DISCUSSION
Our present study is the first to evaluate long-term clinical outcomes
after AF/AT ablation procedures guided by UHD mapping system, in
patients with clinical HF, with either preserved or reduced LVEF. We
showed that recurrence rates after complex ablations were not lower in
HF patients than in non-HF patients. There was no difference in the
mortality rates, whereas HF patients were more likely hospitalized for
HF worsening during follow-up. Nevertheless, as expected, CA was
associated with greater NYHA and LVEF improvements in HF patients
compared to controls.
CA of complex atrial arrhythmias has been shown to be safe and able to
improve prognosis of patients with HF, particularly in cases with HFrEF.
Nevertheless, those patients are at high risk of recurrence, and
reported rates varied from 27-73% after one procedure to 23-34% after
repeated ablation on or off antiarrhythmic drug
therapy.4,7–9,13,14. Data are more limited in HFpEF
patients, but they also seem to benefit from CA, despite high recurrence
rates.7,8,15 HF has been identified as an independent
risk factor for AF/AT recurrence in several reports that compared CA
outcomes in patients with or without HF.7,9,14 These
lower success rates in HF could be related to different mechanisms:
atrial enlargement and structural remodelling, due to chronic high
filling-pressures and/or mitral regurgitation, that favours perpetuation
of AF and a higher proportion of persistent AF; ischemia or the
cardiomyopathy itself that can also alter atrial myocardium; but also
patients’ frailty, that can prevent from long-lasting procedures’
completion. There were only few studies that directly compared outcomes
of CA of AF between HF and control patients. Chen et al reported a 27%
rate of AF recurrence in patients with systolic dysfunction after PVI
achieved without 3D mapping, whereas patients with normal cardiac
function had only 13% of recurrence (p=0.03).9 Using
a standard 3D mapping system, Cha et al reported respectively 38%, 25%
and 16% one-year recurrence in patients, whether they had systolic
dysfunction, diastolic dysfunction, or normal cardiac
function.7 Furthermore, success rates of AF ablation
were previously reported lower in patients with LVEF<50%
compared to patients with LVEF>50%.13Black-Maier et al. recently published outcomes of CA of AF in both HFrEF
and HFpEF patients with respectively 32.6% and 33.9% of recurrence
(p=NS), but lower rates of repeated ablations than in our
study.15 Our present one-year recurrence rates were
consistent with previous reports. Moreover, HF status was not a
predictive factor of AF/AT recurrence, as well as the alteration of LVEF
among HF patients. Yang et al. reported that patients with previous CA
of AF would rather have AT than AF recurrence, depending on the degree
of atrial remodelling. Patients with more dilated atria and lower left
atrial bipolar voltage were likely to have AF recurrence suggesting that
HF patients should preferably relapse in AF.16 It is
important to note that ATs were the most frequent arrhythmia in our
study population in both groups. AF and AT share the same precipitants
and are often studied as interchangeable diagnosis, even an important
proportion of patients with AF would not experience AT and vice-versa.
In the particular setting of HF patients, the overlap between AF and AT
is important and should justify to study these atrial arrhythmias
together.17 In our study, the high proportion of AT
was consistent with the high proportion of repeated procedures as
previous ablation can lead to additional atrial scar and subsequent
complex ATs. In our study, the type of arrhythmia was not predictive of
recurrence. The UHD mapping system we used was already reported to be
able to improve comprehension and ablation success of complex post-AF
ablation ATs.18,19
In our study, we identified mitral regurgitation, hypertrophic
cardiomyopathy and persistent AF as predictive factors of recurrences. A
multicentre registry also highlighted higher recurrence rates in HF
patients with persistent AF compared to controls, whereas the results of
CA for paroxysmal AF were not different between HF patients and
controls.14 Data about CA in this setting are scarce,
but a systematic review has already reported higher recurrence rates in
patients with hypertrophic cardiomyopathy compared to controls and with
mitral regurgitation that amplifies and aggravates the atrial
remodelling.20
The other important result of our present work is the beneficial effect
of CA on both NYHA class and LVEF in patients with HF. In patients with
HFrEF, CA of persistent AF, using a 3D mapping system, was already
reported to improve LVEF, peak oxygen consumption, and Minnesota living
with HF questionnaire score.4 Another study reported
better improvement in 6 minutes walking distance, Minnesota score and
LVEF, after PVI compared to atrioventricular node ablation combined with
cardiac resynchronization.3 Moreover, the CASTLE-AF
trial, reported a decrease in a composite endpoint of mortality and
hospitalization for HF in the CA group compared to control group, in
patients with HFrEF.6 Another study conducted in
patients with HFpEF, showed that only patients who maintained sinus
rhythm had improvement in echographic parameters.8 We
also reported here, that AF/AT recurrence was associated with lower
improvement in functional status and LVEF. Black-Maier et al reported
similar effect of CA on AF recurrence and NYHA improvement in both HFrEF
and HFpEF groups, as we did, but they did not include AT in their
analysis. They also showed a trend towards a greater improvement in NYHA
class in patients with HFpEF that nearly reached statistical
significance.15 Likewise, our patients with HFrEF did
not improve their NYHA class more than HFpEF patients, despite a
significant larger increase in LVEF.
Despite longer procedures with longer mapping duration in the HF group,
there was no difference in fluid intake and no acute HF, even in
patients with reduced LVEF. Our present complications rates were similar
with those previously reported in HF patients or with this particular
mapping system. The TRUE-HD study, the largest prospective study
assessing outcomes of this novel UHD mapping system, reported a 4%
complications rate. 21 We acknowledge that our
patients did not present severely depressed LVEF, as the median LVEF was
45% in the HF group. Nevertheless, they had associated comorbidities
and were more fragile than the non-HF patients. Acute HF events were not
rare in patients with HFpEF (3.8%) and HFrEF (6.2%) after CA of AF in
a previous report using the same LVEF cut-off values.15