Impending rupture of abdominal aortic aneurysm due to apixaban use

Abstract

Direct oral anticoagulants (DOAC) are useful for preventing embolism and venous thrombosis in patients with atrial fibrillation. There are also reports that DOAC can dissolve existing intracardiac thrombus. Here, we report a case in which DOAC lysed a thrombus in an abdominal aortic aneurysm (AAA), resulting in impending rupture of the AAA. An 85-year-old woman was admitted to our hospital with a diagnosis of congestive heart failure. She has had atrial fibrillation and started taking DOAC. Computed tomography (CT) performed on admission revealed an AAA with a large amount of intraluminal thrombus (ILT). Fifty days after the start of DOAC, she visited our hospital with the chief complaint of severe abdominal pain. CT showed no enlargement of the AAA, but the ILT in the AAA had dissolved. She was diagnosed with an impending rupture of an AAA. She underwent emergency aortic replacement with a Y-shaped vascular prosthesis. When using DOAC in patients with aortic aneurysms with ILT, we need to be aware of the risk of the thrombus dissolving.

<Learning objective: Direct oral anticoagulants (DOAC) are useful for preventing thrombosis in patients with atrial fibrillation. However, we experienced a case of abdominal aortic aneurysm in which intraluminal thrombus in the abdominal aortic aneurysm was dissolved by the use of DOAC, leading to impending rupture. It was considered as a complication that should be noted when using DOAC.>

Introduction

Direct oral anticoagulants (DOACs) are useful for preventing embolism and venous thrombosis in patients with atrial fibrillation [1,2]. There are also reports that DOAC can dissolve existing intracardiac or intravenous thrombus [3]. Here, we report a case in which DOAC lysed a thrombus in an abdominal aortic aneurysm (AAA), resulting in impending rupture of the AAA.

Case report

An 85-year-old woman visited our hospital with a complaint of dyspnea. Plain chest radiography showed cardiac dilatation and pulmonary congestion. Electrocardiogram showed atrial fibrillation and echocardiography showed severe mitral regurgitation due to tethering. She was diagnosed with heart failure due to severe mitral regurgitation and atrial fibrillation. A computed tomography (CT) performed on admission showed an AAA with a vessel diameter of 44 mm. There was a large amount of thrombus inside the AAA (Fig. 1a,b).

Fig. 1.

(a and b) Abdominal aortic aneurysm (AAA) on computed tomography (CT) when the patient was hospitalized for heart failure. (c and d) AAA on CT when the patient came to our hospital complaining of abdominal pain 50 days after the start of direct oral anticoagulant. The arrow indicates the finding that the thrombus in AAA has dissolved and disappeared.

Treatment with diuretics improved heart failure. Oral administration of DOAC (apixaban 2.5 mg twice a day) was started to prevent embolism of atrial fibrillation. Heart failure improved and she was discharged on the 12th hospital day.

Fifty days after the start of DOAC, she visited our hospital with the chief complaint of severe abdominal pain. Her blood pressure was high at 178/78 mmHg. CT showed no enlargement of the AAA, but intraluminal thrombus (ILT) in the AAA had dissolved (Fig. 1c,d). Blood tests and CT showed no cause of abdominal pain other than AAA. D-dimer was 2.9 μg/ml at the time of the previous discharge, but this time it had risen to 7.2 μg/ml.

She was diagnosed with an impending rupture of an AAA due to the dissolution of ILT by using DOAC. She underwent emergency aortic replacement with a Y-shaped vascular prosthesis.

The postoperative course was good and the abdominal pain improved.

The pathological findings showed that the etiology of AAA was atherosclerotic. The pathological findings showed disappearance of the intima and thinning of the media of the AAA, which was consistent with the impending rupture of the AAA.

Discussion

In the literature, there is no report of a case in which ILT in AAA was dissolved by use of DOAC, leading to impending rupture. There is a report that the intracardiac thrombosis was dissolved by using DOAC [3]. A previous study pointed out that DOACs have a thrombolytic effect even on chronic clot by their potential to inhibit thrombin bound to fibrin and fibrin degradation products [4].

In the literature, Cameron et al. stated that ILT reduces mechanical stress in the arterial wall and contributes to maintaining stabilization of the aortic aneurysm. They also stated that the volume of the ILT in AAA strongly correlates with aneurysmal size and growth [5]. It is inconclusive whether the ILT in the aneurysm is protective for the aneurysm. In our case, dissolution of the ILT resulted in impending rupture of the aneurysm, and it was considered that the ILT was protective for the aneurysm.

There are no clear studies on the use of DOACs and the clinical outcome of AAA. A previous study indicated that the ILT seems to contribute to the size, growth, and proteolytic injury of the arterial wall of aneurysm. But, ILT may decrease mechanical stress on the aortic wall and maintain AAA stability [6]. Although antithrombotic therapy could reduce proteolytic injury, it could concurrently reduce mechanical stability of the aneurysm [5,7]. It is unclear whether the use of DOAC is useful or harmful for aortic aneurysms. From our case, it was considered that the thrombolytic action of DOAC has the function of reducing the mechanical stability of the aneurysm and increasing the risk of rupture.

In our case, the D-dimer elevation on admission with impending ruptured AAA was relatively mild, which was insufficient to indicate thrombolysis. We considered that the increase in D-dimer on admission was relatively mild because the thrombus gradually dissolved after the initiation of apixaban.

We have not checked for D-dimer from the start of apixaban to the admission of the impending rupture of the AAA. If D-dimers were regularly measured, it might be possible to estimate how the ILT had dissolved.

Limitation

This is a case report, and it is necessary to accumulate cases.

In this case, it is unknown when the ILT in AAA had existed, and it was possible that the ILT was dissolved by DOAC because it was a fresh thrombus.

Conclusion

When using DOAC in patients with aneurysms with ILT, we need to be aware of the risk of the thrombus dissolving.

Declaration of Competing Interest

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Written informed consent was obtained from the patient and our local institutional review board approved the study protocol. The study was carried out according to the Declaration of Helsinki.