Cerebral Embolism in Elderly Patients with Atrial Fibrillation.

Novalvular (nonrheumatic) atrial fibrillation (NVAF) is the most common cardiac condition associated with presumed embolic stroke, accounting for approximately half of the cardiogenic embolic infarctions. Of autopsied stroke patients in the Tokyo Metropolitan Geriatric Hospital, cerebral infarction was found in 75%, intracranial hemorrhage in 19%, and coexisting cerebral hemorrhage and cerebral infarction in 6%. Twenty-eight percent of the cerebral infarctions were embolic infarctions of cardiac origin, 56% of which were caused by NVAF. The incidence of cardiogenic brain embolism ranged from 6 to 23% of the ischemic strokes, and NVAF is the most frequent substrate for brain embolism. Atrial fibrillation increases in its incidence with increasing age. Chronic AF was observed in 10%, and paroxysmal AF in 7% of the autopsied elderly patients. Most of them were nonrheumatic AF. Twenty-two percent of the AF patients had large cerebral infarction, and 15% had medium-sized cortical infarction at the autopsy. NVAF is a very important cause of fatal massive cerebral infarction in the elderly. Of 56 patients with fatal massive cerebral infarction who died within 2 weeks after the strokes, 25 (45%) had embolic stroke associated with NVAF. Anticoagulant therapy prevents recurrent cerebral embolism of cardiac origin. The proper time to initiate anticoagulant therapy following cardiac brain embolism is controversial. Immediate initiation of anticoagulant therapy can reduce the early recurrence, but can result in secondary brain hemorrhage or hemorrhatic transformation. Patients with NVAF may have a lower risk of recurrence during the first 2 to 4 weeks following the initial embolic stroke compared with other cardioembolic sources. Cerebral embolism with NVAF can recur during a long period. Long-term anticoagulant therapy (warfarin) prevented recurrent embolic brain infarction with a very low incidence of major hemorrhagic complications in elderly patients with NVAF. It appears that warfarin can be given safely in elderly patients over a long period, provided that adequate anticoagulation is maintained. Long-term anticoagulation is also standard therapy for the primary prevention of embolism in patients with AF who have rheumatic mitral stenosis or prosthetic valves. However, the role of anticoagulation for patients with NVAF has been uncertain. Recently, the results of three prospective randomized trials that examined the benefits of warfarin or aspirin for stroke prophylaxis (primary prevention) in patients with NVAF were reported. All three studies revealed a significant reduction in the stroke rate for patients treated with warfarin and a small incidence of major hemorrhagic complications. The role of aspirin for stroke prevention in NVAF is less clear, AFASAK study indicated no benefit of aspirin therapy, while SPAF study showed a reduction of stroke