Atrial Fibrillation
Figure 3: Comparison of Kaplan-Meier Analysis for Freedom from Death by Any Cause Between Four Studies
0.2 0.4 0.6 0.8 1.0
0.0 0 500 1,000 AF: 126 (n) (Gasparini et al.18 CRT + AVJ Abl p
Two other prospective studies investigated the effects of pacing mode in the management of AF with rapid ventricular rates following AVJ ablation. The Optimal Pacing SITE (OPSITE) trial26
showed that rate
control achieved by AVJ ablation significantly improved symptoms and functional status, while no difference between the two pacing modalities, whether LV or RV, was detected. However, the study population presented significantly less compromised LV function at enrolment. The Left Ventricular-Based Cardiac Stimulation Post AV Nodal Ablation Evaluation (PAVE)27
trial further confirmed the benefits
of the ‘ablate and pace’ approach using different pacing modes. The latter study observed greater benefits with BIV pacing mode in patients with depressed LV EF (considered as ≤45%) and/or in NYHA functional class III.
1,500 ) 14% per year
AF: 125 (n) (Gasparini et al.18) 14.2% per year AF: 96 (n) (Tolosana et al.20) 14% per year AF–abl: 118 (n) (Delnoy et al.21
The figure is adapted from (red) Gasparini et al.,18 et al.20
and (blue) Delnoy et al.21 ) 4.6% per year (green) Khadjooi et al.,19 (purple) Tolosana AF = atrial fibrillation; AF-drugs = atrial fibrillation with
preserved atrio-ventricular (AV) node conduction; AF-abl = atrial fibrillation group with ablated AV node; SR = sinus rhythm.
emphasising that when the survival curves of the HF patients treated with a combined device-based/drug regimen are compared,22
2,000 2,500
Further observational studies analysed the acute and short-term effects of AVJ ablation in HF patients with AF who were treated with CRT. These patients demonstrated an increase in global LV function, mitral regurgitation reduction and an increase in exercise capacity.28–30 Other studies confirmed the chronic effects of CRT in this patient subgroup and reported improvements in NYHA class, exercise capacity and global LV function.17,24,25,31,32
It is important to stress that
these benefits appear to be confined to AF patients with previous AVJ ablation or spontaneous low-rate AF.
the total
mortality rate was remarkably high, amounting to >14% per year of both separate cohorts of non-ablated patients (see Figure 3). Therefore, it follows that in HF patients treated with CRT who present a high or intermediate AT/AF burden, the pursuit of an aggressive treatment strategy, such as AVJ ablation, is warranted.
Atrioventricular Junction Ablation for the Management of Atrial Fibrillation in Heart Failure Patients Treated with Cardiac Resynchronisation Therapy
Until recently, AVJ ablation in AF patients treated with CRT has mainly been confined to selected patients in whom high-rate AF or atrial tachycardia jeopardises satisfactory BIV stimulation (BVP%), and also to CRT–implantable cardioverter defibrillator (ICD) recipients receiving inappropriate ICD interventions.23
discharges during fast AF, constituting approximately 30% of all ICD interventions23
One large observational prospective investigation17 specifically
evaluated the effects of AVJ ablation on CRT delivery using a pre- defined protocol. This study showed that only those AF patients who underwent AVJ ablation (and thus approaching 100% effective BIV pacing) showed significant improvements in LVEF, LV end-systolic volume definition (LVESV) and exercise capacity. Furthermore, a significantly higher proportion of responders (responders defined as patients with a ≥10% reduction in LVESV) was observed in the AVJ ablation group (68%) compared with the non-ablated group (18%) at 12 months. Subsequently, a more extensive observational multicentre study performed by the same group, revealed that CRT combined with AVJ ablation conferred a significant reduction of deaths by any cause compared with CRT alone, particularly by reducing deaths by progressive HF.
The problem of inappropriate ICD
with an important negative impact on the quality of life of patients, may be completely and definitively solved by AVJ ablation. However, in the context of CRT in HF patients with concomitant AF, there is a growing amount of evidence supporting the usefulness of AVJ ablation. This relatively simple procedure may be useful to optimise CRT delivery by eliminating the deleterious haemodynamic effects of a competing, irregular and spontaneous intrinsic rhythm. The MUltisite STimulation In Cardiomyopathies (MUSTIC) AF randomised trial24
was the
first randomised trial demonstrating possible benefits of CRT in HF patients with permanent AF and conventional indications for CRT, showing that in these patients the preferred mode of ventricular stimulation was BIV compared with RV. The study enrolled AF patients with either slow-rate AF or patients who had undergone previous ablation of the AV node; the effects between pacing modes were compared using a cross-over design with two three-month periods. While no difference was found in the intention-to-treat analysis between the two modes (due to the high numbers of drop-outs), HF patients who per protocol completed the study significantly improved in terms of functional status24
with BIV pacing. The majority of patients25 these effects for one year. 94 maintained
Current observational data on AF populations treated with CRT shows that the benefits of AVJ ablation in allowing appropriate CRT delivery seems to outweigh the risks associated with pacemaker dependency creation. The peculiarity of CRT devices (using both an RV and LV pacing lead for ventricular stimulation) should, theoretically, reduce the risks of pacemaker dependency related to lead fractures or malfunction, even more by using bipolar leads. Nonetheless, the fear of pacemaker dependency remains a limiting aspect for the wider spread of AVJ ablation.
Sinus Rhythm Resumption After Cardiac Resynchronisation Therapy in Patients with Permanent Atrial Fibrillation
CRT may positively affect atrial electrophysiology (especially by lessening the stretch and change in local and systemic hormonal state). Analyses of small retrospective data sets suggest the possibility that CRT may contribute to the maintenance of SR.33
Reviewed AF
trend data in CRT, as measured by the implanted device, found a reduction in AF burden after a few months of CRT. Moreover, when successfully treated with CRT, some patients with long-standing or permanent AF exhibit a surprising resumption of spontaneous SR (SRR)
EUROPEAN CARDIOLOGY
Survival from death by any cause
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