Tricuspid Valve Leaflets-Lead Interaction: Adjunctive Role of Functional Cardiac Computed Tomography for Clinical Decision Making.

The diagnostic approach toward the management of cardiac implantable electronic device-related tricuspid regurgitation is challenging and undefined. Functional cardiac computed tomography angiography provides a complementary role to echocardiography in the evaluation of lead-leaflet interaction which can help the clinical decision-making process, as presented in this case series.

Impact of Atrial Fibrillation Triggers on Long-Term Outcomes of a Second Catheter Ablation of Nonparoxysmal Atrial Fibrillation.

Background: Catheter ablation (CA) of atrial fibrillation (AF) triggers, including non-pulmonary vein (PV) foci, contributes to improved procedural outcomes. However, the clinical significance of an AF trigger ablation during second CA procedures for nonparoxysmal AF is unknown. Methods and Results: We enrolled 94 patients with nonparoxysmal AF undergoing a second CA. Intracardiac cardioversion during AF using high-dose isoproterenol was performed to determine the presence or absence of AF triggers. PV re-isolations were performed if PV potentials recurred, and if AF triggers appeared from any non-PV sites, additional ablation was added to those sites. We investigated the incidence of atrial arrhythmia recurrence (AAR) >3 months post-CA. Of the 94 enrolled patients, AF triggers were identified in 65 (69.1%), and of those with AF triggers, successful elimination of the triggers was achieved in 47 patients (72.3%). Multivariate analysis revealed that no observed AF triggers were a significant predictor of AAR (hazard ratio [HR] 1.97, 95% confidence interval [CI] 1.21-3.46, P=0.019). In a subanalysis of the patients with AF triggers, multivariate analysis showed that unsuccessful trigger ablation was significantly associated with AAR (HR 5.84, 95% CI 2.79-12.22, P<0.01). Conclusions: Having no observed AF triggers during a second CA session significantly increased the risk of AAR, as did unsuccessful CA of AF triggers.

Preprocedural Computed Tomography Planning for Surgical Aortic Valve Replacement.

BACKGROUND: Selection of transcatheter valve size using preprocedural computed tomography (CT) is standardized and well established. However, valve sizing for surgical aortic valve replacement (SAVR) is currently performed intraoperatively by using sizers, which may result in variation among operators and risk for prosthesis-patient mismatch. This study evaluated the usefulness of CT annulus measurement for SAVR valve sizing. METHODS: This study included patients who underwent SAVR using Inspiris or Magna Ease and received preoperative electrocardiogram-gated CT imaging. Starting from June 2022, study investigators applied a CT sizing algorithm using CT-derived annulus size to guide minimum SAVR label size. The final decision of valve selection was left to the operating surgeon during SAVR. The study compared the appropriateness of valve selection (comparing implanted size with CT-predicted size) and prosthesis-patient mismatch rates without aortic root enlargement between 2 cohorts: 102 cases since June 2022 (CT sizing cohort) and 180 cases from 2020 to 2021 (conventional sizing cohort). RESULTS: Implanted size smaller than CT predicted size and severe prosthesis-patient mismatch were significantly lower by CT sizing than by conventional sizing (12% vs 31% [P = .001] and 0% vs 6% [P = .039], respectively). Interoperator variability was a factor associated with implanted size smaller than CT predicted with conventional sizing, whereas it became nonsignificant with CT sizing. CONCLUSIONS: Applying CT sizing to SAVR led to improved valve size selection, less prosthesis-patient mismatch, and less interoperator variability. CT sizing for SAVR could also be used to predict prosthesis-patient mismatch before SAVR and identify patients who need aortic root enlargement.

Comprehensive Myocardial Assessment by Computed Tomography: Impact on Short-Term Outcomes After Transcatheter Aortic Valve Replacement.

BACKGROUND: Quantification of myocardial changes in severe aortic stenosis (AS) is prognostically important. The potential for comprehensive myocardial assessment pre-transcatheter aortic valve replacement (TAVR) by computed tomography angiography (CTA) is unknown. OBJECTIVES: This study sought to evaluate whether quantification of left ventricular (LV) extracellular volume-a marker of myocardial fibrosis-and global longitudinal strain-a marker of myocardial deformation-at baseline CTA associate with post-TAVR outcomes. METHODS: Consecutive patients with symptomatic severe AS between January 2021 and June 2022 who underwent pre-TAVR CTA were included. Computed tomography extracellular volume (CT-ECV) was derived from septum tracing after generating the 3-dimensional CT-ECV map. Computed tomography global longitudinal strain (CT-GLS) used semi-automated feature tracking analysis. The clinical endpoint was the composite outcome of all-cause mortality and heart failure hospitalization. RESULTS: Among the 300 patients (80.0 ± 9.4 years of age, 45% female, median Society of Thoracic Surgeons Predicted Risk of Mortality score 2.80%), the left ventricular ejection fraction (LVEF) was 58% ± 12%, the median CT-ECV was 28.5% (IQR: 26.2%-32.1%), and the median CT-GLS was -20.1% (IQR: -23.8% to -16.3%). Over a median follow-up of 16 months (IQR: 12-22 months), 38 deaths and 70 composite outcomes occurred. Multivariable Cox proportional hazards model, accounting for clinical and echocardiographic variables, demonstrated that CT-ECV (HR: 1.09 [95% CI: 1.02-1.16]; P = 0.008) and CT-GLS (HR: 1.07 [95% CI: 1.01-1.13]; P = 0.017) associated with the composite outcome. In combination, elevated CT-ECV and CT-GLS (above median for each) showed a stronger association with the outcome (HR: 7.14 [95% CI: 2.63-19.36]; P < 0.001). CONCLUSIONS: Comprehensive myocardial quantification of CT-ECV and CT-GLS associated with post-TAVR outcomes in a contemporary low-risk cohort with mostly preserved LVEF. Whether these imaging biomarkers can be potentially used for the decision making including timing of AS intervention and post-TAVR follow-up will require integration into future clinical trials.

Feasibility of Redo-Transcatheter Aortic Valve Replacement in Sapien Valves Based on In Vivo Computed Tomography Assessment.

BACKGROUND: Our aim was to assess the feasibility of repeat transcatheter aortic valve (TAV) replacement for degenerated Sapien3 (S3) prostheses by simulating subsequent implantation of S3 or Evolut, using in vivo computed tomography-based sizing and the impact on coronary and patient-prosthesis mismatch risks. METHODS: Computed tomography scans from 356 patients with prior S3 TAV replacement implantation were analyzed. The in vivo sizing for second TAV based on averaged area of 3 levels of outflow, mid (narrowest) and inflow, was compared with in vitro recommendations, that is, same size as index S3 for second S3 and 1 size larger for Evolut. Risks of coronary obstruction and patient-prosthesis mismatch were determined by valve-to-aorta distance and estimated effective orifice area, respectively. RESULTS: Overall, the majority of patients (n=328; 92.1%) had underexpanded index S3 with an expansion area of 94% (91%-97%), leading to significant differences in size selection of the second TAV between in vivo and in vitro sizing strategies. Expansion area <89% served as a threshold, resulting in 1 size smaller than the in vitro recommendations were selected in 45 patients (13%) for S3-in-S3 and 13 (4%) for Evolut-in-S3, while the remaining patients followed in vitro recommendations (P<0.01, in vivo versus in vitro sizing). Overall, 57% of total patients for S3-in-S3 simulation and 60% for Evolut-in-S3 were considered low risk for coronary complications. Deep index S3 implantation (odds ratio, 0.76 [interquartile range, 0.67-0.87]; P<0.001) and selecting Evolut as the second TAV (11% risk reduction in intermediate- or high-risk patients) reduced coronary risk. Estimated moderate or severe patient-prosthesis mismatch risk was 21% for S3-in-S3 and 1% for Evolut-in-S3, assuming optimal expansion of the second TAV. CONCLUSIONS: Redo-TAV replacement with S3-in-S3 and Evolut-in-S3 could be feasible with low risk to coronaries in ≈60% of patients, while the remaining 40% will be at intermediate or high risk. The feasibility of redo-TAV replacement is influenced by sizing strategy, type of second TAV, native annular anatomy, and implant depth.

Deformation of transcatheter heart valves with mitral valve-in-valve.

BACKGROUND: The use of oversizing in mitral valve-in-valve (MViV) procedures can lead to non-uniform expansion of transcatheter heart valves (THV). This may have implications for THV durability. AIMS: The objective of this study was to assess the extent and predictors of THV deformation in MViV procedures. METHODS: We examined 33 patients who underwent MViV with SAPIEN prostheses. The extent of THV deformation (deformation index, eccentricity, neosinus volume, asymmetric leaflet expansion and vertical deformation) and hypoattenuating leaflet thickening (HALT) were assessed using cardiac computed tomography (CT), performed prospectively at 30 days post-procedure. For descriptive purposes, the THV deformation index was calculated, with values >1.00 representing a more hourglass shape. RESULTS: Non-uniform underexpansion of THV was common after MViV implantation, with a median expansion area of 74.0% (interquartile range 68.1-84.1) at the narrowest level and a THV deformation index of 1.21 (1.13-1.29), but circularity was maintained with eccentricity ranging from 0.24 to 0.28. The degree of oversizing was a key factor associated with greater underexpansion and a higher deformation index (ß=-0.634; p<0.001; ß=0.594; p<0.001, respectively). Overall, the incidence of HALT on the 30-day postprocedural CT was 27.3% (9 of 33). Most patients (32 of 33) were on anticoagulation therapy, but the prothrombin time and international normalised ratio (PT-INR) at the time of the CT scan was <2.5 in 23 of 32 patients. Among patients with a PT-INR of <2.5, HALT was predominantly observed with a high THV deformation index of ≥1.18. CONCLUSIONS: THV deformation, i.e., underexpansion and an hourglass shape, commonly occurs after MViV implantation and is negatively affected by excessive oversizing. Optimising THV expansion during MViV could potentially prevent HALT.

Deformation of Transcatheter Heart Valve Following Valve-in-Valve Transcatheter Aortic Valve Replacement: Implications for Hemodynamics.

BACKGROUND: Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) may be associated with adverse hemodynamics, which might affect clinical outcomes. OBJECTIVES: This study sought to evaluate the extent and predictors of transcatheter heart valve (THV) deformity in ViV TAVR and the relation to postprocedural hemodynamics. METHODS: We examined 53 patients who underwent ViV TAVR in surgical heart valves with self-expanding Evolut prostheses. THV deformation was examined using cardiac computed tomography prospectively performed 30 days after ViV TAVR, and correlated with 30-day echocardiographic hemodynamic data. RESULTS: Near complete expansion of the functional portion of the implanted ViV prostheses (ie, >90%) was observed in 16 (30.2%) patients. Factors related to greater expansion of the functional portion and consequently larger neosinus volume were absence of polymer surgical frame, higher implantation and use of balloon aortic valvuloplasty or bioprosthetic valve fracture during the procedure (all P < 0.05). Underexpansion of the functional portion, but not the valve inflow frame, was closely associated with mean gradient and effective orifice area at 30 days on echocardiography, with and without adjustment for the sizes of the THV and surgical heart valve. CONCLUSIONS: Underexpansion of the functional portion of THV prostheses is common during ViV TAVR, occurs more frequently with deep implantation and the presence of a polymer surgical stent frame, and is associated with worse postprocedural hemodynamics. Procedural techniques, such as higher implantation and balloon postdilatation, may be used to help overcome problems with THV underexpansion and improve clinical outcomes.

Importance of imaging-acquisition protocol and post-processing analysis for extracellular volume fraction assessment by computed tomography.

BACKGROUND: Computed tomography angiography (CTA) assessment of myocardial extracellular volume fraction (CT-ECV) is feasible, although the protocols for imaging acquisition and post-processing methodology have varied. We aimed to identify a pragmatic protocol for CT-ECV assessment encompassing both imaging acquisition and post-processing methodologies to facilitate its clinical implementation. METHODS: We evaluated consecutive patients with severe aortic stenosis undergoing evaluation for transcatheter aortic valve replacement (TAVR). Pre-contrast and 3-min-delayed CTA were obtained in systole using either helical prospective-ECG-triggered (high-pitch) or axial sequential-ECG-gated acquisition, adding to standard TAVR CTA protocol. Using a dedicated software for co-registration of CTA datasets, three methodologies for ECV measurement were evaluated: (1) mid-septum region of interest (Septal ECV), (2) averaged-global ECV (Global ECV) encompassing 16-AHA segments, and (3) average of septal and lateral segments (Averaged ECVsep and Averaged ECVlat). RESULTS: Among the 142 patients enrolled (median â€‹= â€‹81 years, 44% females), 8 were excluded due to significant imaging artifacts precluding Global ECV assessment. High-pitch scan mode was performed in 68 patients (48%). Suboptimal image quality for Global ECV assessment was associated with high-pitch scan mode (odds ratio: OR â€‹= â€‹2.26, p â€‹= â€‹0.036), along with the presence of intracardiac leads (OR â€‹= â€‹4.91, p â€‹= â€‹0.002), and BMI≥35 â€‹kg/m2 (OR â€‹= â€‹2.80, p â€‹= â€‹0.026). Septal ECV [median â€‹= â€‹29.4%] and Averaged ECVsep [29.0%] were similar (p â€‹= â€‹0.108), while Averaged ECVlat [27.5%] was lower than Averaged ECVsep (p â€‹< â€‹0.001), resulting in lower Global ECV [28.6%]. CONCLUSIONS: Myocardial CT-ECV assessment is feasible using a systolic sequential acquisition pre-contrast, and similar additional 3-min delayed scan. Septal ECV measurement provides similar values to Global ECV and is equally reproducible.

Significance of mitral L-waves in predicting late recurrences of atrial fibrillation after radiofrequency catheter ablation.

BACKGROUND: The mitral L-wave, a prominent mid-diastolic filling wave in echocardiographic examinations, is associated with severe left ventricular diastolic dysfunction. The relationship between the mitral L-wave and outcome of catheter ablation (CA) in patients with atrial fibrillation (AF) has not been established. This study aimed to evaluate the predictive value of mitral L-waves on AF recurrence after CA. METHODS: This was a retrospective and observational study in a single center. One hundred forty-six patients (mean age; 63.9 [56.0-72.0] years, 71.9% male) including 66 non-paroxysmal AF patients (45.2%) who received a first CA were enrolled. The mitral L-waves were defined as a distinct mid-diastolic flow velocity with a peak velocity ≥20 cm/s following the E wave in the echocardiographic examinations before CA. The patients enrolled were divided into groups with (n = 31, 21.2%) and without (n = 115, 78.8%) mitral L-waves. Univariate and multivariate analyses were carried out to determine the predictive factors of late recurrences of AF (LRAFs), which meant AF recurrence later than 3 months after the CA. RESULTS: During a follow-up of 28.8 (15.0-35.8) months, the ratio of LRAFs in patients with mitral L-waves was significantly higher than that in those without mitral L-waves (15 [46.9%] vs. 16 [14.0%], p < .001). A multivariate analysis using a Cox proportional hazard model revealed that the mitral L-waves were a significant predictive factor of LRAFs (hazard ratio: 3.09, 95% confidence interval: 1.53-6.24, p = .002). CONCLUSION: The appearance of mitral L-waves could predict LRAFs after CA.

Preprocedural coronary computed tomography angiography in chronic total occlusion percutaneous coronary intervention: Insights from the PROGRESS-CTO registry.

BACKGROUND: Preprocedural coronary computed tomography angiography (CCTA) can be useful in procedural planning for chronic total occlusion (CTO) percutaneous coronary intervention (PCI). METHODS: We examined the clinical, angiographic and procedural characteristics and outcomes of cases with vs. without preprocedural CCTA in PROGRESS-CTO (NCT02061436). Multivariable logistic regression was used to adjust for confounding factors. RESULTS: Of 7034 CTO PCI cases, preprocedural CCTA was used in 375 (5.3%) with increasing frequency over time. Patients with preprocedural CCTA had a higher prevalence of prior coronary artery bypass graft surgery (39% vs. 27%, p < 0.001) and angiographically unfavorable characteristics including higher prevalence of proximal cap ambiguity (52% vs. 33%, p < 0.001) and moderate/severe calcification (59% vs. 41%, p < 0.001) compared with those without CCTA. CCTA helped resolve proximal cap ambiguity in 27%, identified significant calcium not seen on diagnostic angiography in 18%, changed estimated CTO length by >5 mm in 10%, and was performed as part of initial coronary artery disease work up in 19%. CCTA cases had higher J-CTO (2.6 ± 1.2 vs. 2.3 ± 1.3, p < 0.001) and PROGRESS-CTO (1.3 ± 1.0 vs. 1.2 ± 1.0 p = 0.027) scores. After adjusting for potential confounders, cases with preprocedural CCTA had similar technical success (odds ratio [OR]: 1.18, 95% confidence interval [CI], 0.83-1.67) and incidence of major adverse cardiovascular events (OR: 1.47, 95% CI, 0.72-3.00). CONCLUSION: Preprocedural CCTA was used in ~5% of CTO PCI cases. While CCTA may help with procedural planning, especially in complex cases, technical success and MACE were similar with or without CCTA.

Impact of computed tomography on the diagnosis of Takayasu arteritis with acute coronary syndrome: A case series.

Both the diagnosis and treatment of coronary artery involvement with Takayasu arteritis (TA) are challenging. In this study, we report different clinical scenarios of two TA cases without Typical symptoms of TA that initially presented in the form of acute coronary syndrome (ACS). Patient 1 was a 24-year-old Japanese woman without coronary risk factors who presented with exertional chest pain, dyspnea, and syncope. Invasive coronary angiography (ICA) revealed a considerable lesion of the right coronary artery and the left main trunk. Ventricular fibrillation was observed immediately after the procedure. Despite conventional treatment, she died on day 16. Patient 2 was a 34-year-old Japanese woman without coronary risk factors who developed cardiogenic shock during a treadmill test for exertional chest pain. Coronary computed tomography angiography confirmed severe left main stenosis, presenting as ACS caused by TA. She was started on steroid therapy before coronary artery bypass grafting, resulting in a good postoperative course and no recurrence of chest pain. Therefore, coronary computed tomography angiography likely is useful for the early diagnosis of TA in young women with typical chest symptoms of ACS. It may help in avoiding complications associated with ICA. Learning objective: When young women with a low pre-test probability of coronary artery disease present with typical anginal symptoms, Takayasu arteritis (TA) should be suspected despite the absence of symptoms such as fever, fatigue, or myalgia. Coronary computed tomography angiography is safe for rapid diagnosis and decision-making when patients suspected of having TA initially manifest an unstable condition such as acute coronary syndrome.

The inducibility and focus of atrial fibrillation after ablation in patients with tachycardia-induced heart failure.

BACKGROUND: The inducibility of atrial fibrillation (AF) and incidence of nonpulmonary vein (nonPV) triggers in patients with heart failure (HF) have not been elucidated. Furthermore, the relationship between AF triggers and the change in the left ventricular (LV) function after catheter ablation (CA) remains unclear. METHODS: A total of 101 consecutive patients with a history of HF due to tachycardia who underwent CA of AF were prospectively enrolled (64.8 ± 10.7 years, male 72.3%, and paroxysmal AF 15.8%). According to the AF inducibility by isoproterenol (ISP), the patients were divided into two groups: inducible AF (66.3%) and noninducible AF (33.7%). Furthermore, inducible AF was categorized into a PV type (61.2%) and nonPV type (38.8%). This study investigated the AF recurrence and change in the LV ejection fraction (LVEF) after CA. RESULTS: AF recurred in 35 patients (34.7%) during the follow-up period (41.6 ± 26.8 months). Kaplan-Meier curves showed that patients with noninducible AF had just as bad an AF recurrence rate as those with the nonPV type. Cox proportional hazards models also revealed that noninducible AF (Hazard-ratio, 5.74; 95% CI, 1.81-18.13) was associated with a higher risk of recurrence. The LVEF significantly improved after the CA (from 49.1 ± 16.3% to 67.0 ± 7.9%). However, the nonPV type was associated with a lower improvement in the LVEF (Odds-ratio, 0.18; 95% CI, 0.05-0.70). CONCLUSION: The AF inducibility was associated with AF recurrence. Furthermore, the nonPV triggers were associated with a lesser improvement in the LVEF. Confirming the AF inducibility and triggers was important to predict the outcome after CA.

Predictive value of the cardio-ankle vascular index for recurrence of atrial fibrillation after catheter ablation.

BACKGROUND: The predictive value of the cardio-ankle vascular index (CAVI) for estimating the efficacy outcome of catheter ablation (CA) in atrial fibrillation (AF) patients is unclear. We aimed to examine the predictive performance of the CAVI for recurrences of atrial arrhythmias after CA. METHODS: We enrolled a total of 193 patients with AF (paroxysmal 126 and non-paroxysmal 67) who underwent initial CA procedures at our institute, and CAVI measurements were conducted between January 2016 and March 2017. We evaluated recurrences of atrial arrhythmias after the first CA procedure as a clinical outcome. The CAVI value was assessed and the enrolled patients were divided according to the optimal CAVI value cut-off point (9.5) in the atrial arrhythmia recurrence group. RESULTS: During a mean follow-up of 31.3 (17.5-43.0) months, 74 (32.5%; PaAF 41 and 49.3%; non-PaAF 33) patients had recurrences of atrial arrhythmias. The recurrence ratio of atrial arrhythmias was significantly higher in patients with a high CAVI (≥9.5) than those with a low CAVI (<9.5) (log rank test; p = 0.018). A univariate analysis showed the association between higher CAVI values and recurrences of atrial arrhythmias (p = 0.072). Multivariate analyses using a Cox proportional hazard model after adjusting for other clinical factors revealed that the CAVI value was determined to be a significant predictive factor of a recurrence of atrial arrhythmias after CA (Hazard ratio: 1.44, 95% confidence interval: 1.17-1.78, p < 0.01). CONCLUSIONS: The CAVI was significantly associated with a recurrence of atrial arrhythmias after CA in AF patients.

Lung sound analysis in infants with risk factors for asthma development.

BACKGROUND AND OBJECTIVES: Using a lung sound analysis, the prognosis of asthma was investigated in infants with risk factors for asthma development by a long-term observation. METHODS: A total of 268 infants were included (median age: 8 months old). The lung sound parameters (the ratio of the third and fourth area to the total area under the curve [A3/AT and B4/AT], and the ratio of power and frequency at 50% and 75% of the highest frequency [RPF50 and RPF75]) were evaluated at the first visit. At 3 years old, using a questionnaire, we examined the relationship between the lung sound parameters and risk factors of asthma development. RESULTS: Among the 268 infants, 175 infants were in good health and 93 had a history of acute respiratory infection (ARI) within 7 days at the first visit. Among the 3- to 12-month-old infants with an ARI, the A3/AT, B4/AT values in those with a history of asthma/asthmatic bronchitis, atopic dermatitis, and atopy were smaller than in the infants without such histories. Among the 13- to 24-month-old infants with an ARI, the A3/AT and B4/AT values in those with a wheezing history were larger than in the infants without such a history. CONCLUSIONS: The characteristics of the lung sounds in infants with risk factors for asthma development were demonstrated over long-term follow-up. Lung sound analyses may be useful for assessing the airway condition of infants.

SPinPong - Virtual Reality Table Tennis Skill Acquisition using Visual, Haptic and Temporal Cues.

Learning an advanced skill in sports requires a huge amount of practice and players also have to overcome both physical difficulties and the dullness of repetitive training. Returning a fast spin shot in table tennis could be taken as an example, as athletes need to judge the spin type and decide the racket pose within a second, which is difficult for beginners. Therefore, in this paper, we show how to design an intuitive training system to acquire this specific skill using different cues in Virtual Reality (VR). Using VR, we can easily provide visual information, attach haptic devices, and distort the speed of time, however, it is difficult to decide which types of information could benefit the training. In an initial study, by comparing real world training with VR training, we showed the effect of VR training and obtained some insights about augmentation for training spin shots. The training system was then improved by adding three new conditions using different visualizations and temporal distortions, as well as a haptic racket for creating realistic feedback. Finally, we performed a detailed experiment, which suggest a significant improvement of skill for each condition compared to the baseline, while a qualitative evaluation indicates that both users' motivation and their understanding of spin are increased by using our system.

Role of Intracardiac Defibrillation During the Ablation Procedure as a Predictor of Atrial Fibrillation Recurrence After Catheter Ablation.

Intracardiac defibrillation (IDF) is performed to restore sinus rhythm (SR) during radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). This study aimed to investigate the change in the IDF threshold before and after RFCA during the ablation procedure and determine whether the IDF threshold after RFCA was associated with the AF substrate and AF recurrence. A total of 141 consecutive patients with drug-refractory persistent AF (age 62.5 ± 10.3 years, 84.4% male) were enrolled in this study. Before RFCA, we initially performed IDF with an output of 1 J. When IDF failed to restore SR, the output was gradually increased to 30 J. After RFCA, we attempted pacing-induced AF to provoke other focuses of AF. When AF was induced, we performed IDF again to terminate AF with outputs of 1 to 30 J. The change in the IDF threshold to restore SR before and after RFCA was evaluated. After RFCA, the IDF threshold for restoring SR significantly decreased (from 11.5 ± 8.6 J to 4.0 ± 3.8 J, P < 0.001). During the follow-up (24.3 ± 12.2 months), SR was maintained in 107 patients (75.9%). The multivariate analysis using a Cox proportional-hazards model revealed that an IDF threshold of > 5 J after RFCA was significantly associated with the AF recurrence (HR, 3.99; 95% confidence interval 1.93-8.22; P = 0.0001). RFCA decreased the IDF threshold for restoring SR in patients with persistent AF. The IDF output of > 5 J after RFCA could be a predictor of AF recurrence independent of the AF substrate.

Comparing immersiveness and perceptibility of spherical and curved displays.

Curved displays are believed to create a feeling of immersiveness similar to virtual reality. However systematic studies are needed to demonstrate that this is, in fact, true and under what conditions. In an experimental study 24 participants compared five different displays (concave, convex, hemisphere, sphere and a flat display) in terms of their immersiveness and perceptibility, and they also rated their overall preferences. Both immersiveness and perceptibility affected overall preference ratings. Participants gave higher preference ratings to the convex and concave displays, which were rated high in immersiveness and perceptibility, but gave lower preference ratings to the hemisphere/spherical display which had high ratings on immersiveness but low ratings on perceptibility. The study results imply that curved displays do indeed create a feeling of immersiveness. Concave and convex displays were rated highly favorably and should receive more attention for applications where visual experience and a feeling of immersiveness is particularly important.