Author + information
- Maciej Wójcik, MD∗ (, )
- Alexander Berkowitsch, PhD and
- Thomas Neumann, MD
- ↵∗Department of Cardiology, Medical University of Lublin, SPSK Nr 4, ul. Jaczewskiego 8, 20-869 Lublin, Poland
We read with interest the paper by Packer et al. (1), which demonstrated lower recurrence of atrial fibrillation (AF) after cryoballoon ablation (CB), as compared with antiarrhythmic drug (AAD) therapy. Nevertheless, the data brings several questions:
1. Selection of few patients is unclear. The authors included, against their study protocol (patients with >2 episodes of paroxysmal atrial fibrillation [PAF], without structural heart disease, for whom at least 1 AAD failed).
2. 22% patients with “early persistent AF”. What is a definition of “early persistent AF”? Are these PAF patients with high AF-burden (2)?
3. 21 patients with coronary artery disease (CAD) and 1 patient without previous AAD failure;
4. 82 patients were enrolled for AAD treatment. Was the selection of AAD randomized? Was any patient randomized to previously failed AAD(s)? Continuation of previously ineffective AAD(s) therapy had to result in an exaggerated failure.
5. Even the most experienced operator needs time to adopt to a new technology. The STOP-AF investigators randomized 163 patients in 26 centers for CB (i.e., approximately 6 patients per center). After a cross-over, 228 patients (approximately 9 patients per center) had CB performed. The presented long procedure and fluoroscopy exposure times (371 and 63 min, respectively) are characteristic for very early stage in learning curve (3) (Fig. 1). Higher rates of permanent phrenic nerve palsy (PNP) and pulmonary vein stenosis, than reported by others (3–6), seem to further support our opinion. Even though, CB was superior to AAD.
6. The use of a smaller cryoballoon is associated with a higher incidence of PNP (5). Low CB temperature early during the freezing cycle is a sensitive warning sign of impending PNP (7). Persistent PNP can be avoided with interruption of CB application in case of loss of phrenic nerve capture and/or abrupt drop in CB temperature. Data on the mode of PN monitoring during a procedure and the minimum temperature reached in patients with permanent PNP are missing.
7. CB outcome is worse in patients with non-pulmonary AF (5), enlarged left atrium (6) and impaired renal function (6). The presented 1-year success rate after a single CB procedure (58%) was lower than previously reported (5) and more recently reported (3,6) by single centers. Is it only of a result of early operators' experience or patients' characteristics? Data describing patients with CB-failure would be helpful to understand the discrepancy.
8. CB eliminates focal triggers in pulmonary veins (PV)s but cannot be expected to reach non-PV triggers or stop/reverse structural remodeling in persistent AF. Repeated CB is successful only in case of AF related to PV reconnection. Thirty-one patients had repeated CB during the blanking period. How many of these patients had PV reconnections? Was the time, between index and repeated procedure, long enough for local tissue healing after index CB? Otherwise, the repeated procedure should had been postponed in time.
We believe that, as STOP-AF trial will have potentially high influence on future recommendations and with the introduction of a second generation of cryoballoons (with even higher rate of PV strictures observed ), the above questions need clear answers.
- 2013 American College of Cardiology Foundation
- Packer D.L.,
- Kowal R.C.,
- Wheelan K.R.,
- et al.
- Vogt J.,
- Heintze J.,
- Gutleben K.J.,
- Muntean B.,
- Horstkotte D.,
- Nolker G.
- Neumann T.,
- Vogt J.,
- Schumacher B.,
- et al.