Incidence and Factors Associated With the Occurrence of Pulmonary Vein Narrowing After Cryoballoon Ablation

Comprehensive review of pulmonary vein stenosis post-atrial fibrillation ablation: diagnosis, management, and prognosis

Pulmonary vein stenosis (PVS) can occasionally occur in the follow-up after pulmonary vein isolation (PVI) for atrial fibrillation (AF). During PVI, ablation is performed at the PV ostium or distal part, leading to tissue damage. This damage can result in fibrosis of the necrotic myocardium, proliferation, and thickening of the vascular intima, as well as thrombus formation, further advancing PVS. Mild-to-moderate PVS often remains asymptomatic, but severe PVS can cause symptoms, such as dyspnea, cough, fatigue, decreased exercise tolerance, chest pain, and hemoptysis. These symptoms are due to pulmonary hypertension and pulmonary infarction. Imaging evaluations such as contrast-enhanced computed tomography are essential for diagnosing PVS. Early suspicion and detection are necessary, as underdiagnosis can lead to inappropriate treatment, disease progression, and poor outcomes. The long-term prognosis of PVS remains unclear, particularly regarding the impact of mild-to-moderate PVS over time. PVS treatment focuses on symptom management, with no established definitive solutions. For severe PVS, transcatheter PV angioplasty is performed, though the risk of restenosis remains high. Restenosis and reintervention rates have improved with stent implantation compared with balloon angioplasty. The role of subsequent antiplatelet therapy remains uncertain. Dedicated evaluation is essential for accurate diagnosis and appropriate management to avoid significant long-term impacts on patient outcomes.

Incidence of pulmonary vein stenosis in two types of cryoballoon systems

Background

Currently, two types of cryoballoon (CB) systems are available for catheter ablation of atrial fibrillation (AF). Since the POLARx (Boston Scientific) is softer during freezing than the Arctic Front Advance Pro (AFA-Pro; Medtronic), it tends to go more deeply into the pulmonary vein (PV), risking PV stenosis.

Methods

Ninety-one patients underwent initial CB ablation for paroxysmal AF (AFA-Pro 56; POLARx 35). Twenty-six from each group were extracted using propensity score matching. The PV cross-sectional area (PVA) was measured by tracing the area within the PV plane at 5-mm intervals from the PV ostium in a distal direction for 20 mm or to the bifurcation in each PV. The PVA was compared before and 3 months after ablation.

Results

Time to balloon temperatures of -30 and - 40°C was significantly shorter and the nadir temperature was significantly lower with POLARx than with AFA-Pro. In the left inferior (LI) PV and right superior (RS) PV, the freezing balloon position was significantly deeper in POLARx than in AFA-pro. The freezing position in RSPV with mild to moderate narrowing was deeper than those without (10.2 ± 3.3 mm vs. 8.2 ± 1.8 mm, p = .01). In RSPV, the reduction of PVA tended to be greater with the POLARx than with the AFA-Pro (26.1% ± 14.1% vs. 19.9% ± 10.3%, p = .07).

Conclusion

There was no significant difference in the incidence of PV stenosis between POLARx and AFA-Pro. However, if POLARx goes deep into the PVs, we will still have to be careful.

Changes in pulmonary vein size and narrowing depend on the cardiac cycle before and after pulmonary vein isolation

Accurate measurement of the pulmonary vein dimension (PVD) is important for determining stenosis and efficacy following pulmonary vein isolation (PVI). Little is known about the quantitative evaluation of the impact of the cardiac cycle on pulmonary vein (PV) morphology before and after PVI. This study aims to investigate variations in the ostial size of the PV during the cardiac cycle before and after PVI and the effect of the cardiac cycle on PV stenosis and reduction rate using cardiac computed tomography (CT). Sixty-eight patients with atrial fibrillation who underwent cardiac CT before and after PVI at our institution between 23 January 2021 and 5 February 2022 were retrospectively analyzed. The maximum and minimum PVD were measured at each segment before and after the PV. Each PV was evaluated according to the PVD reduction rate (ΔPVD), calculated as follows: (1 - post-PVD/pre-PVD) × 100 (%). The average dimension of all PVs at the end-diastolic frame was significantly reduced compared to that at the end-systolic frame before PVI. The average dimensions of the right superior and right inferior PV at the end-diastolic frame were significantly reduced compared with those at the end-systolic frame following PVI. The average reduction rate of dimension-classified stenosis of PVs, except for the left inferior PV at the end-diastolic frame, was significantly reduced compared with that at the end-systolic frame. The cardiac cycle affects PVD assessment, including PV stenosis, after PVI. PVD measurement is recommended to be unified to the end-systolic frame of the cardiac cycle to avoid underestimating PV stenosis before and after PVI, ensuring appropriate management and follow-up.

Pulmonary vein narrowing after pulsed field versus thermal ablation

AIMS

When it occurs, pulmonary vein (PV) stenosis after atrial fibrillation (AF) ablation is associated with significant morbidity. Even mild-to-moderate PV narrowing may have long-term implications. Unlike thermal ablation energies, such as radiofrequency (RF) or cryothermy, pulsed field ablation (PFA) is a non-thermal modality associated with less fibrotic proliferation. Herein, we compared the effects of PFA vs. thermal ablation on PV narrowing after AF ablation.

METHODS AND RESULTS

ADVENT was a multi-centre, randomized, single-blind study comparing PFA (pentaspline catheter) with thermal ablation-force-sensing RF or cryoballoon (CB)-to treat drug-refractory paroxysmal AF. Pulmonary vein diameter and aggregate cross-sectional area were obtained by baseline and 3-month imaging. The pre-specified, formally tested, secondary safety endpoint compared a measure of PV narrowing between PFA vs. thermal groups, with superiority defined by posterior probability > 0.975. Among subjects randomized to PFA (n = 305) or thermal ablation (n = 302), 259 PFA and 255 thermal ablation (137 RF and 118 CB) subjects had complete baseline and 3-month PV imaging. No subject had significant (≥70%) PV stenosis. Change in aggregate PV cross-sectional area was less with PFA (-0.9%) than thermal ablation (-12%, posterior probability > 0.999)-primarily driven by the RF sub-cohort (-19.5%) vs. CB sub-cohort (-3.3%). Almost half of all PFA PV diameters did not decrease, but the majority (80%) of RF PVs decreased, regardless of PV anatomic location.

CONCLUSION

In this first randomized comparison of PFA vs. thermal ablation, PFA resulted in less PV narrowing-thereby underscoring the qualitatively differential and favourable impact of PFA on PV tissue.

Pulmonary Vein Stenosis After Catheter Ablation of Atrial Fibrillation Using a Cryoballoon, Hot Balloon, or Laser Balloon

BACKGROUND

Pulmonary vein stenosis (PVS) after PV isolation (PVI) for atrial fibrillation (AF) is a severe complication that requires angioplasty. This study aimed to compare the reduction of the cross-sectional PV area (PVA) and the incidence of PVS after cryoballoon (CB)-PVI, hot balloon (HB)-PVI, or laser balloon (LB)-PVI.

METHODS AND RESULTS

A total of 320 patients who underwent an initial catheter ablation procedure for AF using a CB, HB, or LB in 2 hospitals were included. They underwent contrast-enhanced multidetector CT before and 3 months after the procedure. In all 4 PVs, the reduction in PVA was more significant in the LB group than in the CB or HB groups, respectively. Moderate (50-75%) and severe (>75%) PVS were observed in 5.3% and 0.5% of the PVs, respectively. Although moderate PVS was more frequently observed in the LB group than in the CB or HB groups (8.2%, 3.8%, and 5.0%; P=0.03), the incidence of severe PVS was similar in the LB, CB, and HB groups (0.3%, 0.5%, and 1.0%; P=0.46). Symptomatic PVS requiring intervention occurred in 1 (0.3%) patient.

CONCLUSIONS

Although the reduction in cross-sectional PVA and the incidence of moderate PVS after LB-PVI was more significant than after CB-PVI or HB-PVI, it rarely led to severe PVS. Symptomatic PVS requiring intervention was rare after the balloon ablation of AF.

Adverse events in cryoballoon ablation for pulmonary vein isolation: Insight from the Food and Drug Administration Manufacturer and User Facility Device Experience

Background

Real-world clinical data on the adverse events related to the use of cryoballoon catheter for pulmonary vein isolation remains limited.

Objective

To report and describe the adverse events related to the use of Artic Front cryoballoon catheters (Arctic Front, Arctic Front Advance, and Arctic Front Advance Pro) reported in the Food and Drug Administration's (FDA) Manufacturers and User Defined Experience (MAUDE) database.

Methods

We reviewed all the adverse events reported to the FDA MAUDE database over a 10.7-year study period from January 01, 2011 to September 31, 2021. All events were independently reviewed by two physicians.

Results

During the study period, a total of 320 procedural-related adverse events reported in the MAUDE database were identified. The most common adverse event was transient or persistent phrenic nerve palsy (PNP), accounting for 48% of all events. This was followed by cardiac perforation (15%), pulmonary vein stenosis (8%), transient ischemic attack or stroke (6%), vascular injury (4%), transient or persistent ST-elevation myocardial infarction (3%), hemoptysis (2%), pericarditis (2%), and esophageal ulcer or fistula (1%). There were six reported intra-procedural death events as a result of cardiac perforation.

Conclusion

The two most common procedural adverse events associated with cryoballoon ablation were PNP and cardiac perforation. All cases of procedural mortality were due to cardiac perforation.

Using the pre-freezing technique results in a wider area of antral isolation during cryoballoon pulmonary vein isolation in patients with atrial fibrillation

The "pre-freezing" technique was a method in which a fully inflated balloon after the start of freezing was pressed against the pulmonary vein (PV) during cryoballoon ablation and has been applied especially in large-size PVs. Of 556 patients who underwent cryoballoon ablation for atrial fibrillation (AF), the pre-freezing technique was applied to 48 patients. The resulting 2:1 propensity score-matched data set included 120 patients. Using the pre-freezing technique, all left-superior PVs, all left-inferior PVs, and 95% of right-superior PVs were successfully isolated. In most right-inferior PVs, complete sealing using the pre-freezing technique was challenging, and this technique was not applied. Procedure time was similar between the two groups. In the pre-freezing group, the percentage of the left atrial posterior wall isolated was larger (47.6 ± 10.3 vs. 42.8 ± 15.7%, P = 0.006), and the postoperative reduction of diaphragmatic compound motor action potentials tended to occur less frequently (2.5 vs. 12.5%, P = 0.07), and the reduction of the cross-sectional LSPV area was smaller (17.5 ± 12.2 vs. 27.2 ± 19.8%, P = 0.03) than the conventional group. The AF-free rate of the two groups was similar between the two groups (P = 0.15). The pre-freezing technique was a simple method that can isolate a wider surface area during cryoballoon PV isolation. While the postoperative AF recurrence was comparable, the postoperative reduction in the cross-sectional PV area was less than that of the conventional method, which may reduce the risk of PV stenosis.

Atrial fibrillation ablation: the position of computed tomography in pre-procedural imaging

Atrial fibrillation (AF) is the most common supraventricular arrhythmia. Despite significant advances in its treatment, it still remains one of the leading causes of cardiovascular morbidity and mortality. In the last two decades, pulmonary vein isolation (PVI) was developed as the most effective treatment option. The reported effectiveness of a single ablation procedure ranges from 40% to 69% with single, and up to 88% with repeated procedures, with acceptable safety profile. The PubMed database was searched, using terms including ‘atrial fibrillation ablation’, ‘pulmonary vein isolation’, ‘computed tomography’, ‘pulmonary vein anatomy’ and ‘ovality index’. Papers were reviewed for relevance and scientific merit. Different imaging techniques are used for pre-procedural assessment of left atrial (LA) anatomy, of which computed tomography (CT) is the most common. It allows assessing pulmonary vein (PV) anatomy, the LA wall thickness in different regions and the left atrial appendage (LAA) anatomy, together with excluding the presence of intracardiac thrombi. Pre-procedural PVs imaging is important regardless of the selected ablation technique, however, cryoballoon (CB) ablation seems to be particularly anatomy-dependent. Additionally, CT also permits assessment of several PVs characteristics (geometry, dimensions, angulations, the ostium area, orientation and ovality index (OI), which are essential for the patients’ qualification and designing the strategy of AF ablation. In this paper, we have reviewed the role of CT imaging in patients undergoing ablation procedure due to recurrent/symptomatic atrial fibrillation. Moreover, we discussed the relevant literature.

Pulmonary Vein Angioplasty for Pulmonary Vein Stenosis After Ablation Therapy for Atrial Fibrillation - A Report of 7 Cases

BACKGROUND

Pulmonary vein (PV) stenosis after atrial fibrillation (AF) ablation is rare; however, it remains a serious complication. PV angioplasty is reportedly an effective therapy; however, a dedicated device for PV angioplasty has not been developed, and the detailed procedural methods remain undetermined. This study describes the symptoms, indications, treatment strategies, and long-term outcomes for PV stenosis after AF ablation.

METHODS AND RESULTS

This study retrospectively analyzed 7 patients with PV stenosis after catheter ablation for AF and who had undergone PV angioplasty at our hospital during 2015-2021. PV stenosis occurred in the left superior (5 patients) and left inferior (2 patients) PV. Six patients had hemoptysis, chest pain, and dyspnea. Seven de novo lesions were treated using balloon angioplasty (BA) (3 patients), a bare metal stent (BMS) (3 patients), and a drug-coated balloon (DCB) (1 patient). The restenosis rate was 42.9% (n=3; 2 patients in the BA group and 1 patient in the DCB group). The repeat treatment rate was 28.6% (2 patients in the BA group). Stenting was performed as repeat treatment. One patient with subsequent repeat restenosis development underwent BA. Ten PV angioplasties were performed; there were no major complications.

CONCLUSIONS

Regarding PV angioplasty after ablation therapy for AF, stenting showed superior long-term PV patency than BA alone; therefore, it should be considered as a standard first-line approach.

Catheter ablation for atrial fibrillation: impact on mortality, morbidity, quality of life, and implications for the future

Despite the advances in technologies and techniques in the field of catheter ablation for cardiac arrhythmias, it is estimated that the prevalence of atrial fibrillation (AF) will further increase in the nearest future. The latest trials have proven the beneficial effect on mortality after pulmonary vein isolation in patients with impaired left ventricular function, while no such effect has been seen in patients without left ventricular dysfunction. This raises the question of whether catheter ablation for AF is still suited for the latter patient cohort or whether the endpoint of mortality is not adequate enough. Not only does pulmonary vein isolation reduce the burden of atrial fibrillation, but it also somehow alters the patients’ perception of it in the case of recurrence. Independent of the presence of ventricular dysfunction, patients experience a relief of AF-related symptoms, which is accompanied by an increase in quality of life based on the available patient-reported outcome measures, despite AF recurrence. Trials that are currently recruiting patients seek to unveil the accountable circumstances for these remaining uncertainties and help expand our understanding of a procedure that has been routinely performed for two decades.

Characteristics of anatomical difficulty for cryoballoon ablation: insights from CT

Background

The limited availability of balloon sizes for cryoballoon leads to anatomical limitations for pulmonary vein (PV) isolation. We conducted a comprehensive systematic analysis on procedural success rate, atrial fibrillation (AF) recurrence rate and complications of cryoballoon ablation in association with the anatomy of the left atrium and PV based on preprocedural CT to gain insights into proper treatments of patients with AF using cryoballoon.

Method

A systematic search of literature databases, including PubMed, Web of Science and Cochrane Library, from the inception of each database through February 2021 was conducted. Search keywords included ‘atrial fibrillation’, ‘cryoballoon ablation’ and ‘anatomy’.

Results

Overall, 243 articles were identified. After screening, 16 articles comprising 1396 patients were included (3, 5 and 8 for acute success, AF recurrence and complications, respectively). Regarding acute success and AF recurrences, thinner width of the left lateral ridge, higher PV ovality, PV ostium-bifurcation distance, shorter distance from the non-coronary cusp to inferior PVs, shallower angle of right PVs against the atrial septum and larger right superior PV (RSPV) were associated with poor outcomes. Regarding complications, shorter distance between the RSPV ostium and the right phrenic nerve, larger RSPV-left atrium angle, larger RSPV area and smaller right carina width were associated with incidences of phrenic nerve injury.

Conclusion

This study elucidated several key anatomical features of PVs possibly affecting acute success, AF recurrence and complications in patients with AF using cryoballoon ablation. CT analysis has helped to describe benefits and anatomical limitations for cryoballoon ablation.

Safety, efficacy, and cost-performance of a simplified cryoballoon ablation procedure for paroxysmal atrial fibrillation

BACKGROUND

The search for a less invasive and lower cost cryoballoon-based strategy for atrial fibrillation (AF) ablation has resulted in a simplified procedure that may be suitable for cryoballoon ablation (CBA). Here, we compared procedural characteristics and outcomes between conventional CBA and simple CBA.

METHODS

We enrolled 628 consecutive patients who underwent initial CBA for AF (age, 69 ± 12 years; female, 263 (42%); paroxysmal AF, 576 (92%); CHA₂DS₂-VASc score, 2.7 ± 1.6 points). Simple CBA was characterized by the minimal procedure required to isolate pulmonary veins, including the following: (1) CBA was performed without guidance from a 3-D mapping system; (2) a coronary sinus electrode and esophageal temperature probe were not used; (3) a waiting period after pulmonary vein isolation was not set; and AF induction by isoproterenol and atrial burst stimuli were not performed.

RESULTS

Simple CBA was performed in 240 (38%) patients. Procedural time (49 ± 18 versus 85 ± 27 min, p < 0.01) was shorter, and total procedural costs (20,699 ± 8,091 versus 30,350 ± 11,647 US dollars, p < 0.01) were lower with simple CBA than conventional CBA. Freedom from AF recurrence during the 12-month study period (79.8% versus 78.4%, p = 0.52) and complication rate (8.8% versus 13.1%, p = 0.09) were similar between the two groups.

CONCLUSION

Compared with conventional CBA, simple CBA reduced procedural time and procedural costs while providing comparable outcomes.

Long-term course of phrenic nerve injury after cryoballoon ablation of atrial fibrillation

While phrenic nerve palsy (PNP) due to cryoballoon pulmonary vein isolation (PVI) of atrial fibrillation (AF) was transient in most cases, no studies have reported the results of the long-term follow-up of PNP. This study aimed to summarize details and the results of long-term follow-up of PNP after cryoballoon ablation. A total of 511 consecutive AF patients who underwent cryoballoon ablation was included. During right-side PVI, the diaphragmatic compound motor action potential (CMAP) was reduced in 46 (9.0%) patients and PNP occurred in 29 (5.7%) patients (during right-superior PVI in 20 patients and right-inferior PVI in 9 patients). PNP occurred despite the absence of CMAP reduction in 0.6%. The PV anatomy, freezing parameters and the operator’s proficiency were not predictors of PNP. While PNP during RSPVI persisted more than 4 years in 3 (0.6%) patients, all PNP occurred during RIPVI recovered until one year after the ablation. However, there was no significant difference in the recovery duration from PNP between PNP during RSPVI and RIPVI. PNP occurred during cryoballoon ablation in 5.7%. While most patients recovered from PNP within one year after the ablation, PNP during RSPVI persisted more than 4 years in 0.6% of patients.

Anatomical changes in the pulmonary veins and left atrium after cryoballoon ablation

BACKGROUND

The anatomical changes in pulmonary veins (PVs) after cryoballoon ablation (CBA) are unclear. We aimed to determine the morphological changes in the PVs and left atrium (LA) along with the predictive factors for clinical PV stenosis.

METHODS

We analyzed data of 320 PVs from 80 patients who underwent CBA for atrial fibrillation (age: 62 ± 10 years, 59 males). All patients underwent pre- and post-procedural cardiac computed tomography. We defined clinical PV stenosis when the cross-sectional area decreased by more than 50%.

RESULTS

The average ostial PV area and LA volume decreased significantly after CBA (pre- vs post-CBA; 2.4 ± 1.0 cm² vs 2.3±1.1 cm² , P < .001, 75.0 ± 23.2 cm³ vs 70.7 ± 21.9 cm³ , P < .001, respectively). There was a significant correlation between the reduction rates of the PV area and those of LA volume (R = 0.411, P < .001). The larger preoperative PV area and greater reduction in LA volume were associated with advanced PV narrowing. Clinical PV stenosis was observed in six PVs, was more common in females (male vs female; 0.8% vs 4.8%, P = .043), and tended to be more frequent in left PVs (left PVs vs right PVs; 3.1% vs 0.6%: P = .107), irrespective of the LA volume reduction.

CONCLUSIONS

The significant reduction of the ostial PV area occurred after CBA, which correlated with the reduction rate of LA volume. The narrowing of the PV was partly produced by the LA volume reduction. Clinical PV stenosis was more common in females and tended to be more frequent in left PVs.

Cool enough? Lessons learned from cryoballoon-guided catheter ablation for atrial fibrillation in young adults

INTRODUCTION

Cryoballoon (CB)-guided ablation of atrial fibrillation (AF) is established in symptomatic AF patients. This study sought to determine the safety and efficacy of CB pulmonary vein isolation (PVI) in young adults.

METHODS AND RESULTS

A total of 93 consecutive patients aged <45 years referred to our center for AF ablation were included in this observational study. All patients received CB-guided PVI according to a standardized institutional protocol. Follow-up was performed in our outpatient clinic using 72-h Holter monitoring and periodic telephone interview. Recurrence was defined as any AF/atrial tachycardia (AT) episode >30 s following a 3-month blanking period. A propensity matched control group consisting of patients older than 45 years were used for further evaluation. Mean age was 35 ± 7 years, 22% suffered from persistent AF, 85% were male. Mean follow-up was 2.6 ± 2 years. At the end of the observational period, 83% of patients were free of any AF/AT episodes. There was an excellent overall 12-month success rate of 92%. In comparison to a matched group the overall recurrence rate was noticeably lower in the young group (15% vs. 27%). Increasing age was associated with a hazard ratio of 1.16 for recurrence. In a multivariate analysis model, left atrial diameter remained as significant predictor of AF/AT recurrence. The complication rate was low, no permanent phrenic nerve palsy was observed.

CONCLUSION

CB-guided PVI in young adults is safe and effective with favorable long-term results. It may be considered as first-line therapy in this relatively healthy population.

Acute Procedural Complications of Cryoballoon Ablation: A Comprehensive Review

Catheter ablation is increasingly performed for treatment of atrial fibrillation (AF). Balloon based procedures have been developed aiming at safer, easier and more effective treatment as compared to point to point ablation. In the present review article, we aimed to discuss acute procedural complications of cryoballoon ablation.

Recent advances in cryoballoon ablation for atrial fibrillation

Introduction: Pulmonary vein isolation (PVI), by catheter ablation, represents the current treatment for drug-resistant atrial fibrillation (AF). Nowadays cryoballoon (CB) is a recognized ablation method in patients with atrial fibrillation, mainly due to its ease of use, leading to reproducible and fast procedures. This novel single shot technology literally revolutionized the approach to AF ablation. Areas covered: The historical development of the cryoballoon, ablation techniques and new approaches beyond the ordinary PVI and complications are summarized here. Expert opinion: Although cryoballoon ablation has greatly standardized the approach to PVI a few critical points still need to be clarified scientifically in order to further uniform this procedure in cath labs worldwide. Duration and dosage of the cryoapplication is undoubtedly a topic of great interest.

Irreversible electroporation for catheter-based cardiac ablation: a systematic review of the preclinical experience

INTRODUCTION

Irreversible electroporation (IRE) utilizing high voltage pulses is an emerging strategy for catheter-based cardiac ablation with considerable growth in the preclinical arena.

METHODS

A systematic search for articles was performed from three sources (PubMed, EMBASE, and Google Scholar). The primary outcome was the efficacy of tissue ablation with characteristics of lesion formation evaluated by histologic analysis. The secondary outcome was focused on safety and damage to collateral structures.

RESULTS

Sixteen studies met inclusion criteria. IRE was most commonly applied to the ventricular myocardium (n = 7/16, 44%) by a LifePak 9 Defibrillator (n = 9/16, 56%), NanoKnife Generator (n = 2/16, 13%), or other custom generators (n = 5/16, 31%). There was significant heterogeneity regarding electroporation protocols. On histological analysis, IRE was successful in creating ablation lesions with variable transmurality depending on the electric pulse parameters and catheter used.

CONCLUSION

Preclinical studies suggest that cardiac tissue ablation using IRE shows promise in delivering efficacious, safe lesions.

Feasibility of late gadolinium enhancement magnetic resonance imaging to detect ablation lesion gaps in patients undergoing cryoballoon ablation of paroxysmal atrial fibrillation

BACKGROUND

Although late gadolinium enhancement magnetic resonance imaging (LGE-MRI) allows the identification of lesions and gaps after a cryothermal balloon (CB) ablation of paroxysmal atrial fibrillation (PAF), the accuracy has not yet been well established.

METHODS

The subjects consisted of 10 consecutive patients who underwent a second ablation procedure among our cohort of 80 patients who underwent LGE-MRI after the CB ablation of PAF. LGE-MRI scar regions were compared with electroanatomical mapping during the second procedure. In the analysis, the unilateral pulmonary vein (PV) antrum was divided into 7 regions.

RESULTS

The gap characterization analysis was performed in 140 regions around 40 PVs in total. There were 16 LGE-MRI gaps around 11 PVs (mean 1.6 ± 1.4 gaps/patient) in 7 patients and 14 electrical gaps around 10 PVs in 8 patients (mean 1.4 ± 1.1 gaps/patient). The locations of 13 electrical gaps were well matched to that on the LGE-MRI, whereas the remaining 1 electrical gap had not been predicted on the LGE-MRI. Compared to the electrical gaps in the second procedure, the sensitivity and specificity of the LGE-MRI gaps were 93% (13 LGE-MRI gaps of 14 electrical gaps) and 98% (123 LGE-MRI scars out of 126 electrical scars), respectively.

CONCLUSION

LGE-MRI can accurately localize the lesion gaps after CB ablation of PAF.

Complications of Cryoballoon Pulmonary Vein Isolation

Since the cryoballoon (CB) was introduced into clinical practice, more than 400,000 patients have undergone a pulmonary vein (PV) isolation with a CB throughout the world. Although the efficacy of the first-generation CB was limited, the recently introduced second-generation CB has achieved a greater uniformity in cooling, which has facilitated a shorter time to PV isolation, shorter procedural times, higher rates of freedom from atrial fibrillation and low rates of PV reconnections. Currently, a single short freeze strategy with a single 28 mm balloon has become the standard technique based on the balance of procedural efficacy and safety. However, enhanced cooling characteristics may also result in a greater potential for collateral damage to non-cardiac structures. Knowledge about the potential complications is essential when performing the procedure. In this article, we describe the important complications that should be noted during a CB procedure, and how to minimise the risk of complications based on our experience.

Low Risk of Pulmonary Vein Stenosis After Contemporary Atrial Fibrillation Ablation - Lessons From Repeat Procedures After Radiofrequency Current, Cryoballoon, and Laser Balloon

BACKGROUND

The incidence of pulmonary vein stenosis (PVS) after AF ablation following contemporary procedures remains unclear. We compared the incidence of PVS/narrowing (PVS/N) after PV isolation (PVI) for (1) 3-D mapping-guided wide-area encircling irrigated radiofrequency current (RFC) ablation; (2) first-third-generation big cryoballoon (CB1-3) ablation; and (3) laser balloon (LB) ablation.

METHODS AND RESULTS

All patients undergoing a second procedure between January 2012 and November 2016 were subgrouped according to index ablation (PVI): RFC; CB; or LB. PVS/N was classified using PV diameter ratio (second/index procedure) on selective PV angiogram performed before ablation: mild, 25-49%; moderate, 50-74%; or severe, ≥75%. A total of 344 patients (1,362 PV) were analyzed (RFC, n=211; 840 PV; CB1, n=21; 82 PV; CB2,3, n=64; 250 PV; LB, n=48; 190 PV). In the LB group, 45 patients (94%) were treated with dose ≥8.5 W. Second procedures were performed on average 14.9±14.1 months after the index procedure. Mild PVS/N was observed in 18.4%, 9.5% and 3.6% of PV in the LB, RFC and CB groups, respectively (P<0.01). Moderate PVS was recognized in 2 PV (0.1%; RFC, LB). Severe PVS was never observed, and no PV intervention/surgery was required.

CONCLUSIONS

The risk for significant PVS is low after RFC/CB. The incidence of mild PVS/N was highest after standard-dose LB ablation and lowest after high-dose CB ablation.

Atrial fibrillation ablation using cryoballoon technology: Recent advances and practical techniques

Atrial fibrillation (AF) affects 1-2% of the population, and its prevalence is estimated to double in the next 50 years as the population ages. AF results in impaired patients' life quality, deteriorated cardiac function, and even increased mortality. Antiarrhythmic drugs frequently fail to restore sinus rhythm. Catheter ablation is a valuable treatment approach for AF, even as a first-line therapy strategy in selected patients. Effective electrical pulmonary vein isolation (PVI) is the cornerstone of all AF ablation strategies. Use of radiofrequency (RF) catheter in combination of a three-dimensional electroanatomical mapping system is the most established ablation approach. However, catheter ablation of AF is challenging even sometimes for experienced operators. To facilitate catheter ablation of AF without compromising the durability of the pulmonary vein isolation, "single shot" ablation devices have been developed; of them, cryoballoon ablation, is by far the most widely investigated. In this report, we review the current knowledge of AF and discuss the recent evidence in catheter ablation of AF, particularly cryoballoon ablation. Moreover, we review relevant data from the literature as well as our own experience and summarize the key procedural practical techniques in PVI using cryoballoon technology, aiming to shorten the learning curve of the ablation technique and to contribute further to reduction of the disease burden.

Practical Techniques in Cryoballoon Ablation: How to Isolate Inferior Pulmonary Veins

Catheter ablation is the most effective treatment option for patients suffering from symptomatic atrial fibrillation. Electrical isolation of the pulmonary veins is the procedural cornerstone. Point-by-point radiofrequency current energy ablation in combination with a 3D electro-anatomical mapping system is the established approach to ablation. In contrast, cryoballoon ablation uses a single-shot approach to facilitate pulmonary vein isolation. However, fixed cryoballoon diameters (28 mm or 23 mm) and non-balloon compliance can lead to technical difficulties in isolating variable pulmonary vein anatomies. This review focuses on key procedural aspects and illustrates practical techniques in cryoballoon pulmonary vein isolation to shorten the learning curve without compromising safety and efficacy. It has a special emphasis on inferior pulmonary veins.