Right ventricular infarction associated with anteroseptal myocardial infarction: a clinicopathologic study of nine cases

RIGHT VENTRICLE FUNCTION IN PATIENTS WITH ANTERIOR MYOCARDIAL INFARCTION: ARE WE SURE IT IS NOT INVOLVED?

The right and left ventricle of heart are intimately connected by anatomical and functional links. Hence, acute changes in cardiac geometry and function can modify the performance and physiology of both sides of the heart, influencing each other. After a brief overview of the anatomy and related imaging techniques for the study of right ventricular function, we report a review on the interesting correlation of acute anterior myocardial infarction and right ventricular function, very often underestimated.

Significance of ST-Segment elevation in V4R lead in patients with anterior myocardial infarction

Background

There is some evidence of the association between ST‐segment elevation in the V4R chest lead and the likelihood of anterior wall myocardial infarction; however, the link of this phenomenon with the location and the severity of the coronary involvements in such patients remains uncertain. We aimed to investigate the ST‐segment elevation in V4R leads in patients with anterior myocardial infarction and also its effect on prognosis as well as the detection and prediction of the location of arterial stenosis in coronary angiography.

Methods

Data collection was performed by reviewing the hospital recorded files of 195 patients’ suspicion of acute myocardial infarction who have been referred within 2 h of the onset of cardiac symptoms. The patients were then categorized into two groups with and without ST elevation in the V4R chest lead.

Results

Comparing two groups showed a significantly higher rate of concurrent ST‐segment elevation in V₁ lead in those with ST‐segment elevation in V4R. Echocardiography on the day after anterior myocardial infarction showed LVEF <40% in 74% and 35.2% of patients with and without ST‐segment elevation in V4R, respectively, indicating a significant difference. The lesions on proximal LAD were more common in the group with ST‐segment elevation in V4R.

Conclusion

Our study emphasized a high likelihood of ST‐segment elevation in V4R lead concurrently with ST‐elevation in V₁ lead. Also, the appearance of ST‐segment elevation in V4R lead can be accompanied with a lower LVEF, myocardial infarct size, involvement of proximal part of LAD, and Wrap around LAD.

The association of right coronary artery conus branch size and course with ST segment elevation of right precordial leads and clinical outcome of acute anterior myocardial infarction

Introduction: Coronary artery disease is the leading cause of death worldwide and electrocardiogram (ECG) is a reliable diagnostic tool to determine a myocardial infarction. The present study tried to compare the relationship between the ECG findings and angiographic findings in patients with acute anterior myocardial infarction. Methods: Seventy-four patients with acute anterior ST elevation myocardial infarction (Ant- STEMI) presenting to the emergency room in the first 12 hours after the onset of symptoms were studied. Upon admission, a full 14-lead ECG (including leads V3R and V4R) were performed. Angiographic and ECG findings, as well as clinical outcome were compared between two groups. The statistical tests including Chi-square and independent t-test were used for data analysis. Results: Small conus branch was seen in 52 (70.3%) and large conus in 22 ( 29.7%) patients. STE in right-sided leads and heart failure were significantly higher in small conus branch group versus large conus branch (88.6% vs 11.4%, P < 0.001 and 34.6% vs 9.1%, P = 0.02 respectively). There was no significant difference in mortality rate between the two groups (5.8% in small conous group vs 0% in large conus group, P = 0.55). There was a significant difference in major adverse cardiac events (MACE) between the two groups (51.9% in small conous group vs 18.2% in large conus group, P = 0.01). Conclusion: In patients with anterior MI, small conus branch was associated with higher rate of major adverse cardiac events mostly because of increased rate of acute heart failure.

Time Dependence of the Effect of Right Ventricular Dysfunction on Clinical Outcomes After Myocardial Infarction: Role of Pulmonary Hypertension

Background

The clinical importance of right ventricular (RV) function in acute myocardial infarction is well recognized, but the impact of concomitant pulmonary hypertension (PH) has not been studied.

Methods and Results

We studied 1044 patients with acute myocardial infarction. Patients were classified into 4 groups according to the presence or absence of RV dysfunction and PH, defined as pulmonary artery systolic pressure >35 mm Hg: normal right ventricle without PH (n=509), normal right ventricle and PH (n=373), RV dysfunction without PH (n=64), and RV dysfunction and PH (n=98). A landmark analysis of early (admission to 30 days) and late (31 days to 8 years) mortality and readmission for heart failure was performed. In the first 30 days, RV dysfunction without PH was associated with a high mortality risk (adjusted hazard ratio 5.56, 95% CI 2.05–15.09, P<0.0001 compared with normal RV and no PH). In contrast, after 30 days, mortality rates among patients with RV dysfunction were increased only when PH was also present. Compared with patients having neither RV dysfunction nor PH, the adjusted hazard ratio for mortality was 1.44 (95% CI 0.68–3.04, P=0.34) in RV dysfunction without PH and 2.52 (95% CI 1.64–3.87, P<0.0001) in RV dysfunction with PH. PH with or without RV dysfunction was associated with increased risk for heart failure.

Conclusion

In the absence of elevated pulmonary pressures, the risk associated with RV dysfunction after acute myocardial infarction is entirely confined to the first 30 days. Beyond 30 days, PH is the stronger risk factor for long‐term mortality and readmission for heart failure.

ST-Segment Elevation in the Right Precordial Leads in Patients with Acute Anterior Myocardial Infarction

BACKGROUND

Elevation of ST segment in leads V3R/ V4R, which is commonly encountered in right ventricular myocardial infarction, may also occur in patients with anterior ST elevation myocardial infarction (STEMI). However, the clinical impact of this finding in the setting of anterior myocardial infarction is not well understood.

AIMS

We aimed to investigate the prognostic value of ST segment elevation in leads V3R/V4R in patients with first acute anterior myocardial infarction.

STUDY DESIGN

Prospective cohort study.

METHODS

Right precordial leads V3R/V4R were recorded in 111 patients admitted with first time anterior myocardial infarction. Patients were allocated into two groups based on the presence or absence of ST elevation in leads V3R/V4R. Demographic, biochemical and echocardiographic data, as well as the angiographic information, were recorded. In-hospital and 3 month mortality, and major adverse cardiac events (MACE), death, heart failure and ventricular dysrhythmia were also compared.

RESULTS

ST elevation in lead V3R or V4R was present in 72 out of 111 patients (64.9%). Involvement of the proximal part of the left anterior descending (LAD) artery was not different in the two groups (44.4% of patients with elevation vs. 53.8% of patients without elevation, p=0.22). Post-myocardial infarction complications, mortality and major adverse cardiac events were similar in the two groups. Left ventricular ejection fraction (LVEF) was significantly lower in patients with ST elevation in V3R/V4R (35 %±8 vs. 38 %±8, p=0.02). Twenty three out of 111 patients (20.7%) developed heart failure, which was similar in the two groups [16 (22.2%) of patients with ST elevation vs. 7 (17.9%) of patients without ST elevation, p=0.39].

CONCLUSION

Although ST elevation in V3R/V4R can be present in patients with left anterior descending artery occlusion, it does not seem to predict the prognosis. Lower left ventricular ejection fraction in this group may play a role in the long-term prognosis; however, this issue needs further investigation.

Microvascular obstruction in the right ventricle in reperfused anterior myocardial infarction. Macroscopic and pathologic evidence in a swine model

INTRODUCTION

Data on right ventricular (RV) involvement in anterior myocardial infarction are scarce. The presence of RV microvascular obstruction (MVO) in this context has not been analyzed yet. The aim of the present study was to characterize the presence of MVO in the RV in a controlled experimental swine model of reperfused anterior myocardial infarction.

MATERIALS AND METHODS

Left anterior descending (LAD) artery-perfused area (thioflavin-S staining after selective infusion in LAD artery), infarct size (lack of triphenyltetrazolium-chloride staining) and MVO (lack of thioflavin-S staining in the core of the infarcted area) in the RV were studied. A quantitative (% of the ventricular volume) and semiquantitative (number of segments involved) analysis was carried out both in the RV and LV in a 90-min left anterior descending balloon occlusion and 3-day reperfusion model in swine (n=15).

RESULTS

RV infarction and RV MVO (>1 segment) were detected in 9 (60%) and 6 (40%) cases respectively. Mean LAD-perfused area, infarct size and MVO in the RV were 33.8 ± 13%, 13.53 ± 11.7% and 3.4 ± 4.5%. Haematoxylin and eosin stains and electron microscopy of the RV-MVO areas demonstrated generalized cardiomyocyte necrosis and inflammatory infiltration along with patched hemorrhagic areas. Ex-vivo nuclear magnetic resonance (T2 sequences) microimaging of RV-MVO showed, in comparison with remote non-infarcted territories, marked hypointense zones (corresponding to necrosis, inflammation and hemorrhage) in the core of hyperintense regions (corresponding to edema).

CONCLUSIONS

In reperfused anterior myocardial infarction, MVO is frequently present in the RV. It is associated with severe histologic repercussion on the RV wall. Nuclear magnetic resonance appears as a promising technique for the noninvasive detection of this phenomenon. Further studies are warranted to evaluate the pathophysiological and clinical implications.

Right ventricular ischemic injury in patients with acute ST-segment elevation myocardial infarction: characterization with cardiovascular magnetic resonance

BACKGROUND

Experimental data show that the right ventricle (RV) is more resistant to ischemia than the left ventricle. To date, limited data are available in humans because of the difficulty of discriminating reversible from irreversible ischemic damage. We sought to characterize RV ischemic injury in patients with reperfused myocardial infarction using cardiovascular magnetic resonance.

METHODS AND RESULTS

In 3 tertiary centers, 242 consecutive patients with reperfused acute ST-segment elevation myocardial infarction were studied with cardiovascular magnetic resonance at 1 week and 4 months after myocardial infarction. T2-weighted and postcontrast cardiovascular magnetic resonance scans were used to depict myocardial edema and late gadolinium enhancement, respectively. Early after infarction, RV edema was common (51% of patients), often associated with late gadolinium enhancement (31% of patients). Remarkably, RV edema and late gadolinium enhancement were found in 33% and 12% of anterior left ventricular infarcts, respectively. Baseline regional and global RV functions were inversely related to the presence and extent of RV edema and RV late gadolinium enhancement. At follow-up, a significant decrease in frequency (25/242 patients; 10%) and extent of RV late gadolinium enhancement was observed (P<0.001). With the use of multivariable analysis, the presence of RV edema was an independent predictor of RV global function improvement during follow-up (β-coefficient=0.221, P=0.003).

CONCLUSIONS

Early postinfarction RV ischemic injury is common and is characterized by the presence of myocardial edema, late gadolinium enhancement, and functional abnormalities. RV injury is not limited to inferior infarcts but is commonly found in anterior infarcts as well. Cardiovascular magnetic resonance findings suggest reversibility of acute RV dysfunction with limited permanent myocardial damage at 4-month follow-up.

Right ventricular involvement in anterior myocardial infarction: a translational approach

AIMS

The aim of the present study was to evaluate the involvement of the right ventricle (RV) in reperfused anterior ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Left anterior descending (LAD)-perfused area (using thioflavin-S staining after selective infusion in proximal LAD artery, %), infarct size (using triphenyltetrazolium chloride staining, %), and salvaged myocardium (% of LAD-perfused area) in the right and left ventricle (LV) were quantified in a 90-min LAD occlusion 3-day reperfusion model in swine (n = 8). Additionally, we studied, using cardiovascular magnetic resonance, 20 patients with a first STEMI due to proximal LAD occlusion treated with primary angioplasty. Area at risk (T2-weighted sequence, %), infarct size (late enhancement imaging, %), and salvaged myocardium (% of area at risk) in the right and LV were quantified. In swine, a large LAD-perfused area was detected both in the right and LV (30 +/- 5 vs. 62 +/- 15%, P< 0.001) but more salvaged myocardium (94 +/- 6 vs. 73 +/- 11%, P< 0.001) resulted in a smaller right ventricular infarct size (2 +/- 1 vs. 16 +/- 5%, P< 0.001). Similarly, in patients a large area at risk was detected both in the right and LV (34 +/- 13 vs. 43 +/- 12%, P = 0.02). More salvaged myocardium (94 +/- 10 vs. 33 +/- 26%, P < 0.001) resulted in a smaller infarct size (2 +/- 3 vs. 30 +/- 16%, P< 0.001) in the RV.

CONCLUSION

In reperfused extensive anterior STEMI, a large area of the RV is at risk but the resultant infarct size is small.

High rate of right ventricular infarction after ligation of mid left anterior descending artery in rats

BACKGROUND

The left anterior descending artery (LAD) supplies the left ventricle in humans. LAD ligation has been commonly used in rats to induce left ventricular (LV) infarction for research purposes. However, the myocardial supply territories of LAD are not well established in rats. We measured the infarction zone in rats after ligation of the mid-LAD.

METHODS

Twenty-four male Sprague-Dawley rats weighing 300-350 g were selected for LAD ligation for the induction of ischemic cardiomyopathy. The surgery was performed under full anesthesia. Left-sided thoracotomy was performed through cuts in the fifth and sixth ribs. Ligation of the LAD was performed 1 to 2 mm distal to a line between the left border of the pulmonary conus and the right border of the left atrial appendage. LAD was ligated after the first diagonal and septal branches. After 24 h, the hearts were removed and stained with Tetrazolium Tetrachloride (TTC) for the detection of infracted areas.

RESULTS

Ligation of LAD induces 85% infarction of the right anterior free wall and anterior right ventricular septum and induces 100% infarction of the anterior free wall of the left ventricle and anterior septum. Infarction after LAD ligation extends all the way to the distal of the ligation site down to the apex of the heart.

CONCLUSIONS

Mid-LAD ligation after the first septal and diagonal branches causes substantial right ventricular infarction in addition to LV infarct in rats. Therefore, the hemodynamic effect of right ventricle infarct should be considered in research involving LAD ligation in rats.

Spatial distribution of right ventricular perfusion abnormalities following acute right coronary artery occlusion: a study by myocardial contrast echocardiography and blue dye staining

OBJECTIVE

Although echocardiography is used for diagnosing right ventricular (RV) infarction produced by right coronary artery (RCA) occlusion, there has been no data on the spatial distribution of RV perfusion abnormalities following acute RCA occlusion. We examined this distribution by myocardial contrast echocardiography (MCE) and blue dye staining in canine models.

METHODS

The RCA was occluded in 10 open-chest dogs. MCE was performed with 0.27 g/min Levovist infusion by harmonic power Doppler with electrocardiogram gated intermittent triggered imaging at baseline and at 90 min after RCA occlusion. The opacification defects were assessed at the basal, middle, and apical levels of the RV free wall by short-axis view. The extent of the risk area of the occluded RCA, expressed as a percentage of the RV free wall, was measured at each level by injecting blue dye at the end of the experiments. In 10 other dogs, the left anterior descending coronary artery (LAD) was occluded by ligating the proximal portion of the LAD to examine the territory of the LAD on the same levels of the RV free wall by injecting blue dye.

RESULTS

Although patchy opacification defects accompanying RV dilation were observed at the basal and middle levels during RCA occlusion, no apical defects were observed in any dogs by MCE. The risk area of the occluded RCA, as delineated by blue dye, was larger in the basal than apical level of the RV free wall in all 10 dogs (basal: 79 +/- 9%; middle: 48 +/- 14%; apical: 3 +/- 6%, p < 0.0001). The risk area of the occluded LAD (basal: 17 +/- 7%; middle: 12 +/- 6%; apical: 6 +/- 6%) was smaller than the risk area of the occluded RCA at the basal and middle levels of the RV free wall (p < 0.0001), and no significant difference was observed at the apical level.

CONCLUSIONS

RV perfusion abnormalities produced by RCA occlusion are larger in the basal than apical level of the RV free wall. This finding elucidates the spatial distribution of the territory of the RCA on the RV free wall, and may help in identifying and assessing RV ischemia by echocardiography in humans. Moreover, the data in the current study indicate that RV infarction may be produced by occlusion of the coronary arteries except RCA, because the territory of the LAD on the RV free wall is clearly delineated.