (8% [6 of 71]) and complication (31% [22 of 71]) rate than ineligible patients (mortality rate 25% [32 of 129], p < 0.01; complication rate 56% [72 of 129], p < 0.01). However, the overall benefit of thrombolysis was restricted to patients with right ventricular infarction complicating acute inferior myocardial infarction (with vs. without thrombolysis, respectively: mortality rate 10% vs. 42%, p < 0.005; complication rate 34% vs. 54%, p < 0.05). In the absence of right ventricular infarction, no difference was observed in the mortality (7% vs. 6%, p = NS) and major in-hospital complication (27% vs. 29%, p = NS) rates, whether or not the patient underwent thrombolytic therapy. Posthospital course over 37 +/- 12 months was not different in patients with and without right ventricular infarction but was best in all patients considered for reperfusion therapy.

CONCLUSIONS

During acute inferior myocardial infarction, the right precordial electrocardiogram is a simple but promising variable to identify a subgroup of patients with an unfavorable course who will benefit most from thrombolytic therapy.

Implications of inferior ST-segment depression in anterior acute myocardial infarction: electrocardiographic and angiographic correlation

This study assesses the significance of inferior ST-segment depression during anterior acute myocardial infarction (AMI) by investigating the relationship between inferior ST-segment depression and (1) the site of the left anterior descending (LAD) coronary artery lesion and (2) ST-segment deviation in the various anterior and lateral leads. We studied 126 patients with anterior AMI who underwent coronary angiography within 21 days of hospitalization. The admission 12-lead electrocardiograms were evaluated for ST-segment amplitude in each lead at 0.08 second after the J-point. Coronary angiography was evaluated for the site and severity of luminal narrowing of the coronary arteries. The site of the culprit lesion in the LAD artery, relative to the origin of the first septal and diagonal branches, was determined. In four patients no lesion was identified in the LAD artery. Of the remaining 122 patients, 40 and 53 patients had a LAD artery lesion proximal to the first septal and first diagonal branches, respectively. Additional luminal narrowing (> or = 70% of diameter) was found in the circumflex and the right coronary arteries in 27 and 37 patients, respectively. ST-segment depression of > 1 mm in leads II, III, and aVF was noted in 24, 29, and 24 patients, respectively. The prevalence of a LAD artery preseptal and prediagonal lesion was higher in patients with inferior ST-segment depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of exercise-induced ST depression in precordial electrocardiographic leads after inferior wall acute myocardial infarction with thallium-201 stress scintigraphy, coronary angiography and two-dimensional echocardiography

Fifty-eight of 220 consecutive patients had exercise-induced ST depression in some or all precordial leads 3 to 12 months after a first inferior myocardial infarction. All 58 patients underwent thallium-201 exercise testing, 2-dimensional echocardiography and coronary angiography. ST depression was confined to leads V1-4 in 22 patients (group A); thallium-201 exercise testing showed reversible anterior perfusion defects and left anterior descending coronary artery disease in 11 of the 22 patients (50%). None of the other 11 with negative thallium-201 exercise test results had significant left anterior descending narrowing, and the anterior ST depression could be explained by asynergy of the posterior wall found on 2-dimensional echocardiography in 10. ST depression appeared in leads V5-6 in 22 patients (group B); reversible anterior perfusion defects and left anterior descending disease was demonstrated in 18 patients (82%). In the other 4 patients posterior wall asynergy was demonstrated. ST depression was seen from leads V1-6 in 14 patients (group C); reversible anterior perfusion defects were seen in 6 patients (43%), 5 of whom had significant left anterior descending disease. Among the other 8 patients without reversible anterior perfusion defects, posterior wall asynergy was found in 6.(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of anterior ST depression in inferior wall acute myocardial infarction

Early tomographic myocardial perfusion imaging with technetium-99m sestamibi was performed during inferior wall acute myocardial infarction to determine the relation between the amount and location of myocardium at risk and the presence or absence or anterior ST depression. The total size of the acute perfusion defect and its lateral and septal borders were measured in 29 consecutive patients who were admitted with > 30 minutes of chest pain and acute inferior ST elevation on their initial electrocardiogram. The 22 patients with anterior ST depression had significantly more left ventricular myocardium at risk than the 19 patients who did not have anterior ST depression (23 +/- 2% of the left ventricle vs 15 +/- 1%, p = 0.008). All 8 patients with > 25% of the left ventricle at risk had anterior ST depression. Patients with anterior ST depression had a significantly greater lateral extent of the acute perfusion defect (49 degrees +/- 8 degrees from the midinferior wall vs 23 degrees +/- 7 degrees, p = 0.002). There was no difference in the septal border of the perfusion defect between patients with and without anterior ST depression (-44 degrees +/- 4 degrees vs -46 degrees +/- 7 degrees, p = NS). No patient had a measurable anterior perfusion defect. Although there is considerable overlap between groups with and without anterior ST depression, anterior ST depression is a simple and readily available indicator of myocardium at risk in inferior wall acute myocardial infarction.