ABC | Volume 112, Nº6, June 2019

Case Report Extensive Anterior Myocardial Infarction ... and Something Else? Andrés Ricardo Pérez Riera, 1 Raimundo Barbosa Barros, 2 Antônio Fernandes Silva e Sousa Neto, 2 Rodrigo Daminello Raimundo, 1 L uiz Carlos de Abreu, 1 Kjell Nikus 3 Faculdade de Medicina do ABC, 1 Santo André, SP – Brazil Hospital Dr. Carlos Alberto Studart Gomes, 2 Messejana, CE – Brazil University of Tampere, 3 Tampere – Finland Mailing Address: Andrés Ricardo Pérez Riera • R. Nicolau Barreto, 258. Postal Code 04583-000, Vila Cordeiro, São Paulo, SP – Brazil E-mail: riera@uol.com.br , arperezriera@gmail.com Manuscript received May 07, 2018, revised manuscript September 20, 2018, accepted October 02, 2018 Keywords Myocardial Infarction/physiopathology; P Wave; Diagnosis Imaging; Arrhythmias, Cardiac; Risk Factors; Percutaneous Coronary Intervention; Drug-Eluting Stents DOI: 10.5935/abc.20190096 Case report A 64-year-old Caucasian female, with a one-week history of stress angina. She was admitted to the hospital 2 hours after the onset of oppressive retrosternal pain at rest. Risk factors: hypertension, smoker, dyslipidemia and diabetes. Figure 1 shows electrocardiography/vectorcardiography (ECG/VCG) at admission. Echo: Ventricular and atrial chambers of normal size (left atrial (LA) size: 30 mm); mild to moderate reduction of left ventricular ejection fraction = 41% by anterior akinesia. The percutaneous coronary intervention was indicated, and two drug-eluting stents were implanted. Introduction Atrial infarction (AI) is rarely diagnosed before death because of its characteristically subtle and nonspecific ECG findings. AI occurs in 0.7 to 52% of ST-elevation myocardial infarctions. Its incidence in autopsy has been widely variable, from 0.7 to 42%, with a large series of 182 patients demonstrating an incidence of 17%. 1 Ischemic damage to the atrial myocardium is usually associated with infarction of cardiac ventricles, but isolated AI can occur. 2 AI ECG patterns The ECG patterns of AI are generally subtle because of the thinner atrial walls and their inability to generate enough voltage to be appreciated on the ECG. This atrial voltage is also often eclipsed by the depolarization of the larger ventricles. Although several AI ECG patterns have been described, none have been validated by prospective studies. The first description of “infarctus auricularis” was made 93 years ago by Cler. 3 Twenty-two years later, Langendorf reported one case of AI found at autopsy that in retrospect could have been recognized antemortem from ECG changes. 4 Hellerstein reported the first case with the correct antemortem diagnosis of AI confirmed by necropsy. 5 There are other potential causes for P wave morphologic abnormalities and PR-segment displacements besides AI. Sympathetic overstimulation, pericarditis, atrial enlargement, and interatrial blocks have been described. 6 Pronounced sympathetic activity produces a descending PR-segment, depressed J point and ascending ST segment with the PR and ST segments having concordant deviations. Pericarditis can cause ECG changes if the inflammation involves the epicardium or the visceral pericardium as the parietal pericardium is electrically inert. Accepted ECG criteria of AI are those proposed by Liu et. Al.: 7 a) Major: • PR-segment elevation > 0.5 mm in leads V 3 and V 6 with reciprocal depression in leads V 1 and V 2 of small amplitude; • PR-segment elevation > 0.5 mm in lead I with reciprocal depressions in II-III; • PR segment depression of >1.5 mm in precordial leads with 1.2 mm depressions in I, II and II, associated with atrial arrhythmia. b) Minor: • P wave with M-shaped, W-shaped, or notched; depression of the PR segment of small amplitude without elevation of this segment in other leads cannot be regarded by itself as positive evidence of AI. • Patients having an acute myocardial infarction with any form of supraventricular arrhythmias, such as atrial fibrillation, atrial flutter, atrial tachycardia, wandering atrial pacemaker and atrioventricular blocks. 8 Regarding the location of AI, the literature evidence is limited and often conflicting. The right atrium (RA) is involved five times as often as the LA. 1 Main complications of AI are: supraventricular arrhythmias, atrial rupture, cardiogenic shock and thromboembolic phenomena in the brain or lungs. Diagnosis currently is made in an appropriate clinical setting with characteristic P-wave shape, eventually the Bayés´s syndrome (complete interatrial block in the Bachman region associated with supraventricular arrhythmias). 9 Theoretically, PR-segment displacements should correlate to the location of the AI in the same manner as ST-segment displacements in ventricular infarction. Thus, involvement of the laterobasal (formerly dorsal) wall, which corresponds to the LA, will result in PR-segment elevation in leads II and III with reciprocal depression in lead I. 5 Likewise, involvement of the anterior 803