A study designed to test two of the latest treatments
— sinus rhythm control and rate control — for
atrial fibrillation (AF) has failed to find any particular
benefit from either of them, but has instead suggested
that the old standby warfarin still has a very useful
role to fill in these patients in driving down stroke
risk. "Anticoagulation therapy should be maintained in
patients who have a history of AF and risk factors for
stroke, even when recurrent AF has not been documented,"
recommend the study authors from the University of Texas
Health Science Center in San Antonio.
GOOD
RHYTHM IS OVERrATED
The data comes from the Atrial Fibrillation Follow-up
Investigation of Rhythm Management (AFFIRM), reported
in the May 23 issue of the Archives of Internal Medicine.
The study enrolled 4,060 patients from the US and Canada,
and followed them up for an average of over three years.
Most of these patients were taking warfarin at the study's
outset. Patients randomized to the sinus rhythm control
group could choose to stop warfarin after at least four
weeks of maintained sinus rhythm on an anti-arrhythmic,
but slightly fewer than half did so. At all points,
at least 70% of trial participants were on warfarin.
Which was just as well for them since warfarin was found
to lower the risk of ischemic stroke by 69% — a
reduction that almost exactly cancels out the 60% increase
of stroke risk posed by uncontrolled fibrillation.
Although the treatments actually
being studied in the trial generated no such benefits,
the benefits of warfarin were equally clear whether
the patient's rhythm was in control or not. "These data
suggest that the beneficial effect of warfarin therapy
exists not only for patients experiencing AF but also
for patients who have a history of AF but who are presumably
in sinus rhythm," say the authors.
There remains one complicating
factor: the main reason why patients at high risk of
stroke are sometimes taken off warfarin is that they
need surgery and can't afford to have anti-thrombotic
agents complicating the task. In many cases that surgery
is necessary to lower the risk of heart attack or even
stroke. The doctor prescribing warfarin will have to
weigh the benefits of anticoagulation against the possible
benefits offered by surgery while the doctor considering
surgery will have to ponder the risks of stopping anticoagulant
therapy.
Arch Intern Med May 23, 2005;165:1185-91
|
