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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 2, March/April 2021
AFRICA
105
recommendations regarding anticoagulant therapy initiation in
these patients are expert recommendations only. Therefore, patient
choice regarding this matter is an important consideration.
12,57
The CHA
2
DS
2
-VASc score seems to also be suitable to
assess the stroke risk in patients who present with AHRE.
21,25,58
A recent study, performed on over 21 000 non-anticoagulated
patients with CIEDs, showed that the annualised risk of systemic
embolism (SSE) was associated with increasing CHA
2
DS
2
-VASc
score and increasing AF duration.
In this study, in patients with a CHA
2
DS
2
-VASc score of 0 to
1, SSE rates were low, regardless of the duration of the device-
detected AF. However, the stroke risk increased, crossing an
actionable threshold, defined as > 1% per year, in patients with
CHA
2
DS
2
-VASc score of 2 with > 23.5 hours of AF, patients
with CHA
2
DS
2
-VASc score of 3–4 and > six minutes of AF, and
patients with a CHA
2
DS
2
-VASc score ≥ 5 even if they presented
with no AF.
58
More studies are necessary to assess if the usual
strategies for stroke risk stratification and bleeding risk apply to
these patients.
Both the ESC taskforce for the 2016 guidelines on the
management of AF and the EHRA consensus for device-
detected subclinical AT recommend using the CHA
2
DS
2
-VASc
score in order to initiate anticoagulation treatment, with similar
indications as in AF. Therefore, the ESC taskforce for the 2016
guidelines on the management of AF recommends initiating oral
anticoagulation when an AHRE is detected with a duration of
more than five to six minutes and an atrial rate of over 180 bpm
in male patients with a CHA
2
DS
2
-VASc score ≥ 1 or in female
patients ≥ 2.
57
The EHRA consensus for device-detected subclinical AT
proposes oral anticoagulation based on the same CHA
2
DS
2
-
VASc values in episodes that are ≥ 5.5 hours.
12
However, the same
consensus mentions that an AHRE episode of only minutes has
a similar stroke risk as one of > 5.5 hours. The question that
arises is whether continuous anticoagulation in these patients
is necessary. The 2019 American Heart Association/American
College of Cardiology/Heart Rhythm Society (AHA/ACC/
HRS)-focused update of the 2014 AHA/ACC/HRS guideline
for the management of patients with AF recommends further
evaluation in patients with AHRE to document clinically
relevant AF in order to guide the treatment
56
(Table 3).
Our approach
In CIED patients we interrogate the device at six weeks after
a successful implantation procedure to assess the functioning
parameters. Afterwards, we interrogate the devices once a year.
If an AHRE episode is observed, we ask for an expert opinion
(rhythmology specialist) to confirm that the recorded episode
is an AHRE instead of an inaccurately labelled (false-positive)
recording. Before considering anti-coagulation therapy, we try to
verify the presence of AF by one of the following: resting ECG,
Holter ECG recording, patient-operated devices or by reviewing
the EGM (if available) to determine if the AHRE was AF.
We sometimes use external ECG monitoring devices in CIED
patients where the data recorded by the device are uncertain.
After we confirm that the recorded episode is in fact AF,
we follow the recommendations of the EHRA consensus for
CIED-detected arrythmias and initiate lifelong anticoagulation
therapy if the episode was longer than 5.5 hours, based on the
patient’s CHA
2
DS
2
-VASc score (≥ 1 for male patients, ≥ 2 for
female patients).
12
In patients presenting with multiple short episodes of AHRE
(≥ five minutes) we follow the same indication, even though the
thromboembolic risk is not as high as in the previous group.
We therefore initiate anticoagulation therapy based on the
CHA
2
DS
2
-VASc score (≥ 1 for male patients, ≥ 2 for female
patients).
12
In patients with a single short episode of ≥ five minutes, we
follow individualised treatment and patient choice based on
the thromboembolic risk (CHA
2
DS
2
-VASc score) and bleeding
risk (HASBLED score). We follow the recommendations of the
same consensus and observe the AF burden of the patient on
multiple follow ups, usually every three to six months, before
initiating lifelong anticoagulation. We initiate anticoagulant
therapy in this group, only in patients with a high/very high risk
of stroke (CHA
2
DS
2
-VASc score > 4) and low bleeding risk,
in which a clear clinical benefit can be anticipated. We do not
usually initiate anticoagulant therapy in patients with AHRE
< five minutes, because of the lack of data in the literature
regarding this duration. Anticoagulant therapy is initiated in
these patients on a case-by-case basis.
12
Our strategy always takes
into consideration patient choice and wishes.
Conclusion
AHRE represent a complex arrhythmic entity that significantly
increases the thromboembolic risk. Further studies are necessary
to understand the underlying pathogenic mechanisms behind
AHRE and to guide the management of this arrythmia and its
complications.
References
1.
Benjamin EJ, Muntner P, Alonso A, Bittencourt MS, Callaway CW,
Carson AP,
et al.
; American Heart Association Council on Epidemiology
and Prevention Statistics Committee and Stroke Statistics subcommit-
tee. Heart Disease and Stroke Statistics – 2019 Update: a report from
the American Heart Association.
Circulation
2019;
139
(10): e56–e528.
2.
Stroke Risk in Atrial Fibrillation working group. Independent predic-
tors of stroke in patients with atrial fibrillation: a systematic review.
Neurology
2007;
69
(6): 546–554.
Table 3. Society guideline recommendations
Guideline
Subclinical
AF duration CHA
2
DS
2
-VASc score
Class of recommendation
Device-detected subclinical atrial tachyarrhythmias: definition, implications
and management; a European Heart Rhythm Association (EHRA) consen-
sus document
12
≥ 5.5 h*
≥ 5.5 h*
≥ 2
1 (men) or 2 (women)
Recommended/indicated
May be used or recommended
ESC 2016 guidelines for the management of atrial fibrillation
57
> 5–6 min ≥ 1 in male patients or 2 in female patients IA
*Data suggests risk is similarly increased by a mere five minutes. AF, atrial fibrillation.