Just another acute myocardial infarction?

Abstract

Introduction: Acute Myocardial Infarction in young people can be challenging to manage, as the underlying pathology can be different to the conventional atherosclerosis with plaque rupture. Case Description: A 36-year old man presented with sudden onset central chest pain and diaphoresis. Apart from smoking he did not have other risk factors for coronary disease. One week prior he underwent elective hip replacement and had been treated with prophylactic clexane to prevent venous thromboembolism. He was on no other regular prescribed or recreational medication. The EKG showed changes consistent with an inferoposterior STEMI. Emergency angiography revealed an occluded left circumflex with heavy thrombus burden. Following prolific thrombus aspiration TIMI 3 flow was restored, the patient became pain-free and the EKG started to normalize. The circumflex artery appeared smooth with no evidence of plaque rupture. An embolic cause was suspected and given that the patient was pain-free he was managed medically with aspirin, clopidogrel, beta-blockers and ace inhibitors and planned to re-study him in 48 hours. Bilateral lower limb ultrasound and CT pulmonary angiography did not reveal deep vein thrombosis or pulmonary embolus. Transthoracic bubble echocardiography revealed right to left shunting on valsava manoevre consistent with a PFO, also visualized on 3D transesophageal echocardiography. At coronary angiography 48 hours later, the circumflex coronary remained smooth with no evidence of further obstruction thus no stent insertion was needed. Histology of the thrombus confirmed a platelet thrombus forming on a foreign plastic material that was likely part of an intravenous cannula. It is likely that the plastic entered the circumflex at the time of orthopedic surgery and acted as nidus for thrombus formation. He has since underwent successful percutaneous closure of his PFO. Discussion: Paradoxical coronary embolism is a rare but recognized clinical entity. It requires a high index of suspicion for diagnosis and should always be considered in young patients presenting with acute myocardial infarction and no obvious coronary lesion as its correct identification can guide appropriate management and preclude inappropriate stent implantation. Implications to clinical practice: 1. Always beware of paradoxical embolism in young patients presenting with a STEMI, particularly if coronary arteries appear smooth. 2. Always be meticulous when inserting intravenous cannulae. Avoid needle re-insertion as this increases the risk of the cannula breaking off and embolizing with adverse outcomes as exemplified in our case.