Marked ST-segment elevation in the precordial and inferior leads in right ventricular myocardial infarction: a case report

This is a report of right ventricular infarction complicated by inferior myocardial infarction in which marked ST-segment elevation was observed in the precordial and inferior leads. A 51-year-old man was admitted with chest pain of one-half hour duration. His admission ECG showed conspicuous ST-segment elevation in the precordial and inferior leads. The maximum magnitude of the ST-segment elevation in the precordial leads was 21 mm in lead V2 and 10 mm in lead II. Echocardiography showed akinesis of the right ventricular free wall and the posterior half of the left ventricle. Angiography revealed a 90% reduction in the diameter of the right coronary artery in its proximal portion, and a normal left coronary system. Recent reports have indicated that precordial ST-segment elevation may reflect right ventricular infarction. However, there has been no previous report of marked ST-segment elevation in the precordial and inferior leads. In right ventricular infarction, the currents of injury usually occur simultaneously in the right ventricular free wall and left ventricular inferior wall, and then are electrically opposed to each other. The diffuse and marked ST-segment elevation observed in this case is thus a rare phenomenon.     

Acute myocardial infarction with simultaneous ST-segment elevation in the precordial and inferior leads: evaluation of anatomic lesions and clinical implications

BACKGROUND: Simultaneous ST-segment elevation in the precordial and inferior leads is a rare ECG finding in patients with acute myocardial infarction (AMI) and its clinical implications rarely have been reported. The purpose of this study was to evaluate the clinical features of this distinctive ECG manifestation and its impact on clinical outcome. METHODS AND RESULTS: Between May 1993 and July 2001 in our hospital, direct percutaneous coronary intervention (dPCI) was performed in 924 patients with AMI. Of these 924 consecutive patients, 37 patients (4.0%) who had simultaneous ST-segment elevation (> or = 1 mm) in the precordial and inferior leads were retrospectively analyzed. Eight of these 37 patients who had a wrapped left anterior descending artery (LADA) occlusion were placed into group 1 (ie, wrapped LADA). Twenty-nine of the 37 patients who had anatomic lesions other than a wrapped LADA in the coronary arteries were placed into group 2 (ie, "nonwrapped" LADA). Group 2 patients had significantly higher incidences of cardiogenic shock (58.6% vs 0%, respectively; p = 0.004), pulmonary edema (43.8% vs 0%, respectively; p = 0.02), and sustained sudden cardiac death due to malignant ventricular tachyarrhythmias (44.8% vs 0%, respectively; p = 0.03) than did group 1 patients. Group 1 patients usually had ST-segment elevations of < 2 mm the inferior leads. However, group 2 patients always had ST-segment elevations of > or = 2 mm in the inferior leads. Univariate analysis demonstrated that the mean (+/- SD) ST-segment elevation in the inferior leads was significantly higher in group 2 patients than in group 1 patients (11.08 +/- 4.18 vs 2.95 +/- 0.92 mm, respectively; p = 0.0001). Coronary angiography demonstrated that the incidence of multivessel disease (93.1% vs 37.5%, respectively; p = 0.002) and the incidence of severe obstructive two-vessel disease (ie, stenosis of > 85%) [93.1% vs 0%, respectively; p = 0.0001] were significantly higher in group 2 than in group 1 patients. Although there was no significant difference in the rate of unsuccessful reperfusion (24% vs 13%, respectively; p = 0.38) between group 2 and group 1 patients, the 30-day mortality rate was significantly higher in group 2 patients than in group 1 patients (48.3% vs 0%, respectively; p = 0.015). CONCLUSIONS: AMI with ECG manifestation of simultaneous ST-segment elevation in precordial and inferior leads can be caused by either a wrapped LADA occlusion or a nonwrapped LADA occlusion. While patients with wrapped LADA occlusions usually have favorable clinical outcomes, patients with nonwrapped LADA occlusions usually have serious clinical presentations and unfavorable clinical outcomes. Specific clinical and ECG features identifying high-risk patients in this clinical setting would be extremely important for early, aggressive, and appropriate management.     

Underlying cardiomyopathy in patients with ST-segment elevation in the right precordial leads.

BACKGROUND: Ventricular fibrillation (VF) and sudden death (SD) may occur in patients with ST-segment elevation in the right precordial leads. The mechanism of such events is unclear, so the aim of the present study was to assess whether there is an underlying morphological or pathological abnormality in these patients. METHODS AND RESULTS: Fourteen consecutive patients (44+/-10 years old, all male) with ST-segment elevation of more than 2 mm in the right precordial leads underwent a cardiac evaluation, including right ventriculography and endomyocardial biopsy. The ST-segment changes after the administration of sodium-channel blockers were also evaluated. Two patients survived documented VF, 11 patients had chest pain or tightness, and another patient had a history of syncope. Only 1 patient had a family history of premature SD. The coronary angiograms were normal in all the patients. VF was induced in 5 patients (36%). Wall motion abnormalities of the right ventricle were detected in 4 patients (29%) and endomyocardial biopsy revealed features of cardiomyopathy in 7 patients (50%). In total, 9 (64%) of 14 patients exhibited wall motion abnormalities and/or pathologic findings. CONCLUSIONS: Underlying cardiomyopathy was present in more than half of the present patients with ST-segment elevation in the right precordial leads.     

Significance of anterior precordial ST-segment depression in acute inferior myocardial infarction

In 70 consecutive patients (pts) with acute transmural inferior infarction, 58 had significant precordial ST depression (group A) and the remaining 12 had no ECG changes in precordial leads (group B) on admission. At the time of hospital discharge, the persistence of anterior ST depression was observed in 13 pts (group A1), normalization in 45 (group A2). Infarct size was significantly greater (p less than 0.05) in group A than in group B (37.6 vs. 23.8 CK-MB gEq). The largest infarct (51.5 CK-MB gEq) and the most serious clinical course was observed in group A1. No significant differences were noticed in the frequency of reinfarction and episodes of acute coronary insufficiency during hospitalization and one-year follow-up between groups. Persistent precordial ST depression is a simple ECG marker of extensive infarction, left ventricular dysfunction and a worse clinical course.     

Significance of right precordial ST elevation in experimental right ventricular infarction

We produced experimental isolated right ventricular infarction (RVI) with closed chest method, and examined ECG changes of right precordial leads and changes of cardiac output (C. O) in 19 dogs. As a result, ECG showed ST depressions in leads, II, III, aVF and V2-V6 and ST elevations in a VR lead in all 15 cases of the proximal occlusion of right coronary artery (RCA). In 10 of 15 dogs ST elevations in some right precordial leads occurred, and the sensitivity of ST elevation in single right precordial lead was 60% (V5R), 53% (V4R) and 47% (V3R and V1), respectively for the detection of RVI. When left circumflex artery (LCX) was occluded, ST elevation in V4R lead after RCA occlusion was blocked. Therefore, it is thought that the sensitivity of ST elevation in right precordial lead may be lower than expectation in identifying RVI. Concerning anterior chest leads, none of 15 dogs with RVI showed ST elevations in leads V2-V6 in this study. If ST elevations in right precordial leads did not appear, variation of C.O was small and C.O reduced in proportion to the extension of ST elevations in right precordial leads.     

Prognostic significance of precordial ST-segment depression during inferior acute myocardial infarction

To study the mechanism and prognostic importance of precordial ST-segment depression during inferior acute myocardial infarction, 162 patients admitted during 1969 through 1982 were identified. Patients with ST depression in leads V1, V2 and V3 had significantly larger infarctions as assessed by a QRS scoring system. Hospital mortality was 4% (3 of 75) among patients without ST depression, and 13% (11 of 87) in patients with ST depression. The relation between the amount of ST depression and hospital mortality was significant (p less than 0.001 by logistic regression), and remained significant (p less than 0.003) after adjusting for other potentially prognostic factors. Among patients discharged from the hospital, the 5-year survival was 92% in those without precordial ST depression and 80% in those with precordial ST depression (p = 0.058 by the Cox model). Precordial ST-segment depression on the admission electrocardiogram during an inferior acute myocardial infarction indicates a larger infarction, predicts a higher hospital mortality and suggests a worse long-term prognosis after discharge.     

Clinical characteristics of precordial ST-segment depression in acute inferior myocardial infarction]

Assessments of the significance of precordial ST segment depression in acute inferior myocardial infarction (AIMI) have yielded conflicting results. Among 92 AIMI patients admitted within 6 hrs after the onset, 65 showed ST depression, and the remaining 27 showed no ST depression. These depressions were present in all of V1-4 (right type; 17), V2-5 (middle type; 10), V3-6 (left type; 13) and V1-6 (broad type; 25). The clinical severity was Forrester subset I in the majority (89%) of patients without ST change, while complications were prevalent in patients with ST depression, especially in the right type (44% were Forrester subset II-IV). Peak CK was 2,150 +/- 399 U/L in patients without ST depression, but it was elevated to 3,172 +/- 811 in patients with ST depression, especially in the right type (4,506 +/- 499). Wall motion evaluated by echocardiography and QRS scores on ECG also revealed greater abnormality in patients with ST change. The initial right coronary angiogram on admission revealed complete occlusion in 76% of these patients with ST depression of whom all of the right type had completely occluded artery. Abnormal motion of the anterior wall, which suggests remote ischemia associated with AIMI was proved neither by left ventriculography nor echocardiography. Hospital mortality in patients with ST depression (9.2%) was as twice as high as that in those without ST depression (4.6%). We concluded that ST depression in patients with acute inferior infarction may not be indicative of remote ischemia but manifests as a mirror image of a large infarction with a complicated clinical course.     

Usefulness of ST-segment elevation in the inferior leads in predicting ventricular septal rupture in patients with anterior wall acute myocardial infarction

The ventricular septum receives its blood supply from the septal perforators of the left anterior descending (LAD) coronary artery and the right coronary artery. However, when the LAD artery extends to the inferior wall, beyond the apex (so-called wrapped LAD), the ventricular septum near the apex receives blood supply only from the LAD artery. As a consequence, ventricular septal rupture (VSR) would seem more likely in myocardial infarction with occlusion of this type of LAD artery. To test this hypothesis, we compared electrocardiographic findings in 21 patients who had anterior acute myocardial infarction that was complicated by VSR with those in 275 patients who had acute myocardial infarction that was not complicated by VSR. We observed ST-segment elevation in all inferior leads (II, III, and aVF) in addition to anterior leads in 42.9% of patients (9 of 21) who had VSR but in only 3.6% of those (10 of 275) who did not have VSR. Abnormal Q waves appeared in all 3 inferior leads in 44.4% of patients (8 of 18) who had VSR but in only 4.0% of those (10 of 250) who did not have VSR. Thus, the incidence of ST-segment elevation and abnormal Q waves in the inferior leads was significantly (p <0.001) greater in the VSR group. In addition, multivariate analysis of patient characteristics, including advanced age, female gender, and coronary morphology, showed VSR to be significantly correlated with ST-segment elevation (odds ratio 16.93, 95% confidence interval 4.13 to 69.30) and abnormal Q waves (odds ratio 13.64, 95% confidence interval 3.16 to 58.79) in the 3 inferior leads. In conclusion, these electrocardiographic findings can be useful predictors of complication by VSR.     

ST segment elevation in anterior precordial leads and right ventricular infarction. Apropos of 6 cases]

ST segment elevation in the anterior precordial chest leads may be observed in some cases of right ventricular infarction alone or associated with left ventricular inferior wall infarction. Six out of 700 patients admitted to our Coronary Care Unit over a 2 year period had right ventricular infarction with these electrocardiographic changes. In three cases, isolated right ventricular infarction was due to occlusion of a right marginal artery (N = 2) or of a small right coronary artery (N = 1) which only vascularised the right ventricle. In 2 cases, right ventricular infarction was associated with a recent or chronic left ventricular inferior wall infarct. This type of ST segment elevation may suggest a left ventricular anterior wall infarct especially when there are no changes in the inferior leads, as was the case in our first patient. However, the dome-like appearance of the ST segment, the reduction in amplitude of ST elevation from V2 to V5, the progressive regression of the ST changes without the appearance of Q waves, are more suggestive of the diagnosis of right ventricular infarction. In addition, normal left ventricular dilatation on echocardiographic examination rapidly confirms the diagnosis.     

Right ventricular infarction. The evolution of ST-segment elevation and Q wave in right chest leads

ST-segment elevation in right chest leads V3R-V7R and Q wave in V3R was measured early (1-4 hours) and late (18-24 hours) after the onset of infarction in six patients. The patients died within 9 days of infarction, and autopsy demonstrated more than 50% necrosis of the right ventricle (inclusion criterion). Abnormal ST elevation was recorded in all patients in the early and late electrocardiograms, but mean ST elevation decreased significantly between these recordings. ST elevation greater than or equal to 1 mm was recorded in all patients in the early electrocardiogram but was present in only three (50%) in the second electrocardiogram. The number of leads exhibiting abnormal ST elevation decreased from 27 (90%) to 24 (80%) (NS), and those exhibiting ST elevation greater than or equal to 1 mm decreased from 24 (80%) to 15 (50%), (p less than 0.05). Q wave in V3R was present in both electrocardiograms in three patients. Evolution of Q wave was seen in only one patient, whereas two patients were without Q wave in both electrocardiograms. These results indicate that ST elevation in V3R-V7R may vanish within the initial 24 hours despite large right ventricular infarction. Furthermore, Q wave in V3R may evolve very early after the onset of right ventricular infarction.     

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.     

ST-segment elevation myocardial infarction

Opinion statement ST-segment elevation myocardial infarction (MI) is an emergency medical condition. Expediting the steps leading to coronary reperfusion is of critical importance in improving survival after acute MI. After the diagnosis of acute MI is made, patients should be treated with oxygen, aspirin, nitroglycerin, beta-blockers, heparin, and analgesics, barring any contraindications. If an experienced cardiac catheterization laboratory is available within 60 to 90 minutes, then catheter-based reperfusion therapy is recommended; otherwise, thrombolysis should be considered as an alternate therapy. Therapy with a reduced-dose thrombolytic agent and a glycoprotein IIb/IIIa receptor inhibitor appears to be of an added benefit in establishing TIMI (Thrombolysis in Myocardial Infarction) 3 flow, but this approach awaits final approval prior to widespread use. The adjunctive use of glycoprotein IIb/IIIa receptor inhibitors with percutaneous transluminal coronary angioplasty, with or without stenting, appears to be beneficial and is being used more frequently in the acute setting. Coronary angiography should be performed in patients who fail to respond to thrombolytic therapy or who have evidence of recurrent ischemia. This procedure should not be routinely performed in patients who have responded to thrombolytic therapy. Four to 6 days after an acute MI event, assessment of left ventricular function is recommended. Submaximal exercise test (with or without nuclear or echocardiographic imaging) should be considered in patients prior to discharge from the hospital—an exception can be made in patients with one-vessel disease treated successfully with percutaneous transluminal coronary angioplasty. After discharge, a regular exercise test should be obtained 4 to 6 weeks after an uncomplicated acute MI event. Secondary prevention measures such as weight loss, cessation of smoking, aspirin, beta-blockers, lipid-lowering agents, and angiotensin-converting enzyme inhibitors should be considered in all patients, barring contraindications.     

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.     

Single right-sided precordial lead in the diagnosis of right ventricular involvement in inferior myocardial infarction.

The ST segment in a single right-sided chest lead, CR4R, has been studied in 92 consecutive patients with acute inferior transmural left ventricular myocardial infarction. A transient ST- segment rise of more than 1 mm. was recorded in 35 patients, and strongly indicated a significant extension of the infarction to the posterior free right ventricular wall according to autopsy findings. This ECG pattern was furthermore associated with right-sided heart failure, hypotension and oliguria. Left heart failure was also common. The short-term prognosis of patients with ST-segment elevation in CR4R was poor.