Echocardiographic features of myocardial rupture after acute myocardial infarction on emergency echocardiography

Article information

Clin Exp Emerg Med. 2023;10(4):393-399

Publication date (electronic) : 2023 June 2

doi : https://doi.org/10.15441/ceem.23.037

Byung Wook Lee, Yong Sung Cha, Sung Oh Hwang, Yoon-Seop Kim, Sun Ju Kim

Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea

Correspondence to: Yong Sung Cha Department of Emergency Medicine, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju 26426, Korea Email: emyscha@yonsei.ac.kr

Co-correspondence to: Sung Oh Hwang Department of Emergency Medicine, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju 26426, Korea Email: shwang@yonsei.ac.kr

Received 2023 March 30; Revised 2023 May 3; Accepted 2023 May 13.

Abstract

INTRODUCTION

Acute myocardial infarction (AMI) complicated by myocardial rupture is often fatal [1]. Myocardial rupture after AMI is generally reported as a subacute complication [2,3] and can occur in the early phase of AMI. If sufficient damage to the myocardium accumulates in the acute phase, myocardial rupture can occur in the early phase of AMI before or at emergency department (ED) arrival.

Clinical manifestations of myocardial rupture may differ based on the location of the injury and hemodynamic consequences. Myocardial rupture includes free wall rupture (FWR) and ventricular septal rupture (VSR), which may result in various significant hemodynamic derangements from the early phase of AMI. The incidence of myocardial rupture reported in clinical studies ranges from 0.31% to 0.45% [2–4]. However, the incidence of myocardial rupture reported on the autopsy of myocardial infarction patients is up to 30.7%, which suggests that a large proportion of myocardial rupture remains undiagnosed [5]. Due to the high mortality rate following myocardial rupture, early diagnosis and prompt surgical treatment are crucial for survival. Therefore, emergency physicians (EPs) should be aware of myocardial rupture during emergency treatment of AMI.

Most current EDs are equipped with echocardiography for immediate performance in AMI patients with suspected myocardial rupture. However, only one report has been published on the early diagnosis of myocardial rupture using echocardiography performed by EPs [6]. The purpose of this study was to investigate the echocardiographic features of myocardial rupture detected by EPs using echocardiography in the ED.

METHODS

RESULTS

Patient characteristics

A total of 7,475 consecutive patients with AMI who presented to the ED was identified during the study period, and only 87 patients had corresponding diagnostic codes. Among the 87 patients, 62 were not compatible with the diagnosis, five had uninterpretable TTE findings due to poor image quality, and five developed myocardial rupture during the hospital stay and were excluded. Finally, 15 patients were included in the analysis (Supplementary Fig. 1, Supplementary Table 1).

The mean patient age was 73.7±9.8 years, and nine patients (60.0%) were male. Hypertension was the most common comorbidity (seven patients, 46.7%), and only one patient (6.7%) had prior coronary artery disease. Three patients (20.0%) presented with AMI of Killip class IV. The anterior wall was the most common infarct location (53.3%). Four patients (26.7%) underwent surgery. The in-hospital mortality was 86.7% (Table 1).

Table 1.

Patient characteristics

Echocardiographic diagnosis of myocardial rupture by EPs

Myocardial rupture in 14 patients (93.3%) was diagnosed based on echocardiography performed by EPs. In one patient (6.7%), a diagnosis of VSR in the apical septum was missed. Types of myocardial rupture included FWR in eight patients (53.3%), VSR in five patients (33.3%), and combined rupture of FWR and VSR in two patients (13.3%) (Table 2).

Table 2.

Types of myocardial rupture (n=15)

Echocardiographic features of myocardial rupture

Diagnostic echocardiographic features were found in 100% of the patients with myocardial rupture, including pericardial effusion for FWR and a visible shunt on the interventricular septum for VSR. Additional echocardiographic features indicating myocardial rupture were thinning or aneurysmal dilatation in nine patients (60.0%), undermined myocardium in six patients (40.0%), abnormal regional wall motions in six patients (40.0%), and pericardial hematoma in six patients (40.0%) (Table 3, Fig. 1, Supplementary Table 2, Supplementary Video 1). The apical septal area was the most common site involved in myocardial rupture (Fig. 2).

Table 3.

Echocardiographic features of the patients based on the type of myocardial rupture

Fig. 1.

Echocardiographic features of myocardial rupture. (A–F) Key features. (G–R) Additional features. (B, D, F, H, J, L, N, P, R) Schematic drawings of echocardiographic images. (A, B) Pericardial effusion (PE). Parasternal long axis view shows pericardial effusion with diastolic collapse of the right ventricle (RV; arrow) indicating cardiac tamponade in a patient with free wall rupture (FWR). (C–F) Visible defect and shunt. Parasternal short axis view shows a visible defect and shunt flow on the interventricular septum (arrow) in a patient with ventricular septal rupture (VSR). (G, H) Thinning of the myocardium. Parasternal short axis view shows thinning of the interventricular septum (arrow) involved in myocardial rupture in a patient with VSR. (I, J) Aneurysmal dilation. Apical four-chamber view shows an aneurysmal dilation of the apical interventricular septum (arrow) in a patient with combined FWR and VSR. (K, L) False aneurysm. Apical two-chamber view shows undermined myocardium resulting in an aneurysm (arrow) in a patient with FWR. (M, N) Undermined myocardium. Apical long axis view shows dissection of the interventricular septum (arrow) in a patient with VSR. (O, P) Undermined myocardium. Parasternal short axis view shows undermined myocardium resulting in an ulceration (arrow) in a patient with FWR. (Q, R) Pericardial hematoma. Subcostal view shows a pericardial hematoma (arrow) in a patient with FWR. LV, left ventricle; LA, left atrium; RA, right atrium; AO, aorta.

Fig. 2.

Schematic illustrations of an anatomic location involving myocardial rupture. Diagram of left ventricular segmentations shows the anatomic location of (A) free wall rupture (FWR) and (B) ventricular septal rupture (VSR). Colors denote the number of patients. Two patients with both FWR and VSR were included. AA, apical anterior; AI, apical inferior; AL, apical lateral; AS, apical septal; BA, basal anterior; BAL, basal anterolateral; BAS, basal anteroseptal; BI, basal inferior; BIL, basal inferolateral; BIS, basal inferoseptal; MA, mid anterior; MAL, mid anterolateral; MAS, mid anteroseptal; MI, mid inferior; MIL, mid inferolateral; MIS, mid inferoseptal.

DISCUSSION

In the present study, key echocardiographic features of myocardial rupture including pericardial effusion for FWR or visible shunt on the interventricular septum for VSR as well as various additional echocardiographic features suggestive of myocardial rupture were presented. The noninflammatory process is mostly attributed to myocardial rupture during the first 24 hours after AMI, although both inflammatory and noninflammatory processes, including cardiomyocyte apoptosis or defective myocardial remodeling, can be involved in the pathogenesis of myocardial rupture [7–9]. Marked alteration of the skeletal framework and an acute change in connective tissue in the central zone of AMI may contribute to myocardial rupture [10]. The cardiac skeleton starts to collapse around the ischemic region within hours of myocardial injury from AMI.

Considering the possibility of myocardial rupture early after AMI, EPs should be aware of the potential presence of myocardial rupture when performing echocardiography in patients with AMI. For early diagnosis of myocardial rupture, echocardiography should be performed in the ED for all patients presenting with symptoms or signs of infarct extension [11]. However, EPs may miss myocardial ruptures if direct evidence is not observed because routine examination with color Doppler imaging focuses on valvular regurgitation. In the present study, diagnosis of myocardial rupture in the apical septum was missed on echocardiography. The EPs performed echocardiography, including routine examinations of color Doppler imaging on cardiac valves; however, they did not observe the affected area of myocardial rupture. This finding indicates that EPs should closely examine the possibility of mechanical complications when performing echocardiography in patients with AMI. In addition, highly prevalent areas of myocardial rupture including the anterior and inferior walls of the left ventricle, noted in the present as well as previous studies, should be closely observed during emergency echocardiographic examination [4,12,13]. In the present study, the incidence of FWR was higher than of VSR; however, in a study in which the mechanical complications during hospitalization were investigated, the incidence of VSR was higher than of FWR [14]. In the present study, the mechanical complications of myocardial infarction were investigated in the ED; in the previous studies, mechanical complications were investigated during the entire hospitalization period. The differences in incidence and pattern of mechanical complications are possibly due to the timing of identification of mechanical complications.

The present study provides detailed echocardiographic features of myocardial rupture. Key echocardiographic features of myocardial rupture were pericardial effusion for FWR and shunt flow through the interventricular septum for VSR. Additional echocardiographic findings suggestive of myocardial rupture may be accompanied by key echocardiographic features such as thinning or aneurysmal dilation of the affected myocardium; undermined myocardium, including endocardial disruption, ulceration, or dissection; and abnormal wall motions, including fluttering or impingement. Therefore, if additional echocardiographic features suggestive of myocardial rupture are observed, EPs should closely examine for myocardial rupture using color Doppler imaging to the affected area during emergency echocardiography.

The echocardiographic features observed in the present study are relatively consistent with the pathological classification of myocardial rupture, which is classified as follows. Type I is an abrupt tear in the wall without thinning; type II involves erosion of the infarcted myocardium covered by a thrombus; and type III is marked thinning of the myocardium and secondary formation of an aneurysm with a central perforation [15]. Type I myocardial rupture can be observed as a visible defect with shunt flow on echocardiography. Type II myocardial rupture can be observed as undermined myocardium including endocardial disruption or ulceration. Type III myocardial rupture is compatible with thinning or aneurysmal dilation with or without a shunt flow on echocardiography. However, autopsy findings may not match the echocardiographic features observed in vivo.

The present study has several limitations. It was a retrospective observational study conducted at a single institution with a relatively small sample size. Due to the nature of the study in which patients were retrospectively selected using ICD-10 codes, cases were possibly missed. Because the skills of an EP to perform echocardiography may vary by institution, limitations may exist in the general application of our experience to all emergency centers. Because only four of 15 patients underwent cardiac surgery due to death from in-hospital cardiac arrest or refractory shock, the relationship between the pattern of mechanical complications and prognosis was unknown. Because patients with mechanical complications undergo rapid deterioration of clinical status, the need for early diagnosis cannot be overemphasized. Autopsy on deceased patients could not be performed to confirm the diagnosis, preventing matching of the echocardiographic findings with pathological features of myocardial rupture.

In summary, the results of the present study showed that myocardial rupture, including FWR and VSR, can be observed with various findings on emergency echocardiography. EPs should be aware of the echocardiographic features suggestive of myocardial rupture for early diagnosis in the ED to help determine life-saving procedures such as pericardiocentesis or emergency cardiac surgery.

SUPPLEMENTARY MATERIAL

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