Late life-threatening arrhythmia in patients with Brugada syndrome: Results from long-term follow-up in a large Japanese cohort.

INTRODUCTION: Most patients with Brugada syndrome (BrS) are first diagnosed in their 40s, with sudden cardiac death (SCD) often occurring in their 50s. Ventricular fibrillation (VF) may occur in some patients with BrS despite having been asymptomatic for a long period. This study aimed to assess the incidence and risk factors for late life-threatening arrhythmias in patients with BrS. METHODS: Patients with BrS (n = 523; mean age, 51 ± 13 years; male, n = 497) were enrolled. The risk of late life-threatening arrhythmia was investigated in 225 patients who had experienced no cardiac events (CEs: SCD or ventricular tachyarrhythmia) for at least 10 years after study enrollment. The incidence of CEs during the follow-up period was examined. RESULTS: During the follow-up of the 523 patients, 59 (11%) experienced CEs. The annual incidences of CEs were 2.87%, 0.77%, and 0.09% from study enrollment to 3, 3-10, and after 10 years, respectively. Among 225 patients who had experienced no CEs for at least 10 years after enrollment, four patients (1.8%) subsequently experienced CEs. Kaplan-Meier analysis revealed significant differences in the incidence of late CEs between patients with and without a history of symptoms (p = .032). The positive and negative predictive values of late CEs for the programmed electrical stimulation (PES) test were 2.9% and 100%, respectively. CONCLUSION: Our results suggest that patients with BrS who are asymptomatic and have no ventricular tachycardia/VF inducibility by PES are at extremely low risk of experiencing late life-threatening arrhythmias.

Incidence of phrenic nerve injury during pulmonary vein isolation using different cryoballoons: data from a large prospective ablation registry.

AIMS: Phrenic nerve injury (PNI) is the most common complication during cryoballoon ablation. Currently, two cryoballoon systems are available, yet the difference is unclear. We sought to compare the acute procedural efficacy and safety of the two cryoballoons. METHODS: This prospective observational study consisted of 2,555 consecutive atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) using either conventional (Arctic Front Advance) (AFA-CB) or novel cryoballoons (POLARx) (POLARx-CB) at 19 centers between January 2022 and October 2023. RESULTS: Among 2,555 patients (68.8 ± 10.9 years, 1,740 men, paroxysmal AF[PAF] 1,670 patients), PVIs were performed by the AFA-CB and POLARx-CB in 1,358 and 1,197 patients, respectively. Touch-up ablation was required in 299(11.7%) patients. The touch-up rate was significantly lower for POLARx-CB than AFA-CB (9.5% vs. 13.6%, p = 0.002), especially for right inferior PVs (RIPVs). The touch-up rate was significantly lower for PAF than non-PAF (8.8% vs. 17.2%, P < 0.001) and was similar between the two cryoballoons in non-PAF patients. Right PNI occurred in 64(2.5%) patients and 22(0.9%) were symptomatic. It occurred during the right superior PV (RSPV) ablation in 39(1.5%) patients. The incidence was significantly higher for POLARx-CB than AFA-CB (3.8% vs. 1.3%, P < 0.001) as was the incidence of symptomatic PNI (1.7% vs. 0.1%, P < 0.001). The difference was significant during RSPV (2.5% vs. 0.7%, P < 0.001) but not RIPV ablation. The PNI recovered more quickly for the AFA-CB than POLARx-CB. CONCLUSIONS: Our study demonstrated a significantly higher incidence of right PNI and lower touch-up rate for the POLARx-CB than AFA-CB in the real-world clinical practice.

Inappropriate shock incidence in patients with subcutaneous implantable cardioverter-defibrillators with concomitant cardiac implantable electronic devices: A single-center cohort study.

BACKGROUND: Subcutaneous implantable cardioverter defibrillators (S-ICDs) are occasionally used in combination with other cardiac implantable electronic devices (CIEDs). However, whether the incidence of inappropriate shock increases in patients with S-ICDs and concomitant CIEDs remains unclear. This study aimed to investigate the association between the concomitant use of CIEDs and the incidence of inappropriate shock in patients with current-generation S-ICDs. METHODS: A total of 127 consecutive patients received an S-ICD. Patients were assigned to two groups depending on concomitant use of CIEDs at the time of S-ICD implantation: patients without other CIEDs (non-combined group, 106 patients) and patients with other CIEDs (combined group, 21 patients). CIEDs included pacemakers, implantable cardioverter defibrillators, cardiac resynchronization therapy pacemakers, and cardiac resynchronization therapy defibrillators. The primary outcome was inappropriate shock, defined as a shock other than ventricular arrhythmia. Hazard ratios and 95% confidence intervals were calculated using a time-varying Cox proportional hazards model which was adjusted for age because age differed between the groups and could be a confounder. RESULTS: During a median follow-up period of 2.2 years (interquartile range, 1.0-3.4 years), inappropriate shock events occurred in 17 (16%) and five (19%) patients of the non-combined and combined groups, respectively. While the age-adjusted hazard ratio for inappropriate shock was 24% higher in the combined than in the non-combined group (hazard ratio = 1.24, 95% confidence interval, 0.39-3.97), this difference was insignificant (p = .71). CONCLUSION: The incidence of inappropriate shock did not differ between patients with and without concomitant use of CIEDs, suggesting that S-ICDs could potentially be combined with other CIEDs without increasing the number of inappropriate shocks. Further studies are warranted to confirm the safety and feasibility of concomitant use of S-ICDs and CIEDs.

Spatial relationship of localized sources of persistent atrial fibrillation identified by a unipolar-based automated algorithm to complex fractionated atrial electrocardiograms and atrial low voltage areas.

INTRODUCTION: Spatial characteristics of localized sources of persistent atrial fibrillation (AF) identified by unipolar-based panoramic mapping software (CARTOFINDER) remain unclear. We evaluated spatial characteristics of bi-atrial AF localized sources in relation to complex fractionated atrial electrocardiograms (CFAEs) and atrial low voltage area (LVAs) (≤0.35 mV during AF). METHODS AND RESULTS: Twenty consecutive patients with persistent AF underwent bi-atrial voltage, CFAE, and CARTOFINDER mapping before the beginning of ablation (18 [90%] patients, initial procedure; 2 [10%] patients, repeat procedure). CFAEs were recorded using the interval confidence level (ICL) mode and defined as sites with a confidence level of ≥80% of maximal ICL number. We elucidated the following: (1) differences in the rate of AF localized sources and CFAEs inside or outside the atrial LVAs; (2) distribution of AF localized sources and CFAEs; and (3) distance between the closest points of AF localized sources and CFAEs. A total of 270 AF localized sources and 486 CFAEs were identified in 20 patients. AF localized sources were confirmed more often outside atrial LVAs than CFAEs (71% vs. 46% outside LVA, p < .001). AF localized sources and CFAEs were diffusely distributed without any tendency in bi-atria. Mean distance between closest AF localized sources and CFAEs was 22 ± 8 mm. CONCLUSION: AF localized sources identified by CARTOFINDER are different therapeutic targets as compared to CFAEs and could be confirmed both inside and outside atrial LVAs.

Combined endo- and epicardial pace-mapping to localize ventricular tachycardia isthmus in ischaemic and non-ischaemic cardiomyopathy.

AIMS: A high-density pace-mapping can depict an abrupt transition in paced QRS morphology from a poor to excellent match, unmasking the critical component of ventricular tachycardia (VT) isthmus from the entrance to exit. We sought to assess pace-mapping at multiple sites within the endo- and epicardial scars to identify the VT isthmus in patients with ischaemic (ICM) and non-ischaemic cardiomyopathy (NICM). METHODS AND RESULTS: Colour-coded maps correlating to the percentage matches between 12-lead electrocardiograms during VT and pace-mapping [referred to as correlation score maps (CSMs)] were analysed. We studied 115 CSMs (80 endo- and 35 epicardial CSMs) in 37 patients (17 ICM, 20 NICM). The CSM with an abrupt change (AC) in pacemap score (AC-type) on the endocardium was more frequently observed in ICM than in NICM [11/39 (28%) vs. 1/41 (2%); P = 0.001]. Among 35 CSMs that were analysed by the combined endo- and epicardial mapping, 10 (29%) CSMs exhibited non-AC-type on the endocardium; however, AC-type was present on the opposite epicardium. Although 24 (69%) CSMs did not show AC-type on both the endocardium and epicardium, 16 of them had either an excellent (>90%) or poor (<0%) correlation score on either side, associated with isthmus exit or entrance, respectively. However, the remaining eight CSMs had neither excellent nor poor scores. CONCLUSION: The CSM may provide electrophysiological information to localize the endo- and epicardial VT isthmus. The absence of AC-type CSM on the endocardium, which is frequently observed in NICM, appears to indicate the sub-epicardial or intramural course of the critical isthmus.

Catheter ablation of ventricular tachycardia in dilated-phase hypertrophic cardiomyopathy: Substrate characterization and ablation outcome.

INTRODUCTION: Catheter ablation is a therapeutic option to suppress ventricular tachycardia (VT) in the setting of dilated-phase hypertrophic cardiomyopathy (DHCM). However, the characteristics of the arrhythmogenic substrate and the ablation outcome are not fully illustrated. METHOD: A total of 23 ablation procedures for drug-refractory sustained monomorphic VTs in 13 DHCM patients (60 ± 11 years, one female, the left ventricular [LV] ejection fraction 39% ± 9%, the LV mass index 156 ± 39 g/m2 ) were performed. The distribution of VT substrate as endocardial or epicardial/intramural was based on detailed mapping and ablation response during VT. RESULT: Two patients underwent ablation of sustained monomorphic VT that was not scar-mediated tachycardia. Of the remaining 11 patients, eight (73%) patients had VT substrate in the basal regions, most frequently at the epicardial and/or intramural basal antero-septum. None of the patients had VT substrate located at the LV inferolateral region. Ablation at the right ventricular septum and the aortic cusps was done in four and five patients, respectively. Other approaches including bipolar and chemical ablations, were done in three and two patients, respectively. Six (55%) out of 11 patients (two patients lost follow-up) had VT recurrence. All the six patients had basal substrate. However, anti-tachycardia pacing was sufficient for VT termination except in one patient. CONCLUSION: Catheter ablation of VT in patients with DHCM is challenging because of the predominant basal anteroseptal epicardial/intramural location of arrhythmogenic substrate. An ablation approach from multiple sites and/or adjunctive interventional techniques are often required.

Prognostic predictors and echocardiographic time course after device replacement in patients treated chronically with cardiac resynchronization therapy devices.

The prognostic predictors of death or heart failure hospitalization and the echocardiographic response after initial cardiac resynchronization therapy (CRT) device replacement (CRT-r) remain unclear. We evaluated the predictors and the echocardiographic time course in patients after CRT-r. Consecutive 60 patients underwent CRT-r because of battery depletion. Patients were divided into two groups depending on the chronic echocardiographic response to CRT (left ventricular end-systolic volume [LVESV] reduction of ≥ 15%) at the time of CRT-r: CRT responders (group A; 35 patients) and CRT nonresponders (group B; 25 patients). The primary endpoint was a composite of death from any cause or heart failure hospitalization. Changes in LVESV and left ventricular ejection fraction (LVEF) after CRT-r were also analyzed. During the mean follow-up of 46 ± 33 months after CRT-r, the primary endpoint occurred more frequently in group B (group A versus group B; 8/35 [23%] patients versus 19/25 [76%] patients, p < 0.001). No significant changes in LVESV and LVEF were observed at the mean of 46 ± 29 months after CRT-r in both groups. A multivariate analysis identified echocardiographic nonresponse to CRT, chronic kidney disease, atrial fibrillation, and New York Heart Association functional class III or IV at the time of CRT-r as independent predictors of the primary endpoint in all patients. Residual echocardiographic nonresponse, comorbidities, and heart failure symptoms at the time of CRT-r predict the subsequent very long-term prognosis after CRT-r. No further echocardiographic response to CRT was found after CRT-r.

Risk stratification in asymptomatic patients with Brugada syndrome: Utility of multiple risk factor combination rather than programmed electrical stimulation.

BACKGROUND: The prognostic value of programmed electrical stimulation (PES) in Brugada syndrome (BrS) remains controversial. Asymptomatic BrS patients generally have a better prognosis than those with symptoms. The purpose of this study was to evaluate the value of nonaggressive PES with up to two extra stimuli and predict clinical factors for risk stratification in asymptomatic BrS patients. METHODS: The study enrolled 193 consecutive asymptomatic BrS patients with type 1 ECG (mean age: 50 ± 13 years, 180 males) who underwent PES using a nonaggressive uniform protocol. Cardiac events (CEs: sudden cardiac death or ventricular tachyarrhythmia) during the follow-up period were examined. RESULTS: During a mean follow-up of 101 ± 48 months, seven asymptomatic patients (3.6%) had a CE. The incidence of CEs was not different between patients with and without inducible ventricular tachyarrhythmia by PES (p = .51). The clinical significance of risk factor combinations, including spontaneous type 1 ECG, family history of sudden cardiac death, QRS duration in lead V2 , and presence of J wave, was evaluated. Using the Kaplan-Meier method according to the number of risk factors, the prevalence of CE in patients with three or four risk factors was determined to be significantly higher than in those with one risk factor (p = .02 and p = .004, respectively). CONCLUSIONS: The present study suggests that inducibility of ventricular tachyarrhythmia does not predict future CEs in asymptomatic BrS patients. Combination analysis of the other four clinical risk parameters may be effective for risk assessment.

Long-term prognosis in patients with non-type 1 Brugada electrocardiogram: Results from a large Japanese cohort of idiopathic ventricular fibrillation.

BACKGROUND: Brugada syndrome (BrS) is diagnosed in patients with ST-segment elevation with spontaneous, drug-induced, or fever-induced type 1 morphology. Prognosis in type 2 or 3 Brugada electrocardiogram (Br-ECG) patients remains unknown. The purpose of this study is to evaluate long-term prognosis in non-type 1 Br-ECG patients in a large Japanese cohort of idiopathic ventricular fibrillation (The Japan Idiopathic Ventricular Fibrillation Study [J-IVFS]). METHODS: From 567 patients with Br-ECG in J-IVFS, a total of 28 consecutive non-type 1 patients who underwent programmed electrical stimulation (PES) (median age: 58 years, all male, previous sustained ventricular tachyarrhythmias [VTs] 1, syncope 11, asymptomatic 16) were enrolled. Cardiac events (CEs: sudden cardiac death or sustained VT/ventricular fibrillation) during the follow-up period were examined. RESULTS: During a median follow-up of 136 months, four patients (14%) had CEs. None of patients with PES- have experienced CEs. There was no statistically significant clinical risk factor for the development of CEs. Using the Kaplan-Meier method, the event-free rate significantly decreased in a group with all 3 risk factors (symptom, wide QRS complex in lead V2 , and positive PES) (p = .01). CONCLUSIONS: Our study revealed long-term prognosis in patients with non-type 1 Br-ECG. The combination analysis of these risk factors may be useful for the risk stratification of CEs in non-type 1 Br-ECG patients. The present study suggests that the patients with all these parameters showed high risk for CEs and need to be carefully followed.

Preprocedural restoration of sinus rhythm and left atrial strain predict outcomes of catheter ablation for long-standing persistent atrial fibrillation.

INTRODUCTION: Catheter ablation (CA) for long-standing persistent atrial fibrillation (LS-AF) remains challenging. We aimed to explore whether sinus rhythm (SR) restoration and left atrium (LA) function after pretreatment with antiarrhythmic drugs (AAD's) and electrical cardioversion (ECV) predict procedural outcomes. METHODS AND RESULTS: We included 100 consecutive patients with LS-AF who were treated with AAD/ECV for at least 3 months before CA. The echocardiographic LA strain during reservoir phase (LASr) was assessed after pretreatment as a marker of LA fibrosis. The recurrence was recorded for ≥1 year after the last procedure. During a 34 ± 16-month follow-up period, the single and multiple procedures and pharmaceutically assisted success rates were 40% and 71%, respectively. Patients with preprocedural SR restoration and higher LASr showed a significantly higher recurrence-free probability after the last CA (logrank P = .001 and P < .001, respectively). Failure of preprocedural SR restoration and LASr ≤8.6% were independently associated with recurrence after the last CA (hazard ratio [HR]: 3.13, 95% confidence interval [CI]: 1.42-6.91, P = .005; HR: 3.89, 95% CI: 1.65-9.17, P = .002, respectively). These parameters added incrementally to the predictive value of AF duration and LA dilatation (P = .03 and P = .002, respectively) and improved the recurrence-risk stratification (net reclassification improvement = 0.39; 95% CI = 0.13-0.65; P = .003). CONCLUSION: In patients with LS-AF, the inability to restore SR and lower LASr after AAD/ECV treatment independently and incrementally predicts the recurrence after CA. These findings might be useful for determining LS-AF ablation candidates.

Stepwise approach to induce infrequent premature ventricular complex using bolus isoproterenol and epinephrine infusion.

BACKGROUND: Paucity of a premature ventricular complex (PVC) during ablation procedures may occur and be associated with a lower success rate. Isoproterenol (ISP) injections are commonly used to induce PVC; however, the induced tachycardia sometimes prevents the appearance of PVC. Epinephrine (EPI) administration may be an alternative strategy to induce PVC due to its smaller effect on heart rate (HR). This study sought to examine the electrophysiological impact of EPI injection, with a stepwise induction protocol, for infrequent intraprocedural PVC. METHODS: We studied 78 consecutive patients who underwent catheter ablation of idiopathic frequent PVC. If no PVC was observed at the beginning of the procedure, ISP (10 µg) was injected. If clinical PVC was not induced by ISP administration, EPI (10 µg) was injected. RESULTS: Of 18 patients without PVC at baseline, ISP injection induced PVC in five patients. Of the remaining 13 patients, EPI injection successfully induced PVC in seven patients (53%). The maximum HR and increments of HR after EPI injection were significantly lower than those after ISP injection (99 ± 15 vs 137 ± 15 bpm, P = .001; 22 ± 10 vs 53 ± 12 bpm, P < .001, respectively). There were no complications related to the induction protocol. CONCLUSION: EPI injection following ISP injection is an effective and safe stepwise approach for the induction of infrequent PVC in the electrophysiology laboratory. It is hypothesized that α- and ß-adrenergic receptor stimulation by EPI injections, with reduced HR acceleration compared to that with ISP injections, may result in the successful induction of PVC.

The Usefulness and Limitations of Impedance Cardiography for Cardiac Resynchronization Therapy Device Optimization.

Identifying the optimal atrioventricular (AV) or interventricular (VV) delay is beneficial for patients using cardiac resynchronization therapy (CRT) devices. Ultrasonic echocardiography (UCG) has been the most commonly used method; however, it requires high technical knowledge. Impedance cardiography (ICG) can calculate stroke volume by measuring changes in transthoracic electric impedance. This study sought to assess the clinical utility of ICG in comparison with that of UCG for the optimization of CRT devices.Patients who underwent CRT device implantation were retrospectively analyzed. One week after implantation, optimization of AV delay (AVD) was performed in every patient with ICG (AVD-ICG) and UCG (AVD-UCG). VV delay (VVD) was then determined according to the optimal AVD using these two methods.Forty-two patients were enrolled. Average AVD-ICG was significantly shorter than AVD-UCG (128 ± 49 versus 146 ± 41 milliseconds, P = 0.018). Five patients (12%) had the same optimized AVD with two methods, and the difference between AVD-ICG and AVD-UCG was ≤ 20 milliseconds in 19 patients (45%). In the multivariate analysis, the presence of postoperative mitral regurgitation (MR) was an independent predictor of AVD-ICG/AVD-UCG mismatch, defined as a difference over 20 milliseconds (odds ratio = 10.71; 95% confidence interval = 1.72 to 66.72; P = 0.018). The results of optimized VVD were similar using both methods.ICG might be a promising tool for the rapid optimization of CRT devices. However, in patients with moderate-to-severe MR, ICG may not be able to optimize AVD.

Impact of coronary artery disease and revascularization on recurrence of atrial fibrillation after catheter ablation: Importance of ischemia in managing atrial fibrillation.

INTRODUCTION: There are few studies analyzing the association between the presence of coronary artery disease (CAD) and recurrence of atrial fibrillation (AF). This study evaluated the clinical impact of concomitant CAD and coronary revascularization on the recurrence of AF after catheter ablation. METHODS AND RESULTS: From April 2008 to December 2015, 700 consecutive patients were treated with pulmonary vein isolation for AF as the initial procedure. Of those, 681 patients who simultaneously underwent coronary angiography were investigated. Patients with at least one coronary stenosis (≥70%) were classified as having obstructive CAD. Of 681 patients, 90 patients had CAD and 42 patients underwent percutaneous coronary intervention (PCI) for lesions with perfusion abnormalities on single-photon emission tomography. The recurrence of AF was significantly more frequent in patients with CAD (56%) than in those without CAD (39%) (P = .0011). On multivariable analysis, the predictors of AF recurrence were persistent or long-standing persistent AF [hazard ratio (HR): 1.36; 95% confidence interval (CI): 1.04-1.77; P = .023], left atrial diameter (HR: 1.04; 95% CI: 1.02-1.06; P < .0001), and concomitant CAD (HR: 1.45; 95% CI: 1.05-1.97; P = .024). The recurrence of AF in patients with PCI (38%) was significantly lower than in those without PCI (72%) (P = .0006), and E/E' significantly improved in patients with PCI (71%) than in those without PCI (42%; P = .001). Performing PCI for concomitant CAD significantly reduced AF recurrence (HR: 0.39; 95% CI: 0.20-0.72; P = .002). CONCLUSION: Patients with CAD had a significantly higher rate of AF recurrence than those without CAD. Coronary revascularization may reduce the recurrence of AF with improvement of left ventricular diastolic function.

A case of TAFRO syndrome, a variant of multicentric Castleman's disease, successfully treated with corticosteroid and cyclosporine A.

We report a case of a 46-year-old woman with fever, pleural effusion, massive ascites, severe edema, hepatosplenomegaly, elevation of serum creatinine level, proteinuria, and severe thrombocytopenia. Her clinical features were compatible with TAFRO syndrome proposed as a variant of multicentric Castleman's disease, that is occasionally associated with poor prognosis. Treatment with corticosteroid improved her symptoms partially. However, thrombocytopenia, ascites, and edema persisted. The use of cyclosporine A successfully improved her condition, resulting in remission.

The prognostic impact of single extra-stimulus on programmed ventricular stimulation in Brugada patients without previous cardiac arrest: multi-centre study in Japan.

Aims: The prognostic value of programmed electrical stimulation (PES) in Brugada syndrome (BrS) remains controversial. One of the reasons for discrepant results may be due to the selection of stimulation protocol. We evaluated the prognostic value of a positive PES result (PES+) according to the inducible pacing sites and the number of extra-stimuli in BrS patients without previous cardiac arrest (CA). Methods and results: We enrolled 224 consecutive BrS patients without previous CA (mean age 51 ± 14 years, 209 males), who underwent PES with the identical protocol. Clinical outcomes of development of CA were explored in the patients with and without PES+ according to sites and number of extra-stimuli. During a mean follow-up period of 76 months, 12 cardiac events (CE: sudden cardiac death or documented VF) occurred (8 with and 4 without PES+). The incidence of CE was not different in patients with and without PES+, those with PES+ from RVA (n = 72) or RVOT (n = 60), and those with and without PES+ by up to 2 extra-stimuli (n = 58). However, in patients that were PES+ by a single extra-stimulus (n = 8) the incidence of CE was significantly higher than in those without PES+ (8.8 vs. 0.6%/year, P < 0.0001). On univariate analysis, syncope, spontaneous type 1 ECG, and PES+ by a single extra-stimulus were associated with CE. Conclusion: Details of the stimulation protocol may be important for risk assessment in BrS patients without previous CA. A single extra-stimulus may be useful in stratifying risk in patients with spontaneous type 1 ECG and syncope.

Clinical Usefulness of Wearable Cardioverter Defibrillator (WCD) and Current Understanding of Its Clinical Indication in Japan.

Prevention of sudden cardiac death (SCD) has become an important issue in today's cardiovascular field, together with various developments in secondary prevention of basic cardiac diseases. The importance of the implantable cardioverter defibrillator (ICD) is now widely accepted because it has exhibited significant improvement in patients' prognoses in ischemic and non-ischemic cardiovascular diseases. However, there is an unignorable gap between the ICD indication in the guidelines and real-world high-risk patients for SCD, especially in the acute recovery phase of cardiac injury. Although various studies have demonstrated a clinical benefit of defibrillation devices, the studies of immediate ICD use in the acute recovery phase have failed to exhibit a benefit in patients from the point of the view of a decrease in total deaths. To bridge this gap, the wearable cardioverter defibrillator (WCD) provides a safer observation period in the acute phase and eliminates inappropriate overuse of ICD in the subacute phase. Here, we discuss the usefulness of the WCD and current understanding of its indications based on various clinical data. In conclusion, WCD is a feasible bridge to therapy and/or safe observation for patients at high risk of SCD, especially in the acute recovery phase of cardiac diseases.

Current Trends in Implantable Cardioverter-Defibrillator Therapy in Children　- Results From the JCDTR Database.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) are being used with increasing frequency in children. Our aim was to examine the current trend of pediatric ICD implantation in Japan. Methods and Results: Data was extracted from the Japanese Cardiac Device Treatment Registry (JCDTR), a nation-wide registry started in 2006. All patients aged less than 18 years who had an ICD implantation registered between 2006 and 2016 were included in the analysis. A total of 201 patients were included, with a median age of 16 years (range 1-18). The underlying cardiac diagnosis was primary electrical disease (67%), cardiomyopathy (26%) and congenital heart disease (4%), with idiopathic ventricular fibrillation (29%) and long QT syndrome (21%) being the 2 most common diagnoses. Implantation indication was primary prevention in only 30 patients (15%). There were 27 patients (13%) aged ≤12 years, with a larger proportion of patients with cardiomyopathy (33%). The indication in younger children was secondary prevention in all cases. Younger children may be under-represented in our study given the nature of the database as it is a predominantly adult cardiology database. CONCLUSIONS: In the past decade, ICD implantation has been performed in approximately 20 children per year in Japan, mostly for secondary prevention. There was no increase in the trend nor a change in age distribution.

Optimal sampling time and clinical implication of the SCN5A promoter haplotype in propafenone therapeutic drug monitoring.

PURPOSE: The clinical usefulness of therapeutic drug monitoring (TDM) of propafenone, a sodium channel blocker, has been unclear due to the lack of information regarding optimal blood sampling time and therapeutic concentration range. Antiarrhythmic effects of sodium channel blockers are affected by the activity of the cardiac sodium channel (SCN5A). We investigated the optimal sampling time and the clinical implication of the SCN5A promoter haplotype in propafenone TDM. METHODS: We evaluated serum concentrations of propafenone, the SCN5A promoter haplotype, and antiarrhythmic efficacy in 55 patients with supraventricular tachy-arrhythmias. Blood samples obtained 1.5-6 and 10-24 h after the last dose were categorized as peak and trough samples, respectively. RESULTS: The peak propafenone concentration was significantly higher in effectively treated patients than that in patients showing insufficient response (337 ± 213 vs. 177 ± 93 ng/mL, P = 0.005), but the trough propafenone concentration was not significantly different between the two groups (68 ± 48 vs. 42 ± 36 ng/mL). Clinically relevant propafenone efficacy was achieved significantly more often in SCN5A haplotype B carriers than in wild-type haplotype A homozygotes (90 vs. 60%, P < 0.05). Among the haplotype A homozygotes, peak propafenone concentration was higher in effectively treated patients than that in patients showing insufficient response (299 ± 177 vs. 177 ± 93 ng/mL, P = 0.061). CONCLUSION: The present study found that antiarrhythmic efficacy of propafenone was associated with peak propafenone concentration rather than trough concentration and was affected by the SCN5A promoter haplotype.

Simultaneous determination of serum propafenone and its metabolites using high-performance liquid chromatography.

Propafenone, a class Ic antiarrhythmic agent, is metabolized to 5-hydroxypropafeone (5-OHP) and N-depropylpropafenone (NDPP). Simultaneous determination of serum propafenone and its metabolites was performed using HPLC equipped with a conventional octadecylsilyl silica column and ultraviolet detector. The wavelength was set at 250 nm. Propafenone and its metabolites in the serum were extracted using diethyl ether. The mobile phase solution, comprising 1-pentanesulfonic acid sodium salt (0.1 m), acetonitrile and acetic acid (280:185:2.5, v/v/v), was pumped at a flow rate of 1 mL/min. The recoveries of propafenone, 5-OHP and NDPP were greater than 85, 82 and 60%, respectively, with the coefficients of variation (CVs) less than 5.4, 1.9 and 2.9%, respectively. The calibration curves were linear for a concentration range of 12.5-1500 ng/mL for propafenone and 2-500 ng/mL for 5-OHP and NDPP (r > 0.999). CVs in the intraday assays were 1.0-3.8% for propafenone, 0.6-2.0% for 5-OHP and 0.6-1.7% for NDPP. CVs in interday assays were 1.3-7.7% for propafenone, 1.1-6.5% for 5-OHP and 5.4-8.0% for NDPP. The present HPLC method can be used to assess the disposition of propafenone and its metabolites for pharmacokinetic studies and therapeutic drug monitoring of propafenone.

Unmasking of a concealed slow pathway by atrioventricular simultaneous basic pacing.

A 71-year-old woman with narrow QRS tachycardia was referred for catheter ablation. The clinical tachycardia was diagnosed as slow/fast form of atrioventricular (AV) nodal reentrant tachycardia (AVNRT) with the upper common pathway. Although neither conventional nor double atrial programmed extrastimulation (APS) showed any evidence of a dual AV nodal pathway, AV simultaneous pacing during basic stimulation preceding APS (AVSP-APS) reproducibly revealed a dual AV nodal pathway as a double ventricular response. The AVSP-APS pacing method may be helpful to unmask a "concealed slow pathway" in patients with AVNRT.