Acute myocardial infarction in a patient with uncorrected tetralogy of Fallot accompanied by coronary artery ectasia: A case report

Abstract

A 63-year-old male with a medical history of uncorrected tetralogy of Fallot (TOF) presented to our hospital due to acute myocardial infarction (AMI). Emergency coronary angiography (CAG) was performed and it showed a severe thrombotic stenosis in the middle right coronary artery (RCA) and total thrombotic occlusion of the posterior descending branch of the RCA. Subsequently, percutaneous coronary artery intervention (PCI) under the guidance of intravascular ultrasound (IVUS) was performed. He was discharged on the 14th day in stable condition. Nine months after the PCI procedure, coronary computed tomography angiography was performed for follow-up, which revealed tetralogy of Fallot and complete resolution of the thrombus and ectasic coronary artery without stenosis. When he was 70 years old, he was transferred to our hospital because of recurrent AMI. As emergency CAG showed total thrombotic occlusion of the middle RCA, IVUS-guided PCI was performed. We experienced a very rare case of AMI in an adult patient with uncorrected TOF accompanied by coronary artery ectasia (CAE). To the best of our knowledge, this is the first case of AMI in an adult patient with uncorrected TOF accompanied by CAE.

<Learning objective: Previous studies have reported that erythrocytosis of cyanotic heart disease and coronary artery ectasia (CAE) increase the risk of acute myocardial infarction (AMI) due to coronary thrombosis. In this report, we describe a very rare AMI case in an adult patient with uncorrected tetralogy of Fallot with CAE. Erythrocytosis of　cyanotic heart disease and CAE can synergistically increase the risk of coronary thrombosis and anticoagulation therapy would be effective to prevent recurrent AMI.>

Introduction

Tetralogy of Fallot (TOF) is known well as one of cyanotic congenital heart diseases, which develop a compensatory erythrocytosis as a result of chronic hypoxemia. Previous studies have reported that erythrocytosis of cyanotic heart disease and coronary artery ectasia (CAE) heighten blood viscosity and activate coagulation, eventually increasing the risk of acute myocardial infarction (AMI) due to coronary thrombosis, regardless of the absence of coronary stenosis or atrial fibrillation [1], [2], [3], [4], [5]. In this case study, we report a very rare case of AMI in an adult patient with uncorrected TOF accompanied by CAE.

Case report

A 63-year-old male with a medical history of uncorrected TOF presented to our hospital with chest pain. His electrocardiogram (ECG) revealed sinus rhythm and an ST-segment elevation of 0.2 mV in the inferior leads (Fig. 1A). A presumptive diagnosis was AMI based on his symptoms and ECG findings, and coronary angiography (CAG) was performed. The CAG showed a severe thrombotic stenosis in the middle right coronary artery (RCA), total thrombotic occlusion of the posterior descending branch of the RCA (Fig. 2A, B), and sluggish coronary blood flow due to the ectasic RCA. Subsequently, percutaneous coronary artery intervention (PCI) under the guidance of intravascular ultrasound (IVUS) was conducted. After advancing guidewire, IVUS examination was performed and it revealed the heavy thrombus burden without plaque in the culprit lesion of the ectasic RCA. Repetitive thrombectomy and balloon dilation were performed. However, the lesions were resistant to repetitive thrombectomy, and the coronary blood flow was partially restored to Thrombolysis in Myocardial Infarction grade (TIMI) 2 flow (Fig. 2C, D).

Fig. 1.

Electrocardiography (ECG). ECG at the first acute myocardial infarction (AMI) event (A), ECG at 8 months after the discharge of first AMI event (B), ECG at the second AMI event (C).

Fig. 2.

Images of CAG at the first and second times of acute myocardial infarction. Images of diagnostic CAG showing a thrombotic severe stenosis (arrow) of middle RCA and total thrombotic occlusion of posterior descending branch (arrow head) in LAO view (A) and cranial view (B). Images of CAG after percutaneous coronary intervention in LAO view (A’) and cranial view (B’). There was still an obstructive filling defect of the posterior descending branch (arrow head). Images of diagnostic CAG showing a total thrombotic occlusion of the middle RCA (arrow) in LAO view (C) and LAO-CRA view (D). Images of CAG after percutaneous coronary intervention in LAO view (C’) and LAO-CRA view (D’), arrow head shows the embolized thrombus.

CAG, coronary angiography; RCA, right coronary artery; LAO, left anterior oblique; LAO-CRA, left anterior oblique-cranial.

Consequently, the patient received continuous intravenous infusion of heparin over 48 hours, and the activated partial thromboplastin time was maintained at twice the baseline level. After the continuous intravenous infusion of heparin, anticoagulation therapy with warfarin was started. The peak serum creatine kinase (CK) level was 2121 U/L, and echocardiography that was performed before discharge revealed the following: left ventricular ejection fraction (LVEF), 55%, bilateral shunt through the ventricular septal defect (VSD), pulmonary to systemic blood flow ratio (Qp/Qs): 1.18, peak velocity across right ventricular outflow tract (RVOT): 1.3 m/sec, peak pressure gradient (PPG) of RVOT: 7.8 mmHg. On the 14th day, he was discharged in a stable condition.

Nine months after the PCI procedure, coronary computed tomography angiography (CCTA) revealed tetralogy of Fallot (Fig. 3A–C), complete resolution of the thrombus in the posterior descending branch, and ectasic coronary artery without stenosis (Fig. 3D, E).

Fig. 3.

Images of coronary CT angiogram performed 9 months after percutaneous coronary intervention. CT images showing overriding aortic root and VSD (asterisk) (A), VSD (asterisk) and right ventricular hypertrophy (arrow head) (B), enlargement of RA and RV, and stenosis of the right ventricular outflow tract (C). CT image revealing ectasic left coronary artery (D) and right coronary artery (E). Dotted line shows the complete resolution of thrombus and the recanalized posterior descending branch.

CT, computed tomography; VSD, ventricular septal defect; Ao, aorta; RV, right ventricle; LV, left ventricle; LA, left atrium; RA, right atrium; PA, pulmonary artery.

When he was 70 years old, he discontinued warfarin therapy for a few days because of abdominal distension and pain. A few days later of the discontinuation of warfarin therapy, he had chest pain and was transferred to our hospital. His blood tests at admission revealed the following: hemoglobin: 21.1 g/dl, red blood cells: 639 × 10⁴ /μl, hematocrit value: 61.3%, white blood cells: 63 × 10² /μl, platelets: 17.1 × 10⁴ /μl, d-dimer: 0.8 μg, CK: 283 U/l, aspartate aminotransferase: 72U/l, alanine aminotransferase: 56U/l, lactate dehydrogenase: 267 U/l, prothrombin time-international normalized ratio: 1.39. Arterial blood gas analysis under 2 L/min oxygen inhalation showed the following: pH: 7.36, PaO²: 66.2 mmHg, PaCO²: 34.4 mmHg, and HCO³: 19.4 mmol/L, SO²: 92.7%. His ECG showed sinus rhythm and an ST-segment elevation of 0.2 mV in the inferior leads (Fig. 1C), and he was diagnosed with recurrent AMI from his symptoms and test findings. As emergency CAG showed total thrombotic occlusion of the middle RCA (Fig. 2A’, B’), IVUS-guided PCI was performed and TIMI2 coronary flow was finally achieved (Fig. 2C’, D’). After the procedure, the anticoagulation therapy with warfarin was restarted. He was discharged on the 14th day in stable condition without any complications. Echocardiography that was performed 2 months after the discharge of second AMI event showed LVEF of 45%, bilateral shunt through the VSD, Qp/Qs of 1.0, peak velocity across RVOT of 3.4 m/sec, PPG of RVOT of 46 mmHg,　and asynergy of right ventricular wall motion.

Discussion

To the best of our knowledge, this is the first case to report AMI in a patient with uncorrected TOF accompanied by CAE.

TOF was firstly reported in 1888 by French physician, Etienne-Louis Arthur Fallot, and is a cyanotic malformation characterized by stenosis of RVOT, VSD, overriding aortic root, and right ventricular hypertrophy. Bertranou et al. reported low survival rates of patients with uncorrected TOF (11% at 20 years, 6% at 30 years, and 3% at 40 years) [6]. However, this patient has lived into his sixth decade without intracardiac repair for TOF. Previous studies have reported that uncorrected TOF survivors tend to have a lesser degree of RVOT obstruction, leading to a well-balanced bidirectional shunt or acyanotic left-to-right shunt, a hypoplastic pulmonary artery, left ventricular hypertrophy, or systemic-pulmonary artery collateral [7], [8]. In this case, a lesser degree of RVOT obstruction (peak velocity across RVOT 1.3 m/sec, PPG of RVOT: 7.8 mmHg), a bidirectional shunt through the VSD, and well-developed pulmonary artery collateral vessels were observed, which presumably contributed to his longevity without intracardiac repair for TOF. After the first AMI event, intracardiac repair of TOF was not considered, because his Qp/Qs ratio was 1.18 and he still had the ability to perform daily activities with awareness of only mild dyspnea.

Izawa at al. reported an AMI case with uncorrected TOF and that had a critical increase in right-to-left shunt in the period after AMI [2]. In our case, echocardiography after the second AMI event showed an increase in right-to-left shunt and a decrease in Qp/Qs ratio as compared with after the first AMI event (from 1.18 to 1.0), the same as in Izawa’s report [2]. Dabizzi et al. reported that 36% of TOF cases were associated with anomalies in coronary course or/and distribution, and sometimes had enlarged conus branch or aberrant vessel crossing over the RVOT [9]. Another previous study has reported that the ventricular hypertrophy increased myocardial oxygen demand and that might have caused the enlargement of coronary artery in order to supply appropriate coronary blood flow to the hypertrophied myocardium [10]. In this case, CAE of the RCA was confirmed, and reactive right ventricular hypertrophy was the most likely cause related to the CAE of the RCA.

There are various mechanisms related to AMI, including thromboembolism derived from left atrial appendage, paradoxical embolism, abnormal coagulation system, and abnormal coronary flow. In this case, the possible mechanisms that related to two AMI events were the following: First, thromboembolism derived from left atrial appendage due to atrial fibrillation (AF). Second, paradoxical embolism caused by deep-vein thrombosis (DVT). Third, local thrombus that formed in the ectasic coronary artery due to sluggish coronary flow. However, this patient did not have history of AF and DVT. Moreover, there was no physical and test finding suggesting AF and DVT; ECG showed sinus rhythm, echocardiography did not reveal thrombus in the left and right ventricles, the d-dimer values that measured at the onset days of two AMI events were within normal range. From these findings, we considered that ectasic coronary artery was the most likely source of thrombus formation in this case.

In the setting of adult patients with cyanotic congenital heart disease, compensatory erythrocytosis can be a risk for thrombus formation due to increased blood viscosity [1]. Previous studies have reported sluggish flow of CAE sometimes causes thrombus formation and induces AMI [3], [4], [5]. In addition to the compensatory erythrocytosis, CAE of the RCA was confirmed in this case. compensatory erythrocytosis and CAE might have caused the elevation of blood viscosity and subsequently activated coagulation, synergistically increased the risk of coronary thrombosis, and finally induced AMI caused by the coronary thrombus.

PCI for AMI case with CAE would be challenging because of high-burden thrombus and large vessel size, and that is associated with high risk of adverse events. In this case, since we could not obtain a TIMI grade 3 flow after PCI because of high-burden thrombus, anticoagulation therapy was performed. Follow-up CCTA at 9 months revealed complete resolution of the thrombus without stenosis. Moreover, this patient developed recurrent AMI after discontinuation of warfarin therapy. Therefore, anticoagulation therapy would be effective to resolve residual thrombus after PCI and prevent AMI events. We experienced a very rare case of AMI in a patient with uncorrected TOF accompanied by CAE. Erythrocytosis of cyanotic heart disease and CAE might synergistically increase the risk of coronary thrombosis, and anticoagulation therapy would be effective to resolve residual thrombus after PCI and to prevent AMI events.

Conflict of interest

The authors declare that there is no conflict of interest.