Silent heart irregularity also raises risk of stroke

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Affecting over 2 million people in the U.S., atrial fibrillation (AF) is the most common cardiac arrhythmia (irregular heart beat) and can be associated with palpitations, chest pains, fainting, and congestive heart failure. The condition can be diagnosed by simply taking a patient s pulse or looking at an ECG. However, some people may not be aware that they have this condition; that is, they have silent AF. This is of some concern, since even silent AF can double the risk of stroke, according to a new study published in the New England Journal of Medicine.

When the atrial chambers of the heart don t contract regularly and forcefully, as is the case with AF patients, blood can pool and lead to clots, thus increasing the risk of stroke, ACSH's Dr. Gilbert Ross explains. In the new study, led by researchers from the School of Medicine at McMaster University in Ontario, over 2,500 hypertensive patients with pacemakers who had no history of atrial fibrillation were recruited. As detected via routine pacemaker monitoring, one-third of the participants experienced AF (defined as an irregular heartbeat lasting at least six minutes), and fully 85 percent of those were unaware of it. Among those who did experience such a silent episode within the first three months of the study, the risk of stroke was doubled, compared to patients who were episode-free. The risk also increased with additional stroke risk factors, such as high blood pressure and diabetes.

That s why these patients should be on anticoagulant therapy, Dr. Ross says. The patient doesn t have to be aware of the condition in order for it to elevate their risk of stroke, but since pacemaker patients are routinely monitored, AF may be diagnosed more frequently among this cohort. On the other hand, he continues, not all cases of AF need to be treated, and currently, there is no consensus on what degree of the condition is dangerous, since treating AF with drugs comes with its own set of risks.

The study authors say their results emphasize the need to more tightly control other known stroke risk factors that are more easily identifiable (hypertension, diabetes) in order to decrease stroke incidence.