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Objective@#Higher levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) are associated with a lower risk of atrial fibrillation (AF). Statin use might exert confounding effects on the paradoxical associations; however, the relationships that distinguish statin users from non-users have not been thoroughly evaluated. @*Methods@#From the Korean National Health Insurance Database, we included 9,778,014 adults who underwent a health examination in 2009. The levels of TC and LDL-C at the health examination were categorized into quartile values of the total study population.We grouped the study population into statin users and non-users and investigated the associations between TC, LDL-C, and the risk of incident AF. @*Results@#Of the total population, 867,336 (8.9%) were taking statins. During a mean followup of 8.2 years, inverse associations of TC – AF and LDL-C – AF were observed; higher levels of TC and LDL-C were associated with the lower risk of AF in the total population. Overall, statin users showed higher AF incidence rate than non-users, but the inverse associations of TC – AF and LDL-C – AF were consistently observed irrespective of statin usage; adjusted hazard ratio with 95% confidence interval was 0.81 (0.79–0.84) for statin users and 0.81 (0.80–0.83) for non-users in the highest TC quartile, and 0.84 (0.82–0.87) for statin users and 0.85 (0.84–0.86) for non-users in the highest LDL-C quartile (all p<0.001). @*Conclusion@#The paradoxical relationship between lipid levels (TC and LDL-C) and the risk of AF remains consistent in both statin users and non-users.
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Background and Objectives@#There is limited evidence regarding machine-learning prediction for the recurrence of atrial fibrillation (AF) after electrical cardioversion (ECV).This study aimed to predict the recurrence of AF after ECV using machine learning of clinical features and electrocardiograms (ECGs) in persistent AF patients. @*Methods@#We analyzed patients who underwent successful ECV for persistent AF. Machine learning was designed to predict patients with 1-month recurrence. Individual 12-lead ECGs were collected before and after ECV. Various clinical features were collected and trained the extreme gradient boost (XGBoost)-based model. Ten-fold cross-validation was used to evaluate the performance of the model. The performance was compared to the C-statistics of the selected clinical features. @*Results@#Among 718 patients (mean age 63.5±9.3 years, men 78.8%), AF recurred in 435(60.6%) patients after 1 month. With the XGBoost-based model, the areas under the receiver operating characteristic curves (AUROCs) were 0.57, 0.60, and 0.63 if the model was trained by clinical features, ECGs, and both (the final model), respectively. For the final model, the sensitivity, specificity, and F1-score were 84.7%, 28.2%, and 0.73, respectively. Although the AF duration showed the best predictive performance (AUROC, 0.58) among the clinical features, it was significantly lower than that of the final machine-learning model (p<0.001).Additional training of extended monitoring data of 15-minute single-lead ECG and photoplethysmography in available patients (n=261) did not significantly improve the model’s performance. @*Conclusions@#Machine learning showed modest performance in predicting AF recurrence after ECV in persistent AF patients, warranting further validation studies.
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Background and Objectives@#Inherited arrhythmia (IA) is a more common cause of sudden cardiac death in Asian population, but little is known about the genetic background of Asian IA probands. We aimed to investigate the clinical characteristics and analyze the genetic underpinnings of IA in a Korean cohort. @*Methods@#This study was conducted in a multicenter cohort of the Korean IA Registry from 2014 to 2017. Genetic testing was performed using a next-generation sequencing panel including 174 causative genes of cardiovascular disease. @*Results@#Among the 265 IA probands, idiopathic ventricular fibrillation (IVF) and Brugada Syndrome (BrS) was the most prevalent diseases (96 and 95 cases respectively), followed by long QT syndrome (LQTS, n=54). Two-hundred-sixteen probands underwent genetic testing, and 69 probands (31.9%) were detected with genetic variant, with yield of pathogenic or likely pathogenic variant as 6.4%. Left ventricular ejection fraction was significantly lower in genotype positive probands (54.7±11.3 vs. 59.3±9.2%, p=0.005). IVF probands showed highest yield of positive genotype (54.0%), followed by LQTS (23.8%), and BrS (19.5%). @*Conclusions@#There were significant differences in clinical characteristics and genetic yields among BrS, LQTS, and IVF. Genetic testing did not provide better yield for BrS and LQTS. On the other hand, in IVF, genetic testing using multiple gene panel might enable the molecular diagnosis of concealed genotype, which may alter future clinical diagnosis and management strategies.
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Background@#As an indicator of electro-mechanical coupling, electromechanical window (EMW) can be used to predict fatal ventricular arrhythmias. We investigated the additive effect of EMW on the prediction of fatal ventricular arrhythmias in high-risk patients. @*Methods@#We included patients who had implantable cardioverter-defibrillator (ICD) implanted for primary or secondary prevention. The event group was defined as those who received an appropriate ICD therapy. We acquired echocardiograms at ICD implantation and follow-up. The EMW was calculated as the difference between the interval from QRS onset to aortic valve closure and QT interval from the electrocardiogram embedded in the continuous wave doppler image. We evaluated the predictive value of EMW for predicting fatal ventricular arrhythmia. @*Results@#Of 245 patients (67.2 ± 12.8 years, 63.7% men), the event group was 20.0%. EMW at baseline (EMW-Baseline) and follow-up (EMW-FU) was significantly different between event and control groups. After adjustment, both EMW-Baseline (odds ratio [OR]adjust 1.02 [1.01– 1.03], P = 0.004) and EMW-FU (ORadjust 1.06 [1.04–1.07], P < 0.001) remained as significant predictors for fatal arrhythmic events. Adding EMW-Baseline significantly improved the discriminating ability of the multivariable model including clinical variables (area under the curve [AUC] 0.77 [0.70–0.84] vs. AUC 0.72 [0.64–0.80], P = 0.004), while a univariable model using EMW-FU alone showed the best performance among models (AUC 0.87 [0.81– 0.94], P = 0.060 against model with clinical variables; P = 0.030 against model with clinical variables and EMW-Baseline). @*Conclusion@#The EMW could effectively predict severe ventricular arrhythmia in ICD implanted patients. This finding supports the importance of incorporating the electro-mechanical coupling index into the clinical practice for predicting future fatal arrhythmia events.
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Background@#The Chiari network (CN) is the net-like embryonic remnants of the right valve of the sinus venosus.Catheter entrapment by CN is a not uncommon complication during catheter manipulation inside the right atrium (RA).Case presentation A 49-year-old man with atrial fibrillation was admitted for cryoablation. Transesophageal echo‑ cardiography revealed a prominent CN in the RA. Through the sheath placed in the right femoral vein, a diagnostic electrophysiologic duo-decapolar (DD) catheter (Livewire, St Jude Medical, St Paul, MN) was advanced. The catheter tip was knotted after multiple rotations in the RA to properly locate the DD catheter at the RA wall and coronary sinus (CS). Initial attempts to disentangle the folded catheter tip by traction and rotation maneuvers were unsuccessful.We inserted the large-bore sheath (Sentrant; Medtronic, 20 Fr) into the patient’s left femoral vein and then, captured the folded catheter tip with the 20-mm circular snare catheter (Snare Kit, Medtronic, Minneapolis, MN). Then, we cut the proximal portion of the DD catheter externally and removed it retrogradely through the Flexcath sheath. We found that the catheter tip was entrapped by the fibrous tissue of the CN. After a successful retrieval, cryoablation was conducted as planned. Follow-up echocardiography did not reveal any peri-procedural complications. @*Conclusions@#The electrophysiological procedure that exists at the RA entails a potential risk of catheter entrapment manipulating the catheter at the RA. If catheter entrapment occurs during the procedure, the entrapped catheter may be removed via a large-bore sheath using a snare catheter.
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Background@#Conventional right ventricular apex (RVa) pacing increases the risk of pacing-induced cardiomyopathy (PICM), especially in elderly patients with a higher ventricular pacing burden. Left bundle branch area pacing (LBBAP) has been suggested as an alternative to conventional RVa pacing. However, there is a lack of evidence that LBBAP may reverse PICM. We report a case of a reversal of PICM after LBBAP.Case presentation An 81-year-old woman with a history of complete atrioventricular block and baseline QRS dura‑ tion of 142 ms received permanent pacemaker implantation with dual pacing. The ventricular lead was placed at the apical direction and paced QRS duration was 146 ms. After 8 months, the patient visited with acute heart failure. The patient’s ventricular pacing burden was > 99%, and echocardiography found severe depression of left ventricular ejec‑ tion fraction (LVEF, 30%), left ventricular dyssynchrony, and global hypokinesia. Despite 3 months of optimal medical management of heart failure, there was minimal improvement in LVEF (35%) and ventricular dyssynchrony persisted.The patient’s presentation was consistent with PICM. LBBAP was performed with a stylet-driven lead and a delivery sheath (Biotronik Selectra 3D, Biotronik, Berlin, Germany). The lead was placed at the area of the left bundle branch trunk and non-selective LBBAP was achieved with a left ventricular activation time of 71 ms, paced QRS duration of 110 ms, and bipolar stimulation to QRS end of 136 ms. After a month, echocardiography found improved LVEF (53%) and N-terminal Pro-B-Type natriuretic peptide was decreased from 1011 to 645 pg/mL. The patient was relieved from dyspnea. @*Conclusions@#We report a case that PICM was resolved after LBBAP. LBBAP could be a rescue therapy for PICM induced by conventional RVa pacing.
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New parameters such as ablation index (AI) have been developed to create reliable ablation lesions. This study was performed to evaluate whether RF energy delivery with the same ablation index creates the similar ablation lesion volume. Ablation lesions were created in 5 pig hearts at ex-vivo state. Ablation was performed using an external-irri‑ gation contact-force sensing catheter on the epicardial side of the left ventricle with 90-degree of angle. RF ablation time was adjusted for targeting AI 600 at 8 different conditions. Lesion volume created with 0–5 g of contact force at 20 W was significantly lower than that of 11–20 g at 40W despite of the same AI (125 ± 76.2 vs. 272 ± 49.5 mm 3
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Background and Objectives@#Atrial tachycardias (ATs) from noncoronary aortic cusp (NCC) uncovered after radiofrequency ablation for atrial fibrillation (AF) are rarely reported. This study was conducted to investigate the prevalence and clinical characteristics of NCC ATs detected during AF ablation and compare their characteristics with de novo NCC ATs without AF. @*Methods@#Consecutive patients who underwent radiofrequency catheter ablation for AF were reviewed from the multicenter AF ablation registry of 11 tertiary hospitals. The clinical and electrophysiological characteristics of NCC AT newly detected during AF ablation were compared with its comparators (de novo NCC AT ablation cases without AF). @*Results@#Among 10,178 AF cases, including 1,301 redo ablation cases, 8 (0.08%) NCC AT cases were discovered after pulmonary vein isolation (PVI; 0.07% in first ablation and 0.15% in redo ablation cases). All ATs were reproducibly inducible spontaneously or with programmed atrial stimulation without isoproterenol infusion. The P-wave morphological features of tachycardia were variable depending on the case, and most cases exhibited 1:1 atrioventricular conduction. AF recurrence rate after PVI and NCC AT successful ablation was 12.5% (1 of 8). Tachycardia cycle length was shorter than that of 17 de novo ATs from NCC (303 versus 378, p=0.012). No AV block occurred during and after successful AT ablation. @*Conclusions@#Uncommon NCC ATs (0.08% in AF ablation cases) uncovered after PVI, showing different characteristics compared to de-novo NCC ATs, should be suspected irrespective of P-wave morphologies when AT shows broad propagation from the anterior interatrial septum.
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Purpose@#We aimed to evaluate the influence of technological advances on ablation outcomes in patients with persistent atrial fibrillation (AF) (PeAF). Radiofrequency ablation for patients with AF has advanced, including contact force (CF)-sensing catheters and the ablation index (AI). @*Methods@#Between 2009 and 2018, we analyzed 173 patients with PeAF who underwent catheter ablation. We cat‑ egorized them into three groups: AF ablation without CF and AI information (no-CF group, n = 63), with CF without AI (CF-only group, n = 49), and with optimal AI-guided ablation (AI group, n = 61). Early (within 3 months, ER) and late (from 3 months to 1 year, LR) AF recurrence after ablation was assessed. Procedure-related complications were also evaluated. @*Results@#The baseline characteristics were similar among the 3 groups, excluding the baseline antiarrhythmic drug history. Additional substrate modification after pulmonary vein isolation was significantly low in frequency in the AI group (71.4%, no-CF; 69.4%, CF-only; 41.0%, AI, p = 0.001). The AI group had a shorter mean procedure-related time than the other groups. Both ER and LR of PeAF showed a trend of reduction with technological advances. With a short experience (less than 1 year), the CF-only group showed more ER and LR than that shown by the AI group. However, with a long experience (more than 1 year), ER and LR occurred similarly in the two groups. Procedure-related compli‑ cations improved with technological advances. @*Conclusion@#As ablation technology advanced, favorable clinical outcomes with short procedural times were observed. However, prospective, large multicenter studies are needed to verify these results.
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Background@#The major cause of recurrence after pulmonary vein (PV) isolation for atrial fibrillation (AF) is PV recon‑ nection, and thicker wall could be associated with reconnection. @*Objectives@#This study aimed to evaluate the wall thickness of the PV antrum in reconnection sites using a threedimensional (3D) wall thickness map. @*Methods@#A total of 91 patients who underwent a second ablation procedure due to AF recurrence were evalu‑ ated. The locations of the PV reconnection sites were confirmed in electroanatomical maps. A 3D atrial wall thickness (AWT) map was created using computed tomography scan data. The AWT values of the ablation lines of the index procedure were graded in each segment of the PV antrum: grade 1, 0.5 2.5 mm. @*Results@#A total of 281 PV reconnection sites among 1256 segments of the PV antrum in 79 patients were detected. The average AWT grades were 2.7 ± 1.0 and 2.2 ± 1.0 in the reconnected and non-reconnected segments, respectively (P < 0.01). Higher AWT grades were observed in the reconnected superior segments of the left superior PV, carina and inferior segments of the left inferior PV, superior and posterior segments of the right superior PV, and posterior and inferior segments of the right inferior PV. @*Conclusion@#The reconnected segments of the PV antrum showed thicker myocardium than the non-reconnected ones in patients with recurrent AF after catheter ablation. A wall thickness map for PV isolation could be considered for customized ablation in order to reduce PV reconnection.
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Background@#This study aims to investigate the current status of AF (atrial fibrillation) catheter ablation in Korea. @*Methods@#The patients who underwent AF catheter ablation from September 2017 to December 2019 were pro‑ spectively enrolled from 37 arrhythmia centers. Demographic data, procedural characteristics, the extent of catheter ablation, acute success of the ablation lesion set, rate and independent risk factor for recurrence of AF were analyzed. @*Results@#A total of 2402 AF patients [paroxysmal AF (PAF) 45.7%, persistent AF (PeAF) 43.1% and redo AF 11.2%] were included. Pulmonary vein isolation (PVI) was performed in 2378 patients (99%) and acute success rate was 97.9%.Additional non-PV ablation (NPVA) were performed in 1648 patients (68.6%). Post-procedural complication rate was 2.2%. One-year AF-free survival rate was 78.6% and the PeAF patients showed poorer survival rate than the ones with other types (PeAF 72.4%, PAF 84.2%, redo AF 80.0%). Additional NPVA did not influence the recurrence of AF in the PAF patients (PVI 17.0% vs. NPVA 14.6%, P value 0.302). However, it showed lower AF recurrence rate in the PeAF patients (PVI 34.9% vs. NPVA 24.4%, P value 0.001). Valvular heart disease, left atrial diameter, PeAF, PVI alone, need of NPVA for terminating AF, and failed ablation were independent predictors of AF recurrence. @*Conclusions@#Additional NPVA was associated better rhythm outcome in the patients with PeAF, not in the ones with PAF. The independent risk factors for AF recurrence in Korean population were similar to previous studies. Further research is needed to discover optimal AF ablation strategy.
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Background and Objectives@#Antithrombotic therapy after percutaneous coronary intervention (PCI) in patients with atrial fibrillation (AF) has changed in recent years with new data from large randomized trials and updates to clinical guidelines. This study aimed to investigate the trends in periprocedural antithrombotic regimens in Korean patients with AF undergoing PCI with non-vitamin K antagonist oral anticoagulants (NOACs). @*Methods@#Using the claims database of the Health Insurance Review and Assessment during 2013–2018, 27,594 patients with AF undergoing PCI were identified. The annual prevalence of PCI and prescriptions of each antithrombotic agent, including antiplatelet agents and oral anticoagulants, within 30 days after PCI were investigated. @*Results@#During 2013–2018, the number of patients with AF undergoing PCI increased up to 1.3-fold (from 3,913 to 5,075 patients per year). After the introduction of NOACs, the proportion of dual antiplatelet therapy (DAPT) decreased from 71.9% to 49.8% but still occupied the largest proportion among antithrombotic regimens. Triple antithrombotic therapy (TAT) use increased from 25.4% to 46.0%, and NOAC has rapidly replaced warfarin as the oral anticoagulant of choice. TAT was preferred to DAPT for patients with CHA2 DS2 -VASc score ≥2. Among various factors, prior intracranial hemorrhage was the most powerful predictor of favoring DAPT use over TAT. @*Conclusion@#Since the introduction of NOACs, the patterns of periprocedural antithrombotic regimens have changed rapidly toward more use of TAT, specifically with NOAC-based regimen. Appropriate stroke prevention with oral anticoagulants is still underutilized in patients with AF undergoing PCI in Korea.
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Background and Objectives@#Antithrombotic therapy after percutaneous coronary intervention (PCI) in patients with atrial fibrillation (AF) has changed in recent years with new data from large randomized trials and updates to clinical guidelines. This study aimed to investigate the trends in periprocedural antithrombotic regimens in Korean patients with AF undergoing PCI with non-vitamin K antagonist oral anticoagulants (NOACs). @*Methods@#Using the claims database of the Health Insurance Review and Assessment during 2013–2018, 27,594 patients with AF undergoing PCI were identified. The annual prevalence of PCI and prescriptions of each antithrombotic agent, including antiplatelet agents and oral anticoagulants, within 30 days after PCI were investigated. @*Results@#During 2013–2018, the number of patients with AF undergoing PCI increased up to 1.3-fold (from 3,913 to 5,075 patients per year). After the introduction of NOACs, the proportion of dual antiplatelet therapy (DAPT) decreased from 71.9% to 49.8% but still occupied the largest proportion among antithrombotic regimens. Triple antithrombotic therapy (TAT) use increased from 25.4% to 46.0%, and NOAC has rapidly replaced warfarin as the oral anticoagulant of choice. TAT was preferred to DAPT for patients with CHA2 DS2 -VASc score ≥2. Among various factors, prior intracranial hemorrhage was the most powerful predictor of favoring DAPT use over TAT. @*Conclusion@#Since the introduction of NOACs, the patterns of periprocedural antithrombotic regimens have changed rapidly toward more use of TAT, specifically with NOAC-based regimen. Appropriate stroke prevention with oral anticoagulants is still underutilized in patients with AF undergoing PCI in Korea.
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BACKGROUND: There is a paucity of information regarding whether contact force (CF)-guided ablation improves the outcomes of pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) by achieving more optimal contact. We sought to assess whether real time CF-guided ablation has an impact on ablation parameters and acute pulmonary vein reconnection (PVR). METHODS: Left or right PVs were randomized to either CF-guided or blinded groups, and the order of CF blindness: CF-guided left PV/CF-blinded right PV, CF-blinded left PV/CF-guided right PV, CF-guided right PV/CF-blinded left PV, and CF-blinded right PV/CF-guided left PV groups. We compared CF parameters and acute PVR between segments ablated by CF-guided and CF-blinded strategies. RESULTS: Sixty patients with drug refractory symptomatic AF were included (paroxysmal AF 73%). CF-guided segments did not show significant differences in CF parameters compared to CF-blinded segments. However, CF-guided segments showed fewer segments with mean CF value <5 g than CF-blinded segments (4.3% vs. 12.4%, p<0.001). Forty-two patients showed acute PVR in 92 segments (8.5%). CF-guided PV segments showed lower acute PVR rate than CF-blinded segments (5.9% vs. 11.1%, p=0.011). CONCLUSIONS: CF-guided ablation could reduce acute PVR after PVI by decreasing the number of segments with poor contact rather than increasing the mean CF during ablation. Better contact guided by CF information might help in improving the results of PVI. Further investigation will be needed to identify the association between the difference in acute reconnection and the long-term outcomes.
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Background@#In patients with atrial fibrillation (AF), most biomarkers are still of limited use due to cost-effectiveness and complexity in clinical practice.Hypotheses Biomarkers from routine blood tests improve the current risk stratification in AF patients. @*Methods@#This prospective study enrolled 600 patients diagnosed with non-valvular AF, of whom 537 were analyzed. Platelet count; platelet distribution width (PDW); red cell distribution width (RDW); and creatinine, D-dimer, and troponin I levels were measured at enrollment. @*Results@#During the mean follow-up period (2.2 ± 0.6 years), 1.9% patients developed ischemic stroke. According to the optimal cutoff of each biomarker, the risk of ischemic stroke was higher in patients with RDW ≥ 13.5%, creatinine ≥ 1.11 mg/dL, or PDW ≥ 13.2% (significant biomarkers; P value: < 0.01, 0.04, or 0.07, respectively). These 3 significant biomarkers had higher information gain than clinical risk factors in predicting ischemic stroke. The cumulative incidence of ischemic stroke was 1.2%, 1.1%, 8.4%, and 40.0% in patients with 0, 1, 2, and 3 significant biomarkers, respectively (P-for-trend < 0.001). Patients with ≥ 2 significant biomarkers had a significantly higher risk of ischemic stroke than those with < 2 significant biomarkers (adjusted hazard ratio 11.5, 95% confidence interval 3.3–40.2, P < 0.001). The predictability for ischemic stroke was significantly improved when ≥ 2 significant biomarkers were added to the CHA2DS2–VASc score (area under the curve 0.790 vs. 0.620, P = 0.043). @*Conclusion@#Routine blood tests can provide better risk stratification of AF along with clinical risk factors.
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Background@#The definitive pathologic diagnosis of cardiac sarcoidosis requires observation of a granuloma in the myocardial tissue. It is common, however, to receive a “negative” report for a clinically probable case. We would like to advise pathologists and clinicians on how to interpret “negative” biopsies. @*Methods@#Our study samples were 27 endomyocardial biopsies from 25 patients, three cardiac transplantation and an autopsied heart with suspected cardiac sarcoidosis. Pathologic, radiologic, and clinical features were compared. @*Results@#The presence of micro-granulomas or increased histiocytic infiltration was always (6/6 or 100%) associated with fatty infiltration and confluent fibrosis, and they showed radiological features of sarcoidosis. Three of five cases (60%) with fatty change and confluent fibrosis were probable for cardiac sarcoidosis on radiology. When either confluent fibrosis or fatty change was present, one-third (3/9) were radiologically probable for cardiac sarcoidosis. We interpreted cases with micro-granuloma as positive for cardiac sarcoidosis (five of 25, 20%). Cases with both confluent fibrosis and fatty change were interpreted as probable for cardiac sarcoidosis (seven of 25, 28%). Another 13 cases, including eight cases with either confluent fibrosis or fatty change, were interpreted as low probability based on endomyocardial biopsy. @*Conclusions@#The presence of micro-granuloma could be an evidence for positive diagnosis of cardiac sarcoidosis. Presence of both confluent fibrosis and fatty change is necessary for probable cardiac sarcoidosis in the absence of granuloma. Either of confluent fibrosis or fatty change may be an indirect pathological evidence but they are interpreted as nonspecific findings.
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BACKGROUND AND OBJECTIVES@#It is difficult to estimate the depth of the focal source by activation mapping. The present study was performed to demonstrate the usefulness of a simple maneuver in estimating the depth of the focal activation source (S).@*METHODS@#A total of 44 sites (15 shallow, depth5.5 mm) were analyzed in 3 canine left ventricles under general anesthesia. A custom-made bipolar needle electrode was used to simulate a focal activation source. A mapping catheter with an electrode tip size of 2 mm, band electrode size of 1 mm, and inter-electrode spacing of 2-10-2 mm was placed at the mapping area. The position of the center of the distal 2 electrodes was kept at the insertion site of the needle electrode. The time interval between distal and proximal electrodes of the mapping catheter (T(tachy)) was measured during needle electrode pacing. The time interval between distal and proximal electrodes (T(pace)) was measured during pacing with distal electrodes of a mapping catheter. Depth index (δ) was defined as T(tachy)/T(pace). Using in vivo data, simulation was performed to evaluate the depth and δ.@*RESULTS@#Ttachy was 24±7.7 ms and 15±5.6 ms for shallow source and deep source simulation, respectively (p5.5 mm.@*CONCLUSIONS@#T(tachy) was shorter and δ was smaller for a deep S than for a shallow S.
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BACKGROUND@#An implantable loop recorder (ILR) is an effective tool for diagnosing unexplained syncope (US). We examined the diagnostic utility of an ILR in detecting arrhythmic causes of US and determining which clinical factors are associated with pacemaker (PM) implantation.@*METHODS@#This retrospective, multicenter, observational study was conducted from February 2006 to April 2018 at 11 hospitals in Korea. Eligible patients with recurrent US received an ILR to diagnose recurrent syncope and document arrhythmia.@*RESULTS@#A total of 173 US patients (mean age, 67.6 ± 16.5 years; 107 men [61.8%]) who received an ILR after a negative conventional workup were enrolled. During a mean follow-up of 9.4 ± 11.1 months, 52 patients (30.1%) had recurrent syncope, and syncope-correlated arrhythmia was confirmed in 34 patients (19.7%). The ILR analysis showed sinus node dysfunction in 24 patients (70.6%), supraventricular tachyarrhythmia in 4 (11.8%), ventricular arrhythmia in 4 (11.8%), and sudden atrioventricular block in 2 (5.9%). Overall, ILR detected significant arrhythmia in 99 patients (57.2%) irrespective of syncope. Among patients with clinically relevant arrhythmia detected by ILR, PM implantation was performed in 60 (34.7%), an intra-cardiac defibrillator in 5 (2.9%), and catheter ablation in 4 (2.3%). In a Cox regression analysis, history of paroxysmal atrial fibrillation (PAF) (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.33–4.12; P < 0.01) and any bundle branch block (BBB) (HR, 2.52; 95% CI, 1.09–5.85; P = 0.03) were significantly associated with PM implantation.@*CONCLUSION@#ILR is useful for detecting syncope-correlated arrhythmia in patients with US. The risk of PM is high in US patients with a history of PAF and any BBB.
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Background@#Although multiple algorithms based on surface electrocardiographic criteria have been introduced to localize idiopathic ventricular arrhythmia (VA) origins from the outflow tract (OT), their diagnostic accuracy and clini‑ cal usefulness remain limited. We evaluated whether local activation time of the His bundle region could differentiate left and right ventricular OT VA origins in the early stage of electrophysiology study. @*Methods@#We studied 30 patients who underwent catheter ablation for OT VAs with a left bundle branch block pat‑ tern and inferior axis QRS morphology. The interval between the local V signal on the mapping catheter placed in the RVOT and His bundle region (V(RVOT)-V(HB) interval) and the interval from QRS complex onset to the local V signal on the His bundle region (QRS-V(HB) interval) were measured during VAs. @*Results@#The V(RVOT)-V(HB) and QRS-V(HB) intervals were significantly shorter in patients with LVOT VAs. The area under the curve (AUC) for the V(RVOT)-V(HB) interval by receiver operating characteristic analysis was 0.865. A cutoff value of ≤ 50 ms predicted an LVOT origin of VA with sensitivity, specificity, and positive and negative predictive values of 100%, 62.5%, 40%, and 100%, respectively. The QRS-V(HB) interval showed similar diagnostic accuracy (AUC, 0.840), and a cutoff value of ≤ 15 ms predicted an LVOT origin of VA with a sensitivity, specificity, and positive and negative predictive values of 100%, 70.8%, 45.2%, and 100%, respectively. @*Conclusion@#The V(RVOT)-V(HB) and QRS-V(HB) intervals could differentiate left from right OT origins of VA with high sensitivity and negative predictive values.
