Department of Neurology, University Hospital Leuven Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium
* Tel.: +3216 344280; fax: +3216 344285 (E-mail: vincent.thijs{at}uz.kuleuven.ac.be).
This editorial refers to "Stroke patients with atrial fibrillation have a worse prognosis than patients without: data from the Austrian Stroke registry" by Steger on
page 1734
Atrial fibrillation (AF), the most common serious cardiac arrhythmia, is not a benign disease. Patients with AF have a 45-fold increased risk of ischaemic stroke and a doubling of the risk of dementia or low cognitive function.1,2 Population-based studies indicate that at age 5059 years, 1.5% of all strokes are caused by AF, whereas at age 8089 the attributable risk is about 23.5%. Patients with AF are also more likely to die with a 1.51.9-fold increase across all age groups.
When a stroke occurs in atrial fibrillation, neurological outcome is more likely to be poor. In the Framingham study, fatal strokes were twice as common with AF.3 In the European Community Stroke Project study, the risk of remaining disabled or handicapped was increased 50% after stroke with AF.4 The cause of the increased disability and mortality is unclear. Patients with AF and stroke have greater initial degrees of neurologic impairment which is the most important predictor of functional outcome after stroke.5 It is unclear why AF causes more severe strokes. Emboli in AF are probably more voluminous and therefore more easily obstruct larger brain vessels, but this has not been definitively established. Emboli in AF preferentially lodge in vessels supplying cortical brain regions affecting areas involved in higher brain function like speech, attention and cognition and in motor areas. Patients with AF are also more likely to have low blood pressure and hypoperfusion caused by congestive heart failure.7 This may further impede flow to viable but critically hypoperfused brain regions surrounding the initial infarct. Finally, it has been suggested that cardiogenic brain emboli more frequently dissolve spontaneously than emboli originating from atherosclerotic plaques, which may give rise to more frequent haemorrhagic transformation of infarcts or reperfusion injury.
In this multi-centre study, Steger et al.6, studied the hospital course of 992 consecutive stroke patients. In-hospital mortality was nearly doubled in patients with AF, especially in patients over age 75, and neurological outcomes were poorer. Patients with AF more frequently had medical complications like pneumonia and were more often treated with antibiotics. As expected, congestive heart failure was also more common with AF. Symptomatic intracerebral haemorrhage (SICH) occurred in 8% of patients, which is an extremely high figure for which the authors do not provide an adequate explanation. In the largest randomized clinical trial of unfractionated heparin in acute stroke, the rate of symptomatic intracerebral haemorrhage was only 1.32.8% depending on the dose of heparin used.8 Although heparin reduced recurrent stroke by up to 50% in this trial, this benefit was offset by the occurrence of symptomatic intracerebral haemorrhage. Heparin, heparinoids and low molecular weight heparin are still often used in the setting of acute stroke and AF for fear of high rates of recurrent stroke. This practice is unfounded: none of the trials using these agents have shown superiority over aspirin and the risk of recurrent stroke in recent trials is less than that which was previously anticipated.9 We suspect that the indiscriminate use of heparin might have lead to the high rate of SICH, although the authors provide no information about the type or dosage of heparin used in their study. The rate of recurrent stroke was 3%, similar to the rates of recurrent stroke with aspirin in the IST-trial.
What are the messages from this study? Patients with AF and stroke are more likely to have poor outcomes; these patients should probably be monitored and treated more aggressively. Clinicians should focus on the management of congestive heart failure in stroke patients with AF and infections; in particular, aspiration pneumonia and urinary tract infections, should be more aggressively prevented through the use of dysphagia evaluations and the less liberal use of urinary tract catheters. Prophylactic antibiotic treatment is under active investigation in patients with severe stroke in randomized trials.10 Heparin should be used very cautiously in patients with AF and stroke, and certainly not used for the prevention of recurrent ischaemic stroke. The combination of antithrombotic agents, which have been shown to work in cardiac patients cannot be used as freely in stroke patients with AF. These patients tend to be older, have more co-morbidities and a higher risk of haemorrhagic stroke as shown by the MATCH trial in which the combination of aspirin and clopidogrel led to a doubling of the rate of intracerebral haemorrhage in comparison with clopidogrel alone.11
Without a doubt, prevention of strokes in AF is even more important. Oral anticoagulants, although highly effective in routine clinical practice as highlighted in the ATRIA-study are substantially underused.12 New prophylactic therapies, both medical and interventional procedures, seem to provide important advantages over oral anticoagulants. The oral thrombin inhibitor ximelagatran does not require monitoring of the INR, although liver function evaluation might be necessary in the first months of treatment.13 Interventional procedures that seal off the left atrial appendage can be used in patients with contraindications to oral anticoagulants.14 It is hoped that these new treatment options will increase the number of patients who are optimally protected from the devastating complications of atrial fibrillation.
Footnotes
doi:10.1016/j.ehj.2004.06.030
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References
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