An Out of Hospital Cardiac Arrest Survivor With Presumed Embolic Myocardial Infarction: Role of Multi–modality Imaging

Abstract Background Myocardial infarction with non–obstructive coronary arteries (MINOCA) refers to a puzzling clinical entity that is characterized by symptoms suggestive of acute coronary syndrome, demonstrates troponin elevation with inconclusive coronary angiogram. The underlying pathophysiologic mechanisms include atherosclerotic cause or non–atherosclerotic causes, such as coronary dissection or coronary embolus. A standardized approach that includes multimodality imaging is necessary to determine underlying aetiology and direct appropriate treatment. Case Summary A 57–year–old male was admitted to our hospital after experiencing cardiac arrest after physical exercise (swimming) treated immediately with cardiac pulmonary resuscitation and two defibrillator–delivered electrical shocks for shockable rhythm before return of spontaneous circulation. Relevant abnormal bloods included a hs–Troponin I elevation. Invasive coronary angiography demonstrated non–obstructed coronary arteries. Subsequent cardiac magnetic resonance imaging (MRI) demonstrated akinesia and an area of subendocardic late gadolinium enhancement in the inferior–lateral wall. This pattern was in keeping with an ischaemic cause, as a recent embolic myocardial infarction. Further investigations, including contrast bubble echocardiogram, were performed in order to identify a cause and source of the embolic infarction and led to the diagnosis of tunnel–like patent foramen ovale with right to left shunting, then confirmed on trans–oesophageal echocardiogram. The patient was treated as myocardial infarction most likely due to embolic phenomena in the presence of a PFO. Therefore, a transvenous ICD was implanted for secondary prevention and the patient underwent percutaneous closure of the PFO. Discussion and Conclusion MINOCA can occur in 5–15% of all acute coronary syndromes and represents a working diagnosis. It is important to identify the underlying aetiology of their presentation to appropriately manage them. In particular, where cardiac MRI demonstraded LGE areas ichaemic patterns, myocardial infarction due to secondary embolism should be considered and the next step in clinical management is to identify potential sources of emboli performing further assessments. Multi–modality imaging with cardiac MRI and echocardiogram (transthoracic, contrast bubble and trans–oesophageal) is important in correctly identifying any source of emboli and the diagnosis of any intra–cardiac shunt.