ABC | Volume 113, Nº4, October 2019

Anatomopathological Correlation Martins et al. Cardiac failure after non-ST-elevation myocardial infarction Arq Bras Cardiol. 2019; 113(4):775-782 Figure 3 – Chest X-ray: massive bilateral pleural effusion and cardiomegaly. right ventricular dilation, a significant enlargement of the left atrium and an absence of changes in the right atrium. Regarding the enhancement, the patient presented late transmural, circumferential multifocal enhancement, with subendocardial involvement sparing the apex. There was no pericardial effusion, but there was massive bilateral pleural effusion. During hospitalization, the patient developed pulmonary focal sepsis, with an initial improvement after the introduction of an antimicrobial regimen. Due to the need for infectious treatment, the team decided to postpone endomyocardial biopsy. Despite the improvement of infectious parameters, there was a worsening in renal function and hemodynamic instability. During the entire hospitalization period, the patient maintained a borderline respiratory pattern requiring noninvasive ventilation and right hemithorax drainage to control respiratory symptoms with serohematic secretion drainage. The patient evolved with pulseless electrical activity, reversed after resuscitation for 15 minutes. However, the patient evolved with a refractory shock, which led the patient to die 12 hours after cardiopulmonary arrest. Due to the diagnostic doubts concerning the case and a lack of improvement after the selected therapy to control the condition, the patient was referred for autopsy with the intention of elucidating the case. Regarding the clinical evaluationof the case, themaindiagnostic hypotheses raisedweremyocardial infarction andmyocarditis, due to the clinical presentation of acute onset heart failure with left ventricular dysfunction. The changes foundonmagnetic resonance imaging, although not typical, reinforced the maintenance of the initial hypotheses. We describe below information about the two clinical entities evaluated in this clinical case. According to the fourth universal definition of MI, it consists in an increase in troponin above the 99% associated with at least one of the other factors (typical ischemic symptoms and/or new ECG abnormalities and/or imaging showing a myocardial loss with a pattern of coronary ischemia and/or thrombosis evidenced during the catheterization or autopsy). 1 Myocardial injury does not include the changes described above and can occur in very common events in practice such as: decompensated heart failure, chronic renal failure, shock, anemia, stroke, myocarditis, Takotsubo cardiomyopathy, among others. 1 Among the five types of AMI, type 2 occurs in the presence of an imbalance between oxygen supply and demand, in the absence of atherosclerotic plaque complications. The threshold for this imbalance to occur varies between individuals and is influenced by ongoing stressors, comorbidities (including cardiac and noncardiac), and pre-existing coronary disease. 1 The mechanisms that influence the aforementioned imbalance are diverse and may occur concomitantly, besides being related to atherosclerosis with a reduction of myocardial perfusion and without plaque rupture, coronary spasm, microvascular dysfunction, coronary embolism, coronary dissection, tachyarrhythmias, bradyarrhythmias, hypoxemia, significant anemia, shock. 1 The prevalence of type 2 AMI is variable in the studies and depends on the type of criteria used. 1 In a real-life study conducted in Sweden with 20,138 patients, 7.1% of AMI hospitalizations were type 2. Patients in this group were older, predominantly female, and had more comorbidities, especially heart failure and atrial fibrillation. 2 In a 2016 study, the main causes of type 2 AMI were - tachyarrhythmias in 36.7%; aortic stenosis in 14.5% and heart failure in 13.7%. 3 Another study observed that approximately 50% of the patients with type 2 AMI had no significant coronary disease. 4 Regarding the initial evaluation of these patients, the most common symptom presented was dyspnea. 3 In addition, ST segment elevation is known to occur in 3-24% of cases. Coronary atherosclerosis is a common angiographic finding among these patients and, in general, they have a worse prognosis. 1 Please note that angiography is not necessary to establish the diagnosis of type 2 infarction. 1 The long-term consequences of type 2 AMI are poorly understood. A study published in 2018 evaluated and 777