Background: For lesion size prediction, each input parameter, including ablation energy (AE), and output parameter, such as impedance, is individually used. We hypothesize that using both parameters ...simultaneously may be more optimal.Methods and Results: Radiofrequency applications at a range of power (30–50 W), contact force (10 g and 20 g), duration (10–60 s), and catheter orientation with normal saline (NS)- or half-normal saline (HNS)-irrigation were performed in excised porcine hearts. The correlations, with lesion size of AE, absolute impedance drop (∆Imp-drop), relative impedance drop (%Imp-drop), and AE*%Imp-drop were examined. Lesion size was analyzed in 283 of 288 lesions (NS-irrigation, n=142; HNS-irrigation, n=141) without steam pops. AE*%Imp-drop consistently showed the strongest correlations with lesion maximum depth (NS-irrigation, ρ=0.91; HNS-irrigation, ρ=0.94), surface area (NS-irrigation, ρ=0.87; HNS-irrigation, ρ=0.86), and volume (NS-irrigation, ρ=0.94; HNS-irrigation, ρ=0.94) compared with the other parameters. Moreover, compared with AE alone, AE*%Imp-drop significantly improved the strength of correlation with lesion maximum depth (AE vs. AE*%Imp-drop, ρ=0.83 vs. 0.91, P<0.01), surface area (ρ=0.73 vs. 0.87, P<0.01), and volume (ρ=0.84 vs. 0.94, P<0.01) with NS-irrigation. This tendency was also observed with HNS-irrigation. Parallel catheter orientation showed a better correlation with lesion depth and volume using ∆Imp-drop, %Imp-drop, and AE*%Imp-drop than perpendicular orientation.Conclusions: The combination of input and output parameters is more optimal than each single parameter for lesion prediction.
Purpose
Clinical implication of local impedance (LI) for radiofrequency (RF) ablation has not been fully established. This study aimed to investigate this point using IntellaNav MiFi OI
TM
catheter.
...Methods
LI and generator impedance drops (ΔLI and ΔGI) were evaluated in excised porcine hearts (
N
= 16) during RF applications at a range of powers (30 and 50 W), contact forces (5–40 g), and durations (10–180 s) using perpendicular or parallel catheter orientation. Additionally, temporal LI changes were assessed.
Results
Of the 240 lesions without steam pops (92.3%), ΔLI showed better correlations with lesion surface area (
ρ
= 0.55 vs 0.36,
P
= 0.004), maximum depth (
ρ
= 0.53 vs 0.14,
P
< 0.001), and lesion volume (
ρ
= 0.64 vs 0.23,
P
< 0.001) than ΔGI. Furthermore, %LI-drop (ΔLI/initial LI) demonstrated stronger correlations with lesion surface area (
ρ
= 0.60 vs 0.55,
P
< 0.001), maximum depth (
ρ
= 0.57 vs 0.53,
P
< 0.001), and volume (
ρ
= 0.69 vs 0.64,
P
< 0.001) than ΔLI. Parallel catheter orientation improved correlation of ΔLI with lesion surface area (
ρ
= 0.63 vs 0.40,
P
= 0.015) and depth (
ρ
= 0.68 vs 0.45,
P
= 0.008) and created a larger surface lesion (36.329.2–42.7 mm
2
vs 28.821.6–34.2 mm
2
,
P
< 0.001) than the perpendicular. LI of the lesions significantly differed between baseline, immediately after RF, and 5 min after (
P
< 0.01). LI reaching plateau, larger initial LI, ΔLI, and %LI-drop, and larger RF power and longer duration were observed in pop lesions (
P
< 0.05).
Conclusions
%LI-drop demonstrated a better correlation with lesion size than ΔLI. LI may be used as an additional parameter to predict lesion size and steam pops. Temporal variation and catheter orientation should be considered to interpret LI.
Background
Although ablation energy (AE) and force-time integral (FTI) are well-known active predictors of lesion characteristics, these parameters do not reflect passive tissue reactions during ...ablation, which may instead be represented by drops in local impedance (LI). This study aimed to investigate if additional LI data improves predicting lesion characteristics and steam pops.
Methods
RF applications at a range of powers (30 W, 40 W, and 50 W), contact forces (8 g, 15 g, 25 g, and 35 g), and durations (10–180 s) using perpendicular/parallel catheter orientations were performed in excised porcine hearts (
N
= 30). The correlation between AE, FTI, and lesion characteristics was examined, and the impact of LI (%LI drop (%LID) defined by the ΔLI divided by the initial LI) was additionally assessed.
Results
Three hundred seventy-five lesions without steam pops were examined. Ablation energy (W × s) and FTI (g × s) showed a positive correlation with lesion depth (
ρ
= 0.824:
P
< 0.0001 and
ρ
= 0.708:
P
< 0.0001), surface area (
ρ
= 0.507:
P
< 0.0001 and
ρ
= 0.562:
P
< 0.0001), and volume (
ρ
= 0.807:
P
< 0.0001 and
ρ
= 0.685:
P
< 0.0001). %LID also showed a positive correlation individually with lesion depth (
ρ
= 0.643:
P
< 0.0001), surface area (
ρ
= 0.547:
P
< 0.0001), and volume (
ρ
= 0.733:
P
< 0.0001). However, the combined indices of AE × %LID (AE multiplied by %LID) and FTI × %LID (FTI multiplied by %LID) provided significantly stronger correlation with lesion depth (
ρ
= 0.834:
P
< 0.0001 and
ρ
= 0.809:
P
< 0.0001), surface area (
ρ
= 0.529:
P
< 0.0001 and
ρ
= 0.656:
P
< 0.0001), and volume (
ρ
= 0.864:
P
< 0.0001 and
ρ
= 0.838:
P
< 0.0001). This tendency was observed regardless of the catheter placement (parallel/perpendicular). AE (
P
= 0.02) and %LID (
P
= 0.002) independently remained as significant predictors to predict steam pops (
N
= 27). However, the AE × %LID did not increase the predictive power of steam pops compared to the AE alone.
Conclusion
LI, when combined with conventional parameters (AE and FTI), may provide stronger correlation with lesion characteristics.
Background/Objectives
The QDOT‐MICRO™ catheter allows very high‐power and short‐duration (vHPSD) ablation. This study aimed to investigate lesion characteristics using different ablation settings.
...Methods
Radiofrequency applications (90 W/4 s, temperature‐control mode with 55°C or 60°C target) were performed in excised porcine myocardium using three different approaches: single (SA), double nonrepetitive (DNRA), and double repetitive applications (DRA). Applications were performed with an interval of 1 min for DNRA, and without interval for DRA.
Results
A total of 480 lesions were analyzed. Lesion depth and volume were largest for DRA followed by DNRA and SA regardless of catheter direction (depth: 3.8 vs. 3.3 vs. 2.6 mm, p < .001 for all comparisons; volume: 176.6 vs. 145.1 vs. 97.0 mm3, p < .001 for all comparisons). Surface area was significantly larger for DRA than for SA (45.1 vs. 38.3 mm2, p < .001) and larger for DNRA than for SA (44.5 vs. 38.3 mm2, p < .001), but was similar between DRA and DNRA (45.1 vs. 44.5 mm2, p = .54). Steam‐pops more frequently occurred for DRA than for SA (15.6% vs. 4.4%, p = .004) and DNRA (15.6% vs. 6.9%, p = .061), but the incidence was similar between SA and DNRA (4.4% vs. 6.9%, p = 1). Although surface area and lesion volume were larger in lesions with steam‐pops than without steam‐pops (46.5 vs. 38.1 mm2, p = .018 and 128.3 vs. 96.8 mm3, p = .068, respectively), lesions were not deeper (pop(+): 2.5 mm vs. pop(−): 2.6 mm, p = .75).
Conclusions
DNRA produces larger lesions than SA without increasing the risk of steam‐pops. DRA produces the largest lesions among the three groups, but with an increased risk of steam‐pops. Even with steam‐pops, lesions do not become deeper in vHPSD ablation.
(Top) Although lesion depth of single radiofrequency applications is small, double RF application with 1 min ‘rest’ interval may produce deeper lesions without increasing steam‐pops in very high‐power and short‐duration (vHPSD) ablation. (Bottom) Lesion depth does not increase with steam‐pops, suggesting a degree of safety for vHPSD ablation.
Better models to identify individuals at low risk of ventricular arrhythmia (VA) are needed for implantable cardioverter-defibrillator (ICD) candidates to mitigate the risk of ICD-related ...complications. We designed the CERTAINTY study (CinE caRdiac magneTic resonAnce to predIct veNTricular arrhYthmia) with deep learning for VA risk prediction from cine cardiac magnetic resonance (CMR). Using a training cohort of primary prevention ICD recipients (n = 350, 97 women, median age 59 years, 178 ischemic cardiomyopathy) who underwent CMR immediately prior to ICD implantation, we developed two neural networks: Cine Fingerprint Extractor and Risk Predictor. The former extracts cardiac structure and function features from cine CMR in a form of cine fingerprint in a fully unsupervised fashion, and the latter takes in the cine fingerprint and outputs disease outcomes as a cine risk score. Patients with VA (n = 96) had a significantly higher cine risk score than those without VA. Multivariate analysis showed that the cine risk score was significantly associated with VA after adjusting for clinical characteristics, cardiac structure and function including CMR-derived scar extent. These findings indicate that non-contrast, cine CMR inherently contains features to improve VA risk prediction in primary prevention ICD candidates. We solicit participation from multiple centers for external validation.
Background
The FlexAbility™ SE catheter has a laser-cut 8Fr 4-mm flexible tip irrigated through laser-cut kerfs with a thermocouple 0.3 mm from the distal end. The TactiCath™ SE catheter has an 8Fr ...3.5-mm tip and 6-irrigation port with a thermocouple 2.67 mm proximal to the tip. We investigated the impact of these differences on the efficacy and safety of radiofrequency (RF) applications.
Methods
RF applications at a range of powers (20 W, 30 W, and 40 W), contact forces (5 g, 15 g, and 25 g), and durations (10–60 s) using perpendicular/parallel catheter orientation were performed in excised porcine hearts. Lesion characteristics and incidence of steam pops were compared.
Results
A total of 540 lesions were examined. The FlexAbility™ SE catheter produced smaller lesion depths (4.0 mm vs. 4.4 mm,
p
= 0.014 at 20 W; 4.6 mm vs. 5.6 mm,
p
= 0.015 at 30 W), surface areas (22.7mm
2
vs. 29.2mm
2
at 20 W,
p
= 0.005; 23.2mm
2
vs. 28.7mm
2
,
p
= 0.009 at 30 W), and volumes (126.1mm
3
vs. 175.1mm
3
,
p
= 0.018 at 20 W; 183.2mm
3
vs. 304.3mm
3
,
p
= 0.002 at 30 W) with perpendicular catheter placement. However, no differences were observed with parallel catheter placement. Steam-pops were significantly less frequently observed with the FlexAbility™ SE catheter (4% vs. 22%,
p
< 0.001) irrespective of catheter direction to the tissue. Multivariate analysis showed that use of the TactiCath™ SE catheter, power ≥ 40 W, contact force ≥ 25 g, RF duration > 30 s, parallel angle, and impedance drop ≥ 20Ω were significantly associated with occurrence of steam-pops.
Conclusions
The FlexAbility™ SE catheter reduced the risk of steam-pops but produced smaller lesions with perpendicular catheter placement compared to the TactiCath™ SE catheter.
Background
Recent studies have shown the improvement in long‐term effectiveness with standardized pulmonary vein isolation (PVI) aimed at creating durable and contiguous lesions with VISITAG SURPOINT ...(VS) in paroxysmal atrial fibrillation (PAF).
Objective
We aimed to assess efficacy of PVI alone strategy using VS in non‐PAF patients and evaluate factors associated with corresponding clinical outcomes.
Methods
Consecutive patients who underwent PVI for persistent/long‐standing persistent AF between May 2017 to July 2019 were studied retrospectively. PVI was performed with 30–50 W guided by VS (posterior target: 400–500, anterior target: 500). Left atrial voltage maps were created during atrial pacing after PVI.
Results
A total of 140 patients (119 males, age 62 ± 10 years, long‐standing persistent AF: 35) were included and followed for median of 454 days. No adverse events were reported in any patients during periprocedural and follow‐up period of up to 28 months. Kaplan–Meier analysis estimated that freedom from atrial tachycardia or AF (AT/AF) without antiarrhythmics at 1‐year was 70%. Radiofrequency delivery with higher power was associated with increased first‐pass isolation rate, but not with freedom from AT/AF. In multivariate analysis, long‐standing persistent AF and % low‐voltage zone (%LVZ) were independent predictors of clinical outcome. The best cut‐off value of %LVZ for predicting AT/AF recurrence was 3.24%. Freedom from AT/AF was 88% in patients with persistent AF and %LVZ < 3.24%, while 27% in those with long‐standing persistent AF and %LVZ ≥ 3.24%.
Conclusions
PVI alone using VS was associated with excellent 1‐year success in patients with persistent AF and %LVZ < 3.24%, but was insufficient in those with long‐standing persistent AF and/or %LVZ ≥ 3.24%.
The purpose of this study was to evaluate the usefulness of intra-atrial dyssynchrony as a marker of underlying left atrial (LA) remodeling to predict recurrence after the first atrial fibrillation ...(AF) ablation.
Catheter ablation for AF remains far from curative with relatively high recurrence rates. One of the causes of recurrence is poor patient selection out of a diverse patient population with different degrees of LA remodeling.
We included 208 patients with a history of AF (59.4 ± 10.0 years of age; 26.0% nonparoxysmal AF) referred for catheter ablation of AF who underwent pre-ablation cardiac magnetic resonance in sinus rhythm. Clinical follow-up was 20 ± 6 months. Using tissue tracking cardiac magnetic resonance, we measured the LA longitudinal strain in each of 12 equal-length segments in 2- and 4-chamber views. We defined intra-atrial dyssynchrony as the standard deviation of the time to the peak longitudinal strain corrected by the cycle length (SD-time to peak strain TPS, %).
Patients with AF recurrence after ablation (n = 101) had significantly higher SD-TPS than those without (n = 107; 3.9% vs. 2.2%; p < 0.001). Multivariable cox analysis showed that SD-TPS was associated with recurrence after adjusting for clinical risk factors, AF type, LA structure and function, and fibrosis (p < 0.001). Furthermore, receiver-operating characteristics analysis showed SD-TPS improved prediction of recurrence better than clinical risk factors, LA structure and function, and fibrosis.
Intra-atrial dyssynchrony during sinus rhythm is an independent predictor of recurrence after the first catheter ablation of paroxysmal or persistent AF. Assessment of intra-atrial dyssynchrony may improve ablation outcomes by refining patient selection.
Display omitted
PDF
