Anticoagulation in the Setting of AFib and Cardiac Amyloidosis
The best answer regarding the need for anticoagulation in this patient is:
The correct answer is: D. Amyloidosis is associated with increased risk of intracardiac thrombus; therefore the patient should be on anticoagulation regardless of CHADS2 score.
Although there are no formal guidelines addressing this specific clinical scenario, but anticoagulation is strongly recommended if a patient with cardiac amyloid develops atrial fibrillation, since the risk of intracardiac thrombus is very high.1,2 In a study on 116 autopsies, the presence of intracardiac thrombus was identified in 33% of cases compared to none of the 40 control patients. The presence of both atrial fibrillation and AL amyloidosis was associated with an extremely high risk for thromboembolism (odds ratio 55, 95% CI 8.1-1131).1
Similarly, a study on 156 patients with cardiac amyloidosis who underwent TEE showed the presence of intracardiac thrombus in 27% of patients. Furthermore, although AL amyloidosis patients were younger and had less atrial fibrillation, AL amyloid had more frequent intracardiac thrombus than the other types (35% versus 18%; P=0.02).2 Other risk factors for thromboembolism included left ventricular diastolic dysfunction, increased right ventricular wall thickness, and faster heart rates, the latter presumably representing a compensatory response to a low stroke volume.1,2
Therefore, the use of CHADS2 score for assessing stroke risk in atrial fibrillation is not of value in cardiac amyloidosis, and all patients should be considered at very high risk regardless of the absence of a high CHADS2 score.1
In the absence of atrial fibrillation, the role of anticoagulation in patients in is uncertain. There is suggestion that there is increased incidence of intracardiac thrombosis in cardiac amyloidosis even while in sinus rhythm. This can be explained by a combination of systolic and diastolic ventricular dysfunction and chronic amyloid infiltrate in the atria leads to atrial mechanical dysfunction atrial mechanical dysfunction,3,4 atrial enlargement, and blood stasis.5,6 In the absence of atrial fibrillation TEE may be vital in identifying those at risk and anticoagulation can be considered in the absence of atrial fibrillation in those with either a diminutive transmitral A wave or depressed left atrial appendage velocity on TTE, particularly if AL type is present.1,2
Amyloidosis is associated with increased hemorrhagic tendency, due to amyloid angiopathy and the coexisting coagulopathy,7,8 however; anticoagulation should not be withheld if indicated unless a clear-cut contraindication exists, which it is not the case in our patient.2
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