Antiphospholipid syndrome as a cause for recurrent myocardial infarction

Abstract

Introduction: This case describes a patient who suffered three myocardial infarctions over a two-week period. Testing confirmed thrombophilia as the etiology.

Case: A 55-year old male initially presented to the emergency department with a complaint of chest pain. Testing showed an elevated troponin at 2.2 ng/ml and ST elevations on electrocardiogram. The patient was transferred to the cardiac catheterization laboratory and a drug-eluting stent was placed. One day after the initial stent placement, in-stent thrombosis of the drug-eluting stent was discovered. Angioplasty and aspiration thrombectomy were performed, and the patient was released from the hospital three days later. 72 h after his discharge, the patient returned to the emergency department due to recurrent chest pain and diaphoresis. Shortly after arrival he became unresponsive and telemetry showed ventricular tachycardia which resolved with cardioversion. Reocclusion of the right coronary artery was again noted in the catheterization laboratory and three bare metal stents were placed. Laboratory testing found presence of anticardiolipin antibody and evidence of PT20201A mutation.

Conclusion: Hypercoagulable states, although an uncommon cause of myocardial infarction, should be considered when investigating the etiology of recurrent coronary events. Prompt treatment is important in the prevention of future occurrences.

Introduction

This case presents an unusual, yet important, cause of recurrent myocardial infarction. Prompt diagnosis is imperative to help prevent future events.

Case presentation

A 55-year-old male with no past medical history initially presented to the emergency department with a 36-h history of chest tightness. Pertinent laboratory data included a troponin of 2.2 ng/ml and ST segment elevation of 2–3 mm in the lateral leads on electrocardiogram. The patient was emergently transferred to the cardiac catheterization laboratory where a drug-eluting stent was successfully placed after aspiration thrombectomy to a mid-vessel lesion occluding his dominant right coronary artery.

Approximately 24 h following intervention, he began complaining of worsening chest pain, which was associated with profound hypotension and shock requiring inotropic support. Troponin was noted to be elevated at 3.47 ng/ml, with worsening ST segment elevations on electrocardiogram. He was taken back to the catheterization laboratory, at which time complete in-stent thrombosis of the recently placed drug-eluting stent in the right coronary artery was visualized. Angioplasty and aspiration thrombectomy was performed with excellent angiographic result. The patient symptomatically improved following the procedure and dobutamine was discontinued. He was subsequently discharged two days later.

Approximately 48 h later, the patient re-presented to the emergency department complaining of chest pain, diaphoresis, and feeling of impending doom. Troponin was noted to be 4.84 ng/ml and he soon thereafter became unresponsive with telemetry revealing ventricular tachycardia. Following synchronized cardioversion, he was transferred to the cardiac catheterization laboratory where there was reocclusion of the right coronary artery proximal to the stent. Thrombectomy with balloon angioplasty was performed and three bare metal stents were placed (Figure 1). His hospitalization was complicated by multi-organ system failure including shock liver with an aspartate aminotransferase greater than 6000 IU/l and alanine aminotransferase greater than 11000 IU/l and renal failure requiring dialysis. Echocardiography showed a left ventricular ejection fraction of 15% with severe right ventricular dysfunction and enlargement. Further laboratory testing revealed evidence of a heterozygous prothrombin 20210A mutation and lupus anticoagulant positivity. Other testing, including platelet-factor 4, serotonin release assay, and PFA-100 were all within normal limits.

Figure 1. Pre- and post- intervention at each time interval (A, B, C) in which the patient presented with chest pain.

This patient was subsequently started on systemic anticoagulation with warfarin and discharged approximately two weeks later. Follow-up 18 months after the initial event showed symptomatic improvement back to the patient's baseline with improvement in cardiac function demonstrating a left ventricular ejection fraction of 50% and normalization of atrial and ventricular enlargements (Figure 2).

Figure 2. Echocardiogram after third myocardial infarction compared with study at 18-month follow-up.

Discussion

This case highlights the importance of diagnosing underlying thrombophilias. As such a condition can prove fatal, prompt diagnosis and treatment are imperative. Stent thrombosis is a well-known complication with an incidence ranging from 1–2% within the first year to slightly over one half percent annually thereafter. Many factors contribute to this condition, including both procedural and patient-inherent variables. These factors should be investigated following thrombosis in an attempt to establish the cause and apply targeted treatments. Abnormalities to be investigated in the setting of recurrent stent thrombosis include hypercoagulable states (1).

Antiphospholipid syndrome is the most common acquired hypercoagulable state, occurring in approximately two percent of the general population. In these patients, binding of antiphospholipid antibodies to certain cell membrane proteins can initiate platelet aggregation and thrombosis. Accelerated atherosclerosis secondary to inflammatory factors has also been reported. Multiple studies have shown that anticardiolipin antibody positivity is associated with arterial and venous thrombosis (2,3). In the Johns Hopkins Lupus Cohort Study, 22% of patients with antiphospholipid syndrome developed a myocardial infarction compared to 9% in patients without this abnormality. Another study showed that up to 38% of patients with positive titers for anticardiolipin antibodies either had coronary, carotid, or peripheral arterial thrombosis (4). Therefore, in patients with such thromboses, antiphospholipid antibodies should be considered as a potential etiology (2,3).

Another disorder that can cause thrombosis is prothrombin 20210A mutation. A mutation in this gene factor leads to an increased amount of circulating thrombin, potentiating the clotting cascade. Although there is currently no consensus as to whether the mutation alone significantly increases the risk of myocardial infarction, studies have suggested a synergistic effect with other coagulopathies as well as with atherogenic risk factors, including smoking (5).

There are no definitive guidelines regarding anticoagulation therapy in patients with hypercoagulable states and arterial thromboses. In general, patients who have had a thrombotic event and positive tests for such coagulopathies, anticoagulation should be continued indefinitely (2).

Conclusion

In patients with recurrent and rapidly developing stent thrombosis, it is important to look beyond the traditional risk factors and consider testing for such coagulation abnormalities.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.