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Outpatient cardiac telemetry detected high rate of paroxysmal AF in patients with cryptogenic stroke
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International Stroke Conference 2012
NEW ORLEANS — Almost 20% of strokes attributed to unknown causes were related to short episodes of atrial fibrillation, according to results of a study presented here.
Researchers examined the medical records of 156 patients (mean age, 68.5 years) who underwent monitoring with Mobile Cardiac Outpatient Telemetry (CardioNet) no more than 6 months after a stroke or transient ischemic attack, most of them for 21 days. Ninety-seven percent were not taking prescription anticoagulation drugs. Of the 156 patients, 17.3% had one or more paroxysmal AF episodes during the monitoring; this number increased over time. Nearly 4% experienced an episode of paroxysmal AF in the first 2 days; 9.2% at 7 days; 15.1% at 14 days; and 19.5% at 21 days (P<.05), after accounting for those who had stopped monitoring early. Two-thirds of the episodes lasted less than 30 seconds; 26% lasted more than 30 seconds; and 7.5% were persistent, Daniel J. Miller, MD, senior staff neurologist at Henry Ford Hospital in Detroit, Mich., said at a press conference.
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“We found that detection [of paroxysmal AF] continued … all the way to 21 days, with statistically significant increases between those time periods, showing that you need to continue monitoring past those time points in order to capture the events. A minimum of 21 days would be required to capture these events,” Miller said.
Premature atrial complex identified on baseline electrocardiogram held the strongest correlation with paroxysmal AF (P=.001), the researchers found. Patients identified at study entry with premature atrial contractions were 13.7 times more likely to have paroxysmal AF compared with those without the condition. Excluding patients who suffered a transient ischemic attack, premature atrial contractions in stroke survivors increased their risk for paroxysmal AF to 17 times.
The researchers identified other risk factors for patients with stroke or TIA. Women had 6.2 times the risk for paroxysmal AF compared with men; in women with stroke alone, the risk was 4.6 times higher. Other risk factors include an increased left atrial diameter, reduced left ventricular ejection fraction and increases in a patient’s NIH Stroke Scale score.
Approximately one-third of all strokes do not have a known cause. Paroxysmal AF carries a very high risk for future stroke, Miller said.
“Future study is needed to determine the length of monitoring beyond 21 days and to investigate the exact association with the short episodes of AF and their risk for recurrent stroke in these patients,” he said. – by Katie Kalvaitis
For more information:
- Miller DJ. Abstract #150/2392. Presented at: the American Stroke Association’s International Stroke Conference 2012; Feb. 1-3, 2012; New Orleans.
Disclosure: Dr. Miller reports no relevant financial disclosures.
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More and more studies, including at least a half dozen here at the International Stroke Conference, are showing that prolonged cardiac monitoring detects AF in a not-insignificant proportion of patients with otherwise cryptogenic stroke. That is particularly important because a patient who has had a stroke and documented AF is at high risk for recurrence and should generally be treated with an anticoagulant, be it with warfarin or one of the newly FDA-approved agents. We have seen a number of reports now with patients who have had mobile cardiac monitoring that stops at around 21 days, but we do not know the optimal duration of monitoring. Preliminary data from Denmark presented at the ISC used an implantable cardiac monitoring device and showed that the yield was not great within the first 21 days, but researchers found more and more episodes [of AF] later. For cardiologists, it is important to appreciate that many cases of so-called cryptogenic stroke may not be cryptogenic. This may be particularly true in patients with seemingly cryptogenic stroke who are also found to have a patent foramen ovale.
– Larry B. Goldstein, MD, FAAN,
FAHA
Cardiology Today Editorial Board member
Disclosure: Dr. Goldstein reports no relevant financial disclosures.
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