Association of left atrial low-voltage area and thromboembolic risk in patients with atrial fibrillation.

Aims: Atrial fibrillation (AF) is associated with thromboembolic events. Currently, the CHA2DS2-VASc score is recommended for thromboembolic risk stratification in non-valvular AF patients. However, recent data suggested a potential role of atrial remodelling on thromboembolism. This study aimed to assess the association between left atrial low-voltage area (LVA) and history of clinical manifest as well as subclinical silent cerebral ischaemia (SCI) in AF patients. Methods and results: Two-hundred patients [64 ± 10.5 years, 75 women (37.5%)] with symptomatic paroxysmal (n = 88, 44%) or persistent AF undergoing pulmonary vein isolation (PVI) were prospectively enrolled. Left atrial LVA (bipolar voltage < 0.5mV) was evaluated by intra-procedural mapping (>300 points per patient) during sinus rhythm. Cerebral delayed-enhancement magnetic resonance imaging was performed after PVI for detection of pre-existing procedural-independent SCI. Over all, 17 patients (8.5%) had previous history of stroke. Pre-existing SCIs were detected in 135 patients (67.5%). Patients with previous stroke (4.0 ± 1.5 vs. 2.1 ± 1.3, P < 0.0001) and pre-existing SCI (2.7 ± 1.3 vs. 1.5 ± 1.4, P < 0.0001) had a significantly higher CHA2DS2-VASc score. LVA was significantly larger in patients with previous stroke (12.5 ± 8.5% vs. 3.4 ± 5.4%, P < 0.0001) as well as pre-existing SCI (5.8 ± 6.9% vs. 0.8 ± 1.7%, P < 0.0001). Multivariate regression analysis revealed that LVA was independently associated with the presence of SCI [hazard ratio (HR) per 1% LVA 1.13 (1.06-1.22), P = 0.0003] and history of stroke [HR per 1% LVA 1.36 (1.19-1.60), P < 0.0001] after adjustment of CHA2DS2-VASc score. Conclusion: Left atrial LVA is associated with history of stroke and SCI in patients with non-valvular AF and might improve thromboembolic risk stratification after confirmation of its predictive value in future studies.

Reduction of Fluoroscopic Exposure Using a New Fluoroscopy Integrating Technology in a 3D-Mapping System During Pulmonary Vein Isolation With a Circular Multipolar Irrigated Catheter.

Pulmonary vein isolation (PVI) is a cornerstone therapy in patients with atrial fibrillation (AF). With increasing numbers of PVI procedures, demand arises to reduce the cumulative fluoroscopic radiation exposure for both the physician and the patient. New technologies are emerging to address this issue. Here, we report our first experiences with a new fluoroscopy integrating technology in addition to a current 3D-mapping system. The new fluoroscopy integrating system (FIS) with 3D-mapping was used prospectively in 15 patients with AF. Control PVI cases (n = 37) were collected retrospectively as a complete series. Total procedure time (skin to skin), fluoroscopic time, and dose-area-product (DAP) data were analyzed. All PVI procedures were performed by one experienced physician using a commercially available circular multipolar irrigated ablation catheter. All PVI procedures were successfully undertaken without major complications. Baseline characteristics of the two groups showed no significant differences. In the group using the FIS, the fluoroscopic time and DAP were significantly reduced from 571 ± 187 seconds versus 1011 ± 527 seconds (P = 0.0029) and 4342 ± 2073 cGycm(2) versus 6208 ± 3314 cGycm(2) (P = 0.049), respectively. Mean procedure time was not significantly affected and was 114 ± 31 minutes versus 104 ± 24 minutes (P = 0.23) by the FIS.The use of the new FIS with the current 3D-mapping system enables a significant reduction of the total fluoroscopy time and DAP compared to the previous combination of 3D-mapping system plus normal fluoroscopy during PVI utilizing a circular multipolar irrigated ablation catheter. However, the concomitant total procedure time is not affected. Thus, the new system reduces the radiation exposure for both the physicians and patients.

Modified energy settings are mandatory to minimize oesophageal injury using the novel multipolar irrigated radiofrequency ablation catheter for pulmonary vein isolation.

AIMS: The multipolar irrigated radiofrequency (RF) ablation catheter (nMARQ™) is a novel tool for pulmonary vein isolation (PVI). We investigated the incidence of thermal oesophageal injury (EI) using the nMARQ™ for PVI. METHODS AND RESULTS: In the initial six patients (Group 1), RF was delivered at the posterior wall with a maximum duration of 60 s and a maximum power (maxP) of 20 W for unipolar ablation, and a maxP of 10 W for the bipolar ablation. In the latter 15 patients (Group 2), RF application was limited at the posterior wall to a maximum duration of 30 s and a maxP of 15 W for unipolar ablation a max P of 10 W for bipolar ablation. Oesophageal temperature monitoring was performed in all patients and ablation was terminated at a temperature rise >41°C. Endoscopy was carried out within 2 days post-ablation. Pulmonary vein isolation was performed during sinus rhythm and was successfully achieved in 83 of 84 PVs except the septal inferior vein in one patient. Charring was seen in 3 of 21 (14.3%) patients without any evidence of embolism. Phrenic nerve palsy occurred in one patient. Endoscopy revealed severe EI in 3 of 6 (50%) patients in Group 1 and in 1 of 15 patients (6.7%) in Group 2. Procedure times between Groups 1 and 2 were similar (228.3 ± 60.2 min vs. 221.3 ± 51.8 min; P = 0.79). CONCLUSION: An unexpectedly high incidence of thermal EI was noted following PVI using the nMARQ™ with the initial ablation protocol. However, the incidence of thermal EI can be sigificantly reduced with limited power and RF application time at the posterior left atrium.

Electrical isolation of a substrate after myocardial infarction: a novel ablation strategy for unmappable ventricular tachycardias--feasibility and clinical outcome.

AIMS: Catheter ablation can abolish clinical ventricular tachycardia (VT) in patients after myocardial infarction (MI). However, VT frequently recurs after ablation. The best ablation strategy is still unknown, particularly in patients with unmappable VTs. We hypothesized that isolation of the arrhythmogenic substrate would be a feasible and effective ablation strategy for the treatment of ischaemic VT. METHODS AND RESULTS: Twelve patients (54 ± 8 years, left ventricular ejection fraction, LVEF 32 ± 13%) underwent catheter ablation for sustained VT (anterior MI = 10, inferior MI = 2). All patients had recurrent defibrillator shocks, including electrical storms in seven patients, despite anti-arrhythmic drugs. During electrophysiological study, 3 ± 2 VTs were induced. Three-dimensional mapping of the left ventricle revealed a low-voltage (<1.5 mV) area with fractionated electrograms and late potentials, with a mean area of 62 ± 20 cm(2). Isolation of the entire low-voltage area was attempted with a circumferential line along the low-voltage area border-zone. Substrate isolation was successfully achieved in 6 of 12 (50%) patients. Focal discharge within the isolated area was demonstrated in three of six (50%) patients. During a median follow-up of 479 [297; 781] days, 8 of 12 patients (66.7%) remained free of VT recurrence after a single procedure. In five of the six patients (83.3%) with successful substrate isolation, there were no VT recurrences when compared with three of the six patients (50%) with no substrate isolation. CONCLUSION: Electrical isolation of the entire substrate is feasible and appears to be an effective treatment in patients with late VT after MI.

In vivo contact force analysis and correlation with tissue impedance during left atrial mapping and catheter ablation of atrial fibrillation.

BACKGROUND: The aim of this study was to evaluate in vivo contact force (CF) and the correlation of CF with impedance during left atrial 3-dimensional electroanatomical mapping and ablation. METHODS AND RESULTS: CF during point-by-point left atrial mapping was assessed in 30 patients undergoing atrial fibrillation ablation. Operators were blinded to the real-time CF data. Data were analyzed according to 11 predefined areas in the left atrial and 6 segments around the ipsilateral pulmonary veins. A total of 3475 mapping and 878 ablation points were analyzed. Median CF during mapping was 14.0g (6.5-26.2; q1-q3), ranging from 5.1g at the ridge to 29.8g at the roof. Median CF at the ridge and mitral isthmus were 5.1g and 6.9g, respectively. Extremely high CF ≥100g was noted in 24 points (0.7%). Median CFs during ablation around the right and left pulmonary veins were 22.8g (12.6-37.9; q1-q3) and 12.3g (6.9-30.2; q1-q3), respectively. The lowest median CFs were recorded at the anterior-superior and anterior-inferior segments of the left pulmonary veins (7.2g and 7.9g). Impedance values during mapping and impedance fall during ablation correlated with the applied CF (R(2)=0.16; P<0.001 and R(2)=0.04; P<0.001) although there was significant overlap. CONCLUSIONS: Excessively high and low CF values can be observed during left atrial mapping and ablation. The low CF obtained at the mitral isthmus and anterior segments of the left pulmonary veins may explain why reconnection after ablation occurs more frequently at these sites. CF and impedance do correlate; however, the impedance for a given CF ranges widely, limiting its use in clinical practice.

Efficacy of additional radiofrequency applications for spontaneous dissociated pulmonary vein activity after pulmonary vein isolation in patients with paroxysmal atrial fibrillation.

BACKGROUND: The aim is to evaluate the efficacy of additional radiofrequency ablation (RFCA) for spontaneous dissociated pulmonary vein activity (DPV-spike) after PV isolation (PVI) in patients with paroxysmal atrial fibrillation (AF). METHODS: One hundred fifty-two consecutive patients with paroxysmal AF referred for RFCA were enrolled. When DPV-spike was documented after PVI, we randomly assigned these patients to receive additional RFCA for DPV-spike or only PVI. We divided them into 4 groups: 87 patients without DPV-spike after PVI (No-spike group), 31 without DPV-spike after additional RFCA (Successful group), 8 with remaining DPV-spike after additional RFCA (Unsuccessful group), and 26 with DPV-spike after only PVI (Spike group). AF recurrence was evaluated among the 4 groups. RESULTS: After PVI, DPV-spike was documented in 87 PVs (14%) from 65 patients. During 16 ± 9 months of follow-up, the incidence of the freedom from AF was significantly higher in the No-spike group than that in the Spike group and Unsuccessful group (P < 0.05), and tended to be higher in the Successful group than that in the Spike group and Unsuccessful group (P = 0.08 and 0.11, respectively). In a multivariate analysis, the remaining PV-spike after ablation was an independent predictor of AF recurrence (HR 2.44; CI 1.10-5.43, P < 0.05). No major complications including PV stenosis were observed during the follow-up. CONCLUSIONS: DPV-spike after PVI may be associated with higher electrical activity within the PVs and may be one of the risk factors for AF recurrence. Additional RFCA for DPV-spike was effective to reduce the AF recurrence after PVI.

Long-term outcome after catheter ablation for left posterior fascicular ventricular tachycardia without development of left posterior fascicular block.

BACKGROUND: Catheter ablation of left posterior fascicular (LPF) ventricular tachycardia (VT) is commonly performed during tachycardia. This study reports on the long-term outcome of patients undergoing ablation of LPF VT targeting the earliest retrograde activation within the posterior Purkinje fiber network during sinus rhythm (SR). METHODS: This study retrospectively analyzed 24 consecutive patients (8 female; mean age 26 ± 11 years) referred for catheter ablation of electrocardiographically documented LPF VT. Programmed stimulation was performed to induce tachycardia, while mapping and ablation was aided by use of a 3D electroanatomical mapping system. Catheter ablation targeted the earliest potential suggestive of retrograde activation within the posterior Purkinje fiber network (retro-PP) recorded along the posterior mid-septal left ventricle during SR if LPF VT was noninducible. RESULTS: Overall, 21/24 (87.5%) patients underwent successful catheter ablation in SR targeting the earliest retro-PP, while 3/24 (12.5%) patients were successfully ablated during tachycardia. In none of the patients, ablation resulted in LPF block. No procedure-related complications occurred. After a median follow-up period of 8.9 (4.8-10.9) years, 22/24 (92%) patients were free from recurrent VT. CONCLUSION: In patients presenting with LPF VT, ablation of the earliest retro-PP along the posterior mid-septal LV during SR results in excellent long-term outcome during a median follow-up period of almost 9 years.

Clinical impact of the number of extrastimuli in programmed electrical stimulation in patients with Brugada type 1 electrocardiogram.

BACKGROUND: Use of programmed electrical stimulation (PES) for risk stratification of Brugada syndrome (BrS) is controversial. OBJECTIVE: To elucidate the role of the number of extrastimuli during PES in patients with BrS. METHODS: Consecutive 108 patients with type 1 electrocardiogram (104 men, mean age 46 ± 12 years; 26 with ventricular fibrillation [VF], 40 with syncope, and 42 asymptomatic) underwent PES with a maximum of 3 extrastimuli from the right ventricular apex and the right ventricular outflow tract. Ventricular arrhythmia (VA) was defined as VF or nonsustained polymorphic ventricular tachycardia >15 beats. Patients with VA induced by a single extrastimulus or double extrastimuli were assigned to group SD (Single/Double), by triple extrastimuli to group T (Triple), and the remaining patients to group N. RESULTS: VA was induced in 81 patients (VF in 71 and polymorphic ventricular tachycardia in 10), in 4 by a single extrastimulus, in 41 by double extrastimuli, and in 36 by triple extrastimuli. During 79 ± 48 months of follow-up, 24 patients had VF events. Although the overall inducibility of VA was not associated with an increased risk of VF (log-rank P = .78), group SD had worse prognosis than did group T (P = .004). Kaplan-Meier analysis in patients without prior VF also showed that group SD had poorer outcome than did group T and group N (P = .001). Positive and negative predictive values of VA induction with up to 2 extrastimuli were, respectively, 36% and 87%, better than those with up to 3 (23% and 81%, respectively). CONCLUSIONS: The number of extrastimuli that induced VA served as a prognostic indicator for patients with Brugada type 1 electrocardiogram. Single extrastimulus or double extrastimuli were adequate for PES of patients with BrS.