Download Screening for undiagnosed atrial fibrillation in the community

REVIEW
URRENT
C
OPINION
Screening for undiagnosed atrial fibrillation in
the community
F. Russell Quinn a and David Gladstone b
Purpose of review
Recent years have seen significant advances in knowledge about the prevalence of ‘silent’ atrial fibrillation
and the morbidity associated with this condition. Data are emerging on improved strategies for screening,
and new technologies for detecting atrial fibrillation are becoming available, making a review of this
field timely.
Recent findings
Studies suggest that, when screening is performed, undiagnosed atrial fibrillation is present in around 1%
of the screened population, rising to 1.4% for those aged at least 65 years. The prevalence of silent atrial
fibrillation is even higher in patients with additional risk factors (e.g. those aged 75 years, patients with
heart failure). Prolonged monitoring of patients with hypertension and an implanted cardiac device showed
subclinical atrial arrhythmias in at least 10% and these patients had a 2.5-fold increased risk of stroke or
systemic embolism. The feasibility of screening for silent atrial fibrillation has been demonstrated in a
number of populations and many new technologies for atrial fibrillation detection exist, which could
improve the efficiency and cost-effectiveness of this process.
Summary
Increased attention is being directed towards screening for silent atrial fibrillation and our ‘toolbox’ for
detecting it is expanding. Whether this will translate into improved outcomes for patients remains to be
proven.
Keywords
ambulatory ECG, atrial fibrillation, screening, stroke, systemic embolism
INTRODUCTION
The prevalence of atrial fibrillation in the population is rising, and about one in four individuals
over age 40 will develop this dysrhythmia [1].
Untreated atrial fibrillation carries on average a
three to five-fold increase in the risk of stroke
and is independently associated with a significant
increase in congestive heart failure, cognitive
impairment and mortality [2 ,3 ,4 ,5 ]. Appropriate antithrombotic therapy can reduce the risk of
stroke by around two-thirds and the risk of all-cause
mortality by one-quarter [6]. Once atrial fibrillation
is identified, there are well-validated risk scores to
determine which patients merit anticoagulation
(e.g. CHADS2 and CHA2DS2-VASc scores) and clear
guidelines to direct clinical care [3 ,7 ,8]. The first
step in delivering evidence-based therapy is to
identify those with the dysrhythmia, which may
be hampered by the fact that at least 30–40% of
those with atrial fibrillation may not be aware that
they have it (’silent AF’) [9 ,10 ] and the first
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manifestation of atrial fibrillation may be an
ischemic stroke.
DOES SILENT ATRIAL FIBRILLATION
MATTER?
Patients with clinically undiagnosed atrial fibrillation are likely to carry a similar risk of stroke and
thromboembolism as those with recognized atrial
a
Libin Cardiovascular Institute of Alberta, Calgary, Alberta and
Sunnybrook Health Sciences Centre, Division of Neurology, Department of Medicine, University of Toronto, and University of Toronto Stroke
Program, Toronto, Ontario, Canada
b
Correspondence to Dr F. Russell Quinn, BA, BM, BCh, MRCP, PhD,
Libin Cardiovascular Institute of Alberta, 3280 Hospital Drive NW,
Calgary, AB T2N 4Z6, Canada. Tel: +1 403 220 5500; e-mail: frquinn
@ucalgary.ca
Curr Opin Cardiol 2014, 29:28–35
DOI:10.1097/HCO.0000000000000018
Volume 29 Number 1 January 2014
Screening for undiagnosed atrial fibrillation Quinn and Gladstone
KEY POINTS
a hazard ratio for thromboembolism of 9.4 compared with those with no AHRE (95% CI 1.8–47.0)
[13 ].
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Silent atrial fibrillation is present in around 1% of
screened populations and at higher rates in older
individuals or those with comorbidities.
Silent atrial fibrillation is associated with an increased
risk of stroke.
Screening for silent atrial fibrillation is feasible and
acceptable, and new technologies may improve
detection of the dysrhythmia in an ambulant
population.
Clear guidelines exist to guide therapy for patients with
documented atrial fibrillation, but further data are
required on the appropriate management of patients
with only brief episodes of atrial fibrillation detected on
ambulatory monitoring.
fibrillation; indeed, their risk may be higher, as
it is unlikely that they will be taking appropriate
antithrombotic therapy. In a retrospective study in
New Zealand of 1242 patients presenting with stroke
where an ECG was available, 219 patients (21%) had
atrial fibrillation recorded, and for 69 patients this
was the first diagnosis of atrial fibrillation (6% of the
total cohort, 32% of those with atrial fibrillation)
[11]. Of the 150 patients with known atrial fibrillation, 29% were taking guideline-recommended
antithrombotic therapy at the time of their stroke,
whereas for those with previously undiagnosed
atrial fibrillation, this figure was 6%.
Further insights into the risks of silent atrial
fibrillation can be gleaned from patients with
implanted pacemakers or defibrillators, in whom
the burden of silent atrial arrhythmias can be
determined. The Asymptomatic Atrial Fibrillation
and Stroke Evaluation in Pacemaker Patients and
the Atrial Fibrillation Reduction Atrial Pacing
Trial (ASSERT) study followed 2580 patients with
pacemakers or defibrillators who were aged 65 years
and older with hypertension, but no prior history
of atrial fibrillation [9 ]. Ten percent of patients
had subclinical atrial high-rate events (AHREs: atrial
rate >190 beats per minute for at least 6 min) in a
3-month monitoring period and these patients had
a subsequent hazard ratio for stroke or systemic
embolism of 2.5 [95% confidence interval (CI)
1.28–4.89], after adjustment for other predictors
of stroke. Similar results were seen in the TRENDS
study, in which more than 5.5 h of AHRE on any day
in the prior 30 days increased the risk of subsequent
thromboembolism 2.2-fold [12]. In a separate study
of 560 patients with heart failure and cardiac
resynchronization therapy devices, presence of
more than 3.8 h of AHRE in 24 h was associated with
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RECENT DATA ON ‘ONE-TIME’ SCREENING
FOR ATRIAL FIBRILLATION
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Lowres et al. [10 ] performed a systematic review
of studies screening for atrial fibrillation at a single
time point in unselected patients in the community.
Thirty studies, representing 122 571 patients, were
included and the overall prevalence of atrial
fibrillation in the total population was 2.3% (95%
CI 2.2–2.4). If only patients aged at least 65 years
were considered, the prevalence was 4.4% (95% CI
4.1–4.6). Previously undiagnosed atrial fibrillation
was found in 1% of the overall population (95% CI
0.89–1.04) and 1.4% of those aged at least 65 years
(95% CI 1.2–1.6). On the basis of these summary
data, the number needed to screen to detect one case
of previously undiagnosed atrial fibrillation would
be 100 for the general population and 71 for those
aged at least 65 years.
Limited data are available concerning the stroke
risk of those with silent atrial fibrillation. Deif et al.
[14 ] reviewed the ECGs of 1459 ambulatory
patients aged more than 65 years presenting for
elective surgery and found previously undiagnosed
atrial fibrillation in 10 (0.7%). The mean CHADS2
score of these patients was 2.2 (standard deviation
1.5) and none with a CHADS2 score more than 1 were
anticoagulated (compared with 65% of patients
with known atrial fibrillation and a CHADS2 score
>1). In a study by Engdahl et al. (see below) [15 ],
the mean CHADS2 score for those with previously
undiagnosed atrial fibrillation detected on a 12-lead
ECG was 1.8 and none of these patients were on
anticoagulation. Thus, a high proportion of those
with silent atrial fibrillation in these studies were
eligible for anticoagulation.
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RECENT STUDIES OF PROLONGED
MONITORING FOR ATRIAL FIBRILLATION
IN THE COMMUNITY
Screening methods relying on a single assessment
for atrial fibrillation will miss many patients with
paroxysmal atrial fibrillation. These patients have a
similar risk of stroke to those with persistent atrial
fibrillation [16,17] and screening strategies should
take this into account. Engdahl et al. [15 ] reported
the results of an elegant study of stratified screening in a community of 92 000 inhabitants in
Sweden. All individuals aged 75 or 76 years were
invited to screening and a 64% response rate was
achieved (848 individuals). Initial screening was
0268-4705 ß 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
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29
Arrhythmias
with atrial fibrillation in whom anticoagulation
would be recommended and this was converted
into a change in therapy in the majority.
(n) 30
25
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ROLE OF NEW TECHNOLOGIES IN
SCREENING FOR ATRIAL FIBRILLATION
15
10
5
There has been a proliferation of new technologies
and devices promising simple and accurate detection of atrial fibrillation, with some examples summarized in Table 1 [15 ,18,19,20 ,21 ,22,23,24 ,25]
and reviewed by Harris et al. [26 ]. Most have only
been validated in select populations enriched for
the presence of atrial fibrillation (e.g. cardiology
outpatients, patients before and after cardioversion), so accurate data on their ‘real-world’
sensitivity and specificity are lacking. Nonetheless,
they may herald a new era of home rhythm
monitoring and may simplify screening for atrial
fibrillation in other settings.
With an ageing population becoming more
technologically advanced [27], it is likely that
manufacturers of smartphones and other portable
electronic equipment will start to incorporate
biological sensors into their devices. Several applications already exist to determine the heart rate
using the inbuilt camera on a number of smartphones. An application to detect atrial fibrillation
by this method is in development [20 ], but has not
yet been tested in a general population. Phone cases
now exist with dry electrodes for recording singlelead ECG tracings (e.g. AliveCor Heart Monitor,
AliveCor Inc., San Francisco, California, USA; ECG
Check, CardiacDesigns, Park City, Utah, USA). The
AliveCor/iPhone system was studied by Lau et al.
[21 ]. A Lead I rhythm strip was obtained, which was
read by two cardiologists and later compared with
the gold standard of a 12-lead ECG. Sensitivity for
atrial fibrillation detection was 95–100%, with a
specificity of 90–94%, giving an overall accuracy
of 94–95%. The authors also developed and optimized an automated algorithm for atrial fibrillation
detection, and, in a validation set of patients, this
had a sensitivity, specificity and overall accuracy
of 98, 97 and 97%, respectively. A study using
this technology to screen for atrial fibrillation
in community pharmacies is currently underway
[22].
Automated blood pressure machines are now
available with algorithms to detect atrial fibrillation
on the basis of pulse irregularity (e.g. WatchBP,
Microlife AG, Widnau, Switzerland; Omron M6,
Omron Corp., Kyoto, Japan), with reasonable diagnostic accuracy [23,24 ,25], although it is likely
that most physicians would want ECG confirmation
of atrial fibrillation before initiating therapy.
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0
1
2
3
4
5
6
7
8
9
10 11 12 13 14
(Days)
FIGURE 1. Time required to detect previously undiagnosed
atrial fibrillation on intermittent ambulatory ECG recording.
Illustration of the yield for AF detection with a single-lead
ECG tracing performed twice per day or when symptoms
were experienced, in 403 ambulatory patients with at least
two CHADS2 risk factors but no prior history of AF. The
vertical axis represents the number of patients still to be
detected, of 30 patients found to have AF by the end of the
study. Note that at the end of the 2-week period there were
still six patients with undetected AF, who were subsequently
picked up on Holter monitors. AF, atrial fibrillation.
Reproduced with permission from [15 ].
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with a 12-lead ECG; then those with sinus rhythm
on ECG, no prior history of atrial fibrillation
and at least two CHADS2 risk factors were given a
hand-held ECG device (Zenicor Medical Systems
AB,Stockholm, Sweden) and made recordings twice
per day (or if they had symptoms) over a 2-week
period. Eighty-one patients had known atrial
fibrillation (9.6% of those screened) and 35 of
these patients were not on oral anticoagulation.
New atrial fibrillation was diagnosed on the initial
ECG in 10 patients (1.2% of those screened). Home
ECG recordings were obtained on 403 individuals
with a CHADS2 score of at least 2, and 30 of
these patients were found to have atrial fibrillation
(see Fig. 1 for an illustration of the time required
to detect these cases). Thus, silent or undiagnosed atrial fibrillation was present in a total of
40 individuals (4.7% of the screened cohort) and
the screening programme identified 75 patients
with atrial fibrillation (known or undiagnosed)
who would merit anticoagulation. Fifty-seven
of these patients did start anticoagulation. This
study is commendable for several reasons: it was
conducted in an unselected general population,
screening was stratified by baseline risk, the screening protocol was simple, acceptable and feasible, the
strategy picked up a significant number of patients
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Volume 29 Number 1 January 2014
Examples
Type of device
Company
Device
Hand-held singlelead ECG with
dry electrodes
Zenicor Medical
Systems AB
Zenicor-EKG
Omron Healthcare
HeartScan
HCG-801
iPhone 4S application
www.co-cardiology.com
Smartphone case
with dry electrodes
AliveCor Inc.
Heart Monitor
Automated BP
machine with AF
detection
algorithm
MicroLife
BP A200 Plus
Reference
standard
Population
studied
Sensitivity
(%)
Specificity
(%)
12-lead ECG
100 patients with
interpreted by
AF, atrial flutter
cardiologist
or sinus rhythm
from cardiology
outpatient clinic
92a
96a
96a
Doliwa et al. [18]
Used for AF
screening by
Engdahl et al.
&&
[15 ]. Sensitivity
and specificity
recalculated for
identification of
AF. Latest device
can send data via
GSM/GPRS
network.
12-lead ECG
508 cardiology
interpreted by
clinic patients
cardiologist
99
96
92
Kaleschke et al.
[19]
Tracings in study
taken with
electrodes in
contact with right
index finger and
chest (close to V4
position).
12-lead ECG
76 adults with AF,
interpreted by
before and after
physician
cardioversion
96.2
97.5
McManus et al.
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[20 ]
Uses iPhone light
and camera to
obtain pulsatile
signals. Specificity
will be overestimated, as all
patients had AF
prior to
cardioversion.
90–94%
(Cardiologist
interpretation
of single-lead
ECG); 97%
(Automated
algorithm)
95a
Lau et al. [21 ]
Being used for AF
screening in
SEARCH-AF trial
[22]. Requires
iPhone.
Marazzi et al. [23]
Based on three
consecutive
measurements
109 patients (39 in 95–100%
12-lead ECG
interpreted by
AF): learning
(Cardiologist
interpretation
cardiologist
cohort; 204
patients (48 in
of single-lead
AF): validation
ECG); 98%
(Automated
cohort
algorithm)
12-lead ECG
503 patients
92a
referred to
interpreted by
cardiologist
hypertension
clinic
PPV (%) Reference
Notes
&
83a
31
Screening for undiagnosed atrial fibrillation Quinn and Gladstone
0268-4705 ß 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Table 1. Performance of novel technologies for atrial fibrillation detection
32
100
12-lead ECG
503 patients
interpreted by
referred to
cardiologist
hypertension
clinic
M6
Omron Healthcare
Information is presented on selected devices with published data regarding AF detection. See text for further discussion. AF, atrial fibrillation; GPRS, General Packet Radio Service; GSM, Global System for
MobileCommunications; PPV, positive predictive value; SEARCH-AF, Screening Education And Recognition in Community pHarmacies of Atrial Fibrillation
a
Recalculated from original manuscript.
Based on single
measurement.
Marazzi et al. [23]
www.co-cardiology.com
94
81a
Deemed ‘irregular’
for each patient
if 2 or 3 of 3
readings were
irregular.
Wiesel et al. [25]
97
BPM BP3MQ1-2D 12-lead ECG
405 general
interpreted by
cardiology
cardiologist
outpatients
89
72a
Individuals did daily
recordings for 30
days. Values
based on logistic
regression model.
100
90
52
Wiesel et al. [24 ]
&
a
BPM BP3MQ1-2D 60-s event
139 ambulatory
recorder ECG,
patients from
repeated if BP
internists’ offices
machine
suggested AF
Device
Company
Type of device
Table 1 (Continued)
Examples
Reference
standard
Population
studied
Sensitivity
(%)
Specificity
(%)
PPV (%) Reference
Notes
Arrhythmias
There have also been rapid advances in devices
for continuous ambulatory ECG monitoring,
either using skin electrodes (e.g. CardioNet MCOT,
CardioNet, Conshohocken, Pennsylvania, USA)
or completely enclosed in one or more adhesive
patches (e.g. ZioPatch, iRhythm Technologies,
Inc., San Francisco, California, USA; Nuvant MCT
System, Corventis, San Jose, California, USA). Some
devices store data and are returned for later analysis,
while some allow real-time transmission of data
to a central monitoring station over the cellphone
network. No clinical trials have yet reported data
using such devices for atrial fibrillation screening in
the general community.
TARGETED SCREENING IN HIGHER-RISK
POPULATIONS
Unselected screening for atrial fibrillation across
the general population is unlikely to be feasible,
acceptable or cost-effective. It makes sense to target
screening strategies to patient groups with a higher
baseline prevalence of atrial fibrillation (thus
reducing the number needed to screen to detect
one case of atrial fibrillation) and/or to patient
groups wherein detection of atrial fibrillation
would be likely to lead to a change in therapy
(e.g. commencing anticoagulation). The intensity
of screening (on-off versus more prolonged
monitoring) can also be varied depending on the
patient’s baseline stroke risk; the more it matters
that atrial fibrillation is detected, the harder
you should look. This was the approach taken by
Engdahl et al. [15 ], wherein those with at least two
CHADS2 risk factors underwent additional 2-week
ambulatory monitoring, with a significant pick-up
rate for atrial fibrillation in this high-risk group
(7.4%).
Age is perhaps the simplest variable that can
aid in targeting screening; with each decade of
advancing age, prevalence roughly doubles [4 ]
and the risk of stroke in the presence of atrial fibrillation increases by around 1.5 to two-fold [28,29].
There is consensus in the guidelines that most
patients aged 75 years and over with atrial fibrillation should be anticoagulated, and, in the European
and Canadian guidelines, the age cut-off where anticoagulation is recommended is 65 [3 ,7 ]. Current
European guidelines suggest that opportunistic
screening for atrial fibrillation with a pulse check,
followed by an ECG if irregularity is detected, should
be performed for patients aged at least 65 years
(Class 1 recommendation) [3 ].
Contemporary data from the UK on the prevalence of atrial fibrillation in patients with certain
risk factors were reported by Davis et al. [4 ]. Atrial
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Volume 29 Number 1 January 2014
Screening for undiagnosed atrial fibrillation Quinn and Gladstone
fibrillation was found in 2% of a cohort of 3960
patients aged 45 years and older randomly selected
from the general population. Of 782 patients with a
prior clinical diagnosis of heart failure, 22.4% were
in atrial fibrillation (around half of these patients
had normal left ventricular systolic function).
In 1161 patients with other risk factors for atrial
fibrillation (prior myocardial infarction, hypertension, angina, diabetes), the dysrhythmia was found
in around 5%. Targeting screening strategies to such
patient groups could be an effective means of reducing the number needed to screen to detect a case of
silent atrial fibrillation.
A further population with a high burden of
undiagnosed atrial fibrillation are those who have
suffered a cryptogenic stroke. Methods for detecting
silent atrial fibrillation in this ‘secondary prevention’ population have been reviewed elsewhere
[26 ,30] and are beyond the scope of the current
review.
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WHAT DO WE DO WITH THE RESULTS OF
SCREENING? HOW MUCH ATRIAL
FIBRILLATION IS TOO MUCH ATRIAL
FIBRILLATION?
A crucial unanswered question remains whether
patients with very brief episodes of atrial fibrillation
detected on prolonged monitoring merit anticoagulation. Studies have shown that patients
with paroxysmal atrial fibrillation share a similar
risk of stroke as persistent atrial fibrillation
and derive similar benefit from anticoagulation
[16,17]. Patients in such studies generally required
documentation of atrial fibrillation on at least two
12-lead ECGs as well as periods of sinus rhythm to be
classified as paroxysmal atrial fibrillation, that is,
the atrial fibrillation episodes had to be sustained
enough to be recorded on a standard ECG. Studies in
patients with implanted devices have given more
information on the clinical impact of shorter
episodes of atrial fibrillation, although it should
be remembered that these patients may not be
representative of the general population. As mentioned earlier, the TRENDS study found that more
than 5.5 h of atrial fibrillation in a single day
increased the risk of thromboembolism [12].
In the ASSERT study, the minimum duration of
AHRE stored by the implanted devices was 6 min
and the median duration of the longest AHRE
was around 3.6 h [9 ]. The presence of any
recorded AHRE (i.e. >6 min) was associated with
an increased risk of ischemic stroke or systemic
embolism (hazard ratio 2.5), but the study was
not powered to determine whether there was a
‘dose–response’ effect for AHRE duration.
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One way to stratify further patients with devicedetected episodes of atrial fibrillation is to combine
information on the duration of AHRE with the
CHADS2 score. Botto et al. [31] obtained data from
568 patients with pacemakers and a history of atrial
fibrillation and divided AHRE episodes on a given
day into those less than 5 min, between 5 min and
24 h and more than 24 h. Patients with a CHADS2
score of 0 had a low risk of thromboembolism,
irrespective of the duration of atrial fibrillation,
whereas those with a CHADS2 score of 3 or more
had a high risk, even if no atrial fibrillation was
detected. The risk of thromboembolism for patients
with a CHADS2 score of 1 or 2 could be stratified by
the duration of atrial fibrillation detected, and, for
the overall cohort, this could be used to dichotomize
patients into those with low risk (0.8% annual risk)
versus high risk (5.0% annual risk). However, no
trial has yet determined whether anticoagulating patients with device-detected atrial fibrillation
impacts clinical outcomes.
BEYOND SILENT ATRIAL FIBRILLATION:
OTHER ADVANTAGES OF SCREENING
PROGRAMMES
As well as detecting silent atrial fibrillation,
instituting systems approaches for atrial fibrillation
screening will also pick up those with known atrial
fibrillation, a population in which rates of anticoagulation in those at moderate or high stroke
risk have remained stubbornly around 50% [32 ].
Identifying these patients may present a point of
contact with the healthcare system wherein their
medication can be reviewed to ensure that it is
consistent with current guidelines. In addition, a
broader consideration than just anticoagulation is
required when atrial fibrillation is detected in any
patient; it should be ensured that appropriate
investigations are carried out into possible underlying causes (e.g. hypertension, cardiomyopathy,
valvular heart disease), and management of the
dysrhythmia should also be addressed (rate-control
or rhythm-control) to minimize the chance of
future complications.
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CONCLUSION
There is a growing body of data demonstrating that
significant morbidity is associated with silent atrial
fibrillation. Recent studies have shown us which
populations carry a high burden of this disease
and advancing technology is giving us new tools
to detect it. Further trials are required to demonstrate the utility, acceptability and cost-effectiveness
of these approaches in ‘real-world’ settings. With
0268-4705 ß 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
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33
Arrhythmias
increasing data from prolonged patient monitoring
(including pacemakers and other implanted
devices), it is still not clear which patients with brief
episodes of atrial fibrillation merit anticoagulation;
clinical trials in this realm are eagerly awaited.
Acknowledgements
No funding was received for this work from any
organization.
Conflicts of interest
No funding was received for this article. Dr F.R. Quinn
has received honoraria from BoehringerIngelheim and
Bristol-Myers Squibb/ Pfizer.
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&
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&&
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&&
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&
65 detects an asymptomatic subset at high risk of stroke. Int J Cardiol 2013;
164:371–372.
One of the few studies to document the baseline stroke risk score for patients with
previously undiagnosed atrial fibrillation. This study also highlighted a clear gap in
therapy; no patients with previously undiagnosed atrial fibrillation and a CHA2DS2VASc score of at least 2 were on anticoagulation.
15. Engdahl J, Andersson L, Mirskaya M, Rosenqvist M. Stepwise screening of
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atrial fibrillation in a 75-year-old population: implications for stroke prevention.
Circulation 2013; 127:930–937.
This study demonstrates the benefits of a stratified screening strategy for atrial
fibrillation, with prolonged monitoring for high-risk patients who do not show atrial
fibrillation on an initial ECG. This is an important step, as screening at a single time
point is likely to miss many patients with intermittent atrial fibrillation. The study also
embraces the use of new technology for atrial fibrillation screening.
16. Hart RG, Pearce LA, Rothbart RM, et al. Stroke with intermittent atrial
fibrillation: incidence and predictors during aspirin therapy. J Am Coll Cardiol
2000; 35:183–187.
17. Hohnloser SH, Pajitnev D, Pogue J, et al. Incidence of stroke in paroxysmal
versus sustained atrial fibrillation in patients taking oral anticoagulation or
combined antiplatelet therapy: an ACTIVE W Substudy. J Am Coll Cardiol
2007; 50:2156–2161.
18. Doliwa PS, Frykman V, Rosenqvist M. Short-term ECG for out of
hospital detection of silent atrial fibrillation episodes. Scand Cardiovasc J
2009; 43:163–168.
19. Kaleschke G, Hoffmann B, Drewitz I, et al. Prospective, multicentre validation
of a simple, patient-operated electrocardiographic system for the detection of
arrhythmias and electrocardiographic changes. Europace 2009; 11:1362–
1368.
20. McManus DD, Lee J, Maitas O, et al. A novel application for the detection
&
of an irregular pulse using an iPhone 4S in patients with atrial fibrillation.
Heart Rhythm 2013; 10:315–319.
This is a neat demonstration that algorithms can be developed to detect atrial
fibrillation making use of the technology that many patients already carry.
21. Lau JK, Lowres N, Neubeck L, et al. iPhone ECG application for community
&
screening to detect silent atrial fibrillation: a novel technology to prevent
stroke. Int J Cardiol 2013; 165:193–194.
This study shows that acceptable ECG tracings for the diagnosis of atrial
fibrillation can be obtained from an iPhone case with dry electrodes.
22. Lowres N, Freedman SB, Redfern J, et al. Screening Education And
Recognition in Community pHarmacies of Atrial Fibrillation to prevent stroke
in an ambulant population aged >¼65 years (SEARCH-AF stroke prevention
study): a cross-sectional study protocol. BMJ Open 2012; 2:1–6.
23. Marazzi G, Iellamo F, Volterrani M, et al. Comparison of Microlife BP A200
Plus and Omron M6 blood pressure monitors to detect atrial fibrillation in
hypertensive patients. Adv Ther 2012; 29:64–70.
24. Wiesel J, Abraham S, Messineo FC. Screening for asymptomatic atrial
&
fibrillation while monitoring the blood pressure at home: trial of regular versus
irregular pulse for prevention of stroke (TRIPPS 2.0). Am J Cardiol 2013;
111:1598–1601.
This study demonstrates good sensitivity and specificity of home-based atrial
fibrillation detection using an automated BP machine compared with tracings from
an ECG event recorder.
25. Wiesel J, Fitzig L, Herschman Y, Messineo FC. Detection of atrial fibrillation
using a modified microlife blood pressure monitor. Am J Hypertens 2009;
22:848–852.
26. Harris K, Edwards D, Mant J. How can we best detect atrial fibrillation? J Royal
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Coll Phys Edinburgh 2012; 42:5–22.
This is a thorough review of atrial fibrillation screening strategies, methods and
technologies. Clinically relevant recommendations are made on the basis of the
evidence to date.
27. Barrett L. Health and caregiving among the 50þ: ownership, use and interest
in mobile technology. AARP Res Strategy Anal 2011. [online]. http://assets.
aarp.org/rgcenter/general/health-caregiving-mobile-technology.pdf [Accessed
11 September 2013]
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Volume 29 Number 1 January 2014
Screening for undiagnosed atrial fibrillation Quinn and Gladstone
28. Marinigh R, Lip GY, Fiotti N, et al. Age as a risk factor for stroke in atrial
fibrillation patients: implications for thromboprophylaxis. J Am Coll Cardiol
2010; 56:827–837.
29. van Walraven C, Hart RG, Connolly S, et al. Effect of age on stroke prevention
therapy in patients with atrial fibrillation: the atrial fibrillation investigators.
Stroke 2009; 40:1410–1416.
30. Seet RC, Friedman PA, Rabinstein AA. Prolonged rhythm monitoring for the
detection of occult paroxysmal atrial fibrillation in ischemic stroke of unknown
cause. Circulation 2011; 124:477–486.
31. Botto GL, Padeletti L, Santini M, et al. Presence and duration of atrial
fibrillation detected by continuous monitoring: crucial implications for the risk
of thromboembolic events. J Cardiovasc Electrophysiol 2009; 20:241–248.
32. Cowan C, Healicon R, Robson I, et al. The use of anticoagulants in the
&
management of atrial fibrillation among general practices in England. Heart
2013; 99:1166–1172.
This study demonstrates the utility of large patient databases for deriving data on
anticoagulant use. It also highlights the underutilization of anticoagulation in
eligible patients.
0268-4705 ß 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
www.co-cardiology.com
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