Multicenter prospective observational study to clarify the current status and clinical outcome in Japanese patients who have an indication for implantable cardioverter defibrillator (ICD) or wearable cardioverter defibrillator (WCD) (TRANSITION JAPAN-ICD/WCD study): Rationale and design of a prospective, multicenter, observational, comparative study.

Background: Despite the positive impact of implantable cardioverter defibrillators (ICDs) and wearable cardioverter defibrillators (WCDs) on prognosis, their implantation is often withheld especially in Japanese heart failure patients with reduced left ventricular ejection fraction (HFrEF) who have not experienced ventricular tachycardia (VT) or ventricular fibrillation (VF) for uncertain reasons. Recent advancements in heart failure (HF) medications have significantly improved the prognosis for HFrEF. Given this context, a critical reassessment of the treatment and prognosis of ICDs and WCDs is essential, as it has the potential to reshape awareness and treatment strategies for these patients. Methods: We are initiating a prospective multicenter observational study for HFrEF patients eligible for ICD in primary and secondary prevention, and WCD, regardless of device use, including all consenting patients. Study subjects are to be enrolled from 31 participant hospitals located throughout Japan from April 1, 2023, to December 31, 2024, and each will be followed up for 1 year or more. The planned sample size is 651 cases. The primary endpoint is the rate of cardiac implantable electronic device implementation. Other endpoints include the incidence of VT/VF and sudden death, all-cause mortality, and HF hospitalization, other events. We will collect clinical background information plus each patient's symptoms, Clinical Frailty Scale score, laboratory test results, echocardiographic and electrocardiographic parameters, and serial changes will also be secondary endpoints. Results: Not applicable. Conclusion: This study offers invaluable insights into understanding the role of ICD/WCD in Japanese HF patients in the new era of HF medication.

"Honey pot"-like lesion formation: Impact of catheter contact angle on lesion formation by novel diamond-embedded temperature-controlled ablation catheter in a porcine experimental model.

BACKGROUND: Novel diamond-embedded catheter enables precise temperature-controlled ablation. However, the effects of contact angle on lesion formation of this catheter are poorly understood. OBJECTIVE: The purpose of this study was to evaluate lesion formation using the temperature-controlled ablation catheter embedded with diamond at different angles in a porcine experimental model. METHODS: Freshly sacrificed porcine hearts were used. Radiofrequency catheter ablation was performed at 50 W for 15 seconds at an upper temperature setting of 60°C. The contact force (5g, 10g, 30g) and catheter contact angles (30°, 45°, 90°) were changed in each set (n = 13 each). Surface width, maximum lesion width, lesion depth, surface area, distance from the distal edge to the widest area, and impedance drop were evaluated. RESULTS: Surface width and maximum lesion width were longer at 30° than at 90° (P <.05). There were no significant differences in the lesion depth by catheter angle except at 30g. Surface area was larger at 30° than at 90° (P <.05). Distance from the distal edge to the widest area was longer at 30° than at 90° (P <.05). There were no significant differences in impedance drop according to catheter angle. CONCLUSION: With diamond-embedded temperature-controlled ablation catheters, lesion width increased at a shallower contact angle, whereas lesion depth did not. Surface area also increased at a shallower contact angle. This catheter created a large ablation lesion on the proximal side of the catheter, which looked like a "honey pot."

Prognostic impact of oral anticoagulation therapy and atrial fibrillation in patients with type B acute aortic dissection.

Background: The prognostic impact of atrial fibrillation (AF) and oral anticoagulation (OAC) therapy in patients with type B acute aortic dissection (AAD) remains unclear. Therefore, we investigated the prognostic impact of AF and OAC therapy in patients with type B AAD. Methods: Consecutive patients diagnosed with AAD were included in this single-center, retrospective study. Patients with type B AAD were selected from the study population and divided into three groups: AF(+)/OAC(+), AF(+)/OAC(-), and AF(-)/OAC(-). The primary end point was major adverse cardiovascular and cerebrovascular events (MACCE), including all-cause death, progressive aortic events, cerebral infarction, and organ malperfusion. Results: In total, 139 patients diagnosed with type B AAD were analyzed. AF was observed in 27 patients (19%). Among them, 13 patients (9%) received OAC therapy for AF. MACCE occurred in 32 patients (23%) during the observation period: all-cause death in four patients, progressive aortic events in 24 patients, cerebral infarction events in two patients, and malperfusion events in two patients. The incidence of MACCE was higher in the AF(+)/OAC(+) group than in the AF(+)/OAC(-) group (hazard ratio[HR]: 3.875; 95% confidence interval [CI]: 1.153-17.496). In contrast, there was no significant difference in the incidence of MACCE between the AF(+)/OAC(-) and AF(-)/OAC(-) groups (HR: 1.001, 95% CI: 0.509-1.802). Conclusion: Among patients with type B AAD, the use of OAC for AF was associated with a higher risk of MACCE.

An adult case of junctional tachycardia diagnosed by premature atrial contractions and atrial overdrive pacing.

We report an adult case with JT, which could be differentiated from slow-fast AVNRT by premature atrial contractions and atrial overdrive pacing.

Optimal local impedance parameters for successful pulmonary vein isolation in patients with atrial fibrillation.

INTRODUCTION: Local impedance (LI) parameters of IntellaNav STABLEPOINT for successful pulmonary vein isolation (PVI) of atrial fibrillation (AF) remain unclear. The purpose of this study was to seek LI data achieving successful PVI. METHODS: Consecutive AF patients who underwent catheter ablation with STABLEPOINT were prospectively enrolled in two centers. PVI was performed under a constant 35-or 40-watt power, 20-s duration, and >5-g contact force. The operators were blinded to the LI data. The characteristics of all ablation points with/without conduction gaps (Unsuccess or Success tags) after the first-attempt PVI were evaluated for the right/left PVs and anterior/posterior wall (RPV/LPV and AW/PW, respectively), and cutoff values of LI data were calculated for successful lesion formation. RESULTS: A total of 5257 ablation points in 102 patients (65 [58-72] years old, 65.7% male) were evaluated. The LI drop values were higher in the Success tags than Unsuccess tags on the LPV-AW and RPV-AW/PW (p < .001), except for the LPV-PW (p = .105). The %LI drop values (LI drop/initial LI) were higher for the Success tags in all areas (15.8 [12.2%-19.6%] vs. 11.6 [9.7%-15.6%] in LPV-AW: p < .001, 15.0 [11.5%-19.3%] vs. 11.4 [8.7%-17.3%] in LPV-PW: p = .035, 15.3 [11.5%-19.4%] vs. 9.9 [8.1%-13.7%] in RPV-AW: p < .001, and 13.3 [10.1%-17.4%] vs. 8.1 [6.3%-9.5%] in RPV-PW, p < .001). The LI drop and %LI drop cutoff values were 20.0 ohms and 11.6%, respectively. CONCLUSIONS: An insufficient LI drop with STABLEPOINT was associated with a gap formation during PVI, and the best cutoff values for the LI drop and %LI drop were 20.0 ohms and 11.6%, respectively.

Lesion size index-guided cavotricuspid isthmus linear ablation.

BACKGROUND: The lesion size index (LSI) predicts radiofrequency (RF) ablation lesion size and is an established parameter for pulmonary vein isolation. However, the effectiveness and safety of LSI for cavotricuspid isthmus (CTI) linear ablation remain unclear. METHODS: This single-center retrospective study included 50 of patients (67 ± 10 years, 68% male) who underwent de novo CTI linear ablation between July 2020 and December 2020. The LSI target was set at 5.0 and 4.0 for the anterior 2/3 and posterior 1/3 segments, respectively. Acute procedural parameters of ablation were evaluated. RESULTS: Acute bidirectional CTI block was achieved in all patients with an RF application time of 4.0 min (3.1-5.0 min), RF application number of 15 ± 7, and length of CTI of 36.9 ± 9.3 mm. First-pass bidirectional conduction block of the CTI was achieved in 39/50 (78%) patients. No major complications were observed. The contact force (CF) per application was significantly lower in the gap tag group than in the non-gap tag group (7 g [7-8 g] vs. 10 g [7-12 g], P = 0.0284). CONCLUSIONS: LSI-guided CTI linear ablation is an effective and safe treatment approach. CF affects gap formation, even when the target LSI is the same.

Atrial late potentials are associated with atrial fibrillation recurrence after catheter ablation.

Background: Previous studies have identified noninvasive methods for predicting atrial fibrillation (AF) recurrence after catheter ablation (CA). We assessed the association between AF recurrence and atrial late potentials (ALPs), which were measured using P-wave signal-averaged electrocardiography (P-SAECG). Methods: Consecutive patients with paroxysmal AF who underwent their first CA at our institution between August 2015 and August 2019 were enrolled. P-SAECG was performed before CA. Two ALP parameters were evaluated: the root-mean-square voltage during the terminal 20 ms (RMS20) and the P-wave duration (PWD). Positive ALPs were defined as an RMS20 <2.2 µV and/or a PWD >115 ms. Patients were allocated to either the recurrence or nonrecurrence group based on the presence of AF recurrence at the 1-year follow-up post-CA. Results: Of the 190 patients (age: 65 ± 11 years, 37% women) enrolled in this study, 21 (11%) had AF recurrence. The positive ALP rate was significantly higher in the recurrence group than in the nonrecurrence group (86% vs. 64%, p = .04), despite the absence of differences in other baseline characteristics between the two groups. In the multivariate analysis, positive ALP was an independent predictor of AF recurrence (odds ratio: 3.83, 95% confidence interval: 1.05-14.1, p = .04). Conclusions: Positive ALP on pre-CA P-SAECG is associated with AF recurrence after CA.

Endovascular thrombectomy using a stent retriever catheter for massive pulmonary thromboembolism.

Acute massive pulmonary thromboembolism (PE) has a high mortality rate of 18%-65%. Along with anticoagulation and thrombolytic therapy, treatment may require a catheter-based thrombectomy or surgical thrombectomy. We report a case of pulmonary thromboembolism treated with a Stent Retriever (Trevo® NXT ProVue Retriever, Stryker, Kalamazoo, MI, USA), which is commonly used to treat stroke. An 81-year-old woman complained of back pain and was transported to our hospital after she became unconscious. Cardiopulmonary resuscitation was initiated before her arrival at the hospital; she returned to spontaneous circulation after arrival. After undergoing computed tomography (CT) scanning, she went into cardiac arrest again, and we established veno-arterial extracorporeal membrane oxygenation and performed catheter thrombectomy using a stent retriever. The left basilar pulmonary artery and the right middle pulmonary artery trunk were retrieved after the stent's deployment, and bilateral pulmonary arteries were confirmed to be reopened. A residual thrombus was present, and Monteplase was administered. A contrast-enhanced CT scan taken on day 15 following admission revealed that the thrombus had disappeared, and echocardiography revealed improved right ventricular dysfunction. The patient was transferred to another hospital on day 64 for rehabilitation. We report the first case of pulmonary artery thrombosis that was successfully recanalized by endovascular treatment with a stent retriever. The stent retriever may be useful as an endovascular treatment device for PE because it is easier to achieve recanalization using this method compared to conventional treatment methods.

Impact of different dose reduction criteria for anti-Xa direct oral anticoagulants on bleeding complications: A single center observational study.

Background: Each direct oral anticoagulant (DOAC) has different dose reduction criteria. Here, we evaluated the differences in the doses of three anti-Xa DOACs and clinical events based on the dose reduction criteria in patients with atrial fibrillation (AF). Methods: Consecutive AF patients prescribed with anti-Xa DOACs [rivaroxaban (Riva), apixaban (Apix), and edoxaban (Edox)] between April 2011 and May 2016 were retrospectively evaluated. The incidences of thromboembolic and bleeding events were evaluated by the end of December 2020, focusing on the dose proportion. Results: A total of 786 patients (72 ± 10 years old, 66.9% male) were enrolled in this study [Riva (n = 337), Apix (n = 239), and Edox (n = 210)]. The proportion of reduced dose prescriptions was significantly greater for Edox (79.2%) than Riva (38.7%) or Apix (31.9%). A Kaplan-Meier analysis showed that the incidence of minor bleeding was significantly higher in the Apix than other groups (p < .001), even after propensity score matching. The standard dose of Apix had significantly higher bleeding events than the other DOACs (p < .001). Moreover, 23.2% and 51.6% of the patients with a standard dose of Apix were fulfilled with the dose reduction criteria for Riva and Edox and had more minor bleeding events than the unfulfilled ones (p = .046). Conclusions: The patients with a standard dose of Apix had a higher incidence of minor bleeding events than the other dosages. A reduced dose of apixaban was not prone to being chosen because of the dose reduction criteria, which may have been associated with a higher minor bleeding rate in patients with Apix.

Variation in heart rate range by 24-h Holter monitoring predicts heart failure in patients with atrial fibrillation.

AIMS: The analysis of heart rate (HR) changes, such as the HR variability or HR turbulence, has been reported as a marker of cardiovascular events during sinus rhythm; however, those relationships during atrial fibrillation (AF) remain controversial, and those parameters are not commonly used in AF patients. We sought to investigate the relationship between a simple index focused on the HR and heart failure (HF) events in patients with permanent AF. METHODS AND RESULTS: We enrolled 198 patients with permanent AF and evaluated the HR range, defined as the maximum HR minus the minimum HR on 24-h Holter electrocardiogram recordings. The patients were divided into two groups, i.e., the larger (n = 101) and smaller (n = 97) HR range (HRR) groups, determined by the median value. The HF events were defined as hospitalizations for HF or urgent hospital visits due to exacerbations of one's HF status. The observation period of this study was set at 5 years from registration. The median age was 73 (68-77) years, and 29% were female. The median HRR was 84 (63-118) beats per minutes (bpm). During the observational period of 1825 days (median), HF events occurred in 37 (0.047 per patient-year) patients. In a log-rank test, the larger HRR group had more frequent HF events than the smaller HRR group (P = 0.0078). In the adjusted Cox proportional hazards model using the significantly different factors from the univariate analysis (Model 1) and factors and medications associated with HF (Model 2), the larger HRR group had a higher prevalence of HF events than the smaller HRR group for both models [Model 1, adjusted hazard ratio = 3.21, 95% confidence interval (CI) 1.593-6.708, P = 0.0009; Model 2, adjusted hazard ratio = 3.12, 95% CI 1.522-6.685, P = 0.002]. When analysed using the time-dependent Cox proportional hazards model, the HRR was associated with HF with a statistically significant difference in both the univariate and multivariate analyses [hazard ratio = 1.01, 95% CI 1.006-1.020, P = 0.0002; Model 1, adjusted hazard ratio = 1.02, 95% CI 1.011-1.027, P < 0.0001; Model 2, adjusted hazard ratio = 1.01, 95% CI 1.008-1.021, P = 0.0003). There was no significant difference in the chronotropic medications between the two groups. CONCLUSIONS: In patients with permanent AF, a larger HRR was associated with HF events.

Esophagogastric complications in radiofrequency and cryoballoon catheter ablation of atrial fibrillation.

INTRODUCTION: Direct comparison studies about the incidence of esophagogastric complications between radiofrequency (RF) and cryoballoon (CB) catheter ablation (CA) for atrial fibrillation (AF) have been scarce. We sought to elucidate the relationship between the pulmonary vein isolation (PVI) modalities and esophagogastric complications. METHODS: The study population consisted of 254 patients who underwent CA for AF from November 2017 to October 2018. Finally, 160 patients were enrolled and divided into the RF and CB groups. Esophageal ulcers, gastric hypomotility, and exfoliative esophagitis detected by esophagogastroduodenoscopy were defined as esophagogastric complications in this study. RESULTS: The median age was 68 years old, with 34% being females. Esophagogastric complications were observed in 42.5% of patients who underwent CA. According to the detailed esophagogastric complications, the RF group had a higher prevalence of esophageal ulcers than the CB group (19% vs. 0%, p < .0001). There was no significant difference between the two groups regarding gastric hypomotility and exfoliative esophagitis (18% vs. 28%; p = .15 and 16% vs. 21%; p = .42, respectively). CONCLUSION: Asymptomatic esophagogastric complications were common in CA for AF. The incidence of esophageal ulcers was higher in the RF group than in the CB group, whereas the other esophagogastric complications did not significantly differ.

Atrial flutter with an epicardial and endocardial breakthrough in the cavotricuspid isthmus.

We performed cavotricuspid isthmus (CTI) linear ablation for atrial flutter; however, the tachycardia cycle length was not changed at all. In such cases, repeated or broad line ablation is usually performed. We presented that high-density three-dimensional mapping after the first CTI linear ablation, which revealed the complex tachycardia circuit with the epicardial and endocardial breakthrough.

Catheter contact angle influences local impedance drop during radiofrequency catheter ablation: Insight from a porcine experimental study with 2 different LI-sensing catheters.

BACKGROUND: Local impedance (LI) can indirectly measure catheter contact and tissue temperature during radiofrequency catheter ablation (RFCA). However, data on the effects of catheter contact angle on LI parameters are scarce. This study aimed to evaluate the influence of catheter contact angle on LI changes and lesion size with two different LI-sensing catheters in a porcine experimental study. METHODS: Lesions were created by the INTELLANAV MiFi™ OI (MiFi) and the INTELLANAV STABLEPOINT™ (STABLEPOINT). RFCA was performed with 30 W and a duration of 30 s. The contact force (CF) (0, 5, 10, 20, and 30 g) and catheter contact angle (30°, 45°, and 90°) were changed in each set (n = 8 each). The LI rise, LI drop, and lesion size were evaluated. RESULTS: The LI rise increased as CF increased. There was no angular dependence with the LI rise under all CFs in the MiFi. On the other hand, the LI rise at 90° was lower than at 30° under 5 and 10 g of CF in STABLEPOINT. The LI drop increased as CF increased. Regarding the difference in catheter contact angles, the LI drop at 90° was lower than that at 30° for both catheters. The maximum lesion widths and surface widths were smaller at 90° than at 30°, whereas there were no differences in lesion depths. CONCLUSION: The LI drop and lesion widths at 90° were significantly smaller than those at 30°, although the lesion depths were not different among the 3 angles for the MiFi and STABLEPOINT.

Fibrillation cycle length predicts cardiovascular events in patients with long-standing persistent atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with an increased risk of heart failure (HF), stroke, and death. Although fibrillation cycle length (FCL) is used as a surrogate for atrial refractoriness, its impact on outcomes remains unclear. This study aimed to identify predictors of cardiovascular events, including FCL, in patients with long-standing persistent AF. METHODS: The study included 190 consecutive patients with long-standing persistent AF (mean age 74 years, 74% male). Patients with valvular AF or hemodialysis-dependent end-stage renal disease and those on anti-arrhythmic drugs were excluded. The primary composite outcome was occurrence of cardiovascular events (myocardial infarction, HF), cerebrovascular events (stroke, transient ischemic attack), and all-cause death. FCL was calculated by fast Fourier transformation analysis of fibrillation waves in the surface electrocardiogram. RESULTS: Over a median follow-up of 2.6 years, the primary outcome occurred in 31 patients (cardiovascular events, n = 18; cerebrovascular events, n = 8; all-cause death, n = 5). In multivariate analysis, longer FCL and history of HF were independent predictors of these outcomes. In a Cox proportional hazards model adjusted for age, sex, and history of HF, patients with an FCL > 160 ms (cut-off determined by receiver-operating characteristic curve analysis) were at increased risk of the outcome (hazard ratio 12.9; 95% confidence interval 4.99-44.10; p < 0.001). CONCLUSIONS: FCL was independently associated with cardiovascular outcomes in patients with long-standing persistent AF.

Reduced atrial conduction velocity is associated with the recurrence of atrial fibrillation after catheter ablation.

The recurrence of atrial fibrillation (AF) after catheter ablation (CA) is still an unsolved issue. Although structural remodeling is relatively well defined, the method to assess electrical remodeling of the atrium is not well established. In this study, we evaluated the relationship between atrial conduction properties and recurrence after CA for AF. One hundred six consecutive patients (66 ± 11 years old, male: 68%) who underwent CA for AF with a CARTO system from July 2016 to July 2019 were enrolled in this study. An activation map of both atria was constructed to precisely evaluate the total conduction time, distance, and conduction velocity between the earliest and latest activation sites during sinus rhythm. All parameters were compared between the patients with or without AF recurrence. Of the patients, 27 had an AF recurrence (Rec group). The left atrial (LA) conduction velocity was significantly slower in the Rec group than in the non-Rec group (101.2 ± 17.9 vs. 116.9 ± 18.0 cm/s, P < 0.01). Likewise, the right atrial (RA) conduction velocity was significantly slower in the Rec group than in the non-Rec group (81.1 ± 17.5 vs. 103.6 ± 25.4 cm/s, P < 0.01). A multivariate logistic analysis demonstrated that the LA and RA conduction velocities were independent predictors of AF recurrence, with adjusted odds ratios of 0.95 (95% confidential interval: 0.91-0.98, P < 0.01) and 0.94 (0.89-0.98, P < 0.01), respectively. In conclusion, slower conduction velocity of the atrium was associated with AF recurrence after pulmonary vein isolation.

Novel Predictor for New-Onset Atrial High-Rate Episode in Patients With a Dual-Chamber Pacemaker.

Background: The incidence of new-onset atrial high-rate episode (AHRE) is higher among patients with cardiac implantable electronic devices (CIEDs) than in the general population. We sought to elucidate the clinical factors associated with AHRE in CIED patients, including P-wave dispersion (PWD) in sinus rhythm. Methods and Results: In all, 101 patients with CIEDs newly implanted between 2010 and 2014 were included in the study. PWD was measured at the time of device implantation via a body-surface electrocardiogram. AHRE was defined as any episode of sustained atrial tachyarrhythmia (>170 beats/min) recorded in the device's memory. Patients were divided into an AHRE (n=34) and non-AHRE (n=67) group based on the presence or absence of AHRE within 1 year of device implantation and compared. Mean (±SD) patient age was 75±11 years. A greater incidence of sick sinus syndrome (P=0.05) and longer PWD (62.6±13.1 vs. 38.2±13.9 ms; P<0.0001) were apparent in the AHRE than non-AHRE group. Multivariate analysis revealed that PWD was an independent predictor of new-onset AHRE (odds ratio 1.11; 95% confidence interval 1.06-1.17; P<0.0001). In logistic regression analysis, receiver-operating characteristic curve analysis (area under the curve 0.90; P<0.001) suggested the best cut-off value for PWD was 48 mm (sensitivity 73.8%, specificity 77.9%). Conclusions: PWD is a simple but feasible predictor of new-onset AHRE in patients with CIEDs.

Optimized lesion size index (o-LSI): A novel predictor for sufficient ablation of pulmonary vein isolation.

BACKGROUND: Although the lesion size index (LSI) has been well established, it is sometimes difficult to achieve first-pass pulmonary vein isolation (PVI) and to avoid acute pulmonary vein reconnections, even with LSI-guided procedures. The purpose of this study was to assess the predictive accuracy of a novel parameter, the optimized lesion size index (o-LSI), to perform PVI. METHODS: The voltage maps created by the Advisor™ high-density (HD) grid catheter before PVI in 35 atrial fibrillation (AF) patients were examined for an association between the voltage amplitude and insufficient ablation sites (IAS), which were defined as either (i) spontaneous reconnection sites, (ii) dormant PV conduction sites unmasked with 20 mg of adenosine triphosphate disodium hydrate (ATP) injection, or (iii) PV-LA gap sites after the initial PVI. RESULTS: IAS was observed in 25/1417 of the total ablation sites. IAS was significantly associated with higher bipolar voltage areas (4.20 ± 2.68 vs 2.43 ± 1.93 mV, P < .0001) but not with LSI. A novel index, o-LSI (defined as LSI/bipolar voltage), was significantly lower in IAS than in others (1.14 [0.82, 1.81] vs 2.35 [1.31, 4.80] LSI/mV). By receiver operating characteristic analysis, an o-LSI of 2.04 was the best cutoff value for the prediction of IAS (88% sensitivity and 55% specificity, P < .0001, areas under the curve: 0.742). CONCLUSION: Low o-LSI was strongly associated with IAS, potentially providing a novel index to improve first-pass PV isolation.

Energy loss by right ventricular pacing: Patients with versus without hypertrophic cardiomyopathy.

BACKGROUND: Right ventricular (RV) pacing causes left ventricular (LV) dyssynchrony sometimes resulting in pacing-induced cardiomyopathy. However, RV pacing for hypertrophic obstructive cardiomyopathy is one of the treatment options. LV flow energy loss (EL) using vector flow mapping (VFM) is a novel hemodynamic index for assessing cardiac function. Our study aimed to elucidate the impact of RV pacing on EL in normal LV function and hypertrophic cardiomyopathy (HCM) patients. METHODS: A total of 36 patients with dual-chamber pacemakers for sick sinus syndrome or implantable cardioverter defibrillators for fatal ventricular tachyarrhythmias were enrolled. All patients were divided into two groups: 16 patients with HCM (HCM group) and others (non-HCM group). The absolute changes in EL under AAI (without RV pacing) and DDD (with RV pacing) modes were assessed using VFM on color Doppler echocardiography. RESULTS: In the non-HCM group, the mean systolic EL significantly increased from the AAI to DDD modes (14.0 ± 7.7 to 17.0 ± 8.6 mW/m, P = .003), whereas the mean diastolic EL did not change (19.0 ± 12.3 to 17.0 ± 14.8 mW/m, P = .231). In the HCM group, the mean systolic EL significantly decreased from the AAI to DDD modes (26.7 ± 14.2 to 21.6 ± 11.9 mW/m, P < .001), whereas the mean diastolic EL did not change (28.7 ± 16.4 to 23.9 ± 19.7 mW/m, P = .130). CONCLUSIONS: RV pacing increased the mean systolic EL in patients without HCM. Conversely, RV pacing decreased the mean systolic EL in patients with HCM.

Canagliflozin Suppresses Atrial Remodeling in a Canine Atrial Fibrillation Model.

Background Recent clinical trials have demonstrated the possible pleiotropic effects of SGLT2 (sodium-glucose cotransporter 2) inhibitors in clinical cardiovascular diseases. Atrial electrical and structural remodeling is important as an atrial fibrillation (AF) substrate. Methods and Results The present study assessed the effect of canagliflozin (CAN), an SGLT2 inhibitor, on atrial remodeling in a canine AF model. The study included 12 beagle dogs, with 10 receiving continuous rapid atrial pacing and 2 acting as the nonpacing group. The 10 dogs that received continuous rapid atrial pacing for 3 weeks were subdivided as follows: pacing control group (n=5) and pacing+CAN (3 mg/kg per day) group (n=5). The atrial effective refractory period, conduction velocity, and AF inducibility were evaluated weekly through atrial epicardial wires. After the protocol, atrial tissues were sampled for histological examination. The degree of reactive oxygen species expression was evaluated by dihydroethidium staining. The atrial effective refractory period reduction was smaller (P=0.06) and the degree of conduction velocity decrease was smaller in the pacing+CAN group compared with the pacing control group (P=0.009). The AF inducibility gradually increased in the pacing control group, but such an increase was suppressed in the pacing+CAN group (P=0.011). The pacing control group exhibited interstitial fibrosis and enhanced oxidative stress, which were suppressed in the pacing+CAN group. Conclusions CAN and possibly other SGLT2 inhibitors might be useful for preventing AF and suppressing the promotion of atrial remodeling as an AF substrate.