Lifetime Pattern of Atrial Fibrillation and the Risks of Stroke and Death in a Population-based Cohort of Men (from The Manitoba Follow-Up Study)
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Atrial fibrillation (AF) is associated with stroke and mortality. The arrhythmia can be sustained or intermittent. Previous studies that have used fixed covariates and short-time horizons to examine the relation between the pattern of AF and the occurrence of events have produced conflicting results. The Manitoba Follow-Up Study includes 3,983 originally healthy men who have been followed with routine examinations since 1948. AF status during each visit was classified into the following patterns: free of AF, newly diagnosed; intermittent AF-in sinus;intermittent AF-in AF; sustained AF. We created adjusted Cox proportional hazards models with time-dependent covariates to estimate risks for stroke and death according to AF pattern. After 167,982 person-years of follow-up and 66,297 electrocardiograms (ECGs), 548 men had at least 1 ECG documenting AF, 799 had a stroke, and 3173 died. Relative to men free of AF, sustained and newly diagnosed AF were associated with stroke (hazard ratio [HR] 1.85, 95% confidence interval [CI] 1.33 to 2.59 and HR 1.71, 95% CI 1.10 to 2.66, respectively) and death (HR 2.48, 95% CI 2.11 to 2.92 and HR 2.03, 95% CI 1.64 to 2.52, respectively). Intermittent AF was associated with death (HR 2.41 95% CI 1.58 to 3.68 in AF and HR 1.71 95% CI 1.44 to 2.03 in sinus), but not with stroke (HR 0.68, 95% CI 0.22 to 2.13 in AF and HR 1.02 95% CI 0.72 to 1.45 in sinus). Antithrombotic therapy was associated with a reduced risk of the outcomes. In conclusion, longitudinal analysis of patterns of AF evolving over time provided evidence that the associated risks of stroke and death vary considerably with rhythm classification on serial ECGs.
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