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Background/objectives: Sodium channel blockers are used to unmask the diagnostic ECG pattern of the Brugada syndrome (BrS) in case of a non-diagnostic baseline ECG. The aim of the study was to determine clinical and ECG predictors of a positive challenge test in patients suspected to the BrS., Methods: A total of 106 consecutive patients (91 men; mean age, 35 ± 12 years) suspected of the BrS underwent the intravenous sodium channel blocker challenge test with procainamide or flecainide., Results: Of the 106 patients, positive tests were detected in 20 (19%) patients. During test, a transient episode of a second-degree atrioventricular block and isolated ventricular ectopies were observed in 1 (0.9%) and 2 (1.9%) patients, respectively. A QRS prolongation ≥ 30% was observed in 4 (3.8%) patients. Baseline QRS duration in V1 ≥ 110 ms had a sensitivity of 70% and a specificity of 80% for a positive response. An ST-segment elevation ≥ 0.17 mV in V2 had a sensitivity of 60% and a specificity of 82% for a positive response. Of the multiple clinical and ECG variables entered into a binary logistic regression analysis, a history of syncope (P=0.001), previous cardiac arrest (P=0.001), baseline QRS duration in V1 ≥ 110 ms (P=0.001), and baseline ST-segment elevation in V2 ≥ 0.17 mV (P=0.012) emerged as the independent predictors of a positive response to the intravenous challenge with sodium channel blockers., Conclusion: The results of the sodium channel blocker challenge test can be predicted by clinical presentation and baseline ECG features., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Aims: Despite the several electrocardiographic (ECG) criteria, misclassification may still occur in differential diagnosis of the regular paroxysmal supraventricular tachycardia (PSVT). The aim of the present study was to evaluate the diagnostic accuracy of the aVR lead in ECG differentiation of atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT)., Methods and Results: A 12-lead ECG was recorded in 150 consecutive patients (96 women, mean age, 45 ± 13.5 years) with drug-refractory regular PSVT during both sinus rhythm and tachycardia. All ECGs were reviewed by two experienced electrophysiologists who had no knowledge of the tachycardia mechanism. The ECG recordings were evaluated for standard criteria as well as our newly proposed criterion of pseudo-r' in the lead aVR. Mechanism of arrhythmia was confirmed by the electrophysiological study and the successful catheter ablation. Patients with AVNRT were older (50 ± 10 vs. 37 ± 15 years, P = 0.001), predominantly female (71 vs. 53%, P = 0.03), and presented with slower tachycardia (175 ± 25 vs. 186 ± 26 b.p.m., P = 0.01). Among the ECG criteria of the AVRT diagnosis, visible P-wave with RP interval ≥ 100 ms had highest diagnostic accuracy (sensitivity 79%, specificity 87%, and positive predictive value 79%). For AVNRT diagnosis, pseudo-r' in aVR had a higher sensitivity, specificity, and predictive values compared with the conventional criteria of the pseudo-r' in V1 and pseudo-s in inferior leads (all P < 0.05)., Conclusions: New criterion of pseudo-r' in lead aVR appears to be more accurate than the standard ECG criteria for ECG diagnosis of AVNRT.

In this article, we report 2 young patients (a 15-year-old adolescent girl and a 25-year-old man) with drug-refractory palpitations. Admission electrocardiograms showed runs of ventricular tachycardia with left bundle-branch block morphology, left inferior axis, early precordial QRS transition, and positive QRS complex in lead I. In right ventricular mapping, the earliest activation site was found in the His bundle region. Aortic root mapping showed a very early fractionated ventricular signal with large atrial potential and no His potential in the noncoronary cusp region. Radiofrequency energy application in this region resulted in tachycardia termination within 5 to 10 seconds. During a 3- to 6-month follow-up period, the patients remained asymptomatic, and the electrocardiogram showed no ventricular arrhythmias., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Atrial fibrillation (AF) is a commonly encountered cardiac arrhythmia. Predicting the conditions under which AF terminates spontaneously is an important task that would bring great benefit to both patients and clinicians. In this study, a new method was proposed to predict spontaneous AF termination by employing the points of section (POS) coordinates along a Poincare section in the electrocardiogram (ECG) phase space. The AF Termination Database provided by PhysioNet for the Computers in Cardiology Challenge 2004 was applied in the present study. It includes one training dataset and two testing datasets, A and B. The present investigation was initiated by producing a two-dimensional reconstructed phase space (RPS) of the ECG. Then, a Poincare line was drawn in a direction that included the maximum point distribution in the RPS and also passed through the origin of the RPS coordinate system. Afterward, the coordinates of the RPS trajectory intersections with this Poincare line were extracted to capture the local behavior related to the arrhythmia under investigation. The POS corresponding to atrial activity were selected with regard to the fact that similar ECG morphologies such as P waves, which are corresponding to atrial activity, distribute in a specific region of the RPS. Thirteen features were extracted from the selected intersection points to quantify their distributions. To select the best feature subset, a genetic algorithm (GA), in combination with a support vector machine (SVM), was applied to the training dataset. Based on the selected features and trained SVM, the performance of the proposed method was evaluated using the testing datasets. The results showed that 86.67% of dataset A and 80% of dataset B were correctly classified. This classification accuracy is in the same range as or higher than that of recent studies in this area. These results show that the proposed method, in which no complicated QRST cancelation algorithm was used, has the potential to predict AF termination.

Introduction: Research indicates that music can affect heart rate, blood pressure, and skin conductance. Music can stimulate central emotions in the brain and release biochemical materials that change the physiologic state. We sought to compare changes in the electrical function of the heart in response to music., Method: Subjects were asked to listen to 2 types of music, namely, sedative and arousal music, in conjunction with two 30-second periods of complete silence. The experiment was conducted in 4 segments: the first and third parts were silence, and the second and fourth parts were music. First, the response to each type of music was compared with that to the preceding period of silence. Next, the responses to both types of music were compared. Finally, the response to music regardless of the type was compared with that to silence., Results: The amplitude of polarization and depolarization changed in response to different kinds of music. The electrical function of the heart in response to music, irrespective of the music type, differed from that in response to silence. The 2 types of music impacted the electrical function of the heart in different ways: the arousal music influenced T-wave maximum amplitude, whereas no such change was recorded in response to the sedative music., Conclusions: The bandwidth of the polarization and depolarization of the heart rate and R-wave amplitude increased in response to music by comparison with silence. In addition, the heart did not seem to try to synchronize with music. The mean R-wave amplitude in sedative music is higher than the arousal music, so our heart works differently when different types of music are heard., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Aims: To predict response to cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and intraventricular conduction delay., Methods and Results: The study population consisted of 82 consecutive HF patients with standard CRT indications. Patients were classified as responders, if they were alive without cardiac decompensation and experienced >or=15% decrease in left ventricular end-systolic volume. Sixty-eight percent of the enrolled patients responded to CRT. When compared with non-responders, responders had a wider baseline QRS width (P = 0.001), more marked QRS shortening (DeltaQRS) immediately after CRT (P = 0.001), and a better improvement in aortic velocity time integral (VTI) 24 h after CRT (P = 0.02). Moreover, there was a trend towards a greater baseline intraventricular dyssynchrony in the responder group (P = 0.07). By multivariable logistic regression, the baseline QRS width (OR: 0.95, 95% CI: 0.90-0.97, P = 0.001), DeltaQRS (OR: 1.038, 95% CI: 1.012-1.064, P = 0.003), and acute aortic VTI (OR: 0.81, 95% CI: 0.68-0.96, P = 0.017) emerged as independent predictors of response to CRT. Receiver operating characteristic curve analysis identified a QRS width >145 ms, DeltaQRS >20 ms, and aortic VTI >14 cm to predict responders., Conclusion: A positive response to CRT was observed in 68% of the patients. Cardiac resynchronization therapy response is predictable using simple electrocardiographic and echocardiographic data.

Aims: From the spectrum of electrocardiogram (ECG) changes that may occur in hypertrophic cardiomyopathy (HCM), there is no criterion reported to be useful for risk stratification. We sought to determine whether there was a relationship between the resting ECG findings and prognosis in patients with HCM., Methods and Results: We retrospectively analysed data on 173 consecutive patients admitted to our centre with a diagnosis of HCM. The 12-lead ECGs were assessed for underlying rhythm, PR interval, QRS voltages, QRS width, corrected QT interval, ST-segment deviation, T-wave inversion, and left atrial enlargement (LAE). During a mean follow-up of 50 months, 6.4% of patients had a combined endpoint [sudden death or appropriate implantable cardioverter-defibrillator (ICD) therapy]. The frequency of the combined endpoint was greater in patients with syncope, non-sustained ventricular tachycardia, maximal left ventricular (LV) wall thickness >or=30 mm, and ST-segment depression in the high lateral leads (all P < 0.05). Other ECG findings (LV hypertrophy, LAE, abnormal Q wave, abnormal ST-T changes, and underlying rhythm), family history of sudden death, and LV outflow obstruction were not related to the combined endpoint. The results of our multivariate analysis demonstrated that ST-segment depression in the high lateral leads (OR: 20.0, 95% CI: 12.7-27.5; P = 0.0001) and syncope (OR: 19.0, 95% CI: 11.7-26.9; P = 0.0001) were the predictors of sudden death or appropriate ICD therapy in patients with HCM., Conclusion: The results of this study indicated that, in addition to generally accepted risk factors, ST-segment depression in the high lateral leads could be of prognostic significance in HCM patients.

Background: In patients with mild to moderate left ventricular dysfunction (LVD) (35% pound LVEF pound 50%) who present with syncope, demonstration of tachy and/or brady-arrhythmia has prognostic value. In this group of patients electrophysiological study (EPS) is often necessary., Methods: A total of 53 consecutive patients with mild to moderate LVD and history of undetermined syncope underwent EPS. Sinus node function, His-Purkinje system conduction and ventricular electrical stability were evaluated., Results: Twenty eight patients (52.8%) had induction of sustained monomorphic ventricular tachycardia (VT) and five (9.4%) patients had a sustained ventricular arrhythmia other than monomorphic VT (ventricular flutter, ventricular fibrillation, and polymorphic VT) induced during EPS. Abnormal sinus node function and/or His-Purkinje system conduction was found in five (9.4%) patients. Age, gender, history of myocardial infarction, type of underlying heart disease and history of revascularization were not predictors of VT induction. Wide QRS morphology independently, and lower left ventricular ejection fraction and presence of pathologic q wave in precordial leads dependently, could increase risk of VT induction., Conclusions: The EPS can determine which patient with syncope and mild to moderate LVD is likely to benefit from placing an ICD for prevention of sudden cardiac death. Pathologic precordial q wave, wide QRS morphology and lower left ventricular ejection fraction could be predictors of VT induction during EPS. Wide QRS morphology has an independent effect in this category.

Aims: The aim of this study was to assess the significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure (HF) patients considered eligible for cardiac resynchronization., Methods and Results: A total of 200 consecutive HF patients (158 males, mean age 56 +/- 13.5 years) with standard indications for cardiac resynchronization therapy (CRT) were evaluated prospectively. The prevalence of an interventricular mechanical delay > or = 40 ms was lower in patients with pure right bundle branch block (RBBB) than that in those with RBBB plus left fascicular hemiblock (RBBB-LFH) and those with left bundle branch block (LBBB) (33 vs. 50 vs. 54%, P = 0.05). A maximal difference in peak myocardial systolic velocity among all 12 segments (Ts) > 100 ms was found in 63% of the patients with LBBB, whereas it was present in 31% of the patients with pure RBBB and in 42% of those with RBBB-LFH (P < 0.001). A standard deviation of Ts (Ts-SD) > 34 ms was present in 58% of the LBBB subjects, but in only 29% and 42% of the patients with pure RBBB and RBBB-LFH, respectively (P < 0.001). Intraventricular dyssynchrony, however, was not different in patients with pure RBBB and in those with RBBB-LFH in terms of maximal difference in Ts (P = 0.25) and Ts-SD (P = 0.17)., Conclusions: Although LBBB was more often associated with intraventricular dyssynchrony, ECG sign of additional left ventricular (LV) conduction delay is not a helpful tool for the identification of intra-LV mechanical dyssynchrony in HF patients with RBBB who would benefit from CRT.

Background: Cardiac resynchronization therapy (CRT) has been accepted as an established therapy for advanced systolic heart failure. Electrical and mechanical dyssynchrony are usually evaluated to increase the percentage of CRT responders. We postulated that QRS notch can increase mechanical LV dyssynchrony independently of other known predictors such as left ventricular ejection fraction and QRS duration., Methods: A total of 87 consecutive patients with advanced systolic heart failure and QRS duration more than 120 ms with an LBBB-like pattern in V1 were prospectively evaluated. Twelve-lead electrocardiogram was used for detection of QRS notch. Complete echocardiographic examination including tissue Doppler imaging, pulse wave Doppler and M-mode echocardiography were done for all patients., Results: Eighty-seven patients, 65 male (75%) and 22 female (25%), with mean (SD) age of 56.7 (12.3) years were enrolled the study. Ischemic cardiomyopathy was the underlying heart disease in 58% of the subjects, and in the others it was idiopathic. Patients had a mean (SD) QRS duration of 155.13 (23.34) ms. QRS notch was seen in 49.4% of the patients in any of two precordial or limb leads. Interventricular mechanical delay was the only mechanical dyssynchrony index that was significantly longer in the group of patients with QRS notch. Multivariate analysis revealed that the observed association was actually caused by the effect of QRS duration, rather than the presence of notch per se., Conclusions: QRS notch was not an independent predictor of higher mechanical dyssynchrony indices in patients with wide QRS complex and symptomatic systolic heart failure; however, there was a borderline association between QRS notch and interventricular delay.

Background: Prediction of accessory pathway (AP) location before radiofrequency ablation has become increasingly important for patients with AP; this is especially true for posteroseptal (PS) APs., Objective: To identify electrocardiographic and electrophysiologic predictors of pathway location in patients with manifest posteroseptal AP., Methods: A detailed electrocardiographic analysis, electrophysiologic study, and ablation were performed in 94 patients with single manifest posteroseptal AP (mean age 35.0 +/- 13.8 years; 56 males)., Results: Localization was right PS in 68 patients, left PS in 19 patients, and coronary sinus and its branches in seven patients. Common to all the patients with posteroseptal AP was a negative delta in at least two inferior leads. The most sensitive and specific parameter for differentiating left posteroseptal APs from right posteroseptal APs was an R/S ratio >or=1.0 in lead V1 (sensitivity 100% and specificity 100%). The R-wave amplitude in lead I (sensitivity 54%, specificity 67%), and delta ventricularatrial interval (sensitivity 75%, specificity 87%) had much lesser sensitivity and specificity in this regard. The epicardial posteroseptal APs were discriminated from endocardial variant by the positive delta in aVR (sensitivity 71% and specificity 99%) and negative delta in II (sensitivity 100% and specificity 20%). Delta wave polarity in V1 was not helpful for differentiating right-sided from left-sided posteroseptal APs., Conclusions: This study demonstrated that in patients with posteroseptal AP, successful ablation site could be predicted to be on the right or left endocardial surface using R/S ratio in lead V1. Necessity for Coronary sinus catheterization and angiography is predictable using delta wave polarities in leads aVR and II.

Background: Approximately 30% of all accessory pathways (APs) are located in the septal area, and understanding the electrocardiographic and electrophysiologic of these APs is crucial for safe and effective ablation of these pathways., Objective: In this study, the electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and posteroseptal APs were investigated in detail to elucidate unique electrical properties of APs in each location., Methods: From April 2002 to October 2006, a total of 120 patients with a septal AP-mediated tachycardia were enrolled in the study. A detailed examination including electrocardiographic analysis and electrophysiologic study was performed in all patients., Results: A total of 120 patients, including 98 patients with posteroseptal APs, 14 patients with anteroseptal APs, and 8 patients with midseptal APs, were studied. The anteroseptal APs could be differentiated from the midseptal APs by the 2 or more positive delta waves in inferior leads, whereas there is significant overlap in electrocardiographic features of midseptal and posteroseptal APs. The mean tachycardia cycle length was significantly shorter in patients with midseptal AP compared with those with anteroseptal and posteroseptal APs (284 +/- 49 ms vs 342 +/- 46 ms vs 350 +/- 68 ms, P = .03). The AH interval during tachycardia was also shorter in patients with midseptal APs (149 +/- 16 ms vs 200 +/- 51 ms vs 168 +/- 48 ms, P = .04). The patients with posteroseptal AP had a significantly higher incidence of atrial fibrillation (35%) than those with either midseptal (12%) or anteroseptal (14%) APs (P = .04). The patients with posteroseptal APs also had a significantly shorter antegrade effective refractory period of the AP (276 +/- 54 ms) than those with either midseptal (313 +/- 71 ms) or anteroseptal (325 +/- 61) APs (P = .036)., Conclusion: Electrocardiographic analysis is a reliable method for differentiation of the anteroseptal from the midseptal APs, whereas the same is not true for the midseptal and posteroseptal APs. Midseptal APs were characterized by faster orthodromic tachycardia, whereas posteroseptal APs had a higher inducibility of atrial fibrillation.

Background: Head-up tilt test (HUTT) is a well-established diagnostic tool in patients with suspected vasovagal syncope. Identification of factors that predict a positive HUTT result could simplify diagnostic steps. The aim of this study was to assess the correlation between clinical characteristics of patients with suspected neurocardiogenic syncope or presyncope and results of HUTT., Materials and Methods: The study group consisted of 90 patients (55 men, 35 women; mean age, 43.2 +/- 17 years) with a history of syncope or presyncope. Cardiological and neurologic test findings were normal in every patient. The patients were tilted to a 70 degrees position for 45 minutes. If the first phase produced a negative response, the patients received 400 mug of sublingual nitroglycerin for the second phase and continued to be tilted for an additional 15 minutes., Results: Sixty-four patients had a positive HUTT result, characterized by a vasodepressive response in 26 patients, mixed response in 24 patients, and cardioinhibitory response in 14 patients. In logistic regression analysis, the presence of prodromal symptoms was a predictor of a positive HUTT result (P = .002)., Conclusion: We showed that the prognostic performance of clinical features, including the time interval between the last episode and HUTT, the number of syncope or presyncope episodes, age, and sex, was not ideal. The presence of prodromal symptoms might be more likely to predict a positive response during HUTT.

Background: As in the general population, atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardia in the elderly patients. We tried to compare electrophysiologic characteristics, efficacy, and risks of the radiofrequency (RF) catheter ablation of the slow pathway in elderly and young patients with AVNRT., Methods: Between April 2001 and March 2005, 268 consecutive patients (190 females; mean age, 49 +/- 14 years) with AVNRT underwent RF catheter ablation at our institution. The patients were categorized into 2 groups: group 1 consists of patients younger than 65 years (n = 156), and group 2 consists of patients 65 years or older (n = 112)., Results: Compared with the younger subgroup, elderly patients more often had structural heart disease (11.6% vs 2.5%, P = .004), but there were no statistically significant differences in sex and symptoms during tachycardia (all P > .05). AVNRT cycle length was significantly longer in group 2 than in group 1 patients (P = .005). Among the conduction intervals of tachycardia, only atrio-his interval was significantly longer in group 2 patients (P = .007). The ablation fluoroscopy time, RF pulse duration, target temperature, applied energy, and number of RF applications were comparable in the 2 groups (All P > .05). Risk of atrioventricular block, pericardial effusion, and vascular thrombosis were similar in both groups (All P > .05). During follow-up with duration of 14 months, similar rate of recurrence was observed in the 2 groups (P = .94)., Conclusions: In elderly patients, slow pathway ablation is as effective and safe as in younger patients. Therefore, when considering different treatment options in elderly patients, an increased risk of complications or lower efficacy should not be a factor in determining the best therapeutic approach.

Accessory pathways with anterograde decremental conduction properties usually are characterized by presence of antegrade preexcitation during atrial pacing. We report a 38-year-old man with frequent episodes of palpitation. No evidence of ventricular preexcitation was seen during sinus rhythm or atrial pacing. All electrophysiologic maneuvers were compatible with an antidromic tachycardia using atriofascicular pathway as the antegrade limb and the atrioventricular nodal pathway as retrograde limb. Radiofrequency ablation at recording site of accessory pathway potential resulted in cure of tachycardia with no recurrence during 3-month follow-up. This report indicated that atriofascicular pathway-mediated tachycardia should be considered in differential diagnosis of all cases of wide complex tachycardia with left bundle branch morphology and left axis.

Objective: We conducted this study to compare the rate of >/=1 inappropriate therapy between ICDs from two manufacturers which use different discriminatory protocols., Method: One hundred sixty two patients (mean age 58 +/- 13 years, 126 male) who received ICDs between January 2001 and 2005 were included in the study. Clinical, electrocardiographic, and ICD stored data and electrograms were collected and analyzed. Immediately after implantation all the detection and discrimination criteria were activated with the nominal values in order to compare the two discriminatory protocols under the default manufacturer's settings., Results: During the follow up period of 14.3 +/- 10 months, 49 (30%) patients received >/=1 inappropriate ICD therapy. The rate of >/=1 inappropriate ICD therapy in manufacturer A and B ICDs was 26% (n = 29) and 41% (n = 20), respectively. Comparing the rate of >/=1 inappropriate ICD therapy between the two groups by Kaplan-Meier analysis and the log rank test resulted in P = 0.04., Conclusion: Having all discriminatory variables activated with the nominal values, discriminatory performance differs between the two manufacturers. Further larger-scale studies are warranted to prospectively compare the performance of various available ICDs' discriminatory protocols, and define the optimum combination of discriminators in each ICD to decrease the rate of inappropriate therapy.

Microvolt T-wave alternans (TWA) testing involves measuring variation in the morphology of the T-wave on an every other beat basis. The magnitude of the variation observed is typically on the order of a few microvolts. Thus in order to detect microvolt TWA, specialized recording and signal processing methods must be employed for reliable measurement. Additionally, microvolt TWA is not generally present at rest even in patients at risk of ventricular tachyarrhythmias and therefore exercise stress, pharmacologic stress, or atrial pacing must be utilized in order to elevate the heart rate. A positive MTWA test is one in which sustained TWA is present with an onset heart rate < or = 110 bpm. With current instrumentation, microvolt TWA represents an inexpensive, convenient non-invasive testing modality. Microvolt TWA has been evaluated prospectively in a variety of patient populations as a means of predicting occurrence of ventricular tachyarrhythmic events and its association with the genesis of ventricular arrhythmias has been demonstrated. Future role of microvolt TWA testing in noninvasive risk stratification is awaiting results of ongoing clinical trials. In this article, we tried to review the techniques, interpretation, indications, clinical studies, and future perspectives of microvolt TWA.

Background: Several studies have documented the prognostic significance of the signal-averaged electrocardiogram (SAECG) both after myocardial infarction and nonischemic cardiomyopathy. However, whether the SAECG can identify patients with implantable cardioverter-defibrillator (ICD) who receive appropriate therapy has not been hitherto completely investigated., Methods: Between August 2002 and August 2004, 83 consecutive ICD patients who had had SAECGs recorded were enrolled in this study. All patients were followed up in the outpatient ICD clinic, and interrogated electrograms were collected., Results: Over 9.0 +/- 2.8 months of follow-up, 27 (32%) patients had appropriate ICD therapy for ventricular tachycardia or fibrillation; 15 (55.6%) patients had abnormal; and the remaining 12 (44.4%) had normal SAECGs. Of the 56 patients with no appropriate therapy, 27 (48.2%) and 29 (51.8%) patients had abnormal and normal SAECGs, respectively. There were no statistically significant differences between the 2 groups in SAECG findings (P = .41). A Cox regression analysis showed that the left ventricular ejection fraction was the only predictor of appropriate therapy (P = .02). Subgroup analysis of the patients with coronary artery disease and spontaneous monomorphic ventricular tachycardia indicated that left ventricular ejection fraction (P = .03) and abnormal SAECG (P = .02) were predictors of appropriate therapy., Conclusions: Our data demonstrate that except for the subgroup of patients with coronary artery disease presenting with monomorphic ventricular tachycardia, the SAECG did not predict ventricular tachyarrhythmia recurrence and, hence, appropriate ICD therapy. Thus, SAECG findings should generally not be a factor in decision for ICD implantation.

A 23-year-old man presented with sick sinus syndrome and Brugada-like ECG pattern. Coved type ECG (type 1) converted to saddleback configuration (type 2) when R-R interval decreased and it changed to coved type pattern with increasing R-R cycle length. During stable heart rate, there was no change in Brugada ECG pattern. The R-R interval effect on these patterns can be explained by intensity or kinetics of ion currents and autonomic tone.

Outflow tract ventricular tachycardia (OT-VT) can originate from several different segments of the outflow tract. Various ECG criteria have been proposed for localization of OT-VTs. We present two patients, one with left and one with right OT-VT. We used local ventricular electrograms in the coronary sinus to localize the focus of the OT-VT. Mapping of local ventricular electrograms in the coronary sinus may be a simple and effective method for differentiating right versus left ventricular outflow tract tachycardias. However, the diagnostic value and precision of this method should be evaluated in a series of patients before its implementation in the OT-VT ablation decision algorithm.

Background: Brugada syndrome (BrS) is characterized by ST‐segment elevation in the right precordial leads, which is not explained by ischemia, electrolyte disturbances, or obvious structural heart disease. Aim: In present study, we aim to evaluate presentation, long‐term outcome, genetic findings, and therapeutic interventions in patients with BrS. Methods: Between September 2001 and June 2022, all consecutive patients with diagnosis of BrS were enrolled in the present study. All patients gave written informed consent for the procedure, and the local ethical committee approved the study. Results: Of the 76 cases, 79% were proband and 21% were detected during screening after diagnosis of BrS in a family member. Thirty‐three (43%) patients had a typical spontaneous electrocardiogram (ECG) pattern. Thirty percent of the patients were symptomatic; symptomatic patients were more likely to have spontaneous type 1 Brugada ECG pattern in their ECGs (p =.01), longer PR interval (p =.03), and SCN5A mutation (p =.01) than asymptomatic patients. The mean PR interval was considerably longer in men than women (p =.034). SCN5A mutation was found in 9 out of 50 (18%) studied patients. Fifteen percent received appropriate implantable cardioverter‐defibrillator (ICD) therapy and inappropriate ICD interventions were observed in 17%. Presentation with aborted SCD or arrhythmic syncope was the only predictor of adverse outcome in follow‐up (odds ratio: 3.1, 95% confidence interval: 0.7–19.6, p =.001). Conclusions: Symptomatic patients with BrS are more likely to present with spontaneous type 1 Brugada ECG pattern, longer PR interval, and pathogenic mutation in SCN5A gene. Appropriate ICD interventions are more likely in symptomatic patients and those with SCN5A mutation. [ABSTRACT FROM AUTHOR]

Background: Electrocardiography (ECG), as an easily accessible modality, is usually helpful in hypertrophic cardiomyopathy (HCM) diagnosis. The purpose of this study was to evaluate the role of ECG in differentiating between obstructive (OHCM) and non-obstructive (NOHCM) HCM. Methods: The present study is a cross-sectional analysis of HCM patients referred to our center between 2008 and 2017. The study variables included age, sex, clinical presentation, medications, and ECG characteristics including PR interval, QRS width, QTc duration, Tpeak-Tend interval, QRS axis, QRS transition, ventricular hypertrophies, atrial abnormalities, ST-T abnormalities, and abnormal Q waves. Results: The HCM sample consisted of 200 patients (55% males; age 45.60±15.50 y) from our HCM database. We compared the clinical and ECG characteristics of 143 NOHCM patients with those of 57 OHCM patients. The OHCM group was significantly younger than the NOHCM group (age =41.7 vs 47.0 y; P=0.016). The initial clinical presentation was similar between the 2 forms (P>0.05), and palpitations were the dominant symptom. Baseline ECG intervals, including PR (155.6 vs 157.9 ms), QRS (82.5 vs 82.0 ms), and QTc (430.5 vs 433.0 ms), were similar (all Ps>0.050). There were no differences regarding baseline rhythm, atrial abnormalities, QRS transition, ventricular hypertrophies, axis changes, ST-T changes, and abnormal Q waves between the HCM groups (all Ps>0.05). Conclusion: The present study showed that standard 12-lead ECG had no role in distinguishing patients with the obstructive and non-obstructive forms of HCM. [ABSTRACT FROM AUTHOR]

The catheter ablation of idiopathic ventricular arrhythmias is accepted as a first-line treatment as it successfully eliminates about 90.0% of such arrhythmias. One of the most challenging ventricular arrhythmias originates from the left ventricular summit (LVS), a triangular epicardial space with the left main bifurcation as its apex. This area accounts for about 14.0% of LV arrhythmias. The complex anatomy of this region, accompanied by proximity to the major epicardial coronary arteries and the presence of a thick fat pad in this region, renders it a challenging area for catheter ablation. This article presents a review of the anatomy of the LVS and relevant regions and discusses novel mapping and ablation techniques for eliminating LVS ventricular arrhythmias. Additionally, we elaborate on the electrocardiographic (ECG) manifestations of arrhythmias from the LVS and their successful ablation via the direct approach and the adjacent structures. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most commonly treated arrhythmia in clinical practice and is often found in association with an atrial septal defect (ASD). However, ASD closure rarely confers complete arrhythmia control. A 23-year-old man presented to our center with frequent episodes ofpalpitations. AF was documented in 12-lead electrocardiography, and echocardiography showed a secundum-type ASD, 14 mm in size, with a significant left-to-right shunt. ASD closure was performed successfully with an ASD occluder device with no residual shunting. During follow-up, the patient experienced several episodes of AF. Thirteen months after the ASD closure, cryoballoon pulmonary vein isolation was done successfully with no complications. During a 12-month follow-up, he had no symptoms or AF recurrences, and echocardiography showed no residual shunting. This study showed that cryoballoon pulmonary vein isolation could be performed successfully without residual shunts in patients with ASD closure devices. [ABSTRACT FROM AUTHOR]

Introduction: Myocardial perfusion imaging using gated SPECT and phase analysis is an effective tool in evaluation of mechanical dyssynchrony. The purpose of this study was to determine the normal ranges of global and regional phase parameters. Methods: A total of 100 patients with normal resting and stress electrocardiograms, low pretest likelihood for coronary artery disease and a normal gated MPI study were recruited in the study. All of the patients underwent a standard 2-day stress/rest gated MPI study according to standard protocols. The reconstructed images were further analyzed by Cedar-Sinai's quantitative gated SPECT. Left ventricular phase indices were provided both globally and regionally for both genders and the normal interquartile range of these parameters were defined. Results: Normal ranges of global and wall-based regional phase parameters are presented both in unisex and in gender-specific formats. Both global (P<0.001) and major LV regional phase parameters (P<0.05) are found to be significantly different between the two genders with a significant positive association between end-diastolic volume with phase global indices (P<0.01). There is also more synchronized phase distribution in phase analysis results of post-exercise gated MPI as compared to the phase analysis of the same patients at resting state. Conclusion: Normal ranges of phase indices are defined in this article by using Cedar-Sinai's QGS software. As normal ranges of phase dyssynchrony parameters are gender-specific and are related to LV volume, stress or resting state and stress type, the need for careful incorporation of these data is indicated in interpretation of phase studies. [ABSTRACT FROM AUTHOR]

Introduction: Congenital long QT syndrome (LQTS) is a cardiac disorder characterized by QT interval prolongation at basal ECG. Different LQTS genes encode ion channel subunits or proteins involved in regulating cardiac ionic currents. Long QT syndrome type 6 (LQT6) is caused by mutation in the KCNE2 gene. Our research aimed to analyze genetic variants of KCNE2 gene causing the disease in Iranian population. Methods: Twenty nine patients consented for participation in the study. They were diagnosed based on Schwartz's criteria. After DNA extraction from peripheral blood cells, two exons of the KCNE2 gene were amplified. Afterwards, PCR-SSCP was carried out for screening the possible mutated gene variants. As the last verification step, direct sequencing was done to determine the sequence. Results: All samples were detected by PCR-SSCP and sequenced. None of the patients had the mutation in the KCNE2 gene. Conclusion: Investigating a genetic variant associated with LQTS, in Iranian patients clinically diagnosed with LQT6, no association was found between the disease and KCNE2 gene. Other previously identified genes, especially the major genes, should be considered for further investigation. [ABSTRACT FROM AUTHOR]

Background: Noninvasive techniques for the localization of the accessory pathways (APs) might help guide mapping procedures and ablation techniques. We sought to examine the diagnostic accuracy of strain imaging for the localization of the APs in Wolff-Parkinson-White syndrome. Methods: We prospectively studied 25 patients (mean age = 32 ± 17 years, 58.3% men) with evidence of pre-excitation on electrocardiography (ECG). Electromechanical interval was defined as the time difference between the onset of delta wave and the onset of regional myocardial contraction. Time differences between the onset of delta wave (δ) and the onset of regional myocardial contraction (δ-So), peak systolic motion (δ-Sm), regional strain (δ-ε), peak strain (δ-εp), and peak strain rate (δ-SRp) were measured. Results: There was a significant difference between time to onset of delta wave to onset of peak systolic motion (mean ± SD) in the AP location (A) and normal segments (B) versus that in the normal volunteers (C) [A: (57.08 ± 23.88 msec) vs. B: (75.20 ± 14.75) vs. C: (72.9 0 ± 11.16); p value (A vs. B) = 0.004 and p value (A vs. C) = 0.18] and [A: (49.17 ± 35.79) vs. B: (67.60 ± 14.51) vs. C: (67.40 ± 6.06 msec); p value ( A vs. B) < 0.001 and p value (A vs. C) = 0.12, respectively]. Conclusion: Our study showed that strain imaging parameters [(δ-So) and (δ-Strain)] are superior to the ECG in the localization of the APs (84% vs. 76%). [ABSTRACT FROM AUTHOR]

A 37-year-old man, known case of mitral valve replacement, was referred for ablation. Meticulous mapping showed the earliest signal in the distal coronary sinus (CS). Endocardial ablation via transseptal approach failed to permanently ablate the accessory pathway. Similarly, ablation within the CS was unsuccessful. Finally, the mapping catheter was introduced into the vein of Marshall (VoM) and a very early signal was obtained. In the first 3 seconds of the radiofrequency energy application within the VoM, delta wave disappeared. During 1-year follow-up, the patient had no recurrence of the palpitations and electrocardiogram showed no delta wave. (PACE 2013; 36:e132-e135) [ABSTRACT FROM AUTHOR]

Aims Despite the several electrocardiographic (ECG) criteria, misclassification may still occur in differential diagnosis of the regular paroxysmal supraventricular tachycardia (PSVT). The aim of the present study was to evaluate the diagnostic accuracy of the aVR lead in ECG differentiation of atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT). Methods and results A 12-lead ECG was recorded in 150 consecutive patients (96 women, mean age, 45 ± 13.5 years) with drug-refractory regular PSVT during both sinus rhythm and tachycardia. All ECGs were reviewed by two experienced electrophysiologists who had no knowledge of the tachycardia mechanism. The ECG recordings were evaluated for standard criteria as well as our newly proposed criterion of pseudo-r′ in the lead aVR. Mechanism of arrhythmia was confirmed by the electrophysiological study and the successful catheter ablation. Patients with AVNRT were older (50 ± 10 vs. 37 ± 15 years, P = 0.001), predominantly female (71 vs. 53%, P = 0.03), and presented with slower tachycardia (175 ± 25 vs. 186 ± 26 b.p.m., P = 0.01). Among the ECG criteria of the AVRT diagnosis, visible P-wave with RP interval ≥100 ms had highest diagnostic accuracy (sensitivity 79%, specificity 87%, and positive predictive value 79%). For AVNRT diagnosis, pseudo-r′ in aVR had a higher sensitivity, specificity, and predictive values compared with the conventional criteria of the pseudo-r′ in V1 and pseudo-s in inferior leads (all P < 0.05). Conclusions New criterion of pseudo-r′ in lead aVR appears to be more accurate than the standard ECG criteria for ECG diagnosis of AVNRT. [ABSTRACT FROM PUBLISHER]

Background: The signal-averaged electrocardiography is a noninvasive method to evaluate the presence of the potentials generated by tissues activated later than their usual timing in the cardiac cycle. The purpose of this study was to demonstrate the correlation between the filtered QRS duration obtained via the signal-averaged electrocardiography and left ventricular dimensions and volumes and then to compare it with the standard electrocardiography. Methods: We included patients with advanced systolic left ventricular dysfunction (ejection fraction ≤ 35%). All the patients underwent surface twelve-lead electrocardiography, signal-averaged electrocardiography, and echocardiography. Results: The study included 86 patients with a mean age of 54.66 ± 13.23 years. The mean left ventricular ejection fraction was 18.31 ± 5.49%; the mean QRS duration was 0.14 ± 0.02 sec; and 52% of the patients had left bundle branch block. The mean filtered QRS duration was 145.87 ± 24.89 ms. Our data showed a significant linear relation between the filtered QRS duration and left ventricular end-systolic volume, left ventricular end-diastolic volume, left ventricular end-systolic diameter, and left ventricular end-diastolic diameter; the correlation coefficient was, however, not good. There was no significant correlation between the QRS duration and left ventricular diameters and volumes. Conclusion: The filtered QRS duration has a better correlation with left ventricular dimensions and volumes than does the QRS duration in the standard electrocardiography. [ABSTRACT FROM AUTHOR]

Aims: To predict response to cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and intraventricular conduction delay. [ABSTRACT FROM PUBLISHER]

Aims: From the spectrum of electrocardiogram (ECG) changes that may occur in hypertrophic cardiomyopathy (HCM), there is no criterion reported to be useful for risk stratification. We sought to determine whether there was a relationship between the resting ECG findings and prognosis in patients with HCM. [ABSTRACT FROM PUBLISHER]

Aims: The aim of this study was to assess the significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure (HF) patients considered eligible for cardiac resynchronization. [ABSTRACT FROM PUBLISHER]

Background: Cardiac resynchronization therapy (CRT) has emerged as an established therapy for congestive heart failure. However, up to 30% of patients fail to respond to CRT despite prolonged QRS. Objectives: This study aimed at defining the prevalence of interventricular and intraventricular dyssynchrony in heart failure patients with different QRS durations. Methods: A total of 123 consecutive patients with severe heart failure (LVEF < 35% and NYHA class III–IV) were prospectively evaluated using 12-lead electrocardiogram and complete echocardiographic examination including tissue Doppler imaging. Results: According to the QRS duration, 56 patients had a QRS duration ≤120 ms (Group 1), 33 patients had a QRS duration between 120 and 150 ms (Group 2), and 34 patients had a QRS duration ≥150 ms (Group 3). Intraventricular dyssynchrony was present in 36% of Group 1 patients, in 58% of Group 2 patients, and in 79% of Group 3 patients (P < 0.000). Linear regression demonstrated a weak relation between QRS and intraventricular dyssynchrony. A greater proportion of patients with interventricular dyssynchrony was observed in Group 3 or Group 2 compared to patients with normal QRS duration (32% in Group 1 vs. 51.5% in Group 2 vs. 76.5% in Group 3, P < 0.000). Linear regression demonstrated a significant relation between QRS duration and interventricular mechanical delay. Conclusions: Although both interventricular and intraventricular dyssynchrony increased with the increasing QRS duration, the correlation between intraventricular mechanical and electrical dyssynchrony was weak. The lack of intraventricular dyssynchrony in a fraction of patients with standard CRT indication by QRS duration may provide us insight into the nonresponders rates. [ABSTRACT FROM AUTHOR]

A 45-year-old woman underwent radiofrequency ablation (RFA) for symptomatic idiopathic left ventricular tachycardia (ILVT). The clinical arrhythmias had two different patterns, a wide QRS tachycardia with right bundle branch block (RBBB) and left axis deviation (LAD) and another with RBBB and right axis deviation (RAD). The electrophysiology study localized the origin of tachycardias to the midinferior and superior ventricular septum, respectively. RFA terminated successfully ILVT with RBBB and LAD morphology, but another pattern could not be ablated. Noncontact mapping revealed the earliest site of activation at the superior septum. RFA at this site terminated successfully ILVT with RBBB and RAD. [ABSTRACT FROM AUTHOR]

A response by Majid Haghjoo to a letter to the editor about his article on "Electrocardiographic and Electrophysiologic Predictors of Successful Ablation Site in Patients with Manifest Posteroseptal Accessory Pathway" in the January 2008 issue is presented.

This article focuses on the suppression of electrical storm by oral quinidine in a patient with Brugada syndrome. A 41-year-old man was presented with two episodes of resuscitated cardiac arrest over 3 months. Rhythm recorded during resuscitation was ventricular fibrillation. Resting ECG was not typical for Brugada syndrome, thus pharmacologic provocation was performed. Procainamide infusion unmasked coved type ST-segment elevation in right precordial leads confirming the diagnosis of Brugada syndrome. Because of aborted cardiac death and typical Brugada changes in provoked ECG, a single chamber ICD was implanted. Following quinidine administration, ECG abnormalities normalized, unifocal PVCs were suppressed and nocturnal palpitations relieved.

Background: This study attempted to identify the role of combined conventional and novel echocardiographic techniques in evaluation of left atrial (LA) function to predict the postoperative atrial fibrillation (POAF). Methods: In this cross-sectional study, subjects with sinus rhythm who were candidates for CABG were enrolled. Preoperative LA function was evaluated by conventional echocardiography and 2-dimensional strain imaging based-velocity vector imaging (VVI). VVI-derived systolic peak positive, early and late diastolic strain rate were measured. Using tissue Doppler study, systolic peak velocities (Sm), early diastole (Em), atrial systole (Am) and AEMi were also measured. The patients were observed during their hospital stay. The primary endpoint of the study was postoperative AF lasting > 5minutes. Results: POAF occurred in 12.7% of patients. Age, LA volume index (LAVI), LA area, LA empting fraction (LAeF) and cardiopulmonary bypass time were found to be the independent predictors of POAF. TDI-derived velocities were similar in study groups. LA systolic strain rate (SRs) and early diastolic strain rate were impaired in patients with no significant difference between those who developed POAF and those who did not. Conclusions: Conventional echocardiography could be used as a feasible method for evaluating subclinical atrial dysfunction in patients undergoing CABG and the use of VVI- based 2-dimensional strain imaging may need further studies. [ABSTRACT FROM AUTHOR]