When asked by CSWN, he too agreed that
“Stroke is only one effect of AF on the brain—another is dementia. AF also increases hospitalizations, increases heart failure, increases mortality,
etc. Thus, preventing stroke is only one aspect of AF
care, but it is a very important element of care.”
Indeed, if a University of Minnesota study is
correct, the cognitive decline in people with AF is
mediated by subclinical cerebral infarcts (SCIs) as
detected by magnetic resonance imaging. The study
was led by Lin Yee Chen, MD, a University of Minnesota cardiologist who analyzed 935 participants
of the Atherosclerosis Risk in Communities Study.16
Among participants without SCIs on MRI scans, incident AF was not associated with cognitive decline.
In contrast, incident AF was associated with greater
annual average rate of decline in word fluency
(p = 0.002) among participants with prevalent SCIs
“Our findings have important clinical and public
health implications,” he said. “They raise the possibility of anticoagulation as a strategy to prevent
cognitive decline in patients with AF.”
Protecting the Brain
Despite available data, the need looms large for sizable
multicenter studies to examine the effects of NOACs,
rhythm and rate control, and left atrial appendage
occlusion on long-term cognitive function. Heart rate
may be important because Bunch et al. have found a
linear, and inverse risk association with heart rate and
dementia with lower heart rates increasing dementia
risk. The Utah team is planning a randomized trial of
pacing rates and their effect on cognition. Also, they
will do further work in evaluating a genetic marker
that tracks for early-onset AF and stroke and those
patients who have very high dementia rates.
Until large multicenter and randomized clinical
trial data are completed, what can be done now to
save the brain?
According to Dr. Prystowsky, one way to lower
stroke risk and better protect the brain: assess risk using the broader CHA2DS2-VASc risk assessment tool (a
Class I recommendation in the current ACC/AHA guidelines).17 With prior stroke, TIA, or a CHA2DS2-VASc
score > 2, oral anticoagulants are recommended (Class
I recommendation) based on shared decision making,
with a discussion of the risk of stroke and bleeding that
considers patient preferences (also a Class I recommendation). “In my own experience,” said Dr. Prystowsky, “it
takes about 10 minutes to go over this with my patients.
It’s a very important decision that is well worth the time
and then you make a shared decision.”
Dr. Bunch said he is trying to reinforce that
warfarin is safe if it’s managed well. As a participant
in the pivotal trial for rivaroxaban and a member of
that trial’s stroke advisory committee, Dr. Bunch said
some clinics put people on warfarin for the first time
and then didn’t check their INR until 4–5 weeks later.
That approach, he said, is “exposing people to crazy
ranges of therapeutic. As a community that uses warfarin, we have to get away from those practices.”
Catheter ablation is emerging as an effective
alternative to maintain patients in sinus rhythm. Short
term, AF ablation seems to increase postoperative
ACC.org/CSWN
cognitive dysfunction; it’s detectable in 24% of patients
at day 2 and 13% at 90 days.18 However, in the longer
term, ablation shows promise for decreasing the
risk of all types of dementia.19 Besides maintaining
sinus rhythm and oral anticoagulation, there is also
evidence that aggressive risk factor modification may
reduce the likelihood or delay the onset of dementia.20
Dr. Bunch said the risk for dementia among all
AF patients is lowest among his patients treated
with catheter ablation who maintain sinus rhythm
long term. Yes, the low rates of dementia likely
reflect healthier patients selected for ablation, the
complex system of catheter ablation, and resulting
follow-up care. Nevertheless, Dr. Bunch suspect that
it also reflects cessation of long-term anticoagulation
exposure, improving cardiac output, and minimizing
beat-to-beat variability in some low-risk patients.
Dr. Bunch said he and his team get e-mails from
all over the world wondering about effective therapeutic strategies and their first message is always, “If you
have