RESUMO
OBJECTIVE: The aim of this study is to identify the risk factors in Chinese with nonvalvular atrial fibrillation and stroke, using case-control methodology. METHODS: A total of 4 511 adult patients diagnosed with atrial fibrillation were identified from 18 hospitals over a 2-year period. There were 1 086 patients with rheumatic valvular atrial fibrillation and 3 425 patients with nonvalvular atrial fibrillation. Among the nonvalvular atrial fibrillation patients, 827 had ischemic stroke. The data of the patients having nonvalvular atrial fibrillation with stroke was compared with those having nonvalvular atrial fibrillation without stroke (n = 2 598). The effect of each variable on stroke was assessed with a logistic regression analysis. RESULTS: The studied cases with stroke and controls without stroke were similar in terms of percentage with sex, a past history of congestive heart failure, myocardial infarction, and mean left atrial size. Cases were significantly older than controls (73.3 +/- 9.2 vs. 68.2 +/- 12.3, P < 0.001) and more likely to have a history of hypertension (71.0% versus 51.6%, P < 0.001) and diabetes (17.9% vs. 11.1%, P = 0.001). There is strong evidence that left atrial (LA) thrombi make AF patients highly risky for stroke. In multivariate analysis, age > or = 75 (OR 1.76; 95% CI 1.08 approximately 2.98), history of hypertension (OR 1.52; 95% CI 1.28 approximately 1.80), diabetes (OR 1.39; 95% CI 1.11 approximately 1.76), high systolic blood pressure (OR 1.71; 95% CI 1.21 approximately 2.28), LA thrombi (OR 2.77; 95% CI 1.25 approximately 6.13) were independently associated with stroke. The lack of the association between left ventricular dysfunction and stroke is due to the relatively incorrect diagnosis of heart failure in the context of atrial fibrillation. CONCLUSIONS: Our analysis suggests that old age, hypertension, diabetes, high systolic blood pressure and LA thrombi detected with echocardiography are independent risk factors, which should be considered when decision of long-term anticoagulation therapy to prevent stroke with nonvalvular atrial fibrillation is to be made.
