February 3, 2012

Unexplained Strokes?

(Ivanhoe Newswire)-- A whopping one out of every three stroke survivors leave the hospital without knowing the cause of their stroke.

Irregular heart rhythms appear to cause about one-fifth of strokes for which a cause is known.

"Identifying and treating these patients for irregular rhythm could reduce the recurrence of stroke by 40 percent compared to reducing the risk by treating them with aspirin," Daniel J. Miller, M.D., the study's first author and a senior staff neurologist at Henry Ford Hospital in Detroit, Michigan, was quoted as saying; "The cause doesn't make a difference if there isn't a treatment, and recently two new medications — dabigatran and rivaroxaban — have been approved by the FDA to treat this problem."

A study confirmed a report from 2008 that discovered 23 percent of individuals whose heart rhythms were measured by automated monitors for 21 days had intermittent, or paroxysmal atrial fibrillation (PAF). Episodes of PAF can last for a few seconds or a few days.

The study suggested that erratic heart beats of less that half a minute may indicate extended episodes of PAF that lead to acute blood clotting in a patient's heart with otherwise unknown causes for their stroke. Since the study, doctors have argued the importance of PAF to their patients.

Miller and his team examined medical records of 156 patients who had undergone monitoring no more then six months after a stroke or a transient ischemic attack (TIA). Ninety-seven percent were not taking any prescription anticoagulation medications.

Of the total patients, 27 had one or more PAF episodes during monitoring and the number increased greatly over time. 3.9 percent of the patients experienced an episode of PAF, in the first 2 days. The percentage rose to 9.2 percent after one week, 15.1 percent at two weeks and 19.5 percent by three weeks, after accounting for those that had stopped monitoring early.

Patients identified at study entry with premature atrial contractions – the most common type of erratic heartbeats – were 13.7 times more likely to have PAF than those without the rhythm problems. "That's a very high risk," Miller said.

Excluding TIA patients, the presence of premature atrial contractions in stroke survivors increased their risk of PAF to 17 times. Each one level increase in a patient's National Institutes of Health Stroke Scale increased the risk of AF by 20 percent. The 42 point scale provides physicians a standardized method to assess a patient's stroke-induced impairment.

"Patients with stroke of unknown origin should have at least 21 days of MCOT monitoring to reliably detect paroxysmal atrial fibrillation in order to reduce their risk of future stroke," Miller said.

SOURCE: American Stroke Association's International Stroke Conference 2012, February 2, 2012