Repolarization indicates electrical instability in ventricular arrhythmia originating from papillary muscle.

AIMS: Cardiac arrhythmia originating from the papillary muscle (PM) can trigger ventricular fibrillation (VF) and cause sudden cardiac death even in the absence of structural heart disease. Most premature ventricular contractions, however, are benign and hitherto difficult to distinguish from a potentially fatal arrhythmia. Altered repolarization characteristics are associated with electrical instability, but electrophysiological changes which precede degeneration into VF are still not fully understood. METHODS AND RESULTS: Ventricular arrhythmia (VA) was induced by aconitine injection into PMs of healthy sheep. To investigate mechanisms of degeneration of stable VA into VF in structurally healthy hearts, endocardial high-density and epicardial mapping was performed during sinus rhythm (SR) and VA. The electrical restitution curve, modelling the relation of diastolic interval and activation recovery interval (a surrogate parameter for action potential duration), is steeper in VA than in non-arrhythmia (ventricular pacing and SR). Steeper restitution curves reflect electrical instability and propensity to degenerate into VF. Importantly, we find the parameter repolarization time in relation to cycle length (RT/CL) to differentiate self-limiting from degenerating arrhythmia with high specificity and sensitivity. CONCLUSION: RT/CL may serve as a simple index to aid differentiation between self-limiting and electrically instable arrhythmia with the propensity to degenerate to VF. RT/CL is independent of cycle length and could easily be measured to identify electrical instability in patients.

A Simplified Approach to Pulmonary Vein Visualization during Cryoballoon Ablation of Atrial Fibrillation.

Background and Objectives: Selective pulmonary vein (PV) angiography has been established as the gold standard for PV visualization in cryoballoon (CB)-based pulmonary vein isolation (PVI). We sought to simplify this approach to reduce procedural complexity and radiation exposure. Materials and Methods: Patients with paroxysmal and recently diagnosed persistent AF undergoing CB-based PVI from January 2015 to December 2017 were retrospectively analyzed. Patients underwent either selective PV angiography or conventional left atrial (LA) angiography for PV visualization. Results: A total of 336 patients were analyzed. A total of 87 patients (26%) received PV angiography and 249 (74%) LA angiography. LA angiography required fewer cine-sequences for PV visualization, translating into a significant reduction in procedure duration, fluoroscopy time and dose area product. Additionally, less contrast medium was utilized. PV occlusion by the CB, CB temperature and time to isolation showed no significant differences. The number of CB applications and total application time (LA angiography: 1.4 ± 0.02 vs. PV Angiography: 1.6 ± 0.05; p < 0.0001; LA angiography: 297.9 ± 4.62 vs. PV-Angiography: 348.9 ± 11.03; p < 0.001, respectively) per vein were slightly but significantly higher in the PV angiography group. We observed no difference in late AF recurrence (24.7% LA angiography vs. 21.3% PV angiography; p = 0.2657). Conclusions: A simplified protocol, using LA angiography for PV visualization, entails a reduction in procedure time and radiation exposure while equally maintaining procedural efficiency and safety in both groups.

Atrial Fibrillation and Transvenous Lead Extraction-A Comprehensive Subgroup Analysis of the GermAn Laser Lead Extraction RegistrY (GALLERY).

Background: Atrial fibrillation is the most common arrhythmia and has been described as driver of cardiovascular morbidity and risk factor for cardiac device-related complications, as well as in transvenous lead extraction (TLE). Objectives: Aim of this study was to characterize the procedural outcome and risk-factors of patients with atrial fibrillation (AF) undergoing TLE. Methods: We performed a subgroup analysis of all AF patients in the GALLERY (GermAn Laser Lead Extraction RegistrY) database. Predictors for all-cause mortality were assessed. Results: A total number of 510 patients with AF were identified with a mean age of 74.0 ± 10.3 years. Systemic infection (38.4%) was the leading cause for TLE, followed by local infection (37.5%) and lead dysfunction (20.4%). Most of the patients (45.9%) presented with pacemaker systems to be extracted. The total number of leads was 1181 with a 2.3 ± 0.96 leads/patient. Clinical procedural success was achieved in 97.1%. Occurrence of major complications was 1.8% with a procedure-related mortality of 1.0%. All-cause mortality was high with 5.9% and septic shock being the most common cause. Systemic device infection (OR: 49.73; 95% CI: 6.56−377.09, p < 0.001), chronic kidney disease (CKD; OR: 2.67; 95% CI: 1.01−7.03, p = 0.048) and a body mass index < 21 kg/m2 (OR: 6.6; 95% CI: 1.68−25.87, p = 0.007) were identified as independent predictors for all-cause mortality. Conclusions: TLE in AF patients is effective and safe, but in patients with systemic infection the mortality due to septic shock is high. Systemic infection, CKD and body mass index <21 kg/m2 are risk factors for death in patient with AF undergoing TLE.

Pulsed field ablation in patients with complex consecutive atrial tachycardia in conjunction with ultra-high density mapping: Proof of concept.

INTRODUCTION: Catheter-ablation (CA) of consecutive left atrial tachycardias (LAT) can be challenging. Pulsed field ablation (PFA) yields a novel nonthermal CA technology for treatment of atrial fibrillation (AF). There is no data regarding PFA of LAT. This study sought to investigate PFA of consecutive LAT following prior CA of AF. METHODS: Consecutive patients with LAT underwent ultrahigh-density (UHDx) mapping. Subsequent to identification of the AT mechanism, PFA was performed at the assumed critical sites for LAT maintenance. Continuous ablation lines were performed if required and evaluated with pre- and post-PFA HDx-mapping. RESULTS: Fifteen patients (age 70 ± 10, male 73%) who underwent 3.6 ± 2 prior AF-CA procedures were included. The total mean procedure and fluoroscopy times were 141 ± 43 and 18 ± 10 min, respectively. All 19 of 19 (100%) LAT were successfully ablated with PFA. Two AT located at the right atria required RF-ablation. LAT were identified as localized reentry (n = 1) and macro-reentry LAT (n = 18) and targeted with PFA. All LAT terminated with PFA either to sinus rhythm (9/15) or a secondary AT (6/15 and subsequently to SR); 63% (12/19) terminated with the first PFA-application. All lines (13 roof, 11 anterior, 1 mitral) were blocked. LA-posterior-wall isolation (LAPWI) was successfully achieved when performed (10/10). AF/AT free survival was 80% (12/15) after 153 [88-207] days of follow-up. No procedure-related complications occurred. CONCLUSION: PFA of consecutive LAT is feasible and safe. Successful creation of ablation lines and LAPWI can be achieved in a short time. PFA may offer the opportunity for effective ablation of atrial arrhythmias beyond AF.

A novel wide-band dielectric imaging system to guide radiofrequency ablation for pulmonary vein isolation.

INTRODUCTION: Recently, the wide-band dielectric mapping system Kodex-EPD was introduced. This study reports the first clinical experience using a novel system to guide pulmonary vein isolation (PVI) with radiofrequency (RF) ablation. METHODS AND RESULTS: The study included 20 consecutive patients undergoing de-novo PVI for symptomatic paroxysmal or persistent atrial fibrillation guided by Kodex-EPD. The primary efficacy endpoint was successful PVI. Secondary endpoints included procedural parameters and complications. In all 20 patients (mean age 68 ± 8 years, 12 male patients, paroxysmal fibrillation in 14/20 [70%] patients), PVI was successfully completed. One patient underwent additional cavo-tricuspid isthmus ablation for concomitant typical atrial flutter and one patient required additional ablation of a focal atrial tachycardia. A conventional three-dimensional image of the left atrium as well as the innovative endocardial panoramic view were used to guide catheter manipulation and ablation. Median procedure time was 115 [1st; 3rd quartile 93,75; 140] min and median total fluoroscopy time was 9.9 [9.7; 11.2] min, of which a median of 0.8 [0.6; 0.9] min was required to create left atrial maps. Complete left atrial imaging using Kodex-EPD was achieved within a median of 7.1 [5.7; 8.3] min. Median RF ablation time was 45.1 [34.6; 58.7] min. No major complications were observed. CONCLUSION: RF ablation PVI guided by Kodex-EPD seems safe and feasible. The system provides effective three-dimensional guidance for PVI.

Sleep apnea predicts cardiovascular death in patients with Marfan syndrome: a cohort study.

Background: Surgical replacement of the aortic root is the only intervention that can prevent aortic dissection and cardiovascular death in Marfan syndrome (MFS). However, in some individuals, MFS also causes sleep apnea. If sleep apnea predicts cardiovascular death, a new target for predictive, preventive, and personalized medicine (PPPM) may emerge for those individuals with MFS who have sleep apnea. Methods: This is an investigator-initiated study with long-term follow-up data of 105 individuals with MFS. All individuals were screened for sleep apnea regardless of symptoms. Cardiovascular death served as a primary endpoint, and aortic events as a secondary outcome. Results: Sleep apnea with an apnea-hypopnea index (AHI) > 5/h was observed in 21.0% (22/105) with mild sleep apnea in 13% (14/105) and moderate to severe sleep apnea in 7.6% (8/105). After a median follow-up of 7.76 years (interquartile range: 6.84, 8.41), 10% (10/105) had died, with cardiovascular cause of death in 80% (8/10). After adjusting for age and body mass index (BMI), the AHI score emerged as an independent risk factor for cardiovascular death (hazard ratio 1.712, 95% confidence interval [1.061-2.761], p = 0.0276). The secondary outcome of aortic events occurred in 33% (35/105). There was no effect of the AHI score on aortic events after adjusting for age and BMI (hazard ratio 0.965, 95% confidence interval [0.617-1.509]), possibly due to a high number of patients with prior aortic surgery. Interpretation: Sleep apnea is emerging as an independent predictor of cardiovascular death in MFS. It seems mandatory to screen all individuals with MFS for sleep apnea and to include these individuals, with both MFS and sleep apnea, in further studies to evaluate the impact of preventive measures with regard to cardiovascular death. Supplementary Information: The online version contains supplementary material available at 10.1007/s13167-022-00291-4.

The impact of ultra-high-density mapping on long-term outcome after catheter ablation of ventricular tachycardia.

Ultra-high-density (UHD) mapping can improve scar area detection and fast activation mapping in patients undergoing catheter ablation of ventricular tachycardia (VT). The aim of the present study was to compare the outcome after VT ablation guided by UHD and conventional point-by-point 3D-mapping. The acute and long-term ablation outcome of 61 consecutive patients with UHD mapping (64-electrode mini-basket catheter) was compared to 61 consecutive patients with conventional point-by-point 3D-mapping using a 3.5 mm tip catheter. Patients, whose ablation was guided by UHD mapping had an improved 24-months outcome in comparison to patients with conventional mapping (cumulative incidence estimate of the combination of recurrence or disease-related death of 52.4% (95% confidence interval (CI) [36.9-65.7]; recurrence: n = 25; disease-related death: n = 4) versus 69.6% (95% CI [55.9-79.8]); recurrence: n = 31; disease-related death n = 11). In a cause-specific Cox proportional hazards model, UHD mapping (hazard ratio (HR) 0.623; 95% CI [0.390-0.995]; P = 0.048) and left ventricular ejection fraction > 30% (HR 0.485; 95% CI [0.290-0.813]; P = 0.006) were independently associated with lower rates of recurrence or disease-related death. Other procedural parameters were similar in both groups. In conclusion, UHD mapping during VT ablation was associated with fewer VT recurrences or disease-related deaths during long-term follow-up in comparison to conventional point-by-point mapping. Complication rates and other procedural parameters were similar in both groups.

Pulsed-field ablation combined with ultrahigh-density mapping in patients undergoing catheter ablation for atrial fibrillation: Practical and electrophysiological considerations.

BACKGROUND: Pulsed-field ablation (PFA) yields a novel ablation technology for atrial fibrillation (AF). PFA lesions promise to be highly durable, however clinical data on lesion characteristics are still limited. OBJECTIVE: This study sought to investigate PFA lesion creation with ultrahigh-density (UHDx) mapping. METHODS: Consecutive AF patients underwent PFA-based pulmonary vein isolation (PVI) using a multispline catheter (Farwave, Farapulse Inc.). Additional ablation, including left atrial posterior wall isolation (LAPWI) and mitral isthmus ablation (MI) were performed in a subset of persistent AF patients. The extent of PFA-lesions and decrease of LA-voltage were assessed with pre- and post PFA UHDx-mapping (Orion™ catheter and Rhythmia™ 3D-mapping system, Boston Scientific). RESULTS: In 20 patients, acute PVI was achieved in 80/80 PVs, LAPW isolation in 9/9 patients, MI ablation in 2/2 (procedure time: 123 ± 21.6 min, fluoroscopy time: 19.2 ± 5.5 min). UHDx-mapping subsequent to PVI revealed early PV-reconnection in five case (5/80, 6.25%). Gaps were located at the anterior-superior PV ostia and were successfully targeted with additional PFA. Repeat UHDx mapping after PFA revealed a significant decrease of voltage along the PV ostia (1.67 ± 1.36 mV vs. 0.053 ± 0.038 mV, p < .0001) with almost no complex electrogram-fractionation at the lesion border zones. PFA-catheter visualization within the mapping system was feasible in 17/19 (84.9%) patients and adequate in 92.9% of ablation sites. CONCLUSION: For the first time illustrated by UHDx mapping, PFA creates wide antral circumferential lesions and homogenous LAPW isolation with depression of tissue voltage to a minimum. Although with a low incidence, early PV reconnection can still occur also in the setting of PFA.

Medical, Interventional, and Surgical Treatment Strategies for Atrial Fibrillation.

BACKGROUND: Atrial fibrillation is the most common type of cardiac arrhythmia; the lifetime risk for a 55-year-old person to develop atrial fibrillation is 37%. In recent years, years there have been various distinct changes in the clinical management of AF. METHODS: This review is based on a selective search for literature on the treatment of AF and the prevention of thromboembolic complications. The updated guideline of the European Society of Cardiology (ESC) for the diagnosis and treatment of AF was also taken into consideration. RESULTS: The main components of AF management are the comprehensive treatment of risk factors and concomitant diseases, as well as the prevention of thromboembolic complications, usually with non-vitamin-K-dependent oral anticoagulants or vitamin K antagonists, according to individual risk stratification. Beyond this, either rate or rhythm control are viable treatment concepts. Symptomatic patients in whom reversible causes have been ruled out should be offered rhythm-control therapy early in their course. In patients with risk factors and/or heart failure, an early rhythm control strategy has been found to be beneficial. As antiarrhythmic drugs often prove to be ineffective over the long term, catheter ablation is now becoming increasingly important in AF management. CONCLUSION: The clinical management of atrial fibrillation consists of a multimodal approach with risk stratification, lifestyle modification, prevention of thromboembolism, and, if possible, early rhythm control therapy.

A case report of cryoballoon-based pulmonary vein isolation in a patient with situs inversus abdominalis and levocardia.

BACKGROUND: Cryoballoon-based pulmonary vein isolation (cbPVI) is a standardized treatment of atrial fibrillation. In complex anatomies, radiofrequency ablation (rfPVI) is usually preferred. We describe the first cbPVI in a rare patient with SI and levocardia. CASE SUMMARY: A 41-year-old male patient with paroxysmal atrial fibrillation was referred to our clinic after a previous, unsuccessful cbPVI procedure. Observation of an atypical lead-wire position due to an abnormal anatomy of the inferior vena cava led to its initial termination. A subsequent thoraco-abdominal computed tomography revealed situs inversus abdominalis and levocardia and the procedure was re-attempted in our clinic. Transseptal puncture (TSP) was guided via transoesophageal echocardiography and fluoroscopy, using a SL0-Sheath and a standard BRK-needle. Advancement of the sheath initially failed but after additional dilatation with an Inoue® dilator, transseptal passage of the sheath was successful. Due to the unusual antero-cranial TSP, the septal pulmonary veins (PV) contrasted poorly. After repeat TSP, a steerable FlexCath Advance® sheath was introduced into the left atrium using an Amplatz Super Stiff® guidewire. Subsequently, all PV were intubated with the Achieve® catheter, over which a 2nd generation cryoballoon was introduced. Despite the practical challenges in this case, all PV were isolated. DISCUSSION: The main challenges include the achievement of transseptal access and manipulation of the cryoballoon to achieve a patent seal of the pulmonary veins. cbPVI eliminates the need for constant re-positioning of the ablation catheter and might facilitate the creation of durable lesions under such difficult anatomical conditions.

Supervised Obesity Reduction Trial for AF ablation patients: results from the SORT-AF trial.

AIMS: Weight management seems to be beneficial for obese atrial fibrillation (AF) patients; however, randomized data are sparse. Thus, this study aimed to investigate the influence of weight reduction on AF ablation outcomes. METHODS AND RESULTS: SORT-AF is an investigator-sponsored, prospective, randomized, multicentre, and clinical trial. Patients with symptomatic AF (paroxysmal or persistent) and body mass index (BMI) 30-40 kg/m2 underwent AF ablation and were randomized to either weight-reduction (group 1) or usual care (group 2), after sleep-apnoea-screening and loop recorder (ILR) implantation. The primary endpoint was defined as AF burden between 3 and 12 months after AF ablation. Overall, 133 patients (60 ± 10 years, 57% persistent AF) were randomized to group 1 (n = 67) and group 2 (n = 66), respectively. Complications after AF-ablation were rare (one stroke and no tamponade). The intervention led to a significant reduction of BMI (34.9 ± 2.6-33.4 ± 3.6) in group 1 compared to a stable BMI in group 2 (P < 0.001). Atrial fibrillation burden after ablation decreased significantly (P < 0.001), with no significant difference regarding the primary endpoint between the groups (P = 0.815, odds ratio: 1.143, confidence interval: 0.369-3.613). Further analyses showed a significant correlation between BMI and AF recurrence for patients with persistent AF compared with paroxysmal AF patients (P = 0.032). CONCLUSION: The SORT-AF study shows that AF ablation is safe and successful in obese patients using continuous monitoring via ILR. Although the primary endpoint of AF burden after ablation did not differ between the two groups, the effects of weight loss and improvement of exercise activity were beneficial for obese patients with persistent AF demonstrating the relevance of life-style management as an important adjunct to AF ablation in this setting. TRIAL REGISTRATION NUMBER: NCT02064114.

Specific electrogram characteristics impact substrate ablation target area in patients with scar-related ventricular tachycardia-insights from automated ultrahigh-density mapping.

INTRODUCTION: Substrate-based catheter ablation approaches to ventricular tachycardia (VT) focus on low-voltage areas and abnormal electrograms. However, specific electrogram characteristics in sinus rhythm are not clearly defined and can be subject to variable interpretation. We analyzed the potential ablation target size using automatic abnormal electrogram detection and studied findings during substrate mapping in the VT isthmus area. METHODS AND RESULTS: Electrogram characteristics in 61 patients undergoing scar-related VT ablation using ultrahigh-density 3D-mapping with a 64-electrode mini-basket catheter were analyzed retrospectively. Forty-four complete substrate maps with a mean number of 10319 ± 889 points were acquired. Fractionated potentials detected by automated annotation and manual review were present in 43 ± 21% of the entire low-voltage area (<1.0 mV), highly fractionated potentials in 7 ± 8%, late potentials in 13 ± 15%, fractionated late potentials in 7 ± 9% and isolated late potentials in 2 ± 4%, respectively. Highly fractionated potentials (>10 ± 1 fractionations) were found in all isthmus areas of identified VT during substrate mapping, while isolated late potentials were distant from the critical isthmus area in 29%. CONCLUSION: The ablation target area varies enormously in size, depending on the definition of abnormal electrograms. Clear linking of abnormal electrograms with critical VT isthmus areas during substrate mapping remains difficult due to a lack of specificity rather than sensitivity. However, highly fractionated, low-voltage electrograms were found to be present in all critical VT isthmus sites.

Respiratory sinus arrhythmia is reduced after pulmonary vein isolation in patients with paroxysmal atrial fibrillation.

INTRODUCTION: Respiratory sinus arrhythmia (RSA) describes heart rate (HR) changes in synchrony with respiration. It is relevant for exercise capacity and mechanistically linked with the cardiac autonomic nervous system. After pulmonary vein isolation (PVI), the current therapy of choice for patients with paroxysmal atrial fibrillation (AF), the cardiac vagal tone is often diminished. We hypothesized that RSA is modulated by PVI in patients with paroxysmal AF. MATERIAL AND METHODS: Respiratory sinus arrhythmia, measured by using a deep breathing test and heart rate variability parameters, was studied in 10 patients (64 ±3 years) with paroxysmal AF presenting in stable sinus rhythm for their first catheter-based PVI. Additionally, heart rate dynamics before and after PVI were studied during sympathetic/parasympathetic coactivation by using a cold-face test. All tests were performed within 24 h before and 48 h after PVI. RESULTS: After PVI RSA (E/I difference: 7.9 ±1.0 vs. 3.5 ±0.6 bpm, p = 0.006; E/I ratio: 1.14 ±0.02 vs. 1.05 ±0.01, p = 0.003), heart rate variability (SDNN: 31 ±3 vs. 14 ±3 ms, p = 0.006; RMSSD: 17 ±2 vs. 8 ±2 ms, p = 0.002) and the HR response to sympathetic/parasympathetic coactivation (10.2 ±0.7% vs. 5.7 ±1.1%, p = 0.014) were diminished. The PVI-related changes in RSA correlated with the heart rate change during sympathetic/parasympathetic coactivation before vs. after PVI (E/I difference: r = 0.849, p = 0.002; E/I ratio: r = 0.786, p = 0.007). One patient with vagal driven arrhythmia experienced AF recurrence during follow-up (mean: 6.5 ±0.6 months). CONCLUSIONS: Respiratory sinus arrhythmia is reduced after PVI in patients with paroxysmal AF. Our findings suggest that this is related to a decrease in cardiac vagal tone. Whether and how this affects the clinical outcome including exercise capacity need to be determined.

Impact of the ablation technique on release of the neuronal injury marker S100B during pulmonary vein isolation.

AIMS: S100B, a well-known damage-associated molecular pattern protein is released acutely by central and peripheral nerves and upon concomitant denervation in pulmonary vein isolation (PVI). We aimed to investigate whether the ablation technique used for PVI impacts S100B release in patients with paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: The study population consisted of 73 consecutive patients (age: 62.7 ± 10.9 years, 54.8% males) undergoing first-time PVI with either radiofrequency (RF; n = 30) or cryoballoon (CB; n = 43) for paroxysmal AF. S100B determined from venous plasma samples taken immediately before and after PVI increased from 33.5 ± 1.8 to 91.1 ± 5.3 pg/mL (P < 0.0001). S100B release in patients undergoing CB-PVI was 3.9 times higher compared to patients with RF-PVI (ΔS100B: 21.1 ± 2.7 vs. 83.1 ± 5.2 pg/mL, P < 0.0001). During a mean follow-up of 314 ± 186 days, AF recurrences were observed in 18/71 (25.4%) patients (RF-PVI: n = 9/28, CB-PVI: n = 9/43). Univariate Cox regression analysis indicated that an increase in S100B was associated with higher freedom from AF in follow-up (hazard ratio per 10 pg/mL release of S100B: 0.83; 95% confidence interval: 0.72-0.95; P = 0.007). CONCLUSION: The ablation technique used for PVI has an impact on the release of S100B, a well-established biomarker for neural damage.

Outcome after tailored catheter ablation of atrial tachycardia using ultra-high-density mapping.

INTRODUCTION: Tailored catheter ablation of atrial tachycardias (ATs) is increasingly recommended as a potentially easy treatment strategy in the era of high-density mapping (HDM). As follow-up data are sparse, we here report outcomes after HDM-guided ablation of ATs in patients with prior catheter ablation or cardiac surgery. METHODS AND RESULTS: In 250 consecutive patients (age 66.5 ± 0.7 years, 58% male) with ATs (98% prior catheter ablation, 13% prior cardiac surgery) an HDM-guided catheter ablation was performed with the support of a 64-electrode mini-basket catheter. A total of 354 ATs (1.4 ± 0.1 ATs per patient; mean cycle length 304 ± 4.3 ms; 64% macroreentry, 27% localized reentry, and 9% focal) with acute termination of 95% were targeted in the index procedure. A similar AT as in the index procedure recurred in five patients (2%) after a median follow-up time of 535 days (interquartile range (IQR) 25th-75th percentile: 217-841). Tailored ablation of reentry ATs with freedom from any arrhythmia was obtained in 53% after a single procedure and in 73% after 1.4 ± 0.4 ablation procedures (range: 1-4). A total of 228 patients (91%) were free from any arrhythmia recurrence after 210 days (IQR: 152-494) when including optimal usual care. CONCLUSIONS: Tailored catheter ablation of ATs guided by HDM has a high acute success rate. The recurrence rate of the index AT is low. In patients with extensive atrial scaring further ablation procedures need to be considered to achieve freedom from any arrhythmia.

Contemporary analysis of phrenic nerve injuries following cryoballoon-based pulmonary vein isolation: A single-centre experience with the systematic use of compound motor action potential monitoring.

BACKGROUND: Phrenic nerve injury (PNI) remains one of the most frequent complications during cryoballoon-based pulmonary vein isolation (CB-PVI). Since its introduction in 2013, the use of compound motor action potential (CMAP) for the prevention of PNI during CB-PVI is increasing; however, systematic outcome data are sparse. METHODS: The CMAP technique was applied in conjunction with abdominal palpation during pacing manoeuvres (10 mV, 2 ms) from the superior vena cava for 388 consecutive patients undergoing CB-PVI between January 2015 and May 2017 at our tertiary arrhythmia centre. Cryoablation was immediately terminated when CMAP amplitude was reduced by 30%. RESULTS: Reductions in CMAP amplitude were observed in 16 (4%) of 388 patients during isolation of the right veins. Of these, 11 (69%) patients did not manifest a reduction in diaphragmatic excursions. The drop in CMAP amplitude was observed in 10 (63%) patients during ablation of the right superior pulmonary veins (PVs) and in 7 (44%) patients during ablation of the right inferior PVs. Postprocedural persistent PNI was observed in three of four patients for a duration of 6 months, with one of these patients remaining symptomatic at the 24-month follow-up. One of the four patients was lost to long-term follow-up. CONCLUSIONS: All PNIs occurred during right-sided CB-PVI and were preceded by a reduction in CMAP amplitude. Thus, the standardized use of CMAP surveillance during CB-PVI is easily applicable, reliable and compared with other studies, results in a lower number of PNIs.

Ultra-high-density mapping of conduction gaps and atrial tachycardias: Distinctive patterns following pulmonary vein isolation with cryoballoon or contact-force-guided radiofrequency current.

INTRODUCTION: The aim of this study was to investigate electrophysiological findings in patients with arrhythmia recurrence undergoing a repeat ablation procedure using ultra-high-density (UHDx) mapping following an index procedure using either contact-force (CF)-guided radiofrequency current (RFC) pulmonary vein isolation (PVI) or second-generation cryoballoon (CB) PVI for treatment of atrial fibrillation (AF). METHODS AND RESULTS: Fifty consecutive patients with recurrence of AF and/or atrial tachycardia (AT) following index CF-RFC PVI (n = 21) or CB PVI (n = 29) were included. A 64-pole mini-basket mapping catheter in combination with an UHDx-mapping system-guided ablation was used. RFC was applied using a catheter tip with three incorporated mini-electrodes. PV reconnection rates were higher after CF-RFC PVI (CF-RFC: 2.5 ± 1.3 PVs vs CB: 1.4 ± 0.9 PVs; P = .0025) and left PVs were more frequently reconnected (CF-RFC: 64% PVs vs CB: 35% PVs; P = .0077). Fractionated signals along the antral index ablation line (FS) were found in 30% of CB-PVI patients (CF-RFC: 9.5% vs CB:30%; P = .098) targeted for ablation. In five cases, FS were a critical part of maintaining consecutive AT. The main AT mechanism found during reablation (n = 45 ATs) was macroreentry (80% [36/45], CF-RFC: 78.9% vs CB: 80.8%; P = 1.0) with a variety of circuits throughout both atria. CONCLUSION: UHDx mapping is sensitive in detecting conduction gaps along the index ablation line. Left PVs are more frequently reconnected after initial CF-RFC PVI. FS are a common finding after CB PVI and can maintain certain forms of ATs. ATs after index PVI are mostly macroreentries with a broad spectrum of entities.

Local impedance guides catheter ablation in patients with ventricular tachycardia.

AIMS: Catheter contact and local tissue characteristics are relevant information for successful radiofrequency current (RFC)-ablation. Local impedance (LI) has been shown to reflect tissue characteristics and lesion formation during RFC-ablation. Using a novel ablation catheter incorporating three mini-electrodes, we investigated LI in relation to generator impedance (GI) in patients with ventricular tachycardia (VT) and its applicability as an indicator of effective RFC-ablation. METHODS AND RESULTS: Baseline impedance, Δimpedance during ablation and drop rate (Δimpedance/time) were analyzed for 625 RFC-applications in 28 patients with recurrent VT undergoing RFC-ablation. LI was lower in scarred (87.0 Ω [79.0-95.0]) compared to healthy myocardium (97.5 Ω ([82.75-111.50]; P = .03) while GI did not differ between scarred and healthy myocardium. ΔLI was higher (18 Ω [9.4-26.0]) for VT-terminating as compared to non-terminating RFC-ablation (ΔLI 13 Ω [8.85-18.0]; P = .03), but did not differ for ΔGI between terminating vs nonterminating RFC-ablation. Correspondingly, LI drop rate was higher for RFC-ablation terminating the VT compared with RFC-ablation not terminating the VT (0.63 Ω/s [0.52-0.76] vs 0.32 Ω [0.20-0.58]; P = .008) while there was no difference for GI drop rate. ΔLI was higher in patients with nonischemic cardiomyopathy vs patients with ischemic cardiomyopathy (16 Ω [11.0-20.0] vs 11.0 Ω [7.85-17.00]; P = .003). CONCLUSION: Our findings suggest that LI is a sensitive parameter to guide RFC-ablation in patients with VT. LI indicates differences in tissue characteristics and generally is higher in patients with nonischemic cardiomyopathy. Hence, the etiology of the underlying cardiomyopathy needs to be considered when adopting LI for monitoring catheter ablation of VT.

Advanced mapping strategies for ablation therapy in adults with congenital heart disease.

BACKGROUND: Ultra-high density mapping (HDM) is a promising tool in the treatment of patients with complex arrhythmias. In adults with congenital heart disease (CHD), rhythm disorders are among the most common complications but catheter ablation can be challenging due to heterogenous anatomy and complex arrhythmogenic substrates. Here, we describe our initial experience using HDM in conjunction with novel automated annotation algorithms in patients with moderate to great CHD complexity. METHODS: We studied a series of consecutive adult patients with moderate to great CHD complexity and an indication for catheter ablation due to symptomatic arrhythmia. HDM was conducted using the Rhythmia™ mapping system and a 64-electrode mini-basket catheter for identification of anatomy, voltage, activation pattern and critical areas of arrhythmia for ablation guidance. To investigate novel advanced mapping strategies, postprocedural signal processing using the Lumipoint™ software was applied. RESULTS: In 19 patients (53±3 years; 53% male), 21 consecutive ablation procedures were conducted. Procedures included ablation of atrial fibrillation (n=7; 33%), atrial tachycardia (n=11; 52%), atrioventricular accessory pathway (n=1; 5%), the atrioventricular node (n=1; 5%) and ventricular arrhythmias (n=4; 19%). A total of 23 supraventricular and 8 ventricular arrhythmias were studied with the generation of 56 complete high density maps (atrial n=43; ventricular n=11, coronary sinus n=2) and an average of 12,043±1,679 mapping points. Multiple arrhythmias were observed in n=7 procedures (33% of procedures; range of arrhythmias detected 2-4). A total range of 1-4 critical areas were defined per procedure and treated within a radiofrequency application time of 16 (interquartile range 12-45) minutes. Postprocedural signal processing using Lumipoint™ allowed rapid annotation of fractionated signals within specific windows of interest. This supported identification of a practical critical isthmus in 20 out of 27 completed atrial and ventricular tachycardia activation maps. CONCLUSIONS: Our findings suggest that HDM in conjunction with novel automated annotation algorithms provides detailed insights into arrhythmia mechanisms and might facilitate tailored catheter ablation in patients with moderate to great CHD complexity.