Table 4. Association between duration of atrial fibrillation (AF) by tertile and MRI measured brain volumes: The AGES-Reykjavik Study.

Duration of AF	Total brain volume	Gray matter volume	White matter volume
No AF (ref)	70.2	43.7	25.2
1	69.5*	43.1*	25.0
2	69.4*	42.9†	24.9*
3	69.3†	43.0†	25.0
P for linear trend	0.012	0.011	0.16

Data are adjusted mean percentage of total intracranial volume, adjusted for age, sex, education level, hypertension, myocardial infarction, diabetes mellitus, heart failure, smoking, alcohol use, hypercholesterolemia, body mass index, height and cerebral infarcts on MRI. For tertiles of AF duration the values are < 3.7 years for tertile 1 (n= 105), 3.7 – 8.6 years for tertile 2 (n=105) and > 8.6 years for tertile 3 (n=105). Comparison to no AF:

^*P<0.05,

^†P<0.01,

^‡P<0.001

MRI = magnetic resonance imaging