Clinical significance of "reciprocal" S-T segment depression in acute myocardial infarction. Relative contributions of infarct size and ischemia at a distance

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.

Isolated inferior wall ST segment depression as an early sign of acute anterior wall myocardial infarction

BACKGROUND

Reciprocal changes may accompany ST segment elevation in the ischemic territory during acute myocardial infarction (AMI). We examined the hypothesis that isolated inferior ST segment depression on admission is an early sign of anterior wall infarction.

METHODS

49 patients admitted to the coronary care unit between January 1996 and June 2008 who presented with inferior ST segment depression in the absence of ST segment elevation. Electrocardiograms (ECGs) obtained on admission and at 24-48 h were reviewed. Culprit artery was determined based on angiographic and echocardiographic data.

RESULTS

All patients had ST segment depression in the inferior leads on admission. A subgroup (55%) presented with concomitant ST segment depression in V5-V6. Follow-up ECG showed that 35% developed ST segment elevations and/or T wave inversions in anterior wall leads over 24-48 h. The left anterior descending (LAD) artery or one of its branches was the culprit in 60% of the patients. Sum of ST segment depression, V5-V6 involvement or presence of 'hyperacute' T waves did not predict LAD involvement.

CONCLUSION

Isolated ST segment depression in the inferior wall leads during ACS is usually an early sign of anterior wall AMI, in which the LAD or one of its branches is the culprit artery.

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.

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.

Relation of ST-segment changes in inferior leads during anterior wall acute myocardial infarction to length and occlusion site of the left anterior descending coronary artery

We investigated the relation between left anterior descending (LAD) coronary artery morphology and inferior lead ST-segment changes to elucidate the clinical significance of such changes in 159 patients with anterior wall acute myocardial infarction (AMI). Patients with 1-vessel LAD artery lesions were divided into an ST depression group (n = 40), an ST elevation group (n = 25), and a no-ST-change group (n = 94) based on ST-segment changes in the inferior leads. The relation between each group and the infarct-related lesion and the presence of a wrapped LAD artery was then investigated. The percentage of patients with the infarct-related lesion in the proximal LAD artery was significantly higher in the ST depression group and significantly lower in the ST elevation group. The percentage of patients with a wrapped LAD artery was significantly higher in the ST elevation group and significantly lower in the ST depression group. The wall motion index determined echocardiographically was significantly higher in the ST depression group and the no-ST-change group than in the ST elevation group. Our findings suggest that inferior lead ST-segment changes during anterior wall AMI arise as a result of competition between reciprocal changes caused by high lateral wall AMI due to lesions of the proximal LAD artery, which depress the ST segment, and inferoapical wall AMI due to a wrapped LAD artery, which elevates the ST segment. In patients with no ST-segment changes, echocardiography was useful for distinguishing the amount of affected LAD artery territory.

Angiographic and clinical significance of 'transient' ST-segment depression in the lateral chest leads in anterior wall acute myocardial infarction

This study aimed to clarify the significance of ST-segment depression in the lateral chest leads in anterior wall acute myocardial infarction (AMI) with ST-segment elevation. A total of 196 patients with their first anterior wall AMI (< or =6h) were divided into 2 groups according to the presence (group A, n=39) or absence (group B, n=157) of ST-segment depression > or =0.1 mV in V5 and/or V6 on the admission electrocardiogram. Patients with electrocardiographic confounding factors were excluded. No patients had persistent ST-segment depression in the lateral chest leads. Emergency coronary angiography revealed that group A had higher incidences of occlusion of the left anterior descending coronary artery (LAD) proximal to its first septal branch (77% vs 51%, p<0.01) and good collateral circulation than group B (46% vs 25%, p<0.05). Peak creatine kinase levels were significantly lower in group A than in group B (2060+/-1099 vs 2873+/-2077 IU/L, p<0.01). Left ventricular ejection fraction in the chronic phase was significantly greater in group A than in group B. Regional wall motion in the infarct region in the chronic phase was better in group A than in group B. These results indicate that patients with 'transient' ST-segment depression in the lateral chest leads in anterior wall AMI had a relatively smaller infarct size, despite their higher incidence of occlusion of the LAD proximal to its first septal branch, because of their higher incidence of good collateral circulation.

The relationship of inferior ST depression, lateral ST elevation, and left precordial ST elevation to myocardium at risk in acute anterior myocardial infarction

The purpose of this study was to examine the relationship between the presence or absence of ST segment depression in inferior leads (II, III, and aVF) and ST segment elevation in lateral (I and aVL) or left precordial (V5 and V6) leads with the amount and location of myocardium at risk for infarction in patients with acute anterior myocardial infarction. Forty-three patients with anterior infarctions were injected with technetium 99m-sestamibi when they were first seen and underwent tomographic imaging to measure the amount and location of myocardium at risk. Patients with inferior ST depression (n = 10) compared with those without ST depression (n = 33) had perfusion defects that extended significantly further into the lateral wall (47 degrees vs 20 degrees, p = 0.04) and larger anterior injury vectors (6.47 vs 4.92, p = 0.008). There was no significant association with the percentage of myocardium at risk, disease of the right coronary artery, the presence of an inferior perfusion defect, or the size of the inferior injury vector. Among the patients with ST elevation in lateral leads (n = 16) compared with those without (n = 27), there was a significantly more lateral defect border (47 degrees vs 25 degrees, p = 0.007) and a larger anterior injury vector (6.07 vs 4.81, p = 0.01). There was no significant correlation with the percentage of myocardium at risk. A significant relationship could not be demonstrated between the presence of ST elevation in the left precordial leads and any measure of the amount or location of myocardium at risk. These data support the theory that inferior ST depression in patients with transmural anterior ischemia is a "reciprocal" finding and does not represent inferior ischemia. The presence of inferior ST depression or lateral ST elevation is associated with a more lateral perfusion defect. Neither of these ECG findings is associated with the amount of myocardium at risk for infarction.

Implications of inferior ST-segment elevation accompanying anterior wall acute myocardial infarction for the angiographic morphology of the left anterior descending coronary artery morphology and site of occlusion

Inferior ST-segment elevation during anterior wall acute myocardial infarction (AMI) due to left anterior descending (LAD) coronary artery occlusion is unusual and was not previously investigated. This study tested the hypothesis that inferior ST-segment elevation during anterior AMI predicts a specific angiographic morphology that satisfies 2 necessary conditions: (1) mass of ischemic anterior wall myocardium is relatively small, resulting in a weaker anterior injury current and less reciprocal inferior ST-segment depression; and (2) there is concomitant inferior wall transmural ischemia that further shifts the inferior ST segments upward. The study group consisted of 42 consecutive patients with anterior AMI undergoing angiography at 4.1 days (range 0 to 14). Coronary angiograms were examined for 3 features: (1) site of LAD artery occlusion (a distal obstruction implying a smaller mass of ischemic anterior wall myocardium), (2) LAD artery extension onto inferior wall of left ventricle (termed a "wrap around" vessel), and (3) collateral flow from LAD artery to inferior wall. The latter 2 features would be expected to contribute to inferior wall transmural ischemia. Acute inferior ST-segment elevation (sum of ST-segment deviation in leads II, III and aVF greater than or equal to 3.0 mm) was seen in 7 patients (16%). A greater number of LAD artery branches proximal to the site of occlusion was significantly correlated with less inferior ST-segment depression (r = 0.59, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Inferior ST segment changes during acute anterior myocardial infarction: a marker of the presence or absence of concomitant inferior wall ischemia

The significance of inferior ST segment changes during acute anterior myocardial infarction was studied in 60 patients with acute anterior infarction who had angiographic visualization of the entire distribution of the left anterior descending artery after thrombolytic therapy with streptokinase. In 34 patients (Group 1) this artery supplied the anterior wall of the left ventricle up to or including the apex but did not reach the inferior wall; in 16 patients (Group 2) it continued beyond the apex onto the inferior wall of the left ventricle; and in 10 patients with prior inferior infarction (Group 3) it partially supplied the inferior wall of the left ventricle through collateral channels to an occluded right or dominant circumflex coronary artery. Consistent with this anatomy, evidence of inferior wall ischemia was significantly more frequent in Groups 2 and 3 than in Group 1 by thallium-201 scintigraphy (91 versus 7%) and by contrast left ventriculography (91 versus 13%). There was no difference in the magnitude of precordial ST segment elevation among the three groups but the inferior ST segment depression was significantly smaller in Groups 2 and 3 with concomitant inferior wall ischemia than in Group 1 (aVF: -0.5 +/- 0.7; -0.5 +/- 1.0; -1.8 +/- 0.8 mm, respectively; p less than 0.001) with 10 of the 26 patients in Groups 2 and 3 having an elevated or isoelectric ST segment in aVF compared with none of the 34 patients in Group 1 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and prognostic importance of persistent precordial (V1-V4) electrocardiographic ST segment depression in patients with inferior transmural myocardial infarction

Forty-three consecutive patients with acute inferior transmural myocardial infarction but no history or electrocardiographic evidence of prior myocardial infarction were evaluated prospectively to assess the clinical and prognostic importance of persistent precordial (V1-V4) ST segment depression. Patients were evaluated within 24 hr of admission by history, physical examination, cardiac enzyme levels, right heart catheterization, and radionuclide angiography; all were followed for 1 year. Ten of the 43 patients (group I) had persistent anterior precordial ST segment depression, defined as 1 mm or greater in one or more precordial leads (V1-V4) 24 hr after admission to the coronary care unit, and 33 patients (group II) did not. Clinical variables that differed between groups I and II, respectively, included mean age (67 +/- 9 [+/- 1 SD] vs 59 +/- 8 years; p less than .01), incidence of Killip class II to IV (100% vs 33%; p less than .001), and average peak creatine kinase concentration (2878 +/- 1139 vs 1511 +/- 1034 IU/liter; p less than .001). Hemodynamic differences between groups I and II included a higher pulmonary arterial wedge pressure (19 +/- 4 vs 11 +/- 5 mm Hg; p less than .001) and a lower cardiac index (2.0 +/- 0.5 vs 2.6 +/- 0.7 liters/min/m2; p less than .05). An evaluation of left ventricular ejection fraction and wall motion index by radionuclide angiography showed that group I had a lower ejection fraction (44 +/- 11% vs 53 +/- 10%; p less than .05) and higher wall motion index (1.7 +/- 0.4 vs 1.4 +/- 0.3; p less than .05) compared with group II.(ABSTRACT TRUNCATED AT 250 WORDS)