Author + information
- Edmond M. Cronin, MB BCh BAO,
- Patrick Collier, MB BCh BAO, PhD,
- Oussama M. Wazni, MD,
- Brian P. Griffin, MD,
- Wael A. Jaber, MD and
- Walid I. Saliba, MD∗ ()
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio
- ↵∗Department of Cardiovascular Medicine/Desk J2, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio 44195
To the Editor:
Persistent iatrogenic atrial septal defect (iASD) after transseptal puncture for radiofrequency (RF) ablation of atrial fibrillation (AF) using 8-F sheaths has been reported at rates of 0 to 19% at medium-term follow-up, depending on the transseptal puncture technique, the follow-up interval, and whether transthoracic echocardiography (TTE) or transesophageal echocardiography was used for assessment (1). Cryoballoon ablation is an emerging technology for the treatment of patients with AF that uses a 12-F inner diameter (15-F outer diameter) sheath (FlexCath, Medtronic, Minneapolis, Minnesota). The effect of this larger sheath size is poorly described; a single study using transesophageal follow-up in only 13 patients (without a comparison group) reported residual iASD in 38% at 6 months and 31% at 9 months (2). We aimed to assess the prevalence of persistent iASD in a larger group undergoing cryoballoon ablation of AF compared with RF ablation.
We performed a retrospective analysis of consecutive patients who underwent first-time cryoballoon ablation of AF between October 2011 and July 2012 and matched them with consecutive patients who were treated with RF ablation. TTE, including Doppler interrogation of the interatrial septum, was performed in all patients before ablation and again at follow-up. Patients with patent foramen ovale or prior transseptal puncture were excluded, as were those without a follow-up TTE at least 1 month post-procedure. TTEs were read and adjudicated for persistence of iASD by a reviewer blinded to the type of ablation. Continuous variables are presented as mean ± SD. Means were compared with Student t test and categorical variables with chi-square test or Fisher exact test as appropriate. All tests were 2-sided, and a p value of <0.05 was considered significant. Analysis was performed using SPSS (PASW Statistics release 18; IBM, Armonk, New York).
Of 63 consecutive patients undergoing cryoballoon ablation, 10 were excluded due to prior transseptal catheterization and 11 due to lack of post-procedure TTE. The remaining 42 patients were matched with 42 consecutive patients undergoing RF ablation after applying the same exclusion criteria. Baseline characteristics were similar between groups; mean age was 59.9 ± 11.3 versus 60.6 ± 8.9 years, 38.1% versus 33.3% were female, 76.2% versus 69.0% had paroxysmal AF, 35.7% versus 38.1% had structural heart disease, 9.5% versus 11.9% had left ventricular systolic dysfunction, and 40.5% versus 42.9% were treated with dabigatran for periprocedural anticoagulation, respectively. Double transseptal puncture with two 8-F sheaths was used in all patients undergoing RF ablation. Twenty of the cryoballoon procedures (47.6%) included a single transseptal puncture through which the 12-F sheath was advanced, and 22 (52.4%) included an additional 8-F transseptal puncture for the circular mapping catheter.
Follow-up TTE was performed 118.2 ± 40.7 days post-procedure (114.7 ± 27.3 days for the cryoballoon group vs. 121.6 ± 50.8 days for the RF group; p = 0.44). Seven new iASDs were detected in the cryoballoon group (16.7%) versus 1 (2.4%) in the RF group (p = 0.029). In the cryoballoon group, multiple univariate analyses of age, sex, type of AF, structural heart disease, double or single transseptal puncture, duration of procedure, and type of anticoagulant did not predict persistent iASD.
AF recurred in 2 (28.6%) and 17 (50%) patients with and without iASD (p = 0.271), respectively, during a mean follow-up of 228.0 ± 96.5 days. No new migraine or embolic events were noted. One patient with a persistent iASD (Fig. 1) reported reduced exercise capacity post-procedure; magnetic resonance imaging demonstrated moderate left superior and inferior pulmonary vein stenosis in addition to iASD, quantitative lung perfusion scan was normal, and cardiac catheterization demonstrated no gradient between the left pulmonary veins and the left atrium. The iASD was therefore believed to be the cause of the patient’s symptoms. It was measured at 10.4 mm and closed with a 25-mm Helex device (Gore, Flagstaff, Arizona) 303 days post-procedure with subsequent resolution of the patient’s symptoms. Another patient with persistent iASD and heart failure (left ventricular ejection fraction of 20%) had a significant “step up” in the right ventricle at subsequent right heart catheterization during an episode of decompensation. A 5 × 5–mm defect in the interatrial septum was noted and repaired during implantation of a ventricular assist device 177 days post-procedure. It was not clear in either case whether the iASD played a definitive role in the symptoms.
Persistent iASD was significantly more common after cryoballoon ablation than RF ablation and was not predicted by clinical variables in this patient sample. Although this study was retrospective and nonrandomized, similar baseline patient variables and the absence of an effect of procedure duration, number of transseptal punctures, and type of anticoagulant suggests that this finding is due to the larger sheath size of the cryoballoon system. It is possible that manipulation of the relatively stiff sheath and balloon catheter, sometimes including so-called advanced maneuvers to satisfactorily occlude the right inferior pulmonary vein, may stretch the interatrial septum and have an additive effect on the incidence of iASD beyond that accounted for by sheath size alone. We did not prospectively record the use of specific maneuvers and therefore were unable to formally analyze for an association with persistent iASD. Although all transseptal punctures were performed through the fossa ovalis guided by intracardiac echocardiography, a slightly more anterior site was often targeted for cryoballoon procedures, and we cannot exclude the possibility that a systematic difference in puncture site influenced our results. Our estimate may be a minimum value given the suboptimal sensitivity of TTE for detection of small secundum-type ASDs (3).
There are few data on the long-term effects of such iASDs. A prospective transesophageal study of patients receiving the Watchman left atrial appendage occlusion device, delivered through a slightly smaller sheath with a 14-F outer diameter, found an incidence of iASD of 34% at 45 days, which decreased to 7% at 1 year, and did not report any adverse effects (4). Likewise, adverse effects attributable to iASD were not reported in the recently published prospective STOP-AF (Sustained Treatment Of Paroxysmal Atrial Fibrillation) trial; however, this was not a predefined endpoint and the study did not report post-procedure echocardiographic imaging (5). In our experience, 2 patients experienced symptoms or had documented hemodynamic significance in the course of follow-up. This suggests that we should be vigilant with regard to the effect of a larger transseptal sheath size and that further study is required to determine long-term sequelae and spontaneous closure rates over time.
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