Abstract
Background
Left atrial (LA) size represents atrial fibrillation (AF) burden and a predictor of AF-related stroke. CHA2DS2-VASc score is also a well-established predictor of AF-related stroke. It is unknown whether these two factors are correlated and complimentary to each other, or one of them is a major determinant of stroke risk for AF patients.
Methods
A total of 708 patients from the National Taiwan University AF Registry were followed upto 15 years. LA size was measured by M-mode of echocardiography and the CHA2DS2-VASc score was calculated as measures of stroke risk. Primary endpoints during follow-up were defined as ischemic strokes or transient ischemic accidents.
Results
Both LA size and CHA2DS2-VASc score were associated with the risk of stroke in univariate analyses (c statistic 0.662 [0.601 to 0.723] for CHA2DS2-VASc score and 0.595 [0.516 to 0.674] for LA size). There was a positive correlation between LA size and CHA2DS2-VASc score (r=0.17, P<0.0001). Patients with higher CHA2DS2-VASc scores had a higher mean LA size (P<0.01 for trend). When combining LA size and CHA2DS2-VASc score in the multivariate Cox model, only CHA2DS2-VASc score remained statistically significant to predict the thromboembolic endpoint (hazard ratio 1.39 [1.20–1.63]; P<0.001).
Mode of anlysis Harzard ratio (95% confidence interval) P value Univariate analysis* CHADS2-VASc score 1.42 (1.22–1.66) <0.001 Left Atrial Size 1.30 (1.04–1.62) 0.019 Multivariate analysis* CHADS2-VASc score 1.39 (1.20–1.63) <0.001 Left atrial size 1.20 (0.96–1.48) 0.106
Conclusion
There is a positive correlation between echocardiographic LA size and CHA2DS2-VASc score. LA size is not an independent predictor of AF-related stroke, but provides a diagnostic value to predict stroke risk through its association with CHA2DS2-VASc score. Calculation of CHA2DS2-VASc score may replace measurement of echocardiographic LA size when evaluating the risk of AF-related stroke.
CHA2DS2-VASc score, left atrial size and atrial fibrillation as stroke risk factors in the Tromsø Study
