Ablation outcomes in patients with HCM
Atrial fibrillation with a rapid ventricular response causes an increase
in the heart rate, shorter diastolic filling time, and loss of an
effective atrial contraction, which contributes to a reduction in the
cardiac output, especially in patients with an impaired diastolic
function such as HCM patients. Pozzoli et al.28reported that the onset of AF was associated with a significant
worsening of the NYHA class, cardiac index, and increased mitral
regurgitation. Therefore, rhythm control for AF in patients with HCM is
of great importance. A previous systematic review showed that the
overall rate of the freedom from an AF/AT recurrence with a single CA
procedure was 38.7% and that with multiple CA procedures was 51.8% in
HCM patients, while those were 49.8% and 71.2% respectively in non-HCM
patients29. In the present study, the overall rate of
the freedom from AF/AT recurrences with a single CA procedure in HCM
patients was 38%, which was comparable with that reported in the
systematic review. However, the arrhythmia free rate after multiple CA
procedures was 80%, which was better than the previous
studies29,30. The reason for better outcome may be due
to the difference in the number of CA procedures, CA strategy, and usage
of antiarrhythmic therapy after the ablation. The mean number of
ablation procedure in the present study was 1.7 ± 0.8, which was more
frequent than that in the previous reports29.
Regarding the ablation strategy, a posterior wall isolation was
performed in 80% of the subjects and additional mitral isthmus ablation
was performed in one-third of the subjects. Previously, Santangeli et
al.31 reported that non-PV triggers were observed in
the majority of the HCM patients with a late recurrence of AF after
ablation, and elimination of non-PV triggers were associated with an
improvement in the ablation outcome. As non-PV triggers are commonly
observed on the posterior wall and in the coronary
sinus32, those additional ablation lesions might have
improved the success rate33. In the present study,
antiarrhythmic therapy, mostly amiodarone, was continued in 58% of the
HCM patients after the last ablation. Amiodarone contains a risk of
life-threatening side effects including interstitial pneumonia, thyroid
dysfunction, and liver dysfunction, and therefore its discontinuation is
desirable. However, the use of long-term antiarrhythmics was often
required according to the meta-analysis of AF ablation in patients with
HCM29. As atrial remodeling is ongoing due to the
pathologically progressive nature of HCM, an aggressive therapeutic
approach by catheter ablation and anti-arrhythmic agents may be needed
for the maintenance of sinus rhythm in the HCM patients.