Preoperative Prediction of Shock Impedance for Subcutaneous Implantable Cardioverter Defibrillator Using Chest Computed Tomography.

BACKGROUND: High shock impedance is associated with conversion failure among patients with subcutaneous implantable cardioverter defibrillators (S-ICD). Currently, there is no preoperative assessment method for predicting high shock impedance. This study examined the efficacy of chest computed tomography (CT) as a preoperative evaluation tool to assess the shock impedance of S-ICDs.Methods and Results: The amount of adipose tissue adjacent to the device and anteroposterior diameter at the basal heart region were measured preoperatively using chest CT. We examined the correlation between these measurements and shock impedance at the conversion test. We enrolled 43 patients with S-ICDs (mean [±SD] age 54±15 years; body mass index 23±4 kg/m2; PRAETORIAN score 30-270 points; amount of adipose tissue 1,250±716 cm3), who underwent intraoperative conversion tests by inducing ventricular fibrillation, which was terminated with a 65-J shock. A sufficient concordance correlation coefficient was observed between the shock impedance and the amount of adipose tissue (r=0.616, P<0.01) and anteroposterior diameter (r=0.645, P<0.01). In multiple regression analysis, the amount of adipose tissue (ß=0.439, P=0.009) and anteroposterior diameter (ß=0.344, P=0.038) were identified as independent predictive factors of shock impedance. CONCLUSIONS: The preoperative CT-measured amount of adipose tissue and basal heart anteroposterior diameter are independent predictors of shock impedance. These parameters may be more accurate in identifying higher shock impedance in patients with S-ICDs.

Effect of Catheter Ablation for Atrial Fibrillation in Heart Failure With Mid-Range or Preserved Ejection Fraction　- Pooled Analysis of the AF Frontier Ablation Registry and Hokuriku-Plus AF Registry.

BACKGROUND: A recent randomized trial demonstrated that catheter ablation for atrial fibrillation (AF) in patients with heart failure with reduced ejection fraction (EF) is associated with a reduction in death or heart failure. However, the effect of catheter ablation for AF in patients with heart failure with mid-range or preserved EF is unclear.Methods and Results: We screened 899 AF patients (72.4% male, mean age 68.4 years) with heart failure and left ventricular EF ≥40% from 2 Japanese multicenter AF registries: the Atrial Fibrillation registry to Follow the long-teRm Outcomes and use of aNTIcoagulants aftER Ablation (AF Frontier Ablation Registry) as the ablation group (525 patients who underwent ablation) and the Hokuriku-Plus AF Registry as the medical therapy group (374 patients who did not undergo ablation). Propensity score matching was performed in these 2 registries to yield 106 matched patient pairs. The primary endpoint was a composite of cardiovascular death and hospitalization for heart failure. At 24.6 months, the ablation group had a significantly lower incidence of the primary endpoint (hazard ratio 0.32; 95% confidence interval 0.13-0.70; P=0.004) than the medical therapy group. CONCLUSIONS: Compared with medical therapy, catheter ablation for AF in patients with heart failure and mid-range or preserved EF was associated with a significantly lower incidence of cardiovascular death or hospitalization for heart failure.

Revisiting predictors of worse atrioventricular valve and left ventricular systolic function following pacemaker therapy.

BACKGROUND: Predictors of worsening atrioventricular valve regurgitation and left ventricular (LV) systolic function after implantation of a leadless pacemaker (LPM) remain unclear compared with those of a transvenous pacemaker (TPM). METHODS: We retrospectively analyzed 205 patients who were newly implanted with a permanent pacemaker (119 LPMs and 86 TPMs) and underwent transthoracic echocardiography before and 8 ± 5 months after implantation. We evaluated the worsening of tricuspid and mitral regurgitation (TR and MR), defined as at least one-grade aggravation in severity, and changes in LV ejection fraction (LVEF). RESULTS: Worsening TR occurred more frequently in the LPM group compared to the TPM group (33% vs. 20%, p = .04); however, there was no significant difference between the two groups regarding worsening MR (26% vs. 18%, p = .18) and LVEF change (-2 ± 10% vs. -3 ± 8%, p = .40). In multivariable analysis, independent predictors for worsening TR, MR, and LVEF after implantation were found to be (1) the change from sinus rhythm at baseline to atrioventricular asynchronous right ventricular (RV) pacing (odds ratio [OR]: 5.68, 95% confidence interval [CI]: 1.94-16.70, p < .01); (2) the change from non-pacing ventricular contraction at baseline to RV pacing (OR: 2.42, 95% CI: 1.12-5.24, p = .02); and (3) a higher RV pacing burden (ß: -0.05, 95% CI: -0.08--0.02, p < .01), respectively. CONCLUSION: Worsening TR, MR, and LVEF after pacemaker implantation were not associated with the type of pacing device but loss of atrioventricular synchrony or dependency on RV pacing.

Successful Epicardial Radiofrequency Ablation of Ventricular Tachycardia That Shared a Pathway with Bi-Directional Conduction in a Patient with Human Immunodeficiency Virus-Associated Cardiomyopathy.

A 59-year-old man who had been diagnosed with human immunodeficiency virus-associated cardiomyopathy was referred for catheter ablation of ventricular tachycardia (VT). An electrocardiogram (ECG) waveform revealed that the clinical VT originated from the epicardium. A deceleration zone (DZ) was identified on an isochronal late activation map. Moreover, 2 forms of monomorphic VT were induced by different cycle length burst pacings from near the DZ. The morphologies of the 2 VTs with an identical cycle length were very likely to use a shared common pathway with bi-directional conduction around the slow conduction area in the left ventricle posterolateral small epicardial surface area. After ablation of the DZ, the VT was uninducible.

Clinical Outcomes of Non-Atrial Fibrillation Bradyarrhythmias Treated With a Ventricular Demand Leadless Pacemaker Compared With an Atrioventricular Synchronous Transvenous Pacemaker　- A Propensity Score-Matched Analysis.

BACKGROUND: Implanting a ventricular demand leadless pacemaker (VVI-LPM) for patients with non-atrial fibrillation (AF) bradyarrhythmias such as sick sinus syndrome (SSS) or high-grade (i.e., second- or third-degree) atrioventricular (AV) block is not recommended unless they have limited vascular access or a high infection risk; nevertheless, an unexpectedly high number of VVI-LPM implantations have been performed. This study investigated the clinical outcomes of these unusual uses.Methods and Results:This study retrospectively analyzed 193 patients who were newly implanted with a VVI-LPM or an atrioventricular synchronous transvenous pacemaker (DDD-TPM) for non-AF bradyarrhythmias at a high-volume center in Japan from September 2017 to September 2020. Propensity score-matching produced 2 comparable cohorts treated with a VVI-LPM or DDD-TPM (n=58 each). Each group had 20 (34%) patients with SSS and 38 (66%) patients with high-grade AV block. During a median follow up of 733 (interquartile range 395-997) days, there were no significant differences between the VVI-LPM and DDD-TPM groups regarding late device-related adverse events (0% vs. 4%, log-rank P=0.155), but the VVI-LPM group had a significantly increased readmission rate for heart failure (HF) (29% vs. 2%, log-rank P=0.001) and a tendency to have higher all-cause mortality (28% vs. 4%, log-rank P=0.059). CONCLUSIONS: The implantation of a VVI-LPM for non-AF bradyarrhythmias increased the incidence of HF-related rehospitalization at the mid-term follow up compared to the use of a DDD-TPM.

Different Determinants of the Recurrence of Atrial Fibrillation and Adverse Clinical Events in the Mid-Term Period After Atrial Fibrillation Ablation.

BACKGROUND: It is unclear whether there are differences in the clinical factors between atrial fibrillation (AF) recurrence and adverse clinical events (AEs), including stroke/transient ischemic attack (TIA), major bleeding, and death, after AF ablation.Methods and Results:We examined the data from a retrospective multicenter Japanese registry conducted at 24 cardiovascular centers between 2011 and 2017. Of the 3,451 patients (74.1% men; 63.3±10.3 years) who underwent AF ablation, 1,046 (30.3%) had AF recurrence and 224 (6.5%) suffered AEs (51 strokes/TIAs, 71 major bleeding events, and 36 deaths) over a median follow-up of 20.7 months. After multivariate adjustment, female sex, persistent and long-lasting persistent AF (vs. paroxysmal AF), and stepwise increased left atrial diameter (LAd) quartiles were significantly associated with post-ablation recurrences. A multivariate analysis revealed that an age ≥75 years (vs. <65 years), body weight <50 kg, diabetes, vascular disease, left ventricular (LV) ejection fraction <40% (vs. ≥50%), Lad ≥44 mm (vs. <36 mm), and creatinine clearance <50 mL/min were independently associated with AE incidences, but not with recurrences. CONCLUSIONS: This study disclosed different determinants of post-ablation recurrence and AEs. Female sex, persistent AF, and enlarged LAd were determinants of post-ablation recurrence, whereas an old age, comorbidities, and LV and renal dysfunction rather than post-ablation recurrence were AEs determinants. These findings will help determine ablation indications and post-ablation management.

Impact of sinus rhythm maintenance on major adverse cardiac and cerebrovascular events after catheter ablation of atrial fibrillation: insights from AF frontier ablation registry.

The impact of catheter ablation for atrial fibrillation (AF) on cardiovascular events and mortality is controversial. We investigated the impact of sinus rhythm maintenance on major adverse cardiac and cerebrovascular events after AF ablation from a Japanese multicenter cohort of AF ablation. We investigated 3326 consecutive patients (25.8% female, mean age 63.3 ± 10.3 years) who underwent catheter ablation for AF from the atrial fibrillation registry to follow the long-term outcomes and use of anti coagulants after ablation (AF frontier ablation registry). The primary endpoint was a composite of stroke, transient ischemic attack, cardiovascular events, and all-cause death. During a mean follow-up of 24.0 months, 2339 (70.3%) patients were free from AF after catheter ablation, and the primary composite endpoint occurred in 144 (4.3%) patients. The AF nonrecurrence group had a significantly lower incidence of the primary endpoint (1.8 per 100 person-years) compared with the AF recurrence group (3.0 per 100 person-years, p = 0.003). The multivariate analysis revealed that freedom from AF (hazard ratio 0.61, 95% confidence interval 0.44-0.86, p = 0.005) was independently associated with the incidence of the composite event. In the multicenter cohort of AF ablation, sinus rhythm maintenance after catheter ablation was independently associated with lower rates of major adverse cardiac and cerebrovascular events.

Revisit to the Prognostic Value of Premature Atrial Contraction Burden in 24-h Holter Electrocardiography for Predicting Undiagnosed Atrial Fibrillation　- A Propensity Score-Matched Study.

BACKGROUND: The optimum cut-off value of premature atrial contraction (PAC) burden (CV-PACb) in 24-h Holter electrocardiography (24-h ECG) for predicting atrial fibrillation (AF) is debatable, with few validation data.Methods and Results:We retrospectively analyzed 61 patients already diagnosed with AF (AD-AF) and 147 patients never diagnosed with AF (ND-AF), aged ≥50 years, free of heart disease, and who had undergone 24-h ECG and transthoracic echocardiography (TTE). Receiver operating characteristic analysis demonstrated that 0.4% was the optimal CV-PACb differentiating AD-AF from ND-AF, with 69% sensitivity and 72% specificity (area under the curve [AUC] 0.72; 95% confidence interval [CI] 0.65-0.79); however, the left atrial volume index was not significant (AUC 0.60; 95% CI 0.51-0.68). To verify the CV-PACb, new propensity-matched cohorts (i.e., subjects with a PAC burden ≥0.4% and <0.4%; n=69 in each group) were compared based on new detection of AF at a median follow-up of 50 months (interquartile range 12-60 months) Multivariable Cox regression analysis revealed that among 24-h ECG and TTE findings, only PAC burden ≥0.4% was independently associated with incident AF (hazard ratio 5.28; 95% CI 1.28-26.11; P=0.023). CONCLUSIONS: A high PAC burden (≥0.4%) in 24-h ECG was a reliable indicator to identify undiagnosed AF, whereas TTE parameters did not show any predictive value.

Clinical outcomes of ablation versus non-ablation therapy for atrial fibrillation in Japan: analysis of pooled data from the AF Frontier Ablation Registry and SAKURA AF Registry.

Whether ablation for atrial fibrillation (AF) is, in terms of clinical outcomes, beneficial for Japanese patients has not been clarified. Drawing data from 2 Japanese AF registries (AF Frontier Ablation Registry and SAKURA AF Registry), we compared the incidence of clinically relevant events (CREs), including stroke/transient ischemic attack (TIA), major bleeding, cardiovascular events, and death, between patients who underwent ablation (n = 3451) and those who did not (n = 2930). We also compared propensity-score matched patients (n = 1414 in each group). In propensity-scored patients who underwent ablation and those who did not, mean follow-up times were 27.2 and 35.8 months, respectively. Annualized rates for stroke/TIA (1.04 vs. 1.06%), major bleeding (1.44 vs. 1.20%), cardiovascular events (2.15 vs. 2.49%) were similar (P = 0.96, 0.39, and 0.35, respectively), but annualized death rates were lower in the ablation group than in the non-ablation group (0.75 vs.1.28%, P = 0.028). After multivariate adjustment, the risk of CREs was statistically equivalent between the ablation and non-ablation groups (hazard ratio [HR] 0.89, 95% confidence interval [CI] 0.71-1.11), but it was significantly low among patients who underwent ablation for paroxysmal AF (HR 0.68 [vs. persistent AF], 95% CI 0.49-0.94) and had a CHA2DS2-VASc score < 3 (HR 0.66 [vs. CHA2DS2-VASc score ≥ 3], 95% CI 0.43-0.98]). The 2-year risk reduction achieved by ablation may be small among Japanese patients, but AF ablation may benefit those with paroxysmal AF and a CHA2DS2-VASc score < 3.

Clinical Outcomes of Off-Label Underdosing of Direct Oral Anticoagulants After Ablation for Atrial Fibrillation.

Direct oral anticoagulants (DOACs) are sometimes prescribed at off-label under-doses for patients who have undergone ablation for atrial fibrillation (AF). This practice may be an attempt to balance the risk of bleeding against that of stroke or AF recurrence.We examined outcomes of 1163 patients who continued use of a DOAC after ablation. The patients were enrolled in a large (3530 patients) multicenter registry in Japan. The study patients were classified as 749 (64.4%) appropriate standard-dose DOAC users, 216 (18.6%) off-label under-dose DOAC users, and 198 (17.0%) appropriate low-dose DOAC users.Age and CHA2DS2-VASc scores differed significantly between DOAC dosing regimens, with patients given an appropriate standard-dose being significantly younger (63.3 ± 9.4 versus 64.8 ± 9.5 versus 73.2 ± 6.8 years, P < 0.0001) and lower (2.1 ± 1.5 versus 2.4 ± 1.6 versus 3.4 ± 1.4, P < 0.0001) than those given an off-label under-dose or an appropriate low-dose. During the median 19.0-month follow-up period, the AF recurrence rate was similar between the appropriate standard-dose and off-label under-dose groups but relatively low in the appropriate low-dose group (42.5% versus 41.2% versus 35.4%, P = 0.08). Annualized rates of thromboembolic events, major bleeding, and death from any cause were 0.47%, 0.70%, and 0.23% in the off-label under-dose group, while those rates were 0.74%, 0.73%, and 0.65% in the appropriate standard-dose, and 1.58%, 2.12%, and 1.57% in the appropriate low-dose groups.In conclusion, the clinical adverse event rates for patients on an off-label under-dose DOAC regimen after ablation, predicated on careful patient evaluations, was not high as seen with that of patients on a standard DOAC dosing regimen.

Novel Device-Based Algorithm Provides Optimal Hemodynamics During Exercise in Patients With Cardiac Resynchronization Therapy.

BACKGROUND: An adaptive cardiac resynchronization therapy (aCRT) algorithm has been described for synchronized left ventricular (LV) pacing and continuous optimization of cardiac resynchronization therapy (CRT). However, there are few algorithmic data on the effect of changes during exercise.Methods and Results:We enrolled 27 patients with availability of the aCRT algorithm. Eligible patients were manually programmed to optimal atrioventricular (AV) and interventricular (VV) delays by using echocardiograms at rest or during 2 stages of supine bicycle exercise. We compared the maximum cardiac output between manual echo-optimization and aCRT-on during each phase. After initiating exercise, the optimal AV delay progressively shortened (P<0.05) with incremental exercise levels. The manual-optimized settings and aCRT resulted in similar cardiac performance, as demonstrated by a high concordance correlation coefficient between the LV outflow tract velocity time integral (LVOT-VTI) during each exercise stage (Ex.1: r=0.94 P<0.0008, Ex.2: r=0.88 P<0.001, respectively). Synchronized LV-only pacing in patients with normal AV conduction could provide a higher LVOT-VTI as compared with manual-optimized conventional biventricular pacing at peak exercise (P<0.05). CONCLUSIONS: The aCRT algorithm was physiologically sound during exercise by patients.

Current Status and Clinical Outcomes of Oral Anticoagulant Discontinuation After Ablation for Atrial Fibrillation in Japan　- Findings From the AF Frontier Ablation Registry.

BACKGROUND: The safety of discontinuing oral anticoagulant (OAC) after ablation for atrial fibrillation (AF) in Japanese patients has not been clarified.Methods and Results:A study based on the Atrial Fibrillation registry to Follow the long-teRm Outcomes and use of aNTIcoagulants aftER Ablation (AF Frontier Ablation Registry) was conducted. Data were collected from 3,451 consecutive patients (74.1% men; age, 63.3±10.3 years) who had undergone AF ablation at any of 24 cardiovascular centers in Japan between August 2011 and July 2017. During a 20.7-month follow-up period, OAC therapy was discontinued in 1,836 (53.2%) patients; 51 patients (1.5%) suffered a stroke/transient ischemic attack (TIA), 71 (2.1%) suffered major bleeding, and 36 (1.0%) died. Patients in whom OAC therapy was discontinued were significantly younger than those in whom OACs were continued, and their CHA2DS2-VASc scores were significantly lower. The incidences of stroke/TIA, major bleeding, and death were significantly lower among these patients. Upon multivariate adjustment, stroke events were independently associated with relatively high baseline CHA2DS2-VASc scores but not with OAC status. CONCLUSIONS: Although the incidences of stroke/TIA, major bleeding, and death were relatively low among patients for whom OAC therapy was discontinued, stroke/TIA occurrence was strongly associated with a high baseline stroke risk rather than with OAC status. Thus, discontinuation of OAC therapy requires careful consideration, especially in patients with a high baseline stroke risk.

Change in QRS morphology as a marker of spontaneous elimination in verapamil-sensitive idiopathic left ventricular tachycardia.

BACKGROUND: Verapamil-sensitive idiopathic left ventricular tachycardia (verapamil-ILVT) is thought to be due to a reentry within the LV fascicular system. Radiofrequency catheter ablation (RFCA) is effective for elimination of the VT; however, a long-term prognosis of patients with verapamil-ILVT is still unclear. METHODS AND RESULTS: Eighty consecutive verapamil-ILVT patients (62 men, 31 ± 12 years of age, LVEF: 65 ± 4%) were enrolled. Seventy-six (95%) cases of VT involved right bundle branch block and left axis deviation. We retrospectively analyzed changes in the QRS duration (ΔQRS-d) and QRS axis (ΔQRS-axis) during follow-up and compared them with recurrence of VT. During a mean follow-up period of 10 years (2-32 years), no sudden death or heart failure occurred. Fifty-one (64%) patients underwent RFCA, and 46 (90%) of them had no VT without any medication after RFCA. The ΔQRS-d (16 ± 2 vs. 8 ± 1 ms, P = 0.24) and ΔQRS-axis (20 ± 4 vs. 4 ± 3 degrees, P = 0.23) were not different in patients with no VT (VT[-]) and those with recurrence of VT (VT[+]). However, in the remaining 29 patients without RFCA, VT was spontaneously eliminated in 16 patients. The ΔQRS-d (30 ± 6 vs. 6 ± 1 ms, P = 0.002) and ΔQRS-axis (23 ± 4 vs. 5 ± 2 degrees, P = 0.001) were significantly larger in VT(-) patients compared to VT(+) patients during follow-up. CONCLUSIONS: Some verapamil-ILVT patients who show QRS morphology changes over the follow-up period may become free from VT without any invasive or pharmacological treatments, suggesting that further altered LV fascicular conduction might eliminate the reentry of verapamil-ILVT.

Prognostic impact of chronic total coronary occlusion on long-term outcomes in implantable cardioverter-defibrillator recipients with ischaemic heart disease.

AIMS: The prognostic impact of chronic total coronary occlusion (CTO) on implantable cardioverter-defibrillator (ICD) recipients remains unclear. METHODS AND RESULTS: Eighty-four consecutive patients with ischaemic heart disease who received ICD therapy for primary or secondary prevention were analysed. We investigated all-cause mortality and major adverse cardiac events (MACEs) including cardiac death, appropriate device therapy, hospitalization for heart failure, and ventricular assist device implantation. Of the study patients (mean age 70 ± 8 years; 86% men), 34 (40%) had CTO. There were no significant differences in age, left ventricular ejection fraction (LVEF), New York Heart Association functional class III or IV status, and proportion who underwent secondary prevention between patients with CTO (CTO group) and without CTO (non-CTO group). During a median follow-up of 3.8 years (interquartile range 2.7-5.4 years), the CTO group tended to have a higher MACE rate (log-rank P = 0.054) than the non-CTO group. Within the CTO group, there was no difference in the MACE rate between patients with and without viable myocardium. In patients with ICD for secondary prevention (n = 47), 16 patients (34%) with CTO had a higher MACE rate than patients without CTO (log-rank P < 0.01). Cox proportional hazards regression analysis showed that the presence of CTO, but not LVEF, was associated with a higher MACE rate. Multivariate analysis showed that the presence of CTO was a predictor of MACE (P < 0.05). CONCLUSION: In patients with ischaemic heart disease receiving ICD implantation, the presence of CTO has an adverse impact on long-term prognosis, especially as secondary prevention.

Risk factors associated with bleeding after multi antithrombotic therapy during implantation of cardiac implantable electronic devices.

Previous studies showed that continuous anticoagulation or single antiplatelet therapy during implantations of cardiac implantable electronic devices (CIED) was relatively safe. However, the safety of continuous multi antithrombotic therapy (AT) in patients undergoing CIED interventions has not been clearly defined. We sought to evaluate the safety of this therapy during CIED implantations. A total of 300 consecutive patients (mean 69 years old, 171 males) with CIED implantations were enrolled in this study. The patients were divided into 6 groups [No-AT, oral anticoagulant therapy (OAT), single antiplatelet therapy (SAPT), OAT and SAPT, dual antiplatelet therapy (DAPT), triple AT (TAT)], and the perioperative complications were evaluated. Clinically significant pocket hematomas (PH) were defined as PH needing surgical intervention, prolonged hospitalizations, interruption of AT, or blood product transfusions. There were 129, 89, 49, 20, 10, and 3 patients in No-AT, OAT, SAPT, OAT + SAPT, DAPT, and TAT groups, respectively. The occurrence of clinically significant PH and thromboembolism did not differ among 6 groups (p = 0.145 and p = 0.795, respectively). However, high HAS-BLED score and valvular heart disease (VHD) were associated with clinically significant PH (p = 0.014 and p = 0.015, respectively). Continuous multi AT may be tolerated, but patients with high HAS-BLED score or VHD would require a careful attention during CIED implantations.

"Window Sliding" analysis combined with high-density and rapid electroanatomical mapping: its efficacy and the outcome of catheter ablation of atrial tachycardia.

Atrial tachycardia (AT) is a clinically challenging arrhythmia that can occur based on atrial substrates. Nowadays, a rapid construction of three-dimensional electroanatomical maps, which has an analysis function for complex arrhythmias, named 'Window Sliding' (WS) is available. However, little data has revealed the efficacy of this mapping strategy. The aim of this study was to investigate the efficacy of the WS analysis for AT treatments. All patients underwent electrophysiological studies during ATs and the characteristics of the ATs were analyzed using rapid high-density mapping followed by the WS analysis. RFA was then performed. Fifty-five ATs were identified in 34 patients (63 ± 17 year-old) and in 51 activation maps (cycle length, 322 ± 120 milliseconds) were successfully constructed with 644 ± 433 points per map during 5.3 ± 2.5 min. The types of detected ATs were macro-reentries around the mitral (8) and, tricuspid (12) valves, roof-dependent reentry (5), others (13), and focal patterns (13). Of those that underwent RFA, 46 (98%) were treated successfully. Two ATs were abandoned since their critical sites were close to the His bundle and sinoatrial node. During a mean follow-up period of 179 ± 176 days, 7 patients had documented recurrences of AT. This high-density mapping using the WS analysis was useful for creating the entire picture of the ATs in a short time, resulting in favorable RFA outcomes.

Significance of electrocardiogram recording in high intercostal spaces in patients with early repolarization syndrome.

AIMS: Published reports regarding inferolateral early repolarization (ER) syndrome (ERS) before 2013 possibly included patients with Brugada-pattern electrocardiogram (BrP-ECG) recorded only in the high intercostal spaces (HICS). We investigated the significance of HICS ECG recording in ERS patients. METHODS AND RESULTS: Fifty-six patients showing inferolateral ER in the standard ECG and spontaneous ventricular fibrillation (VF) not linked to structural heart disease underwent drug provocation tests by sodium channel blockade with right precordial ECG (V1-V3) recording in the 2nd-4th intercostal spaces. The prevalence and long-term outcome of ERS patients with and without BrP-ECG in HICS were investigated. After 18 patients showing type 1 BrP-ECG in the standard ECG were excluded, 38 patients (34 males, mean age; 40.4 ± 13.6 years) were classified into four groups [group A (n = 6;16%):patients with ER and type 1 BrP-ECG only in HICS, group B (n = 5;13%):ERS with non-type 1 BrP-ECG only in HICS, group C (n = 8;21%):ERS with non-type 1 BrP-ECG in the standard ECG, and group D (n = 19;50%):ERS only, spontaneously or after drug provocation test]. During follow-up of 110.0 ± 55.4 months, the rate of VF recurrence including electrical storm was significantly higher in groups A (4/6:67%), B (4/5:80%), and C (4/8:50%) compared with D (2/19:11%) (A, B, and C vs. D, P < 0.05). CONCLUSIONS: Approximately 30% of the patients with ERS who had been diagnosed with the previous criteria showed BrP-ECG only in HICS. Ventricular fibrillation mostly recurred in patients showing BrP-ECG in any precordial lead including HICS; these comprised 50% of the ERS cohort.

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) Associated With Ryanodine Receptor (RyR2) Gene Mutations　- Long-Term Prognosis After Initiation of Medical Treatment.

BACKGROUND: The long-term prognosis of cardiac ryanodine receptor (RyR2) positive catecholaminergic polymorphic ventricular tachycardia (CPVT) patients after initiation of medical therapy has not been well investigated. This study aimed to assess the recurrence of fatal cardiac event after initiation of medical therapy inRyR2-positive CPVT patients. METHODS AND RESULTS: Thirty-fourRyR2-positive CPVT patients with a history of cardiac events were enrolled. All patients had medical treatment initiated after the first symptom or diagnosis. Exercise stress tests (ESTs) were performed to evaluate the efficacy of the medical therapy. Even after the initiation of medical therapy, high-risk ventricular arrhythmias (VAs), including premature ventricular contraction couplets, bigeminy, and ventricular tachycardia, were still induced in the majority of patients (80.6%). During 7.4 years of follow-up after the diagnosis, 7 of the 34 (20.6%) patients developed fatal cardiac events. Among those 7 patients, 6 (85.7%) were not compliant with either exercise restriction or medication therapy at the time of the events. CONCLUSIONS: Even after initiation of medical treatment, high-risk VAs were induced during EST in mostRyR2-positive CPVT patients. Most fatal recurrent cardiac events occurred in patients who were noncompliant with exercise restriction and/or medical therapy. Medical management including strict exercise restriction should be emphasized to prevent recurrent cardiac event in mostRyR2-positive CPVT patients. (Circ J 2016; 80: 1907-1915).

Pronounced Shortening of QT Interval With Mexiletine Infusion Test in Patients With Type 3 Congenital Long QT Syndrome.

BACKGROUND: Mexiletine is often used for medical therapy in LQT3 patients, however, the usefulness of mexiletine infusion test for LQT3 patients has not been reported. The aim of this study was to evaluate the usefulness of mexiletine infusion test for detecting LQT3 patients. METHODS AND RESULTS: We analyzed response in 12-lead electrocardiogram parameters measured in II or V5 to i.v. mexiletine infusion (2 mg/kg) during sinus rhythm among 31 genotype-positive LQT patients (29 ± 18 years, 12 male). Change in QTc interval after mexiletine was compared between LQT3 (n=15, 24 ± 21 years, 9 male) and other LQT patients (4 LQT1 and 12 LQT2; 34 ± 14 years, 3 male). Baseline RR, QT, and QTc interval were not different between the 2 groups (981 ± 182 vs. 1,023 ± 192 ms; 550 ± 94 vs. 524 ± 75 ms; 556 ± 66 vs. 520 ± 62 ms, respectively). While QTc interval was shortened with mexiletine in both groups (P<0.0001 vs. baseline), degree of QTc shortening (∆QTc) was significantly larger in LQT3 than in LQT1/LQT2 patients (99 ± 39 vs. 48 ± 32 ms; P=0.0004). The sensitivity, specificity and predictive accuracy of mexiletine infusion test for differentiating LQT3 from LQT1/LQT2 were 86.7%, 81.3% and 81.3%, respectively, and the optimal cut-off for ∆QTc was 69 ms on receiver operating characteristic analysis. No pro-arrhythmic event was observed. CONCLUSIONS: Pronounced shortening of QT interval with mexiletine may facilitate genetic testing in patients with LQT3 syndrome.

Diagnostic Value of Right Ventricular Dysfunction in Tachycardia-Induced Cardiomyopathy Using Cardiac Magnetic Resonance Imaging.

BACKGROUND: Predicting tachycardia-induced cardiomyopathy (TIC) in patients presenting with left ventricular (LV) dysfunction and tachyarrhythmias remains challenging. We assessed the diagnostic value of early right ventricular (RV) dysfunction to predict TIC using cardiac magnetic resonance (CMR) imaging. METHODS AND RESULTS: A total of 102 consecutive patients with newly diagnosed LV dysfunction and atrial tachyarrhythmias were examined. Patients whose LV ejection fraction (EF) improved to ≥50% during a 1-year follow-up were diagnosed with TIC, and with dilated cardiomyopathy (DCM) in those whose did not improve. CMR was performed at a median of 23 days after admission, and the TIC and DCM patients exhibited different distributions of EF and end-diastolic volume (EDV) between the LV and RV (both P<0.001, ANCOVA). TIC patients had significantly lower RVEF/LVEF ratio (1.01±0.23 vs. 1.36±0.31, P<0.001) and higher RVEDV/LVEDV ratio (0.96±0.21 vs. 0.73±0.19, P<0.001) compared with DCM patients, suggesting that RV systolic dysfunction and RV dilatation were observed in TIC. In the multivariate analysis, age, RVEF/LVEF ratio, and RVEDV/LVEDV ratio were significant predictors of TIC, and RVEF/LVEF ratio of <1.05 most highly predicted TIC with a sensitivity of 69.1% and specificity of 91.5% (area under the curve 0.860). CONCLUSIONS: Among patients with newly diagnosed LV dysfunction and atrial tachyarrhythmias, age and coexistence of RV dysfunction was a strong predictor of TIC. (Circ J 2016; 80: 2141-2148).