The reason is due to embolisation of stasis-induced thrombi forming in the left atrial appendage. Atrial fibrillation accounts for about 10 percent of ischaemic strokes. The risk of stroke can be estimated using the CHADS2 risk stratification system. It involves 1 point for each of congestive heart failure, hypertension, age greater than 75 years old, diabetes mellitus and 2 point for prior stroke or transient ischemic attack. Leading up to his stroke he had 1 risk factor on the scoring scale, which was his hypertension. This score put his risk of having a stroke at 2.8% per year. Now that he has had a stroke, his risk is increased to a score of 3 which corresponds to 5.9% chance of having a stroke per year. The purpose of the risk stratification system is to determine what treatment should be given for the atrial fibrillation. A score of 0 still means there is risk of stroke but it is not very high; however, an antiplatelet agent, such as 81mg daily dose aspirin, is still recommended. At a score of 1 then antiplatelet or anticoagulation medication should be used and above 2 then anticoagulation should be used. (Ref 2) Hart et al.2 performed a meta-analysis comparing the efficacy of warfarin versus aspirin versus control with a number needed to treat (NNT) endpoint of treating for 1 year to prevent 1 stroke compared to untreated atrial fibrillation patients without previous stroke or transient ischaemic attack. The results of the study were that aspirin versus control has a relative risk reduction of 19 percent (NNT=140), adjusted-dose warfarin versus aspirin has a relative risk reduction of 39 percent (NNT=90) and adjusted-dose warfarin versus control has a relative risk reduction of 64 percent (NNT=40). For the adjusted-dose warfarin versus aspirin arm, it was an analysis of 12 trials of 12,963 patients, found through the Cochrane Stroke Group search
The reason is due to embolisation of stasis-induced thrombi forming in the left atrial appendage. Atrial fibrillation accounts for about 10 percent of ischaemic strokes. The risk of stroke can be estimated using the CHADS2 risk stratification system. It involves 1 point for each of congestive heart failure, hypertension, age greater than 75 years old, diabetes mellitus and 2 point for prior stroke or transient ischemic attack. Leading up to his stroke he had 1 risk factor on the scoring scale, which was his hypertension. This score put his risk of having a stroke at 2.8% per year. Now that he has had a stroke, his risk is increased to a score of 3 which corresponds to 5.9% chance of having a stroke per year. The purpose of the risk stratification system is to determine what treatment should be given for the atrial fibrillation. A score of 0 still means there is risk of stroke but it is not very high; however, an antiplatelet agent, such as 81mg daily dose aspirin, is still recommended. At a score of 1 then antiplatelet or anticoagulation medication should be used and above 2 then anticoagulation should be used. (Ref 2) Hart et al.2 performed a meta-analysis comparing the efficacy of warfarin versus aspirin versus control with a number needed to treat (NNT) endpoint of treating for 1 year to prevent 1 stroke compared to untreated atrial fibrillation patients without previous stroke or transient ischaemic attack. The results of the study were that aspirin versus control has a relative risk reduction of 19 percent (NNT=140), adjusted-dose warfarin versus aspirin has a relative risk reduction of 39 percent (NNT=90) and adjusted-dose warfarin versus control has a relative risk reduction of 64 percent (NNT=40). For the adjusted-dose warfarin versus aspirin arm, it was an analysis of 12 trials of 12,963 patients, found through the Cochrane Stroke Group search