Hints of the Heart: Predictors of Finding Occult Atrial Fibrillation after Stroke
Vikas Pandey, MD
Favilla C, Ingala E, Jara J, Fessler E, Cucchiara B, Messe S, et al. Predictors of Finding Occult Atrial Fibrillation after Cryptogenic Stroke. Stroke. 2015
Imagine you are a detective at the scene of a crime and discover bullet holes in the wall of the crime scene. While every indication in such a scenario would point toward a gun being fired, the situation is not definitive until the culprit weapon used is found. The weapon may not be found at the scene of the crime or with a 24 or 48 hour search, but all common sense would tell us that a gun was used. Similarly, stroke neurologists are dealt with a similar predicament when they see a stroke on imaging that appears embolic in etiology, but treatment is usually not sought until the atrial fibrillation is found, even if other risk factors such as advanced age are present. While short term cardiac monitoring such as cardiac telemetry during the hospital admission and 24-48 hour Holter monitoring may not implicate cardiac arrhythmia as the etiology, the evidence is becoming stronger that long-term cardiac monitoring will eventually be able to find the anomaly in question.
The group out of the University of Pennsylvania devised a trial retrospectively analyzing consecutive patients who underwent 28-day outpatient cardiac telemetry after a cryptogenic stroke or TIA to see if there were certain predictors that could be separated to be able to predict if atrial fibrillation would be found. Their study had a total of 227 patients with stroke or TIA of which 14% (95% CI 9-18%) eventually had paroxysmal atrial fibrillation discovered. 58% of these episodes were greater than or equal to 30 seconds in duration (The ACC/AHA threshold for defining paroxysmal atrial fibrillation). They found that age > 60 years, and prior cortical or cerebellar infarction seen on neuroimaging were independently significant predictors of atrial fibrillation and 33% of the patients with both of these risk factors eventually were found to have atrial fibrillation. Interestingly, they found that none of the “CHADS-VASc” factors or echocardiographic findings, including left atrial size, commonly thought of as a predictor of atrial fibrillation, were not significant predictors in the study.
The study confirms the more recent data that extending the length of time of outpatient cardiac telemetry has been yielding more diagnoses of atrial fibrillation and changing the treatment plan of many patients that have previously been labeled “cryptogenic”. The group’s study fortifies the evidence that long-term outpatient cardiac telemetry is not only cost-effective, but also effective in finding a treatable risk factor for stroke, thus should be a considered as a potent weapon for stroke prevention.