Abstract
Heart failure and atrial fibrillation are often associated. Both
conditions share pathophysiology and risk factor; as an example, atrial
fibrillation may be regarded as either the ‘cause’ or the ‘consequence’
of heart failure. If coexistent, they are associated to very poor
outcome. With this in mind, finding effective therapy for patients
presenting with both heart failure and atrial fibrillation remains of
paramount importance. There are also little evidence of the role and
benefit of surgical atrial fibrillation ablation concomitant to heart
surgery (i.e., coronary or valve surgery).
The interplay between atrial fibrillation (AF) and heart failure (HF)
has been well documented (1). Both AF and HF are responsible for high
morbidity, mortality and also associated with enhanced healthcare cost
(2). Patients with concomitant AF and HF suffer from even worse symptoms
and poorer prognosis (2). Nevertheless, the role of both surgical and
transcatheter atrial fibrillation ablation in patients with reduced left
ventricle function and HF needs further clarification.
Rimac and colleagues investigated the effect of SAFA in patients with
reduced left ventricle ejection fraction (3). Data from 682 patients
with pre-operative AF who underwent cardiac surgery were prospectively
collected and analysed. Of the note, only patients who had isolated
coronary artery bypass grafting, valve surgery or combined valved and
coronary surgery were included in the study cohort. Outcomes of interest
were all-cause mortality (primary outcome) and rehospitalization for HF
(secondary outcome).
Energy sources for the surgical ablation included cryoablation,
monopolar radiofrequency and bipolar radiofrequency ablation.
In order to reduce in between groups clinical differences a propensity
score matching was performed resulting in 291 patients after matching
(132 and 159 for the SAFA and control group respectively).
Interestingly, SAFA was not associated to reduced post-operative AF and
lower all-cause mortality at 30 days. Moreover, concomitant SAFA did not
result in improved survival over a mean follow-up of 6 year not reduced
the incidence of rehospitalization for HF. Finally, concomitant SAFA was
not related to adverse event.
Authors tried to fill a gap in the literature since there are little
evidence on the benefit of atrial fibrillation ablation in the context
of reduced left ventricle function as demonstrated by different trials
(4-6).
Why this neutral finding?
There can be several explanations for that.
First and foremost, due to both baseline patients and surgical
heterogeneity such as persistent and permanent AF, different energy
sources utilized for SAFA, left atrial appendage technique etc.
Importantly, data for completeness of surgical lesions sets could not be
retrieved.
Secondly, as acknowledged by the Authors, the study bears the
limitations of any retrospective research. As a result of that, rhythm
assessment could not be carried out, nor the adherence and effects of
antiarrhythmic medications.
Lastly, propensity score matching technique while can balance observed
baseline covariates between groups, do little to balance unmeasured
characteristics and confounders (7). Unlike controlled randomized trial,
matching has the caveat that unmeasured covariates may lead to biased
results.
A final word of caution. While the Authors have to be commended for this
interesting and original study, I believe that these neutral results
should not undermine the value and the potential of surgical ablation.
Perhaps, prospective or randomized controlled studies are needed to
further clarify the role of SAFA in the context of reduced left
ventricle function.