Invasive cardiac monitoring revealing in cryptogenic stroke
medwireNews: Long-term observation with an implantable cardiac monitoring device detects paroxysmal atrial fibrillation (PAF) in about a quarter of patients with cryptogenic ischemic stroke, research shows.
All 51 patients in the study underwent a full etiologic work up before having surgery to implant the monitor. No patient had evidence of AF, despite undergoing standard electrocardiography and at least 24 hours of Holter monitoring, yet the implantable device detected first PAF episodes in 13 patients after a median of 48 days of monitoring, ranging from 0 days (AF detected at postimplantation check) to 154 days. The median duration of the first PAF episode detected was 6 minutes, ranging from 1 minute to 72 hours.
"These data underscore the importance of prolonged, high-quality recording to detect PAF," write Alexander Flint (Kaiser Permanente, Redwood City, California, USA) and Ashis Tayal (Drexel University College of Medicine, Philadelphia, Pennsylvania, USA) in an editorial accompanying the study in Neurology. "In a patient who requires 5 months of continuous recording to detect a first PAF event, no currently available noninvasive device would be able to make the diagnosis."
Patients who had an episode of PAF during long-term monitoring were significantly older than those who did not, at 59 versus 49 years. More patients with (90.0%) than without (48.5%) PAF had interatrial block, and they also had more atrial premature contractions per day, at a median of 44 versus five, and a higher indexed left atrial volume. Patients with PAF had a higher stroke risk than those without, according to the CHADS2 and CHA2DS2-VASc risk scores.
If confirmed in larger cohorts, these variables could help select which patients to monitor for PAF, allowing for "optimum targeting of resources, with cost benefits," suggest lead researcher Paul Cotter (Addenbrookes Hospital, Cambridge, UK) and team.
In their editorial, Flint and Tayal ask: "When it comes to stroke risk, does the duration of individual PAF episodes matter, or is the driver of stroke risk the state of transition back and forth from an organized atrial contraction to a fibrillating atrium?"
They say that "the thorniest question of all" is at what point the presence and burden of PAF make anticoagulation rather than antiplatelet treatment preferable. They note: "In patients with a low burden of detected PAF, the decision of whether or not to anticoagulate remains a difficult one that should be approached cautiously."
The researchers did not collect data beyond the first PAF episode so they did not assess AF burden, although they note it is likely to be low in most of their patients, given the long median time to the first episode.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter