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.

The efficacy and safety of sacubitril/valsartan in heart failure with reduced ejection fraction patients with hypotension.

Despite previous studies showing that patients with low systolic blood pressure (sBP) in heart failure with reduced ejection fraction (HFrEF) has a poor prognosis, it has few treatment options. This study aimed to investigate the efficacy and safety of sacubitril/valsartan (S/V) in HFrEF patients with hypotension. We included 43 consecutive HFrEF patients with sBP < 100 mmHg despite guideline-directed medical therapy for at least 3 months and who received S/V between September 2020 and July 2021. Patients admitted for acute heart failure were excluded and 29 patients were evaluated for safety endpoints. Furthermore, patients who performed non-pharmacological therapy or died within 1 month were excluded, finally, 25 patients were evaluated for efficacy endpoints. The mean initial S/V dose was 53.0 ± 20.5 mg/day and the mean dosage was increased to 84.0 ± 34.5 mg/day in 1 month. Serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) values significantly decreased from 2200 [interquartile range (IQR): 1462-3666] pg/ml to 1409 (IQR: 964-2451) pg/ml. (p < 0.0001). No significant change in sBP occurred (pre-sBP: 93.2 ± 4.9 mmHg, post-sBP: 93.4 ± 9.6 mmHg, p = 0.91), and no patients discontinued the S/V due to symptomatic hypotension in 1 month after S/V initiation. S/V can be safely introduced in HFrEF patients with hypotension to reduce serum NT-proBNP values. Thus, S/V may be useful for the treatment of HFrEF patients with hypotension.

Angiographic evaluation of the distance from the top of the jugular bulb to the inferior petrosal sinus-internal jugular vein junction: simple classification and identification method for the orifice of the non-visualized inferior petrosal sinus during neuroendovascular surgery.

BACKGROUND: The inferior petrosal sinus (IPS) is the transvenous access route for neurointerventional surgery that is occasionally undetectable on digital subtraction angiography (DSA) because of blockage by a clot or collapse. This study was aimed at analyzing the distance from the jugular bulb (JB) to the IPS-internal jugular vein (IJV) junction and proposing a new anatomical classification system for the IPS-IJV junction to identify the non-visualized IPS orifice. METHODS: DSA of 708 IPSs of 375 consecutive patients were retrospectively investigated to calculate the distance from the top of the JB to the IPS-IJV junction, and a simple classification system based on this distance was proposed. RESULTS: The median distance from the top of the JB to the IPS-IJV junction was 20.8 ± 14.7 mm. Based on the lower (10.9 mm) and upper (31.1 mm) quartiles, IPS-IJV junction variants were: type I, 0-10 mm (22.3%); type II, 11-30 mm (45.8%); type III, > 31 mm (23.9%); and type IV, no connection to the IJV (8.0%). Bilateral distances showed a positive interrelationship, with a correlation coefficient of 0.86. The bilateral symmetry type (visualized IPSs bilaterally) according to our classification occurred in 267 of 300 (89.0%) patients. CONCLUSIONS: In this study, the IPS-IJV junction was located far from the JB (types II and III), with a higher probability (69.6%). This distance and the four-type classification demonstrated high degrees of homology with the contralateral side. These results would be useful for identifying the non-visualized IPS orifice.

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.

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.

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.

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.

Day-to-Day Variation of Early Repolarization Pattern Predicts Life-Threatening Arrhythmias in Patients With Brugada Syndrome.

BACKGROUND: We assessed the relationship between day-to-day variation of the early repolarization (ER) pattern and ventricular tachyarrhythmia (VTA) events in Brugada syndrome (BrS) patients because the clinical implications are unclear.Methods and Results:This retrospective study consisted of 41 patients with BrS who underwent implantable cardioverter-defibrillator (ICD) implantation. BrS was diagnosed by a spontaneous or drug-induced type 1 ECG without structural heart disease. Day-to-day variation of the ER pattern was defined as temporal change in the J-point (≥0.1 mV) on ECG. VTA events were detected via ICD interrogation: 15 patients experienced VTA events during 124±62 months' observation. Day-to-day variation of the ER pattern was positive in 7 patients (17%). In the multivariate Cox proportional hazards model, day-to-day variation of a positive ER pattern (hazard ratio [HR]: 3.475, 95% confidence interval [CI]: 1.105-10.414, P=0.034) and documented history of VTA (HR: 4.802, 95% CI: 1.547-17.995, P=0.006) were independent predictors of VTA events. In patients with electrical storm (ES: n=9), day-to-day variation of the ER pattern was positive in 5 patients (56%). ES events were more frequently observed in patients with a positive day-to-day variation of ER pattern than in those without (P<0.05). CONCLUSIONS: The incidence of day-to-day variation of the ER pattern was higher in patients with arrhythmic events of VTA and/or ES among BrS patients with ICD.

Prediction of Lethal Arrhythmic Events Through Remote Monitoring Using Heart Rate Variability Analysis in Patients with an Implantable Cardioverter Defibrillator.

We prospectively collected device and heart rate data through remote monitoring (RM) of patients with an implantable cardioverter defibrillator (ICD). The objective was to identify the predictors of lethal arrhythmic events (VT/VF).Thirty-three patients (mean age: 50 years) with ICDs [with functionality of heart rate variability (HRV) analysis] were divided into two groups [VT/VF (+), VT/VF (-) ]. Clinical, device (ventricular lead impedance; amplitude of ventricular electrogram), and HRV data were compared between the two groups. The NN interval-index (SDNNi) was calculated for every 5 minutes, and the mean, maximum, minimum, and standard deviation of SDNNi during the 24-hour period were used.During the observation period of 13 ± 10 months, 10 patients experienced VT/VF events. Total mean, max, and min SDNNi were higher in the VT/VF (+) than the VT/VF (-) group (132.9 ± 9.3 versus 93.5 ± 6.1, P = 0.0013; 214.6 ± 10.6 versus 167.0 ± 7.0, P = 0.0007; 71.2 ± 7.5 versus 43.9 ± 4.9, P = 0.0047). On logistic regression analysis, a total mean SDNNi of 100.1, max SDNNi of 185.0 and min SDNNi of 52.0 as cut-off values for prediction of a VT/VF event demonstrated significant receiver operating characteristic (ROC) curves (AUC = 0.86, P = 0.0007; AUC = 0.84, P = 0.0005; AUC = 0.78, P = 0.0030). The max ΔSDNNi, i.e., difference from baseline SDNNi, and min ΔSDNNi in 7 and 28 days preceding VT/VF events were significant predictors of VT/VF events.Time-domain HRV analysis through a RM system may help identify patients at high risk of lethal arrhythmic events; in addition, it may help predict the occurrence of lethal arrhythmic events in specific cases.

Precise Signals with a High-Density Grid Mapping Catheter Are Useful for an Entrainment Study.

Complex atrial tachycardias (ATs) after catheter ablation or a MAZE procedure is sometimes difficult to determine the circuits of the tachycardia. A high-density, grid-shapes mapping catheter has been launched, which can be useful for detecting the detail circuits of tachycardias on three-dimensional mapping systems. The signal quality is also important for performing electrophysiological studies (EPSs), such as entrainment mapping, to identify the circuit. This unique mapping catheter has 1 mm electrodes on 2.5 Fr shafts, which improve the signal quality. The high-quality intracardiac electrograms facilitate differentiating small critical potentials, which allows us to perform detailed entrainment mapping in targeted narrow areas. Here, we describe a patient with a perimetral AT with epi-endocardium breakthrough after a MAZE surgery and catheter ablation, which was treated successfully along with detailed entrainment mapping using the HD Grid. This catheter with high-quality signals could be a significant diagnostic tool for a classic EPS as well as for the construction of 3D mapping.

Burden of Implanted-Device-Detected Atrial High-Rate Episode Is Associated With Future Heart Failure Events　- Clinical Significance of Asymptomatic Atrial Fibrillation in Patients With Implantable Cardiac Electronic Devices.

BACKGROUND: The relationship between atrial high-rate episode (AHRE) burden (i.e., the frequency of atrial tachyarrhythmia) and heart failure (HF) risk is unclear. We hypothesized that new-onset and higher burden of AHRE are associated with HF. Methods and Results: We included 104 consecutive patients with cardiac implantable electronic devices (CIEDs) capable of continuous atrial rhythm monitoring. Patients with AF history were excluded. To stratify patients, AHREs were evaluated only during the initial 1 year after CIED implantation. The primary endpoint was all-cause death or new-onset or worsening HF that required unplanned hospitalization or readjustment of HF drug therapy. At 1 year after CIED implantation, 34/104 patients (33%) exhibited AHREs. No difference in basal clinical characteristics except for left ventricular ejection fraction between patients with and without new-onset AHREs was found. AHRE groups had more HF events than the non-AHRE group. All patients were divided into 3 groups based on AHRE burden: none, low, and high. Worsening HF was observed in 12 patients (12%). Cox hazard analysis revealed that AHRE and higher AHRE burden were independent predictive factors for worsening HF. The high group showed a higher risk for HF than the non-AHRE groups, but no significant difference was found between the low- and non-AHRE groups. CONCLUSIONS: New-onset higher AHRE burden was associated with subsequent risk for HF in patients with CIEDs.

Real-World Antithrombotic Therapy in Atrial Fibrillation Patients with a History of Percutaneous Coronary Intervention.

Optimal antithrombotic strategy for atrial fibrillation (AF) patients with a history of percutaneous coronary intervention (PCI) has been under debate. The actual prescription trend of antithrombotic therapy for these patients remains unclear, especially in chronic phase.Patients with AF having at least a 1-year history of PCI were retrospectively evaluated in 2010, 2012, 2014, and 2016. A total of 266 patients were finally enrolled in this study. The proportion of patients prescribed with oral anticoagulants (OACs) gradually increased over the study period (56%, 67%, 73%, and 74% in 2010, 2012, 2014, and 2016, respectively). According to the type of OACs, the proportion of direct oral anticoagulant (DOAC), launched in 2011, increased compared with warfarin (DOAC versus warfarin = 3% versus 64% in 2012, 24% versus 49% in 2014, and 32% versus 42% in 2016). Single antiplatelet therapy (SAPT) with OAC was the most popular prescription every year, and its proportion increased over the study period (41%, 44%, 55%, and 59%, respectively). The proportion of OAC monotherapy gradually increased (2%, 3%, 8%, and 9%, respectively), whereas that of triple therapy, i.e., dual antiplatelet therapy with OAC, gradually decreased (14%, 22%, 8%, and 5% in 2010, 2012, 2014, and 2016, respectively).Antithrombotic therapy trends for AF patients with a history of PCI were changing every year. The prescription rate of triple therapy gradually decreased, in contrast, that of OAC monotherapy gradually increased from 2010 to 2016. However, the evidence for OAC monotherapy in these patients remains insufficient.

Contrast Volume and Decline in Kidney Function in Optical Coherence Tomography-Guided Percutaneous Coronary Intervention.

Optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) may increase contrast volume. However, the impact of OCT-guided PCI on the decline in kidney function (DKF) in actual clinical practice remains unclear.Among 1,003 consecutive patients who underwent either OCT-guided or intravascular ultrasound (IVUS)-guided PCI in our institute, we identified 202 propensity score-matched pairs adjusted by baseline factors. The incidence of DKF was compared between the OCT-guided PCI group and the IVUS-guided PCI group. DKF was defined as an increase in serum creatinine level of ≥ 0.5 mg/dL or a relative increase of ≥ 25% over baseline within 48 hours (acute DKF) or 1 month (sustained DKF) after PCI.Baseline characteristics, including the prevalence of chronic kidney disease (54% versus 46%, P = 0.09), were comparable between the OCT- and IVUS-guided PCI groups except for the age. The contrast volume was comparable between the two groups (153 ± 56 versus 144 ± 60 mL, P = 0.09), although it was significantly greater in the OCT-guided PCI group in patients with acute coronary syndrome (ACS; 175 ± 55 versus 159 ± 43 mL, P = 0.04). The incidence of acute DKF (0.5% versus 2.5%, P = 0.22) and sustained DKF (5.0% versus 10.4%, P = 0.31) was comparable between the two groups. Multivariate analysis demonstrated that ACS (odds ratio 4.74, 95% confidence interval 2.72-8.25, P < 0.001) was a predictor of sustained DKF.Compared with IVUS-guided PCI, OCT-guided PCI did not increase the incidence of DKF in actual clinical practice, although the increased contrast volume was observed in ACS cases.

Linagliptin Suppresses Electrical and Structural Remodeling in the Isoproterenol Induced Myocardial Injury Model.

The effect of DPP-4 inhibitor on the electrical and structural remodeling in myocardial injury has not been evaluated. We hypothesized that linagliptin, DPP-4 inhibitor, suppresses myocardial remodeling in the isoproterenol (ISP)-induced myocardial injury model.Sprague-Dawley rats were assigned to 3 groups: 1) sham group, 2) ISP group (subcutaneous ISP injection of 70 mg/kg), and 3) ISP + linagliptin (ISP + Lin) (5 mg/kg/day, p.o.) group. Serum was sampled on day 1 (acute phase) and day 7 (sub-acute phase) to evaluate derivatives of reactive oxidative metabolites (d-ROMs). The electrophysiological study was performed in sub-acute phase for the evaluation of the ventricular effective refractory period (VERP) and monophasic action potential duration (MAPD). The VERP and MAPD were markedly prolonged in the ISP group in comparison with the sham (MAPD20: 14 ± 6 versus 11 ± 3 ms, MAPD90: 57 ± 8 versus 44 ± 7 ms, VERP: 74 ± 22 versus 38 ± 10 ms, P < 0.05). In contrast in the ISP + Lin group, such prolongations were suppressed, and the parameters were shorter than the ISP group (MAPD20: 9 ± 2 ms, MAPD90: 35 ± 6 ms, VERP: 52 ± 13 ms, P < 0.05). ISP treatment induced myocardial injury. The injured area was reduced in the ISP + Lin group in comparison with the ISP group (P < 0.05). Serum d-ROMs level in acute phase was higher in ISP group than the other 2 groups (sham: 214 ± 55 versus ISP: 404 ± 45 versus ISP + Lin: 337 ± 20 U.CARR, P < 0.05).Linagliptin suppressed structural and electrical changes, possibly through the antioxidative effect, in this myocardial injury model.

Antiremodeling Effect of Xanthine Oxidase Inhibition in a Canine Model of Atrial Fibrillation.

In a canine rapid atrial stimulation model of atrial fibrillation (AF), we have demonstrated an increased production of reactive oxygen species (ROS) along with electrical and structural remodeling. In the present study, we hypothesized that antioxidants can suppress atrial remodeling canines with AF. We therefore evaluated the effect of febuxostat, a xanthine oxidase (XO) inhibitor and a pure antioxidant, on atrial remodeling.AF was produced by performing a 3-week rapid atrial pacing (400 bpm) in 13 dogs divided into three groups: pacing + febuxostat group (n = 5; atrial pacing with 50 mg/day of febuxostat (administration); pacing control group (n = 5; atrial pacing without any drug administration); and non-pacing group (n = 3). Electrophysiological studies were conducted in the first 2 groups every week. Atrial tissue fibrosis was evaluated by Azan and immunofluorescent staining of fibronectin. Oxidative stress was evaluated by DHE and FCF-DA staining.Shortening of the refractory period and increase in AF inducibility appeared gradually in the pacing control group, but such changes were suppressed in the pacing + febuxostat group (P = 0.05). The pacing control group showed increase in fibrosis, which was suppressed in the febuxostat group. In DHE and DCF-DA staining, the pacing control group showed an increase in oxidative stress, which was suppressed in the pacing + febuxostat group. The pacing control group exhibited fibronectin expression, which was suppressed in the pacing + febuxostat group.The antioxidant effect of febuxostat may achieve an inhibition of new-onset AF in canines.

Novel Scoring System for Distinction Between Paroxysmal and Non-Paroxysmal Atrial Fibrillation.

BACKGROUND: Distinction of paroxysmal atrial fibrillation (PAF) from non-PAF is important in clinical practice, but this is often difficult at the time of first documented AF. Given that fibrillation cycle length (FCL) is longer in PAF than in non-PAF, the aim of this study was to compare various clinical parameters including FCL to establish a scoring system to distinguish PAF and non-PAF.Methods and Results:The subjects consisted of 382 consecutive patients with AF on digital ECG at the present institute between 2008 and 2011. They were divided into PAF and non-PAF groups according to the following clinical course. Propensity score matching yielded 88 matched patient pairs with similar mean age and gender between the 2 groups. FCL was evaluated using customized fibrillation wave analyzer with fast Fourier transform analysis. On multivariate analysis, higher HR, longer FCL, and smaller LAD were independent predictors of PAF. For the scoring, cut-offs for each parameter were determined according to highest sensitivity and specificity on the ROC curves, and 1 point assigned for each parameter. Using this scoring system, 2 points detected PAF with 64% sensitivity and 84% specificity. CONCLUSIONS: We propose a scoring system including FCL to distinguish PAF from non-PAF. Further studies are needed to validate the results.

Aliskiren suppresses atrial electrical and structural remodeling in a canine model of atrial fibrillation.

Aliskiren, a direct renin inhibitor is expected to achieve sufficient suppression of renin-angiotensin system. We evaluated the effect of aliskiren on the electrical and structural remodeling in a canine atrial fibrillation (AF) model. Twenty-eight dogs were divided into three groups: (1) pacing control group (n = 12), with continuous atrial rapid pacing for 3 or 6 weeks, (2) pacing + aliskiren group (n = 12), with oral aliskiren (30 mg/kg/day), and (3) sham group (n = 4), no pacing nor drug administration. Electrophysiological properties and AF inducibility were evaluated every week. After the protocol, the left atrial tissue was sampled for the further histological and mRNA analysis. The electrical remodeling, AF inducibility, the left atrial enlargement and interstitial fibrosis were observed in pacing control group and were more prominent in the 6-week protocol (vs. 3 week, p < 0.05). The mRNA expressions of matricellular proteins exhibited upregulation in 3-week pacing control, but these upregulations became insignificant in 6 weeks. In contrast, collagen type 3 exhibited significant upregulation in 6 week but not in 3-week protocol. These changes were suppressed in the pacing + aliskiren group. Aliskiren suppressed the atrial remodeling in a canine AF model. This effect was accompanied by the suppression of tissue fibrosis.

The J-wave as a Predictor of Life-Threatening Arrhythmia in ICD Patients.

The J-wave has been reported to be associated with life-threatening ventricular arrhythmia. However, the clinical implication of the J-wave is still unclear in patients with an implantable cardioverter defibrillator (ICD).The study population consisted of 170 ICD patients (age, 56 ± 16 years, 79.4% male) treated at Kitasato University Hospital between 2003 and 2014. Ventricular fibrillation (VF) and ventricular tachycardia (VT) events were documented via ICD interrogation, and the patients were divided into 3 groups: 1) VF event group, 2) VT event group, and 3) No-event group. To predict VT or VF events, univariate and multivariate analysis of clinical data including ECG findings were performed. A J-wave was defined as the presence of notching or slurring of the QRS complex (≥ 0.1 mV) in inferior/lateral leads. Among the 170 patients examined, 23 experienced VF and 38 experienced VT during 54 ± 39 months follow-up. In the multivariate Cox proportional hazards model, the J-wave was identified as an independent predictor for a VF event (HR: 3.886, 95% CI: 1.313-10.568, P = 0.012). In contrast, BNP (HR: 1.002, 95% CI: 1.000-1.003, P = 0.043) and left ventricular diastolic diameter (HR: 1.039, 95% CI: 1.002-1.081, P = 0.049) were independent predictors for a VT event.The results suggest J-waves in the stable phase in an ECG may be a useful predictor for a VF event in ICD patients.

Discrimination of Paroxysmal and Persistent Atrial Fibrillation in Patients With New-Onset Atrial Fibrillation.

Discrimination between paroxysmal and persistent atrial fibrillation (PAF and persistent AF) is important for determining the therapeutic strategy in patients with new-onset AF. We evaluated various clinical factors and P wave morphology to discriminate PAF and persistent AF patients in patients with new-onset AF.The study population consisted of 79 patients with new-onset AF (70.3 ± 10.8 years, female:male 33:46) who were retrospectively selected from 8,632 AF patients in the Kitasato University Hospital ECG storing system. PAF (n = 38) and persistent AF (n = 41) patients were diagnosed by whether the initial PAF episode continued for 1 week. The P wave morphologies were analyzed using the most recent 12 lead-ECG recording of sinus rhythm. P wave dispersion was defined as the difference between the maximum and minimum durations of all leads. Along with these data, various clinical factors were evaluated and compared between PAF and persistent AF patients.Multivariate analysis identified P wave dispersion (56.6 ± 14.8 versus 66.5 ± 12.8 msec, P = 0.002) and left atrial dimension (LAD: 40.2 ± 7.0 versus 47.7 ± 8.2 mm, P < 0.001) as independent factors for discrimination between PAF and persistent AF patients. Combining these two parameters achieved a specificity of 88.9%, a positive predictive value of 81.8%, a sensitivity of 95.3%, and a negative predictive value of 88.9%.In patients with new-onset AF, P wave dispersion and LAD were independent factors for discrimination between PAF and persistent AF.

Efficacy and Limitations of Tachycardia Detection Interval Guided Reprogramming for Reduction of Inappropriate Shock in Implantable Cardioverter-Defibrillator Patients.

The avoidance of inappropriate shock therapy is an important clinical issue in implantable cardioverter-defibrillator (ICD) patients. We retrospectively analyzed therapeutic events in ICD patients, and the effect of tachycardia detection interval (TDI) and tachycardia cycle length (TCL) guided reprograming on the reduction of inappropriate ICD therapy. The clinical determinants of after reprogramming were also evaluated.A total of 254 consecutive ICD patients were included in the study, and the incidence of antitachycardia therapy was evaluated during the follow-up period of 27.3 ± 18.7 months. When inappropriate antitachycardia therapy appeared, TDI was reprogrammed not to exceed the detected TCL and the patients continued to be followed-up. Various clinical parameters were compared between patients with and without inappropriate ICD therapy. During the initial follow-up period of 18.6 ± 15.6 months, ICD therapy occurred in 127/254 patients (50%) including inappropriate antitachycardia pacing (ATP) (12.9%) and shock (44.35%). Determinants of initial inappropriate therapy were dilated cardiomyopathy (DCM), history of therapeutic hypothermia, and QRS duration. Of the 61 patients with inappropriate therapy, 24 received TCL guided reprogramming. During the additional observation period of 17.0 ± 16.8 months, inappropriate therapy recurred in 5/24 patients (2 ATP, 3 shocks). The determinant of these inappropriate therapy events after reprogramming was the presence of supraventricular tachycardia.By applying simple TCL and TDI guided reprogramming, inappropriate therapy was reduced by 79%. The determinant of inappropriate therapy after reprogramming was the presence of supraventricular tachycardia.