Since the early 1990s,1 the risk of ischemic stroke due to atrial fibrillation has been increasingly viewed as safely preventable with anticoagulation, a therapy that had been viewed as relatively unsafe in older and more frail patients. A retrospective study by Tsang and colleagues2 (page 23) addresses equally important observations: Atrial fibrillation is exceedingly common in elderly patients, both with and without ischemic stroke, and is increasing in overall prevalence.
Tsang and colleagues examined the prevalence of atrial fibrillation in a longitudinal case-control study of ischemic stroke patients in Rochester, Minnesota, over three decades from 1960 to 1989. They discovered that the prevalence of atrial fibrillation nearly doubled for each decade, as has been well described,3 but the prevalence of atrial fibrillation had also increased over the epochs in both stroke patients and controls of the age-adjusted populations. These prevalence rates are very high in both groups at 11% to 20% with atrial fibrillation in the stroke patients, and 4% to 12% in the controls. However, the average age of the age-matched cohort (75 years) is also higher than that of other studies and registries of ischemic stroke, which is approximately 65 years.4 Moreover, the influence of the increase in life expectancy over the study period, particularly for a condition such as atrial fibrillation that is so age-dependent, may not have been neutralized completely by the age adjustment. The authors suggest that patients in the later years of their study may have survived better with conditions that are conducive to development of atrial fibrillation, and this argument is also compelling. Finally, a twofold increase in the age-adjusted prevalence of atrial fibrillation in men from the 1970s to the 1990s was noted in the Copenhagen City Heart Study,5 which lends some corroboration to this current study.
In any case, it is clear that the absolute prevalence of atrial fibrillation and atrial fibrillation—associated ischemic stroke have increased to epidemic proportions. Whether or not this increase can be attributed solely to the aging of the population seems to be an issue of lesser importance. It is still routine to encounter patients with chronic atrial fibrillation, both with and without ischemic stroke, whose stroke prevention therapy consists of aspirin or no specific therapy.6 With the continuing increase in atrial fibrillation, this underutilization of therapy must be held up to increasing scrutiny. It is time for atrial fibrillation to become an epidemic that is silent no more.