Can phrenic nerve injury be anticipated by larger cryoballoons?

Recently, a novel size-adjustable cryoballoon has been introduced in clinical practice, which can be inflated to two different diameters (28 and 31 mm). The 31 mm cryoballoon is specifically designed to achieve better contact with remodeled pulmonary veins (PVs) that have wider ostia while avoiding deep cannulation, thereby potentially reducing the risk of phrenic nerve injury (PNI) associated with deep balloon cannulation. However, we encountered two cases of PNI during cryoballoon ablation using the novel system among our initial 25 consecutive case series. Herein, we present two cases that exhibited PNI during freezing of the right superior PV with a size-adjustable balloon. While larger balloons are expected to create a larger area of isolation, the safety of this novel balloon system needs to be evaluated in a large-scale clinical study.

The impact of left atrium size on selection of the pulmonary vein isolation method for atrial fibrillation: Cryoballoon or radiofrequency catheter ablation.

BACKGROUND: Pulmonary vein isolation (PVI) is the cornerstone of ablation strategies for atrial fibrillation (AF), and noninferiority of cryoballoon (CB) over radiofrequency (RF) ablation has been previously reported. One of the risk factors of recurrence is left atrium (LA) enlargement. This study aimed to analyze the impact of LA enlargement on the selection of CB or RF ablation for AF patients. METHODS: A total of 2,224 AF patients (64.4 ±â€¯10.7 years, 65.5% male) who underwent PVI were analyzed retrospectively. Left atrial diameter (LAD) and volume (LAV) were measured using echocardiography before the procedures. LA enlargement was defined as LAD ≥40 mm and LAV index (LAVI) ≥35 mL/m2. Patients undergoing CB and RF ablation were propensity score matched, and 376 matched pairs were evaluated. RESULTS: Cox proportional hazard analysis revealed that LAD (95% CI, 1.01-1.05), LAV (95% CI, 1.01-1.02), and LAVI (95% CI, 1.01-1.03) were independent predictors of recurrence. CB showed equivalent clinical outcomes to those of RF with shorter procedure time required for patients without LA enlargement. CB was inferior to RF in patients with LA enlargement (LAD, 74.5% vs 84.6%, P = .028; LAVI, 74.7% vs 83.4%, P = .015), and large LAVI was associated with a higher prevalence of non-PV foci (35% vs 29%, P = .008). CONCLUSIONS: CB ablation may be recommended for patients without enlarged LA based on the short procedure time and efficacy, whereas RF would be more appropriate in large LAs. LAVI may be a valuable reference to predict PVI outcomes and in selecting the ablation method.

Association between the locations of non-pulmonary vein triggers and ablation outcomes in repeat procedures after cryoballoon ablation of paroxysmal atrial fibrillation.

PURPOSE: We examined the characteristics of non-pulmonary vein (PV) triggers in repeat ablation after cryoballoon ablation for paroxysmal atrial fibrillation (PAF). METHODS: This study evaluated 119 patients undergoing a second ablation procedure for recurrent atrial tachyarrhythmia (ATA) after cryoballoon PV isolation (CB-PVI) for PAF. RESULTS: Fifty-three of 119 (45%) patients had PV reconnection. All reconnected PVs were isolated. No non-PV triggers were elicited in 42/119 (35%) patients (NNPV group). In 77/119 (65%) patients, 139 isoproterenol-induced non-PV triggers, including 45 triggers that initiated AF, were identified. Non-PV triggers initiating AF were observed at the superior vena cava (SVC), left atrial posterior wall (LAPW) including the PV antra, interatrial septum, right atrium, left atrial appendage/mitral anulus, and coronary sinus in 14 (12%), 10 (8%), 8 (7%), 7 (6%), 4 (3%), and 2 (2%) patients, respectively. Non-PV triggers originated from only the SVC and/or LAPW including the PV antra, and the SVC and/or LAPW was isolated in 18/119 (15%) patients (SVC/LAPW group). Non-PV triggers originating from other sites were focally ablated in 59/119 (50%) patients (OS group). During a median 461 days of follow-up, 39/42 (93%), 17/18 (94%), and 38/59 (64%) patients in the NNPV, SVC/LAPW, and OS groups, respectively, remained ATA recurrence-free. The recurrence rate was higher in the OS group than in the NNPV (P = 0.005) or SVC/LAPW groups (P = 0.042). CONCLUSIONS: Over half of patients had non-PV triggers at subsequent ablation after CB-PVI. Non-PV triggers from the SVC/LAPW can be eliminated more successfully than triggers from other sites.

Cryoballoon versus radiofrequency ablation for paroxysmal atrial fibrillation in hemodialysis patients.

INTRODUCTION: Little evidence exists regarding cryoballoon ablation (CBA) of paroxysmal atrial fibrillation (PAF) in hemodialysis (HD) patients. We compared CBA and radiofrequency ablation (RFA) of PAF in HD patients, referring to CBA of PAF in non-HD patients. METHODS AND RESULTS: This historical cohort study examined 88 patients who underwent catheter ablation of PAF, including 21 HD patients with a second-generation 28-mm cryoballoon (CB-HD group), 17 HD patients with a non-force-sensing radiofrequency catheter (RF-HD group), and 50 non-HD patients with a cryoballoon (CB-non-HD group). Pulmonary vein (PV) isolation alone aside from cavotricuspid isthmus ablation was performed in 14 (67%) in the CB-HD group, 12 (71%) in the RF-HD group, and 36 (72%) in the CB-non-HD group (P = 0.95), without isoproterenol-induced non-PV triggers. Non-PV trigger ablation was added to the other patients. The Kaplan-Meier estimated 1-year freedom from atrial tachyarrhythmia recurrence without antiarrhythmic drugs after a single procedure was 76%, 59%, and, 92% in the CB-HD, RF-HD, and CB-non-HD groups, respectively (P = 0.002). The mean procedure time was shorter in the CB-HD group than in the RF-HD group (127 vs. 199 min; P < 0.001). In the second procedure, the median number of reconnected pulmonary veins was 0.5 in the CB-HD group versus 2.0 in the RF-HD group (P = 0.17). CONCLUSION: For PAF in HD patients, CBA showed a comparable single-procedure efficacy to that of RFA with a short procedure time. CBA may be a reasonable initial procedure for HD patients suffering from symptomatic PAF.

Characteristics of the nonpulmonary vein foci induced after second-generation cryoballoon ablation for paroxysmal atrial fibrillation.

INTRODUCTION: Pulmonary vein isolation (PVI) using cryoballoon is effective for patients with paroxysmal atrial fibrillation (PAF); however, few reports have evaluated the non-pulmonary vein (PV) foci after cryoballoon ablation. We aimed to evaluate the characteristics of non-PV foci and predictors of atrial fibrillation (AF) recurrence after cryoballoon ablation. METHODS AND RESULTS: This was a single-center retrospective study of 647 patients with PAF who underwent initial PVI using a second-generation cryoballoon. After PVI, all patients underwent high-dose isoproterenol infusion to assess the existence of non-PV foci. Non-PV foci were observed in 211 patients (32.6%), which were most frequently observed in the superior vena cava. Higher age (odds ratio [OR] = 1.02; 95% confidence interval [CI] = 1.00-1.04; P = .025), female sex (OR = 1.65; 95% CI = 1.13-2.41; P = .009), and lower body mass index (OR = 0.95; 95% CI = 0.89-1.00; P = .049) were significantly associated with non-PV foci. The existence of non-PV foci was an independent predictor of AF recurrence (Hazard's ratio = 1.70; 95% CI = 1.12-2.60; P = .014). When non-PV foci were mappable and successfully ablated, patients with non-PV foci showed similar outcomes with those without non-PV foci (1-year AF-free survival rates of 88.5% vs 91.5%; P = .338). Conversely, when we failed to detect and eliminate non-PV foci because they had multiple origins and were not consistently inducible (multichanging non-PV foci), the 1-year AF-free survival rate was 56.4% even after substrate modification. CONCLUSION: Non-PV foci were observed in one-third of patients with PAF after cryoballoon ablation and were associated with AF recurrence. Catheter ablation for non-PV foci was effective when they were mappable; however, multichanging non-PV foci were associated with worse prognosis.

Differences in the electrophysiological findings of repeat ablation between patients who first underwent cryoballoon ablation and radiofrequency catheter ablation for paroxysmal atrial fibrillation.

INTRODUCTION: Several studies have revealed that second-generation cryoballoon (CB)-based pulmonary vein (PV) isolation is noninferior to radiofrequency (RF)-based PV isolation for patients with drug-refractory paroxysmal atrial fibrillation (AF). However, electrophysiological differences in repeat ablation remain unclear. METHODS AND RESULTS: This study examined electrophysiological differences during the repeat ablation between patients who first underwent RF catheter ablation and CB ablation; PV durability and non-PV AF foci were assessed for these patients. We enrolled 919 and 491 patients who underwent CB ablation (CB group) and RF catheter ablation (RF group), respectively, for paroxysmal AF between January 2013 and June 2017 at our institution. PV isolation using RF ablation involved the left atrium (LA) antrum and part of the LA posterior wall. After 2 years of follow-up, 62 and 80 patients in the CB and RF groups, respectively, underwent repeat ablation. PV reconnections were more frequent in the RF group than in the CB group (left superior PV: 46.2% and 14.5%, P < .001; left inferior PV: 35.0% and 11.2%, P = .001; right superior PV: 40.0% and 22.6%, P = .031; right inferior PV: 36.2% and 19.4%, P = .039; PVs: 39.8% and 16.9%, P < .001). LA AF foci were more frequent in the CB group than in the RF group (27.4% and 7.5%; P = .002). Other non-PV foci were prevalent in both groups. CONCLUSION: Fewer LA-PV reconnections occurred with CB ablation. However, extensive PV isolation may eliminate many LA AF foci.

Identification of an epicardial slow conduction channel using ripple mapping in ablation of postinfarct ventricular tachycardia.

An 82-year-old man underwent redo catheter ablation of ventricular tachycardia (VT) after anterior infarction. A ripple mapping conducting channel (RMCC) was identified within the anterior scar in the left ventricular epicardium during sinus rhythm. Along the RMCC, delayed potentials during sinus rhythm, a good pace map with a long stimulus to the QRS interval, and mid-diastolic potentials during VT were recorded, and epicardial ablation at this site eliminated the VT. These findings suggested that the RMCC in the epicardial scar served as a critical isthmus of the postinfarct VT, and ablation targeting the RMCC was effective.

Propensity-matched comparison of cryoballoon and radiofrequency ablation for atrial fibrillation in elderly patients.

BACKGROUND: Pulmonary vein isolation (PVI) with a cryoballoon (CB) is an effective treatment for atrial fibrillation (AF). The efficacy of CB PVI for elderly patients with AF remains unclear. OBJECTIVE: We aimed to analyze the clinical outcomes of CB ablation compared with radiofrequency (RF) ablation in elderly patients with AF. METHODS: This was a single-center retrospective study of 305 patients older than 75 years with paroxysmal and persistent AF who underwent PVI between January 2012 and August 2017. Patients were matched according to propensity scores in a logistic regression model. The end point of this study was AF/atrial tachycardia recurrence at 12-month follow-up. RESULTS: In total, 198 patients (99 matched pairs) were analyzed. The ratio of paroxysmal AF was 83%, and the mean age was 78 ± 2 years. The mean procedure time was significantly lower in the CB group (134 ± 62 minutes vs 190 ± 51 minutes; P < .001). There was no significant difference between the groups in terms of success rate at 12 months after the procedure (CB 80.5% vs RF 79.4%; P = .72) or incidence of complications (CB 12% vs RF 16%; P = .80). Kaplan-Meier estimates revealed no significant difference between clinical outcomes after PVI with a CB or RF for elderly patients with non-pulmonary vein foci that were all successfully ablated (CB 68.8% vs RF 68.4% at 12 months; P = .835). CONCLUSION: The efficacy of PVI with a CB might be comparable to that of PVI with RF in AF patients older than 75 years and involve a shorter procedure time.