Thomas Phlips

Determinants of Acute and Late Pulmonary Vein Reconnection in Contact Force–Guided Pulmonary Vein Isolation

Background— Pulmonary vein reconnection (PVR) still determines recurrences of atrial fibrillation after contact force (CF)–guided pulmonary vein isolation. We studied whether acute PVR (adenosine and waiting time) and late PVR (at repeat) are explained by incomplete transmurality and contiguity within the deployed radiofrequency circle. Methods and Results— We analyzed 42 CF-guided ipsilateral pulmonary vein isolation procedures. For each radiofrequency tag within the circle, we collected data reflecting lesion depth (time of application, power, impedance drop [&Dgr;-Imp], CF, force–time integral [FTI], and ablation index [AI]) and contiguity (automated interlesion distance [ILD]). Ablation line contiguity index (ALCI) was developed as a novel automated algorithm combining depth and contiguity into one single criterion. Each circle was subdivided into 10 segments. For each segment, we determined its weakest link by annotating timemin, powermin, &Dgr;-Impmin, CFmin, FTImin, AImin, ILDmax, and ALCImin. Compared with segments without PVR (n=758), PVR segments (n=44) were characterized by lower &Dgr;-Impmin (4.8 versus 7.4 &OHgr;), CFmin (8.5 versus 11.8 g), FTImin (351 versus 473 gs), AImin (367 versus 408 arbitrary unit [au]), and higher ILDmax (6.8 versus 5.5 mm). ALCImin was significantly lower in segments with PVR (74% versus 104%; P<0.001) and was associated with the highest accuracy to predict durable segments (area under the curve=0.73). Conclusions— In CF-guided pulmonary vein isolation, PVR is explained by lack of both lesion depth and contiguity within the deployed radiofrequency circle. ALCI, a novel measure combining contiguity and depth, is the most accurate predictor for durable segments. By avoiding weak links in the ablation chain, ALCI-guided ablation is expected to improve success rate of point-by-point radiofrequency ablation.

Cardiac three-dimensional rotational angiography can be performed with low radiation dose while preserving image quality

AIMS The effective radiation dose (ED) of three-dimensional rotational angiography (3DRA) is 5-8 mSv, leading to reticence on its use. We evaluated the potential of 3DRA with a reduced number of frames (RNF) and a reduced dose per frame. METHODS AND RESULTS Three-dimensional rotational angiography was performed in 60 patients (52.5 ± 9.6 years, 16 females) referred for ablation in the right (RA; n = 10) and left atrium (LA; n = 50). In a simulation group (n = 20), the effect of dropping frames from a conventional 248 frames 3DRA LA acquisition was simulated. In a prospective group (n = 40), RNF 3DRA were acquired of LA (n = 30) and RA (n = 10) with 67 frames (0.24 Gy/frame) and 45 frames (0.12 μGy/frame), respectively. Accuracy was evaluated qualitatively and quantitatively. Effective radiation dose was determined by Monte Carlo simulation on every frame. In the simulation group, surface errors increased minimally and non-significantly when reducing frames from 248 to 124, 83, 62, 50, 42, and 31: 0.49 ± 0.51, 0.52 ± 0.46, 0.61 ± 0.49, 0.62 ± 0.47, 0.71 ± 0.48, and 0.81 ± 0.47 mm, respectively (Pearson coefficient 0.20). All 3D LA images were clinically useful, even with only 31 frames. In the prospective group, good or optimal 3D image quality was achieved in 80% of LA and all of RA reconstructions. These accurate models were obtained with ED of 2.6 ± 0.4 mSv for LA and 1.2 ± 0.5 mSv for RA. CONCLUSION Three-dimensional rotational angiography is possible with a significant reduction in ED (to the level of prospectively gated cardiac computed X-ray tomography) without compromising image quality. Low-dose 3DRA could become the preferred online 3D imaging modality for pulmonary vein isolation and other anatomy-dependent ablations.

Clinical assessment and comparison of annotation algorithms in high-density mapping of regular atrial tachycardias

High‐density automated mapping of regular atrial tachycardias (ATs) requires accurate assessment of local activation times (LATs).

Contact Force Variability during Catheter Ablation of Atrial Fibrillation: The Role of Atrial Rhythm and Ventricular Contractions: Co-Force AF Study

Background—In an experimental model, variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation has not been characterized. Methods and Results—In 20 consecutive patients undergoing CF-guided circumferential pulmonary vein isolation, 914 radiofrequency applications (530 in sinus rhythm and 384 in atrial fibrillation) were analyzed. The variability of the 60% CF range (CF60%) was 17±9.6 g. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable, and 26 (3%) with intermittent CF. The mean CF and force-time integral were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability, and force-time integral between applications delivered in sinus rhythm and atrial fibrillation. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine-induced atrioventricular block, the minimum CF significantly increased at 19 sites (5.3±4.4 versus 13.4±5.9 g; P<0.001) and at 16 sites intermittent or variable CF became constant. At only 1 site systolo-diastolic movement remained the main reason for variable CF. Conclusions—CF during pulmonary vein isolation remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during sinus rhythm and atrial fibrillation. The main reasons for CF variability are systolo-diastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are because of ventricular contractions at the large majority of pulmonary vein isolation sites.Background —In an experimental model variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation (PVI) has not been characterized. Methods and Results —In 20 consecutive patients undergoing CF guided circumferential PVI 914 radio-frequency applications (530 in sinus rhythm (SR) and 384 in atrial fibrillation (AF)) were analyzed. The variability of the 60% CF range (CF60%) was 17±9.6 grams. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable and 26 (3%) with intermittent CF. The mean CF and Force Time Integral (FTI) were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability and FTI between applications delivered in SR and AF. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine induced AV block the minimum CF significantly increased at 19 sites (5.3±4.4 vs. 13.4±5.9 grams, p<0.001) and at 16 sites intermittent or variable CF became constant. At only one site systolo-diastolic movement remained the main reason for variable CF. Conclusions —CF during PVI remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during SR and AF. The main reasons for CF variability are systolo-diastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are due to ventricular contractions at the large majority of PVI sites.

Automated verification of pulmonary vein isolation in radiofrequency- and cryoballoon-guided ablation: DE POOTER et al .

Verification of pulmonary vein isolation (PVI) can be challenging due to the coexistence of pulmonary vein potentials and far‐field potentials. This study aimed to prospectively validate a novel algorithm for automated verification of PVI in radiofrequency (RF)‐guided and cryoballoon (CB)‐guided ablation strategies.