Discussion
We encountered two cases of cardiac arrest in patients with persistent
AF with SVR after electrical cardioversion for rhythm control. Both
patients had tolerable LV function and NYHA class II to III dyspnea
despite being on medication. Although their AF showed SVR, and NSVT was
also identified, pacemaker or ICD implantation was not indicated. Thus,
rhythm control strategy could be selected according to the current
guideline.3 However, the patients suffered critical
arrhythmic complications.
The risk of arrhythmic complications of rhythm control in AF patients
with bradyarrhythmia has been pointed out since the
past,4, 5 and current guidelines recommend avoiding
pharmacological cardioversion in patients with SSS or AV conduction
disturbances.3 However, guidelines do not provide a
distinct recommendation for electrical cardioversion in patients with AF
with SVR, and the outcome of rhythm control is unknown for this
sub-population.3 Moreover, in patients with no
previous history of SSS or AV conduction disturbances, the assessment of
the functional status of the SA node or AV node before cardioversion is
challenging.6 Thus, a dilemma arises in the decision
of the rhythm control in patients with symptomatic AF with SVR.
The effect of ventricular rate on the outcome of electrical
cardioversion remains controversial. Shin et al. reported that patients
with lower heart rates before cardioversion were more likely to have
bradyarrhythmic events, but Jussi et al. reported that a lower
ventricular rate does not affect the success of cardioversion or
predispose to complications including
bradyarrhythmia.7, 8 And, there are emerging data that
rhythm control including catheter ablation in cases of predominant AF
and secondary sinus nodal dysfunction can lead to resolution of the
bradyarrhythmia.9 In this respect, rhythm control
strategy could be selected in patients with AF with SVR. However,
meticulous evaluations including history taking, physical examination,
ECG, chest radiography, 24-hour Holter recording, TTE, and treadmill
test should be performed before rhythm control strategy. Additionally,
NSVT was documented in both patients, which might be an ominous sign of
critical arrhythmic events. However, the effect of rhythm control in AF
patients with NSVT has not yet been investigated.