The Anatomic Impact of Sequential,Additional, Ostial Radiofrequency Ablation Following Pulmonary Vein Cryo‐Isolation

Background : Although pulmonary vein (PV) stenosis is a serious complication of radiofrequency PV isolation, the anatomical impact of a combination of two energy sources on PV diameter has not been evaluated. The aim of this study was to evaluate the impact of supplementary point‐by‐point radiofrequency applications (following PV cryoablation) on the PV orifice diameter. Methods : Forty‐nine patients having undergone PV isolation for drug‐refractory atrial fibrillation were included. All had undergone cardiac computed tomography before ablation and again at least 3 months afterwards. When isolation with the cryoballoon was not complete, a conventional irrigated‐tip radiofrequency catheter was used for point‐by‐point applications. Results : Of the 189 target PVs, 117 were isolated with cryotherapy alone (cryo PVs) and 72 required additional radiofrequency (hybrid PVs). The second scan (performed an average of 11.4 ± 5.4 months after) showed a decrease in diameter for all the hybrid PVs (17.2 ± 2.6 to 16.3 ± 3.4 mm; P = 0.037) but no change for the cryo PVs. This change was associated with a decrease in left superior pulmonary vein (LSPV) diameter (19.2 ± 3.0 to 17.8 ± 4.9 mm, P = 0.014). There were no changes in other veins. A subgroup analysis for the LSPV revealed a decrease for the hybrid PVs (18.8 ± 3.6 to 15.9 ± 7.1 mm, P = 0.046) but not for the cryo PVs. Significant PV stenosis was observed in three hybrid PVs (two severe stenosis of the LSPV and one moderate stenosis of the right inferior pulmonary vein) but not in cryo PVs (4.1% vs 0%, respectively; P = 0.023). Conclusions : Cryoballoon ablation of the PV with adjunct, focal, irrigated ostial RF applications may be associated with a higher risk of PV stenosis. (PACE 2012;35:1420–1427)     

Pulmonary vein isolation with real‐time pulmonary vein potential recording using second‐generation cryoballoon: Procedural and biophysical predictors of acute pulmonary vein reconnection

1 Objective

The study sought to evaluate the procedural and biophysical factors related to acute pulmonary vein isolation (PVI) guided by real‐time pulmonary vein (PV) potential recordings.

2 Methods

A total of 180 consecutive patients with drug‐resistant atrial fibrillation (AF) undergoing CB2 (second‐generation version of cryoballoon) ablation were enrolled. Real‐time monitoring of PV potentials was obtained using an inner lumen spiral mapping catheter.

3 Results

Acute isolation was achieved in all PVs without touch‐up ablation. Real‐time assessment of PV disconnection was possible in 611 of 711 (85.9%) PVs. A total of 617 (86.8%) PVs were isolated during the initial freeze. Longer time cycle integration (TCI) (TTI * freeze cycle, TCI) (254.6 ± 112.8 seconds vs 74.1 ± 59.7 seconds, P < 0.001), time to isolation (TTI) (94.3 ± 34.0 seconds vs 46.3 ± 26.2 seconds, P < 0.001), higher nadir temperature (?45.5 ± 5.3°C vs ?50.4 ± 5.5°C, P < 0.001), longer time to ?40°C (77.3 ± 22.7 seconds vs 55.7 ± 23.2 seconds, P < 0.001), faster interval rewarming time at 0°C (9.4 ± 4.3 seconds vs 12.4 ± 4.9 seconds, P = 0.008), and total balloon rewarming time (38.1 ± 11.6 seconds vs 47.7 ± 14.0 seconds, P = 0.003) were observed in PVs with acute reconduction. TTI ≤ 65 seconds predicted absence of acute reconnection with 84.2% sensitivity and 75.7% specificity, whereas TCI ≤ 119 seconds presented 94.7% sensitivity and 80.2% specificity. At a mean follow‐up of 4.7 ± 1.4 months, 82.2% of patients were free of AF. None of those with PV reconnections suffered from AF recurrences.

4 Conclusions

The ablation using CB2 is effective in achieving acute PVI. Real‐time assessment of PVI could be achieved during CB application in 86% of PVs. The incidence of spontaneous PV reconnection is very low, observed in just 3% of isolated PVs. TTI ≤ 65 seconds and TCI ≤ 119 seconds predicted absence of acute PV reconnection. Although they may identify effective cryoapplications in the acute phase, their performance still needs to be verified in the long term.     

Real-time dominant frequency analysis of the pulmonary vein in patients with paroxysmal atrial fibrillation

Background: Paroxysmal atrial fibrillation (PAF) can be treated with pulmonary vein isolation (PVI). A spectral analysis can identify sites of high‐frequency activity during atrial fibrillation (AF). We investigated the role of the PVs on AF perpetuation by dominant frequency (DF) analysis. Methods: Thirty‐one consecutive patients with PAF who underwent PVI were included in the prospective study. DF was calculated in each of the PVs, 16, five, and five sites in the left atrium, the coronary sinus, and the right atrium, respectively. In patients presenting sinus rhythm at the baseline, AF was induced by pacing. The PVs were then divided into two groups; PVs demonstrated the highest DF (HDF‐PV) and others. Results: One patient was excluded from the analysis because sustained AF could not be induced. AF was terminated in 43.3% (13/30) of patients during ablation. Of 92 PVs isolated during AF, 30 and 62 PVs were classified into the HDF‐PV and others, respectively. PAF was more frequently terminated by the HDF‐PV isolation compared to the others (33.3%[10/30] vs 4.8%[3/62], P = 0.0004). Interestingly, nine of the 30 HDF‐PVs showing the highest DF among all 30 regions, including extra PVs, led to AF termination in 88.9% (eight out of nine) of cases. Moreover, the HDF‐PVs isolation resulted in a greater AF cycle length prolongation than the other PVs isolation (12.1±5.0 vs 2.7±7.6 ms, P = 0.007). Conclusion: Termination of PAF was more frequently observed during ablation of the PVs with the highest DF. The PV showing high DF played an important role in the maintenance of PAF. (PACE 2012; 35:28–37)     

Use of the cryoballoon to ablate pulmonary vein‐dependent left atrial flutter

New atrial flutter (AFL) that arises after pulmonary vein isolation (PVI) by catheter or surgical ablation can originate from reconnection of a pulmonary vein (PV). Reisolation of PVs with cryoballoon ablation (CBA) for treatment of peri‐PV AFL after Maze or PVI has not previously been reported. The present case series describes use of CBA to treat post‐PVI and post‐Maze PV‐dependent AFL. In these cases, CBA was used to reisolate the PVs and terminate AFL without requiring additional lesion sets for treatment of AFL.     

A novel double cryoballoon strategy in persistent atrial fibrillation: a pilot study

Aims

Cryoballoon technology is a promising technique in paroxysmal atrial fibrillation (AF) ablation. However, success rates in patients with persistent AF have not been convincing. There is a trend toward performing more extensive procedures that are referred to as ‘pulmonary vein isolation plus.’ To combine pulmonary vein isolation (PVI) and antral substrate modification, we used both the 23-mm and 28-mm cryoballoon in a single approach in patients with persistent AF.

Methods and results

33 consecutive patients (26 men, age 60?±?10?years, LA size 44?±?5?mm) with persistent AF were prospectively included. All patients underwent the “double balloon strategy:” at least two applications at each pulmonary vein (PV) using the smaller 23-mm balloon to isolate the PV at the ostial level plus at least one additional freeze by the 28-mm balloon at the wide PV antral level. 7-day Holter monitors were performed during follow-up at 1, 3, 6, 9, 12, 18 and 24?months post-ablation. 131 of 133 PVs were targeted and isolated (98.4?%). A mean of 14?±?2 cryoballoon applications per patient or 3.5?±?1.5 applications per vein were performed. After a single procedure and mean follow-up of 15?±?3?months, 69.7?% of patients remained in sinus rhythm (3-month blanking period). There were no major complications.

Conclusions

In persistent AF, the “double balloon strategy;” combining the small and large cryoballoon allowed ostial PV isolation followed by antral cryoablation is feasible, safe and associated with a favorable outcome.     

Time course of adenosine-induced pulmonary vein reconnection after isolation: implications for mechanism of dormant conduction

Background: Adenosine (ADO) has been proposed to reconnect isolated pulmonary veins (PVs) postablation through hyperpolarization of damaged myocytes in an animal model. However, PV reconnection can occur via ADO‐mediated sympathetic activation. We sought to determine the mechanism of ADO‐induced PV reconnection in the clinical setting by characterizing its time course and location in patients undergoing PV isolation. Methods: Seventy‐four patients (61 male; age 61 ± 10 years) undergoing PV isolation for atrial fibrillation (54 [73%] paroxysmal and 19 [27%] persistent) were studied. After each PV was isolated, a 12‐mg intravenous bolus of ADO was administered and onset, offset, and location of ADO‐induced PV reconnection and onset and offset of bradycardia were analyzed. Results: In 22 (30%) patients, ADO‐induced PV reconnection occurred in 34 of 270 (13%) PVs. In 24 (71%) PVs, the duration of ADO‐induced reconnection exceeded that of bradycardia. The onset of ADO‐induced reconnection occurred before the onset of bradycardia in 10 (30%) PVs and during bradycardia in 23 (70%) PVs. No PVs exhibited onset of reconnection after resolution of bradycardia. Common sites of PV reconnection included the carinal region (41% of right PVs and 29% of left PVs) and left PV‐atrial appendageal ridge region (35% of left PVs). Conclusions: ADO‐induced PV reconnection occurs during the bradycardic phase of the ADO bolus response and not during the late tachycardic phase. ADO‐induced PV dormant conduction is closely associated with the negative dromotropic effects of ADO and suggests that hyperpolarization of the resting membrane is the unifying mechanism. (PACE 2012;XX:1–8)     

Clinical Impact of an Open‐Irrigated Radiofrequency Catheter with Direct Force Measurement on Atrial Fibrillation Ablation

Background: Electrode‐tissue contact is crucial for adequate lesion formation in radiofrequency catheter ablation (RFCA). Objective: We assessed the impact of direct catheter force measurement on acute procedural parameters during RFCA of atrial fibrillation (AF). Methods: Fifty consecutive patients (28 male) with paroxysmal AF who underwent their first procedure of circumferential pulmonary vein (PV) isolation (PVI) were assigned to either RFCA using (1) a standard 3.5‐mm open‐irrigated‐tip catheter or (2) a catheter with contact force measurement capabilities. Using the endpoint of PVI with entry and exit block, acute procedural parameters were assessed. Results: Procedural data showed a remarkable decline in ablation time (radiofrequency time needed for PVI) from 50.5 ± 15.9 to 39.0 ± 11.0 minutes (P = 0.007) with a reduction in overall procedure duration from 185 ± 46 to 154 ± 39 minutes (P = 0.022). In parallel, the total energy delivered could be significantly reduced from 70,926 ± 19,470 to 58,511 ± 14,655 Ws (P = 0.019). The number of acute PV reconnections declined from 36% to 12% (P = 0.095). Conclusions: The use of contact force sensing technology is able to significantly reduce ablation and procedure times in PVI. In addition, energy delivery is substantially reduced by avoiding radiofrequency ablation in positions with insufficient surface contact. Procedural efficacy and safety of this new feature have to be evaluated in larger cohorts. (PACE 2012; 35:1312–1318)     

Blocking the pulmonary vein to left atrium conduction in addition to the entrance block enhances clinical efficacy in atrial fibrillation ablation

Background: The unidirectional pulmonary vein (PV) to left atrium (LA) conduction after achieving PV entrance block has not been evaluated. Methods: Circumferential PV isolation was performed in 573 consecutive patients with atrial fibrillation (AF). The unidirectional PV to LA conduction and its influence on clinical outcomes were evaluated. Results: A total of 341 ipsilateral PVs (29.7%) with spontaneous activities (SAs) were documented in 231 patients (40.3%). The unidirectional PV to LA conduction was confirmed in 11 ipsilateral PVs (3.2%) of 11 patients (4.8%). Patients were classified to three groups: Group A (had unidirectional PV to LA conduction during SAs), Group B (with SAs but without PV to LA conduction), and Group C (without SAs). During a 30‐minute observation, the reconnection incidence was higher in Group A (45.4%) than in Group B (13.9%, P = 0.042) and Group C (11.5%, P = 0.018). The reconnection time was shorter in Group A (10.8 ± 9.8 minutes) than that in Group B (20.7 ± 8.0 minutes, P = 0.037) and Group C (21.2 ± 8.2 minutes, P = 0.022). All 11 PVs were successfully isolated and bidirectional block was achieved. Conclusion: Unidirectional entrance block with SAs in PVs may not be a good indication of complete PV isolation. Bidirectional block of the PV‐LA junction can reduce the acute PV reconnection and may reduce the chronic AF recurrence in patients undergoing circumferential PV isolation.(PACE 2012; 1–8)     

Mapping and Isolation of the Pulmonary Veins Using the PVAC Catheter

Objectives: We aimed to investigate the feasibility, efficacy, and safety of the pulmonary vein ablation catheter (PVAC) catheter (a novel multielectrode catheter using duty‐cycled bipolar and unipolar radiofrequency energy, Medtronic, Minneapolis, MN, USA) to completely isolate the pulmonary veins (PVs). Methods: Twenty‐seven patients (60 ± 8 years) with paroxysmal atrial fibrillation (AF) underwent PV isolation with the PVAC catheter. PVAC was used for both mapping and isolation of the PVs (PVAC‐guided ablation). After PVAC ablation, presence/absence of PV potentials (PVP) was verified using a conventional circular mapping catheter. In case of residual PVP on the circular catheter, PVAC ablation was continued. Results: After PVAC‐guided ablation 99 of 106 PVs (93%) and 21 of 27 patients (78%) were proven to be isolated. Failure to isolate was due to a mapping failure in four right‐sided PVs and a true ablation failure in three right‐sided PVs. After continued PVAC ablation, 103 of 106 PVs (97%) and 25 of 27 patients (93%) were shown to be isolated. The total procedural time from femoral vein access to complete catheter withdrawal was 176 ± 25 minutes. The actual dwelling‐time of the PVAC within the left atrium was 102 ± 37 minutes. Esophageal T° rise to >38.5° occurred in nine of 19 monitored patients (47%). Conclusions: (1) PVAC‐guided ablation (i.e., mapping and ablation with a single catheter) results in isolation of all PVs in 73% of the patients. (2) An additional circular mapping catheter is required to increase complete isolation rate to 93% of the patients. (3) Given the esophageal T° rise in almost 50% of patients, safety precautions are needed. (PACE 2010; 33:168–178)     

Computational Method to Predict Esophageal Temperature Elevations During Pulmonary Vein Isolation

Background: The esophagus is in close proximity to the posterior wall of the left atrium, which renders it susceptible to thermal injury during radiofrequency (RF) ablation procedures for atrial fibrillation (AF). Real‐time assessment of esophageal position and temperature (T °) during pulmonary vein (PV) isolation has not been extensively explored. Objective: To develop a protocol that allows estimation of the potential for, and avoidance of, esophageal heating. Methods: In consecutive patients who underwent PV isolation, a thermal probe was used to monitor T ° fluctuations in the esophagus during application of RF energy. The tip of the thermal probe was positioned at the level of the targeted PV and RF was discontinued for T ° rise >0.5°C. The proximity of individual PVs to the esophagus was measured from the temperature probe tip to the closest posterior part of the Lasso catheter from review of biplane projections (left anterior oblique 60° and right anterior oblique 30°). These raw distances were entered into the Pythagorean theorem and the actual distance between the esophageal thermal probe and PV antrum was determined. Results: The study cohort included 44 patients (60 ± 11 years, 61% male, 57% lone AF). The thermal probe in the esophagus was closer to the left‐sided PVs (left common pulmonary vein: 20.9 ± 13 mm, left upper pulmonary vein: 20.5 ± 11 mm, left lower pulmonary vein: 23.4 ± 10 mm) than the right‐sided ones (right common pulmonary vein: 31.0 ± 11 mm, right upper pulmonary vein: 41.9 ± 18 mm, right lower pulmonary vein: 34.5 ± 16 mm). A T ° increase >0.5°C occurred during 116/1,495 (7.8%) deliveries. A T ° rise was more likely during ablation of left‐sided PVs than right‐sided PVs (55% vs 10%, P < 0.0001) and when RF was delivered ≤24 mm from the esophagus (sensitivity 91%, specificity 81%, positive predictive value 75%, and negative predictive value 93%). Conclusion: A thermal probe placed in the esophagus provides real‐time T ° monitoring and anatomic localization. A T ° rise is more likely during ablation of left PVs and during RF deliveries within 24 mm of the esophageal thermal probe. (PACE 2010; 33:1239–1248)     

Normal pulmonary veins anatomy is associated with better AF-free survival after cryoablation as compared to atypical anatomy with common left pulmonary vein

Background: Pulmonary vein cryoablation (PVC) is a new approach in the treatment of recurrent atrial fibrillation (AF). Computed tomography (CT) can be used to evaluate the left atrium anatomy and PVs dimensions to facilitate the procedure. In radiofrequency procedures, some anatomic variants such as common left (CLPV) or right (CRPV) PV were reported as factors associated with technical procedure difficulties and potential long‐term complications. We hypothesized that the absence of CLPV as determined by CT would predict better AF‐free survival after PVC. Methods and results: We included 118 consecutive patients (mean age 56 ± 10 years; 77% males) with drug refractory paroxysmal (72%)/persistent (28%) AF, with more than 6 months follow‐up, who underwent PVC. On CT scanning images performed within 1 month prior to ablation, we evaluated PV anatomic patterns: presence of CLPV or CRPV. Each patient was evaluated by 24‐hour Holter monitoring within 1 and 3 months and all patients were periodically evaluated at 1, 3, and 6 months, and every 6 months thereafter. Patients were asked to record their 12‐lead electrocardiogram whenever they experienced symptoms suggestive of AF. Recurrence was defined as AF that lasted at least 30 seconds. CLPV was present in 30 (25%) patients and no patients with CRPV were identified. At the end of the 13 months follow‐up, patients with normal PVs had significantly better AF‐free survival compared to patients with CLPV (67% vs 50%, P = 0.02). The difference was present in patients with paroxysmal AF (P = 0.008) but not in patients with persistent AF (P = 0.92). Conclusion: In patients undergoing cryoballoon PV isolation for AF, the presence of normal PVs pattern is associated with better AF‐free survival as compared to atypical PV anatomy with CLPV, particularly in patients with paroxysmal AF. (PACE 2011; 34:837–843)     

Left Phrenic Nerve Injury during Cryoballoon Ablation of the Left Superior Pulmonary Vein

Transcatheter ablation of the pulmonary veins (PVs) has been established as a therapeutic option for patients with symptomatic atrial fibrillation. Cryothermal energy is an alternative energy source that has been developed to overcome some of the disadvantages of radiofrequency ablation. The major complication of the cryoballoon technique seems to be right‐sided phrenic nerve injury (PNI) following ablation of the right superior PV. This case report describes a left‐sided PNI after cryoballoon ablation of the left superior PV. (PACE 2012; 35:e334–e336)     

Very Late Relapse of Atrial Fibrillation after Pulmonary Vein Isolation: Incidence and Results of Repeat Ablation

Background: There are few data about the incidence of very late (>12 months) arrhythmia relapse after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) and about the success rate of repeat ablation procedures in this population. Methods: All patients treated with PVI for paroxysmal AF were screened in the institution's electrophysiology database. Follow‐up data at 1, 3, 6, and 12 months and yearly thereafter including repetitive (7 days or 1 day) Holter electrocardiograms were assessed as well as the technique and success rate of repeat ablations. Results: Overall, 24 of 356 (6.7%) patients experienced their first AF recurrence more than 12 months after PVI. Of these 24 patients, 14 underwent reablation for paroxysmal (11 patients) or persistent AF (three patients). Repeat ablation included re‐PVI in all 14 patients (43 of 48 initially isolated PVs with recovered left atrial–PV conduction). Ablation of complex fractionated atrial electrograms or left/right atrial lines was performed in eight patients, including the three patients with persistent AF. During follow‐up of 15.1 ± 9 months after the second ablation, 10 of 14 (71%) reablated patients remained in sinus rhythm. Conclusions : After PVI for paroxysmal AF, very late arrhythmia recurrence occurs in less than 10% of patients. The success rate of the repeat procedure is high. (PACE 2010; 33:1258–1263)     

Alleviation of Pulmonary Hypertension by Cardiac Resynchronization Therapy is Associated with Improvement in Central Sleep Apnea

Background: Recent studies have demonstrated that cardiac resynchronization therapy (CRT) reduces sleep apnea in heart failure (HF); however, the mechanism of benefit remains unclear. Methods: Overnight polysomnography (PSG) was performed in consecutive HF patients who were scheduled for CRT implant. Patients with sleep apnea defined by an apnea‐hypopnea index (AHI) of >10/hour were recruited and underwent echocardiogram examination at baseline and 3 months after CRT. Results: Among 37 HF patients screened, 20 patients (54%) had sleep apnea and 15 of them consented for the study. After 3 months of CRT, there was a significant improvement in New York Heart Association functional class (3.1 ± 0.1 vs 2.1 ± 0.1, P < 0.01), quality‐of‐life (QoL) score (62.9 ± 3.3 vs 56.1 ± 4.5, P = 0.02), left ventricular ejection fraction (LVEF, 28.8 ± 2.5% vs 38.1 ± 2.3%, P < 0.01), and reduction in pulmonary artery systolic pressure (PASP, 41.0 ± 2.7 vs 28.6 ± 2.2 mmHg; P < 0.01) compared with baseline. Repeated PSG after CRT demonstrated a reduction in the duration of arterial oxygen desaturation ≤95% (251.2 ± 36.7 vs 141.0 ± 37.1 minutes), AHI (27.5 ± 4.7 vs 18.1 ± 3.0, P = 0.05), and number of central sleep apnea (CSA) (7.8 ± 2.6 vs 3.0 ± 1.3/hour, P = 0.03), but not number of obstructive sleep apnea (OSA, 8.6 ± 3.3 vs 7.2 ± 2.3/hour, P = 0.65) compared to baseline. Percentage change in PASP was significantly correlated with percentage changes in LVEF (r=?0.57, P = 0.04), AHI (r = 0.5, P = 0.05), and number of CSA episodes (r = 0.55, P = 0.02). Conclusions: The results demonstrated that CRT significantly reduces CSA in patients with HF. Importantly, we have noted a decrement of PASP correlated to drop in CSA which maybe one of the mechanisms explaining this observation. Future studies are required to confirm our finding and elucidate other possible mechanisms in this regard.     

Right ventricular rapid pacing in catheter ablation of atrial fibrillation: a novel application for cryoballoon pulmonary vein isolation

Background  Cryoballoon ablation (Arctic Front, Cryocath™) represents a novel technology for pulmonary vein isolation (PVI). The initial phase of a freeze is crucial for cryolesion formation which is determined by local temperature depending on blood flow. We investigated the impact of right ventricular rapid pacing (RVRP) on temperature kinetics in patients (pts) with paroxysmal atrial fibrillation (PAF). Methods and results  Right ventricular rapid pacing was performed from the RV apex. Absolute minimal temperature (MT, °C), temperature slopes [time (s) to 80% MT; dT/dt), area under the curve (AUC) and arterial blood pressure (ABP, mmHg) were compared (group I: with RVRP vs. group II: without RVRP). RVRP (mean duration 55 ± 7 s) was performed in 11 consecutive PAF pts (41 PVs, age 58 ± 9 years, LA size 44 ± 6 mm, normal ejection fraction). Only freezes with identical balloon positions were analyzed (11/41 PVs). RVRP (cycle length 333 ± 3 ms) induced a significant drop in ABP (group I: 45 ± 3 mmHg vs. group II: 100 ± 18 mmHg, p < 0.001). MT was not different between group I and group II (−45.0 ± 4.4 vs. −44.3 ± 3.4°C, p = 0.46), whereas slope (38.0 ± 4.6 s vs. 51.6 ± 14.4 s, p = 0.0034) and AUC (1090 ± 4.6 vs. 1181 ± 111.2, p = 0.02) was significantly changed. In one pt, a ventricular tachycardia was induced. PVI was achieved in 41/41 PVs. Conclusion  Right ventricular rapid pacing significantly accelerates cryoballoon cooling during the initial phase of a freeze possibly suggesting improved cryolesions. K. H. Kuck is a current member of the European Cryocath advisory board. K. R. J. Chun received travel grants from Cryocath.     

Late Gadolinium Enhancement of the Esophagus is Common on Cardiac MR Several Months after Pulmonary Vein Isolation: Preliminary Observations

Background: Pulmonary vein isolation (PVI) as a treatment for atrial fibrillation (AF) is commonly performed. This procedure can damage the esophagus. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) offers noninvasive assessment of scar. We sought to examine the prevalence of esophageal hyperenhancement on LGE‐CMR prior to and following PVI. Methods: Seventy‐four patients underwent LGE‐CMR prior to and 1.7 ± 1.9 months post PVI for AF. Transmural esophageal hyperenhancement was visually assessed. The pre‐ and post PVI esophageal position was measured, relative to the vertebral body. Results: Prior to PVI, 3% (2/74) of patients had esophageal LGE on CMR. At post‐PVI follow‐up, 30% (23/74) of the studies demonstrated new esophageal hyperenhancement adjacent to an ablation site. Most (74%, 17/27) positive esophageal LGE studies were performed >30 days after PVI, while no (0/9) studies performed >2 months post PVI were positive for esophageal hyperenhancement. The presence of post‐procedural esophageal hyperenhancement was not associated with longer ablation time (P = 0.42), use of an irrigated catheter (74% with LGE vs 47% without, P = 0.16), right‐sided esophageal location (56% with LGE vs 39% without, P = 0.17), size of left atrium cavity (58 ± 8 mm with LGE vs 61 ± 10 mm without, P = 0.15), or the timing of the LGE‐CMR study after PVI (36 ± 10 days with LGE vs 60 ± 66 days without, P = 0.09). Conclusion: Though rare before PVI, new esophageal LGE is seen in almost one‐third of patients after PVI. The clinical implications to remain to be explored, but clinicians should be aware of this frequent imaging finding. (PACE 2010; 33:661–666)     

Unipolar and Bipolar Electrogram Characteristics Predict Exit Block during Pulmonary Vein Antral Isolation

Introduction: The usefulness of unipolar electrograms (EGMs) has been reported in assessing lesion transmurality and conduction block along ablation lines. It is unknown whether unipolar and bipolar EGM characteristics predict exit block during pulmonary vein isolation (PVI) procedures. Methods and Results: Twenty patients (63 ± 7 years; 14 males [70%]) undergoing PVI with a circular mapping catheter (CMC) placed outside each PV ostium were retrospectively studied. After entrance block was achieved, pacing at each bipole around the CMC was performed to assess for absence of atrial capture (exit block). Bipolar EGMs recorded before pacing were examined for voltage, duration, fractionation, and monophasic morphology. Unipolar EGMs were examined for positive and negative amplitude, PQ segment elevation, fractionation, and monophasic morphology. The association of these parameters with atrial capture (absence of exit block) at each site was analyzed. After achievement of entrance block, only 23 of 64 PV antra (36%) exhibited exit block. Unipolar EGMs at sites with persistent capture were more likely to be fractionated and had larger negative deflections. Bipolar EGMs at sites with persistent capture showed higher amplitude, longer duration, were more likely to be fractionated, and were less likely to be monophasic. In a multivariate logistic regression model, bipolar and unipolar fractionation, bipolar duration, and lack of bipolar monophasic morphology were independently associated with persistent atrial capture. Conclusion: Specific unipolar and bipolar EGM characteristics are associated with left atrium capture after PV antral isolation. These parameters might be useful in predicting the need for further ablation to achieve exit block. (PACE 2012; 35:1294–1301)     

Segmental pulmonary vein ablation: success rates with and without exclusion of areas adjacent to the esophagus

Background: Catheter ablation has become the first line of therapy in patients with symptomatic recurrent, drug‐refractory atrial fibrillation (AF). The occurrence of an atrioesophageal fistula is a rare but serious complication after AF‐ablation procedures. This risk is even present during segmental pulmonary vein (PV) ablation procedures because the esophagus does frequently have a very close anatomical relationship to the right or left PV ostia. The aim of the present study was to analyze whether the exclusion of areas adjacent to the esophagus does have a significant effect on the success rates after segmental pulmonary vein ablation procedures. Methods: Forty‐three consecutive patients with symptomatic paroxysmal AF were enrolled in this study. In all patients, a segmental PV ablation procedure was performed. The procedures were facilitated by a 3D real‐time visualization of the circumferential mapping catheter placed in the pulmonary veins using the NavX? system (St. Jude Medical, St. Paul, MN, USA; open irrigated tip ablation catheter; 43°C; 30 W). In 21 patients, a complete ostial PV isolation was attempted regardless of the anatomical relationship between the ablation sites and the esophagus (group A). In the remaining 22 patients, the esophagus was marked by a stomach tube and areas adjacent to the esophagus were excluded from the ablation procedure (group B). After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, and 6 months after the ablation procedure. Results: The segmental pulmonary vein ablation procedure could be performed as planned in all patients. In group A, all pulmonary veins could be isolated successfully in 14 out of 21 patients (67%). A mean number of 3.7 pulmonary veins (SD ± 0.5 PVs) were isolated per patient. The main reasons for an incomplete PV isolation were: small diameter of the PVs, side branches close to the ostium, or poorly accessible PV ostia. In group B, all PVs could be isolated successfully in only 12 out of 22 patients (55%; P = 0.54). A mean number of 3.2 PVs (SD ± 0.9 PVs) were isolated per patient (P = 0.05). This was mostly due to a close anatomical relationship to the esophagus. The ablation strategy had to be modified in 16/22 patients in group B because of a close anatomical relationship between the left (n = 10) or right (n = 6) PV ostia and the esophagus. After 3 months, the percentage of patients free from an AF recurrence was not significantly different between the two groups (90% vs 95%; P = 0.61). After 6 months, there was no significant difference between the success rates either (81% vs 82%; P = 1.0). There were no major complications in both groups. Conclusions: The exclusion of areas adjacent to the esophagus results in a moderately higher percentage of incompletely isolated PVs. However, it does not have a significant effect on the AF recurrence rate during short‐term and mid‐term follow‐up.     

Intraprocedural imaging of left atrium and pulmonary veins: a comparison study between rotational angiography and cardiac computed tomography

Background: Atrial fibrillation (AF) ablation is facilitated by anatomical visualization of the left atrium (LA) and the pulmonary veins (PVs). The purpose of this study was to compare accuracy, radiation exposure, and costs between three‐dimensional atriography (3D‐ATG) and cardiac computed tomography (CCT). Methods: Seventy patients with an indication for AF ablation were included. Contrast‐enhanced CCT was performed preoperatively for all patients. In addition, intraoperative 3D‐ATG was performed with contrast medium injection either indirectly into the pulmonary arteries during a breath‐hold (Ind.‐RTA, n = 25) or directly into the LA, during adenosine‐induced asystole (Ad.‐RTA, n = 23), or rapid ventricular pacing (VP‐RTA, n = 22). We evaluated vertical ostial PV diameters and LA volume, time needed to perform, radiation exposure, and procedural cost for each imaging method. Results: The correlation coefficient between 3D‐ATG and CCT for the ostial PV diameters was r = 0.83 for Ind.‐RTA, 0.91 for Ad.‐RTA, and 0.88 for the VP‐RTA method (P > 0.05). The volume correlations were r = 0.87 for Ind.‐RTA, 0.82 for Ad.‐RTA, and 0.8 for VP‐RTA (P > 0.05). Time to perform was 13 ± 5 minutes for ATG and 46 ± 9 minutes for CCT (P < 0.05). Effective radiation dose was 2.2 ± 0.2 mSv for ATG and 20.4 ± 7.4 mSv for CCT (P < 0.05). The procedural cost was estimated at 91–95 € for ATG and at 126–151 € for CCT. Conclusions: 3D‐ATG is an intraprocedural imaging modality that provides anatomical accuracy comparable to that of CCT with significantly lower radiation dose, in less time and at less financial expense (PACE 2011; 34:315–322)     

Effect of Mitral Isthmus Block on Development of Atrial Tachycardia Following Ablation for Atrial Fibrillation

Background: Successful mitral isthmus (MI) ablation may reduce recurrence of atrial fibrillation (AF) and macro‐reentrant atrial tachycardia (AT) after pulmonary vein isolation (PVI) for AF. Objective: To determine if achieving bidirectional MI conduction block (MIB) during circumferential pulmonary vein ablation (CPVA) plus left atrial linear ablation (LALA) affects development of AT. Methods: Sixty consecutive patients with persistent (n = 25) or paroxysmal (n = 35) AF undergoing CPVA plus LALA at the MI and LA roof were evaluated in a prospective, nonrandomized study. Results: PVI was achieved in all patients. Bidirectional MI block was achieved in 50 of 60 patients (83%). During 18 ± 5 months follow‐up, 12 patients (20%) developed recurrent AF and 15 (25%) developed AT. Patients in whom MIB was not achieved at initial ablation had four times higher risk of developing AT (P = 0.008, 95% confidence interval 1.43–11.48) versus patients with MIB. In 12 patients with AT undergoing repeat ablation, 22 ATs were identified, with reentry involving the MI in nine, the LA roof in six, and the ridge between the LA appendage and left PVs in seven. In patients with MIB at initial ablation, recovery of MI conduction was seen in eight of 13 undergoing repeat ablation. Conclusions: AT occurring after CPVA plus LALA is often due to incomplete MI ablation, but may also occur at the LA roof, and ridge between the LA appendage and left PVs. Failure to achieve MI block increases the risk of developing AT. Resumption of MI conduction may also be a mechanism for AT recurrence. (PACE 2010; 460–468)