Self-limited or transient atrial fibrillation (AF) occurring
during an acute reversible precipitant has been referred to as
secondary AF,
1
temporary cause of AF,
2
and AF occurring
transiently during stress.
3
Alternatively, it has been classified
as either ‘reversible’ or ‘provoked’ AF, varying in terms of the
underlying cardiac substrate and risk for AF recurrence.
4
Given
it was described in prior American Heart Association / American
College of Cardiology / Heart Rhythm Society guidelines,
1
we
continue using the defining term ‘secondary AF’. In this article,
we review prior studies and provide an overview of long-term
management approaches to secondary AF. We will use the term
‘primary AF’ to describe established AF, without an associated
secondary precipitant.
Potentially reversible precipitants of secondary AF include
surgery (both cardiothoracic and non-cardiothoracic), acute
cardiac pathology (including acute coronary syndrome (ACS),
myocarditis, acute pericardial disease), acute pulmonary pathology
(including influenza, pneumonia, bronchitis, COPD exacerbation,
pulmonary embolism, pneumothorax and bronchoscopy-related),
acute infection (including sepsis and non-pulmonary infections),
acute alcohol consumption, electrocution, thyrotoxicosis, and
other metabolic disorders.
2,5,6
Secondary AF is not an uncommon
clinical scenario faced by clinicians. In fact, the Framingham
Heart Study showed 31% of patients with first-detected AF had a
secondary, potentially reversible, precipitant. The most common
precipitants observed in this study were cardiothoracic surgery
(30%), acute infection (23%), non-cardiothoracic surgery (20%)
and ACS (18%).
5
Despite its prevalence, studies examining outcomes in
secondary AF are limited. Previous retrospective studies also
have used different definitions of secondary AF. Some have
included only transient AF, and excluded persistent AF,
2,7–9
while others have included all types of AF associated with a
secondary precipitant.
10,11
Moreover, it is unclear if the risks
associated with each secondary precipitant is the same. As a result,
there are limited evidence-based recommendations to guide
management of these patients. In our review, we focus on long
term management of secondary AF. We review AF recurrence
and ischemic stroke; we do not describe the approach to acute
management of AF nor rate and rhythm control strategies in
secondary AF. We highlight the existing research, compare
risks to primary AF, and propose treatment recommendations
for secondary AF. We provide an overview of approaches to
monitoring for AF recurrence and thromboembolic prophylaxis
in this patient population.
Guideline Recommendations
Current AF guidelines do not directly address the recommended
management of patients with secondary AF. The most recent
American Heart Association/American College of Cardiology/
Heart Rhythm Society guidelines acknowledge the limited
long-term data in patients with AF occurring with potentially
‘reversible’ conditions. They state that the AF may recur so these
patients “should receive careful follow-up.”
6
They do provide recommendations on AF associated with
ACS, hyperthyroidism, acute non-cardiac illness, pulmonary
disease and post-op cardiac and thoracic surgery. For patients
with new onset, transient AF as a complication of ACS, “the need
for OAC and duration of OAC should be based on the patient’s
CHA
2
DS
2
VASC risk score.” For acute non-cardiac illnesses
(reversible precipitants such as hypertension, post-operative
state, pulmonary embolism, viral infection), treatment of the
underlying condition and correction of any contributing factors
is advised. “For many of these patients, AF will spontaneously
terminate with correction of the underlying condition.” In
these non-cardiac illnesses, “the role of OAC is less clear, likely
disease-specific and needs to be addressed on the basis of the
patient risk profile and duration of AF”. In hyperthyroidism
and AF, OAC “should be guided by CHA
2
DS
2
VASC risk score”
in thyrotoxicosis. Meanwhile, restoring a euthyroid state often
results in reversion to sinus rhythm, after which, treatment
recommendations with OAC are not provided. In post-operative
cardiothoracic surgery patients, “it is reasonable to administer
antithrombotic medication in patients who develop postoperative
AF, as advised for nonsurgical patients.”
6
European and Canadian guidelines make fewer recommendations
regarding secondary AF. Canadian guidelines make recommendations
on concomitant AF in association with NSTEACS and STEMI,
but do not specifically address patients with self-limited AF
in these diagnoses.
12,13
European guidelines recommend that
long term OAC be considered in patients with AF after cardiac
surgery at risk for stroke considering individual stroke and
bleeding risk.
14
Among these most recent guidelines, there are
no recommendations for management of other precipitants of
secondary AF nor any recommendations on monitoring for AF
recurrence in secondary AF.
6,13,14
AF Recurrence
Existing research does not support the concept that patients with
secondary AF are cured of AF after effective treatment of the
potentially ‘reversible’ associated condition. In the Framingham
Heart Study, 5-, 10-, and 15-year incidences of recurrent AF
were determined after retrospective review of subsequent
outpatient and hospital visits. AF recurrence rates were greater
among individuals without a secondary AF precipitant (59–71%)
compared with those with a precipitant (42–62%).
5
In secondary
AF associated with sepsis, 1- to 5-year rates of recurrent AF were
44–55%, compared to 57–64% in individuals with prior AF.
10
Canadian Journal of General Internal Medicine
28 Volume 13, Special Issue 1, 2018
Atrial Fibrillation Special Issue
