ABC | Volume 115, Nº1, Suplement, July 2020

Case Report A Complicated “One Segment” Myocardial Infarction: The Role of Cardiovascular Imaging Ana Rita Pereira, 1 Ana Rita Almeida, 1 Inês Cruz, 1 Luis Rocha Lopes, 2,3, 4 Maria José Loureiro, 1 Hélder Pereira 1,4 Cardiology Department, Hospital Garcia de Orta EPE, 1 Almada - Portugal Barts Heart Centre, Barts Health NHS Trust, 2 London - England Institute of Cardiovascular Science, University College London, 3 London - England Cardiovascular Center, Lisbon Academic Medical Center, University of Lisbon, 4 Lisbon - Portugal Introduction The incidence of mechanical complications (MC) after myocardial infarction (MI) was reduced to less than 1% with the routine use of primary reperfusion therapies. 1 MC are classified as early, including acute and subacute forms, and late or chronic. 2 The former mostly present as cardiogenic shock 2 and the latter may vary from asymptomatic to sudden death. 3 As all of these conditions may have potentially lethal consequences, timely diagnosis and treatment is necessary. 1-3 Case Report A 57-year-old woman with smoking habits was admitted to the Emergency Department with oppressive anterior chest pain, nausea, and vomiting. Four days earlier, the patient reported similar symptoms with hours of evolution but spontaneous relief. Upon admission, she was conscious and maintained chest pain. Medical examination revealed hypotension, tachycardia, polypnea, and signs of decreased peripheral perfusion. A 12-lead electrocardiogram showed sinus tachycardia with a 4 mm ST-segment elevation in DI and aVL leads, and a 4 mm ST-segment depression in inferior leads. Additional work-up revealed lactic acidosis, elevated systemic inflammatory parameters, and increased myocardial necrosis markers. Transthoracic echocardiogram (TTE) demonstrated a hypertrophic and non-dilated left ventricle with lateral hypokinesia, but with preserved systolic function; a moderate pericardial effusion with partial diastolic collapse of the right cavities; and a dilated inferior vena cava without respiratory variation (Figure 1; Video 1). There were no significant valvular findings and the aortic root and arch were normal. Due to suspicion of subacute ST-elevation myocardial infarction (STEMI) complicated by left ventricular (LV) free wall rupture (FWR), no anti-thrombotic medication was administered, and the patient was submitted to an invasive coronary angiography (ICA) and ventriculography (Video 2). A 90% stenosis of the posterolateral branch was observed, although apparently no occlusive lesion, ventricular rupture or segmental wall motion abnormalities were found. After angiography, her clinical status worsened. Cardiac tamponade was admitted and an emergency percutaneous pericardiocentesis was performed with drainage of 200 mL of hematic fluid with no spontaneous coagulation, resulting in global improvement (Figure 2). Fluid analysis revealed an exudate and normal adenosine deaminase. Microbiological analyses were negative and the cytological test did not reveal neoplastic cells. In order to determine the effusion aetiology, viral serologies, autoimmunity, and thoracoabdominal-pelvic computed tomography were also performed with normal results. Given the absence of a specific diagnosis, a cardiac magnetic resonance imaging (CMR) was performed eight days after hospital admission. It revealed dyskinesia of the mid-segment of the lateral wall in the cine sequences, transmural hyperintense sign in the T2-weighted short-tau inversion recovery images (Figure 3A and 3B) — compatible with oedema — and late transmural enhancement (Figure 3C and 3D) — suggesting myocardial necrosis — of this segment. These findings were compatible with subacute MI of the mid-segment of the lateral wall with no apparent viability. Moreover, the absence of myocardial tissue between the mid- segments of the lateral and inferolateral walls was observed, surrounded by a small saccular protuberance with a narrow neck, suggesting a pseudoaneurysm at that location (Figure 3E and 3F; Video 3). Thus, the initially suspected diagnosis was confirmed: subacute STEMI complicated with LV FWR that evolved to cardiac tamponade and posteriorly to a pseudoaneurysm formation. Due to the risk of fatal complications, the patient was submitted to cardiac surgery. With no need for cardiopulmonary bypass, a coronary artery bypass grafting with saphenous vein graph to the posterolateral artery and a pseudoaneurysm plication were performed. Currently, she is asymptomatic. Discussion FWR is an uncommon and early MC of MI, with a reported incidence of less than 1%. 2 There are two clinical groups: the “blow-out type” (complete or acute rupture) with a macroscopic defect and high-volume bleeding, leading to cardiac tamponade; and the “oozing type” (incomplete or subacute rupture) without an obvious bleeding source and Mailing Address: Ana Rita F. Pereira • Hospital Garcia de Orta EPE – Cardiologia - Avenida Torrado da Silva Almada, 2805-267 – Portugal E-mail: pereira.anaritaf@gmail.com Manuscript received May 17, 2019, revised manuscript September 16, 2019, accepted October 23, 2019 Keywords Heart Rupture; Myocardial Infarction; Aneurysm,False; Diagnostic, Imaging; Echocardiography/methods. DOI: https://doi.org/10.36660/abc.20190323 25