Paradoxical embolism in acute myocardial infarction in a patient with congenital heart disease.

We present a case of a young male with severe pulmonary stenosis, hypoplastic right ventricle, and atrial septal defect. Acute embolic myocardial infarction, followed by cardiac arrest, occurred during hospitalization after Glenn operation. The therapeutic challenges are discussed. Insufficient anticoagulation therapy during the postoperative period was a possible contributing factor leading to embolic myocardial infarction.

INTRODUCTION

Paradoxical embolism causing acute myocardial infarction (AMI) in the setting of patent foramen ovale (PFO) or atrial septal defect (ASD) has been rarely reported.[1-4] The present report describes a case of AMI due to paradoxical embolism in a patient with ASD. This may be related to the presence of intracardiac right to left shunt in the context of hypercoagulable state. Coronary thrombus aspiration was a feasible and an ef fective strategy for the treatment. The presentation also emphasizes the importance of adequate anticoagulation therapy during perioperative period in patients with PFO/ASD and hypercoagulable state.

CASE REPORT

A 16-year-old male known to have congenital heart disease was admitted with dyspnea on exertion (New York Heart Association class II). At 5 months of age, he was diagnosed to have pulmonary stenosis, hypoplastic right ventricle, and ASD. The patient was lost to follow up. At age 15, the patient underwent successful balloon valvuloplasty to pulmonary valve. The peak gradient across pulmonary valve dropped from 100 to 20 mmHg.

On examination, he was cyanosed. He had grade III finger clubbing and elevated jugular venous pressure. Cardiac examination was unremarkable. His oxygen saturation was at 80% on room air. Hemoglobin was 24.1 g/dl and hematocrit was 81%. Electrocardiogram (ECG) showed a sinus rhythm and right bundle branch block [Figure 1a]. Echocardiography showed mild pulmonary stenosis, severe right ventricular hypertrophy, and ASD with right to left atrial shunt [Figure 2].

Figure 1

(a) A baseline electrocardiogram that showed sinus rhythm and right bundle branch block, (b) electrocardiogram immediately after cardiac arrest showed ST segment elevation in the inferior leads and multiple premature atrial beats

Figure 2

An echocardiography that demonstrated atrial septal defect (upper), right to left shunt (arrow) and small severely hypertrophied right ventricle (lower)

Because of persistent symptoms, cyanosis, and right to left atrial shunt, the patient underwent Glenn operation and partial closure of the ASD. Immediate postoperative period was uneventful. The patient was maintained on aspirin 81 mg daily. Two weeks after surgery, while using the incentive spirometry, the patient suddenly collapsed, developed ventricular fibrillation, and required two direct current (DC) shocks. Subsequent ECG showedST-segment elevation in the inferior leads [Figure 1b]. The patient was taken to catheterization laboratory where a total occlusion of the left circumflex coronary artery was treated with thrombus aspiration using Export catheter (Medtronic, Minneapolis, MN, USA). The coronary flow was restored at TIMI flow 3 [Figure 3] with no further stenting. The patient was then maintained on glycoprotein IIB/IIIA inhibitor (Abciximab®) and heparin infusions for 12 hours. Afterwards, he was maintained on oral anticoagulation with warfarin. Few months later, he underwent elective device closure of the ASD/PFO [Figure 4] that resulted in substantial improvement in his symptoms.

Figure 3

(a) Invasive coronary angiography that demonstrated total occlusion of the left circumflex coronary artery with filling defect suggestive of thrombus, (b) the TIMI 3 flow was restored after repeated aspirations of the thrombus

Figure 4

(a), An echocardiography that demonstrated atrial septal defect with right to left shunt, (b) three dimensional echocardiography during device deployment (c and d) echocardiography few days after device deployment where atrial septal device was in place with no residual shunt

DISCUSSION

Paradoxical embolism due to a PFO or an ASD resulting in AMI has been reported in the literature[1-6] but is rarely considered in clinical practice. Coronary embolism should always be suspected in the context of sudden chest pain in patients with valvular prosthesis, chronic atrial fibrillation, dilated cardiomyopathy, infective endocarditis, intracardiac shunts, cardiac myxoma, mural thrombi, and hypercoagulable states.[7-10]

The standard treatment for coronary embolism with ST elevation AMI remains uncertain. However, thrombolysis, percutaneous transluminal coronary angioplasty, and thrombus aspiration have been frequently used.[11-13] Thrombolysis has been associated with distal embolization causing complete obstruction in smaller branches.[12-14] Furthermore, if the source of the embolus is infected vegetation, thrombolysis might be contraindicated. Percutaneous transluminal coronary angioplasty and stenting have been used in some cases with coronary embolism and consequent AMI.[15] Successful catheter aspiration embolectomy has been described by some authors.[91516]

In our patient with recent surgery, thrombolysis was deferred due to substantial risk of bleeding. Therefore, cardiac catheterization with intention of primary intervention was performed. Catheter aspiration embolectomy for the intracoronary thrombus was found very effective precluding the need for stenting. Anticoagulation with heparin and intravenous glycoprotein IIB/IIIA inhibitors was also used to reduce the risk of further embolism.