Stroke risk assessment

Abstract

Certain embodiments provide a method of assessing a risk of thromboembolic stroke in a patient. The method comprises acquiring image data and determining an indicator of a degree of fibrosis of a patient's left atrium (LA) based on the image data. The method also comprises estimating a level of risk of thromboembolic stroke of the patient based on the indicator.

1 . A method of assessing a risk of thromboembolic stroke in a patient, the method comprising:
 determining, from left atrium (LA) tissue image data of a patient, a level of a parameter that is positively proportional or negatively proportional to an amount of abnormal tissue in a wall of the LA of the patient; and   outputting, to an output device, a machine-readable indicator of a comparison between (i) the determined level and (ii) a first threshold level of the parameter, the first threshold level derived from LA tissue image data of at least one person, other than the patient, who has a history of atrial fibrillation (AF);   wherein, when the level of the parameter is positively proportional to the amount of abnormal tissue, levels of the parameter equal to or greater than the first threshold level are indicative of a significantly increased risk of thromboembolic stroke relative to levels of the parameter less than the first threshold level;   wherein, when the level of the parameter is negatively proportional to the amount of abnormal tissue, levels of the parameter equal to or less than the first threshold level are indicative of a significantly increased risk of thromboembolic stroke relative to levels of the parameter greater than the first threshold level.   
     
     
         2 . The method of  claim 1 , wherein the abnormal tissue present in the LA wall comprises at least one of a fibrotic tissue, a necrotic tissue, a tissue comprising apoptotic cells, a scar tissue, a tissue having impaired electrical conduction, an aberrantly electrically remodeled tissue, and a structurally remodeled tissue. 
     
     
         3 . The method of  claim 1 , wherein the level of the parameter comprises a proportion of fibrotic LA wall tissue relative to a total amount of the LA wall tissue. 
     
     
         4 . The method of  claim 3 , wherein the proportion of fibrotic LA wall tissue relative to a total amount of LA wall tissue comprises a ratio of (i) an imaged volume of fibrotic LA wall tissue to (ii) an imaged total volume of LA wall tissue. 
     
     
         5 . The method of  claim 1 , wherein the tissue image data of the patient is acquired before the patient receives treatment with an AF treatment modality. 
     
     
         6 . The method of  claim 5 , wherein the determining occurs before the patient receives treatment with the AF treatment modality. 
     
     
         7 . The method of  claim 1 , further comprising acquiring the image data by detecting a signal of an agent substantially localized at the abnormal LA tissue. 
     
     
         8 . The method of  claim 7 , wherein the agent comprises a magnetic resonance contrast agent, and wherein the detecting comprises performing magnetic resonance imaging. 
     
     
         9 . The method of  claim 8 , wherein the magnetic resonance imaging comprises delayed enhancement magnetic resonance imaging (DE-MRI). 
     
     
         10 . The method of  claim 7 , further comprising localizing the agent to the abnormal LA tissue by exposing the LA tissue to an antibody or antibody component, coupled to the agent, that binds an epitope present in the abnormal LA tissue and not present in normal LA tissue, such that a substantial amount of the agent present at the LA tissue, at the time of image data acquisition, is bound to the abnormal LA tissues through antibody-epitope binding. 
     
     
         11 . The method of  claim 1 , further comprising:
 determining, of the patient, at least one of an existence and a degree of at least one clinical risk factor for stroke other than the level of the parameter; and   estimating a risk of thromboembolic stroke based on the level of the parameter and the at least one of the existence and the degree of the at least one clinical risk factor.   
     
     
         12 . The method of  claim 11 , wherein the at least one clinical risk factor comprises at least one of congestive heart failure, hypertension, age, diabetes, and prior stroke. 
     
     
         13 . A computer-implemented system for assessing a risk of thromboembolic stroke in a patient, the system comprising:
 a processing module that determines, by a computer, from left atrium (LA) tissue image data of a patient, a level of a parameter that is positively proportional or negatively proportional to an amount of abnormal tissue in a wall of the LA of the patient; and   an output module, in communication with the processing module, that outputs a machine-readable indicator of a comparison between (i) the determined level and (ii) a first threshold level of the parameter, the first threshold level derived from LA tissue image data of at least one person, other than the patient, who has a history of atrial fibrillation (AF);   wherein, when the level of the parameter is positively proportional to the amount of abnormal tissue, levels of the parameter equal to or greater than the first threshold level are indicative of a significantly increased risk of thromboembolic stroke relative to levels of the parameter less than the first threshold level;   wherein, when the level of the parameter is negatively proportional to the amount of abnormal tissue, levels of the parameter equal to or less than the first threshold level are indicative of a significantly increased risk of thromboemoblic stroke relative to levels of the parameter greater than the first threshold level.   
     
     
         14 . The system of  claim 13 , wherein the processing module determines, of the patient, at least one of an existence and a degree of at least one clinical risk factor for stroke other than the level of the parameter, and wherein the processing module estimates a risk of thromboembolic stroke based on the level of the parameter and the at least one of the existence and the degree of the at least one clinical risk factor. 
     
     
         15 . A method of assessing a risk of thromboembolic stroke in a patient, the method comprising:
 acquiring image data;   determining an indicator of a degree of fibrosis of a patient's left atrium (LA) based on the image data; and   estimating a level of risk of thromboembolic stroke of the patient based on the indicator.   
     
     
         16 . The method of  claim 15 , wherein the image data is acquired before the patient receives treatment with an atrial fibrillation (AF) treatment modality. 
     
     
         17 . The method of  claim 16 , wherein the determining the indicator occurs before the patient receives treatment with the AF treatment modality. 
     
     
         18 . The method of  claim 15 , wherein the image data is acquired by detecting a signal of an agent substantially localized at abnormal tissue in a wall of the LA. 
     
     
         19 . The method of  claim 15 , further comprising:
 determining, of the patient, at least one of an existence and a degree of at least one clinical risk factor for stroke; and   estimating the level of risk of thromboembolic stroke based on the at least one of the existence and the degree of the at least one clinical risk factor.   
     
     
         20 . The method of  claim 19 , wherein the at least one clinical risk factor comprises at least one of congestive heart failure, hypertension, age, diabetes, and prior stroke.