MedWire News: Undiagnosed atrial fibrillation (AF) is present in nearly 1 in 10 patients with ischemic stroke, a large cohort study has shown.
The finding suggests that current screening methods are failing to detect arrhythmias in a substantial proportion of patients, say the researchers writing in the Journal of Stroke and Cerebrovascular Diseases.
For the study, S Claiborne Johnston (University of California, San Francisco, USA) and fellow investigators sought to characterize the rate, timing, and predictors of delayed detection of AF after stroke.
Using the Virtual International Stroke Trials Archives, they identified data on 3464 patients with acute ischemic stroke who had been assigned to the placebo arms of four clinical treatment trials. Of these, 2504 had no history of AF according to their clinical history or baseline electrocardiogram (ECG).
During 3 months of follow-up, all patients underwent regular ECGs. These revealed AF in 74 (6.9%) patients, equivalent to a detection rate of 301 per 1000 person–years. In two-thirds (68%) of patients, AF was detected more than 48 hours after hospital admission.
In multivariable analysis, the delayed detection of AF was significantly and independently associated with four factors: increasing age (hazard ratio [HR]=1.6 per decade increase); female gender (HR=1.7); absence of hypertension (HR 1.6); and congestive heart failure (HF=1.9).
Summing up their findings, Johnston and team say that a “substantial” proportion of acute stroke patients appear to have undiagnosed AF. They also suggest that the four factors found to predict delayed AF could be used to develop a risk score to identify patients who would benefit most from arrhythmia screening.
“Given that anticoagulation significantly reduces the risk of recurrent stroke in patients with AF, and given the high cost of stroke, it may be worthwhile to obtain more than 48 hours of cardiac monitoring in patients with ischemic stroke of unknown cause,” they write.
“Further research is needed to validate these predictors and identify other predictors of AF to allow targeted screening of patients after ischemic stroke.”
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