Challenges in Screening
There are many uncertainties regarding our current approaches to AF
screening. Remaining questions include which subgroup of patients to
screen, the best modality to use for screening and the subset of
subclinical AF (SCAF) cases likely to benefit from oral anticoagulants
(OAC). Two recently published large screening studies have produced
somewhat contradictory results but provide important new insights about
such questions.
In the ‘clinical outcomes in systematic screening for atrial
fibrillation’ (STROKESTOP)38 trial, population aged 75
to 76 years without an earlier diagnosis of AF were screened using
intermittent ECG recordings over 2 weeks yielded 3% detection of new AF
cases with 90% patients eventually put on OAC.39 AF
detection rate was only 0.5% from the first ECG used to
screen.39 This highlights the low yield of using a
single ECG for screening even in elderly population because of a
paroxysmal nature of the arrhythmia. With further continuation of this
study (median follow up 6.9 years), screening resulted in a slight
benefit in outcomes (i.e., stroke, emboli and bleeding) compared to
standard of care.38 These results suggest that
screening is safe and beneficial in elderly
population.38
In contrast, the ‘implantable loop recorder detection of atrial
fibrillation to prevent stroke’ (LOOP)40 trial
screened patients aged 70-90 years, with at least one additional stroke
risk factor.40 In the intervention group, implantable
loop recorders were used for prolonged monitoring to detect AF and
started on OAC if AF lasted more than 6 minutes. Results showed 3 times
increase in AF detection and OAC initiation however, it did not result
in better outcomes (stroke and emboli prevention) compared to the
control group. Different results from this study have been attributed to
detection of very short episodes of AF with loop recorder which might
not benefit from anticoagulation.40
The best approach to population wide screening also remains unresolved.
Systematic screening using (pulse palpation alongside an ECG) has not
been shown to be superior to opportunistic screening (pulse palpation
followed by ECG if the former is positive) in various clinical
trials.29,41,42