Acute myocardial infarction in a patient positive for lupus anticoagulant: a case report

Background Autoimmune diseases, such as systemic lupus erythematosus (SLE), are associated with thrombosis and atherosclerosis. Presence of lupus anticoagulant is an independent risk factor for atherosclerotic diseases. Case presentation A 56-year-old man with past history of hypertension, and cerebral infarction was admitted to our hospital owing to acute chest pain. He was diagnosed with acute myocardial infarction based on his symptoms and electrocardiogram results, which demonstrated ST elevation in the precordial leads. Coronary angiography images revealed total occlusion at the proximal site of the left anterior descending artery. A drug-eluting stent was deployed, which successfully recovered coronary blood flow. The patient had fever of unknown cause when he was 30 years old; on admission, he presented with a low-grade fever and reddish exanthema affecting both cheeks. Based on his physical signs as well as elevated antinuclear antibodies (anti-double-stranded DNA), decreased lymphocytes, and a positive direct Coombs test, he was diagnosed with SLE. Owing to a positive lupus anticoagulant test, he was also suspected to have antiphospholipid syndrome (APS). Triple antithrombotic therapy, including dual antiplatelet therapy with aspirin and clopidogrel during coronary stenting and single anticoagulation therapy with warfarin, was initiated. Conclusions Careful diagnosis of autoimmune diseases should be performed in patients with thrombosis and atherosclerosis. Moreover, risk factors for coronary artery disease should be strictly controlled in patients with APS.


Background
Antiphospholipid syndrome (APS) is an important cause of acquired thrombophilia and recurrent miscarriages [1]. Venous and arterial thromboses are the common symptoms of APS; however, APS reportedly causes atherosclerotic cardiovascular diseases [2,3]. Here, we report a case of acute myocardial infarction caused by coronary artery stenosis and thrombosis with lupus anticoagulant.

Case presentation
A 56-year-old Japanese man was admitted to our hospital owing to complaints of acute chest pain. At the age of 30 years, he had fever and hypersensitivity to sunlight; the causes of which were undetermined. He was diagnosed with hypertension during his 30s and was treated with antihypertensive drugs. Despite having well-controlled blood pressure levels, he experienced cerebral infarction at the age of 54 years; subsequently, antiplatelet therapy was initiated with 75 mg/day of clopidogrel.
On admission, the patient's blood pressure level and heart rate were 126/70 mmHg and 80 bpm, respectively, and he had reddish exanthema on both cheeks (Fig. 1). His physical examination did not reveal any other abnormal findings. Although chest X-ray images did not reveal any significant finding, electrocardiograms exhibited prominent ST elevation in the precordial leads, thereby suggesting acute anteroseptal myocardial infarction (Fig. 2). Results of laboratory analyses revealed elevated levels of cardiac enzymes, such as creatine kinase (1511 IU/L), troponin T (1.400 ng/mL), and lactate dehydrogenase (454 IU/L). Conversely, cardiovascular risk factors, such as total cholesterol (162 mg/dL), low-density lipoprotein cholesterol (95 mg/dL), and hemoglobin A1c (6.5%), were desirable for the primary prevention of coronary heart disease. The patient had no history of diabetes mellitus or dyslipidemia; further, he was a current smoker, although the frequency was low (two cigarettes per day for the past 30 years), and was underweight (body mass index, 17.9 kg/m 2 ).
Results of emergency coronary angiography revealed abrupt and total occlusion of the left anterior descending artery (LAD) (Fig. 3, left). Access using a guide wire resulted in partial recanalization of the occluded site (Fig. 3, right). The morphology of the lumen and vessel wall was observed by performing intravascular ultrasound (IVUS) and optical coherence tomography (OCT). IVUS images revealed an extremely large thrombus at the occlusive site ( Fig. 4a-1) and an atherosclerotic plaque with calcification proximal to the occlusive site (Fig. 4b). OCT images revealed that the thrombus exhibited strong signal attenuation and obscured underlying vascular structures, suggesting that it was a red thrombus mostly comprising red blood cells ( Fig. 4a-2). Interestingly, there was no distinct evidence of a ruptured plaque. Following balloon dilatation, a drugeluting stent was successfully deployed, which completely recovered coronary blood flow in LAD.
The maximum creatine kinase level that contributed to apical cardiac aneurysm formation was 6381 IU/L. On hospital day 9, anticoagulation therapy with warfarin was initiated to prevent the formation of a left ventricular thrombus. Accordingly, triple antithrombotic therapy was initiated, which included dual antiplatelet therapy with aspirin and clopidogrel during coronary stenting and single anticoagulation therapy with warfarin.
Interestingly, the patient had a low-grade fever since admission but no evidence of infection. Based on the rashes on his cheeks, coexistence of a connective tissue disease was suspected. Additional laboratory tests demonstrated elevated levels of antinuclear antibodies (titer, 1/1280) and anti-double-stranded DNA antibodies (22 IU/mL). Furthermore, the lymphocyte count was low (550 cells/μL) and direct Coombs test result was positive. Based on these findings, the patient was diagnosed with systemic lupus erythematosus (SLE). In addition, the patient was positive for lupus anticoagulant, although a definitive diagnosis of APS requires consistently positive antiphospholipid antibody test results after > 12 weeks. Triple antithrombotic therapy was

Discussion and conclusions
Atherosclerosis and systemic thrombosis may occur as a result of various risk factors, including hypertension, diabetes mellitus, dyslipidemia, and smoking; in addition, autoimmune diseases have been associated with the development of atherosclerotic diseases and systemic thrombosis [4]. Our patient had a history of hypertension and smoking and experienced myocardial infarction, and this could be regarded as a typical clinical course. However, he also exhibited clinical signs of SLE; therefore, we conducted tests to detect lupus anticoagulant, anticardiolipin antibody, and anti-CLGPI, which are the criteria for APS. Ando et al. reported that 0.31 and 0.37% of patients with ST-elevated and non-ST-elevated myocardial infarction, respectively, had SLE [5]. Conversely, Pons-Estel et al. reported that approximately 40% of patients  with SLE had antiphospholipid antibodies and that 50-70% of them may develop APS after 20 years of follow-up [6]. González-Pacheco et al. reported a similar case of a healthy 28-year-old man who showed no sign of coronary risk factors but had APS and experienced acute left main coronary artery thrombosis and ischemic stroke [7]. These studies may include coronary artery thrombosis and atherosclerotic myocardial infarction owing to the progression of coronary plaque. In the current case, multiple intravascular imaging modalities revealed thrombi with severe atherosclerosis in the coronary artery.
Our patient required triple antithrombotic therapy, including dual antiplatelet therapy during coronary stenting and single anticoagulation therapy for preventing left ventricle thrombosis; he also required secondary thromboprophylaxis for APS. Triple antithrombotic therapy is associated with a high risk of bleeding [8]. Despite many receiving anticoagulation therapy, the recurrence rate of thrombosis in patients with APS is very high (2-10% per year) [9].
APS is associated with both thrombosis and atherosclerosis [2,3]. A large amount of atherosclerotic plaques were observed via positive vascular remodeling by performing IVUS and OCT, despite the presence of well-controlled classical coronary risk factors in our patient. Careful diagnosis of co-morbid APS should be performed in patients with thrombosis and atherosclerosis, particularly in those showing specific symptoms associated with SLE, such as rash or arthritis, with the absence of classical risk factors for cardiovascular diseases. In addition, we strongly suggest that cardiovascular risk factors should be strictly controlled in patients with APS.