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Background: Differentiation of supraventricular tachycardia (SVT) with a right bundle branch block (RBBB) pattern from ventricular tachycardia (VT) is difficult, particularly when the R/S ratio in lead V 6 is below 1.0., Objective: We sought to investigate the electrocardiographic criteria for distinguishing between these arrhythmias., Methods: We investigated electrocardiographic parameters from 111 consecutive patients who had RBBB pattern wide QRS complex tachycardia with a reversed R/S ratio in lead V 6 (72 VTs, 39 SVTs). Diagnostic criteria from the previous algorithms were compared with our new criterion, the RS/QRS ratio, which was defined as the ratio of the interval from the onset of the QRS complex to the nadir of the S wave, divided by the QRS width in lead V 6 . The RS/QRS ratio was further tested in a prospective population (31 fascicular VTs, 29 SVTs)., Results: The diagnostic accuracy of previous criteria (Brugada algorithm, Vereckei algorithm, and R-wave peak time criterion) was only modest. However, the RS/QRS ratio in lead V 6 was significantly lower in SVT than in VT (0.36 ± 0.04 vs 0.50 ± 0.08; P < .001). A cutoff value of the RS/QRS ratio >0.41 differentiated VT from SVT with a high diagnostic accuracy (sensitivity 97.2%; specificity 89.7%). When tested in a prospective population with fascicular VT, the diagnostic accuracy of the criteria was maintained (sensitivity 90.3%; specificity 86.2%)., Conclusion: The RS/QRS ratio >0.41 in lead V 6 is a simple and reliable index for distinguishing VT from SVT in RBBB pattern wide QRS complex tachycardia with a reversed R/S complex in lead V 6 . This criterion was particularly useful for the differential diagnosis of fascicular VT from RBBB pattern SVT., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Increased serum uric acid is associated with prevalence and incidence of atrial fibrillation (AF), but there is a lack of studies on the association between serum uric acid and risk of AF in the general population. Methods and Results: We used the data from the Kangbuk Samsung Hospital health screening cohort recorded between 2002 and 2015. The primary outcome was incidence of AF diagnosed on 12-lead electrocardiography. We analyzed and compared the hazard ratios (HR) according to baseline serum uric acid quartiles. The present study involved 282,473 subjects without baseline AF. Mean follow-up was 5.4±3.6 years. During follow-up, AF was identified in 365 subjects (cumulative incidence, 0.13%). After multivariable adjustment, including that for C-reactive protein, the risk of AF was significantly higher in the upper 2 quartiles than in the lowest quartile in men (upper third quartile: adjusted HR, 1.53; 95% confidence interval [CI]: 1.11-2.89; highest quartile: HR, 1.60; 95% CI: 1.13-2.25). In women, even though AF incidence rate was very low (0.6 of 10,000 person-years), the risk of AF in the highest quartile was 6.93-fold that in the lowest quartile (95% CI: 1.53-31.29)., Conclusions: Serum uric acid is significantly and positively associated with incident AF in the Korean general population.

In acute pulmonary thromboembolism (PTE), right ventricular pressure overload impairs right-sided cardiac conduction and repolarization. We hypothesized that if heterogeneity of repolarization between right and left ventricles occurs in acute PTE, there would be the difference of repolarization between them. Therefore, we aimed to evaluate the diagnostic value of corrected QT interval (QTc) difference between leads V1 and V6 (V1 - V6) in patients with acute PTE.A total of 89 patients with suspected acute PTE who underwent computed tomographic angiography (CTA) were enrolled from January to December 2015. PTE was identified by CTA. We compared electrocardiographic (ECG) parameters, especially QTc difference (V1 - V6) between patients with PTE and those without PTE.Acute PTE was finally diagnosed in 45 patients. Clinical situations including the chief complaint were not different between PTE and non-PTE groups. S1Q3T3, a traditional ECG marker, had no diagnostic value for acute PTE. Patients with PTE had a significantly longer mean QTc in V1 (454.6 ± 44.3 vs 417.5 ± 31.3 ms, P < .001) and larger QTc difference (V1 - V6) (34.8 ± 30.5 vs -12.5 ± 16.6 ms, P < .001) than non-PTE controls. QTc difference (V1 - V6) was negative in all patients without PTE. PTE patients had a higher prevalence of T wave inversion in leads III (51.1% vs 29.5%, P = .038) and V1 (82.2% vs 38.6%, P < .001). A QTc difference (V1 - V6) of ≥20 ms identified PTE with 82.2% sensitivity, 100.0% specificity, and 100.0% positive predictive value.QTc difference (V1 - V6) had an excellent diagnostic value for differentiating patients with and without acute PTE.

Background: We tested a hypothesis that the 2 fundamental components of early repolarization (ER), J wave and ST elevation (STE) might have different prevalence and prognostic implications., Methods: The study population comprised 26,345 general ambulatory Korean subjects (mean 48.0±10.2years old, 53.2% male) who underwent medical checkups from January 2002 to December 2002. ER was found in 2950 subjects (11.2%), who were divided into 3 groups (J [J wave only, n=1874, 7.1%], JST [both J wave and STE, n=489, 1.8%], and ST [STE only, n=587, 2.3%])., Results: The prevalence of STE decreased with age, whereas J waves remained at a constant level in all age groups. The most common pattern of ER was the J pattern, with a horizontal/descending ST segment in the inferior leads; in lateral precordial leads, ST or JST patterns with ascending ST segments were more common. During the mean follow-up of 126.0±11.1months, a total of 710 subjects died (2.7%). Subjects in the J group were at higher risk (Hazard ratio 1.60, 95% confidence interval 1.27-2.01, p<0.001), while those in the JST and ST groups showed similar survival outcomes compared to controls without J waves or STE., Conclusions: J waves and STE showed different age and lead distributions and prognostic implications. The presence of the J wave itself was associated with a higher relative risk of mortality. However, due to the low event rate, its clinical significance appears to be limited., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Objective: Hypothermia can induce ECG J waves. Recent studies suggest that J waves may be associated with ventricular fibrillation (VF) in patients with structurally normal hearts. However, little is known about the ECG features, clinical significance or arrhythmogenic potentials of therapeutic hypothermia (TH)-induced J waves., Methods: We analysed ECGs from 240 patients who underwent TH at six major university hospitals in Korea between August 2010 and December 2013. The prevalence, amplitudes and distributions of the J waves and the development of malignant arrhythmia were analysed., Results: The average patient body temperature was 33.5±1.0°C during TH. J waves were observed in 98 patients (40.8%). They were newly developed in 91 cases, and pre-existing J waves were augmented in seven patients. J waves during TH were primarily observed in leads II, III, aVF and V4-6. The average amplitude of the J waves was 0.239±0.152 mV. There were four VF events during TH. These events occurred in three patients who were finally diagnosed with Brugada syndrome, idiopathic VF or early repolarisation syndrome, respectively, and in one patient with non-cardiac aetiology (asphyxia)., Conclusions: J waves were recorded in about 40% of the patients who received TH. They were most frequently observed in the inferior limb leads or lateral precordial leads. Life-threatening VF occurred only rarely (1.7%) during TH and were mainly observed in patients with primary arrhythmic disorder. Although a causal relationship between TH-induced J waves and VF remains unknown, administering TH to this potentially susceptible, high-risk population may require careful attention., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Idiopathic ventricular tachycardia (VT) originating from the outflow tract (OT) usually is considered a benign condition. In rare cases, patients with OT-VT suffer from syncope or even sudden cardiac death. OT-VT is frequently preceded by nonsustained VT (NSVT)., Objective: The purpose of this study was to clarify if the ECG parameters of NSVTs could differentiate malignant from benign OT-VT., Methods: We retrospectively evaluated patients without structural heart disease who had documented OT-NSVT on ECG. ECG parameters were compared between patients with syncope, aborted sudden cardiac death, or ventricular fibrillation (malignant group, n = 36) and patients without syncope (benign group, n = 40)., Results: There were no differences with regard to age and gender between the malignant and benign groups. On analysis of NSVT, the first coupling interval (CI) of NSVT was comparable between the 2 groups (458 ± 87 ms vs 485 ± 95 ms, P = .212). However, the second CI of NSVT beats was significantly shorter in the malignant group (313 ± 58 ms vs 385 ± 83 ms, P < .0001). During 48-month follow-up, the benign group had a significantly lower recurrence of clinical VT than the malignant group (P = .046). The malignant group frequently had more than 1 focus of VT, whereas the benign group showed only a single focus (1.82 vs 1.09, P = .023)., Conclusion: The second CI of NSVT in the malignant group was significantly shorter than that of the benign OT-VT group. Careful measurement of the second CI of NSVT may help identify the malignant form of OT-VT, enabling early treatment to prevent future cardiac events., (Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Differentiation of supraventricular tachycardia (SVT) with a right bundle branch block (RBBB) pattern from ventricular tachycardia (VT) is difficult, particularly when the R/S ratio in lead V6 is below 1.0.Objective: We sought to investigate the electrocardiographic criteria for distinguishing between these arrhythmias.Methods: We investigated electrocardiographic parameters from 111 consecutive patients who had RBBB pattern wide QRS complex tachycardia with a reversed R/S ratio in lead V6 (72 VTs, 39 SVTs). Diagnostic criteria from the previous algorithms were compared with our new criterion, the RS/QRS ratio, which was defined as the ratio of the interval from the onset of the QRS complex to the nadir of the S wave, divided by the QRS width in lead V6. The RS/QRS ratio was further tested in a prospective population (31 fascicular VTs, 29 SVTs).Results: The diagnostic accuracy of previous criteria (Brugada algorithm, Vereckei algorithm, and R-wave peak time criterion) was only modest. However, the RS/QRS ratio in lead V6 was significantly lower in SVT than in VT (0.36 ± 0.04 vs 0.50 ± 0.08; P < .001). A cutoff value of the RS/QRS ratio >0.41 differentiated VT from SVT with a high diagnostic accuracy (sensitivity 97.2%; specificity 89.7%). When tested in a prospective population with fascicular VT, the diagnostic accuracy of the criteria was maintained (sensitivity 90.3%; specificity 86.2%).Conclusion: The RS/QRS ratio >0.41 in lead V6 is a simple and reliable index for distinguishing VT from SVT in RBBB pattern wide QRS complex tachycardia with a reversed R/S complex in lead V6. This criterion was particularly useful for the differential diagnosis of fascicular VT from RBBB pattern SVT. [ABSTRACT FROM AUTHOR]

Aims: Inflammation has been suggested to play a role in the pathogenesis of atrial fibrillation (AF). It is uncertain whether C-reactive protein, a robust inflammatory marker, is associated with AF incidence in Asians with lower levels of C-reactive protein compared with western population. This study aimed to determine the association between C-reactive protein and risk of AF in a large population of Koreans.Methods and results: A total of 402 946 Koreans were enrolled in a health screening programme from January 2002 to December 2013. Among them, 210 208 subjects were analysed during the mean follow-up of 4.59 years (1 062 513 person-years). Atrial fibrillation was identified by electrocardiography at every visits. Atrial fibrillation was identified in 561 subjects (0.1%) at baseline. The median (inter-quartile) baseline C-reactive protein levels were higher in subject with AF than in those without AF [0.9 mg/L (0.4-0.9) vs. 0.4 mg/L (0.2-1.0), P < 0.001]. Subjects in the highest quartile of C-reactive protein had more AF than those in the lowest quartile [adjusted odds ratio (OR) 2.02, 95% confidence interval (CI) 1.45-2.81; P< 0.001]. During a mean follow-up of 4.59 years, AF developed in 261 subjects (0.1%). The highest quartile of baseline C-reactive protein had a 1.68-fold (95% CI 1.06-2.67) increased risk of AF than the lowest quartile in multivariate Cox regression analysis.Conclusion: Baseline C-reactive protein levels are significantly associated with the prevalence of AF and the risk of AF in Korean populations even C-reactive protein concentrations are substantially lower than reported in white populations. [ABSTRACT FROM AUTHOR]