Brugada syndrome in Iran: Insights from a 12-year longitudinal study.

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.

Role of Surface Electrocardiography in Differentiation between Obstructive and Non-Obstructive Hypertrophic Cardiomyopathy.

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.

Clinical outcomes of subcutaneous implantable cardiac defibrillator implantation - Iran SICD registry.

BACKGROUND: The subcutaneous implantable-defibrillator (S-ICD) is a relatively new alternative to the transvenous ICD system to minimize intravascular lead-related complications. This paper presents outcome of SICD implantation in patients enrolled in Iran S-ICD registry. METHODS: Between October 2015 and June 2022, this prospective multicenter national registry included 223 patients with a standard indication for an ICD, who neither required bradycardia pacing nor needed cardiac resynchronization to evaluate the early post-implant complications and long-term follow-up results of the S-ICD system. RESULTS: The mean age of the patients was 45 ± 17 years. The majority (79.4%) were male. Ischemic cardiomyopathy (39.5%) was the most common underlying disorder among patients selected for S-ICD implant. Most study patients (68.6%) had ICD for primary prevention of sudden cardiac death. Seven patients (3.1%) were found to have suboptimal lead positions. Six patients (2.7%) developed a pocket hematoma; all were managed medically. During a mean follow-up of 2 years, the appropriate therapy was recorded in 13% of the patients and inappropriate ICD intervention mainly due to supraventricular tachycardia in 8.9%. Pocket infection was observed in four patients (1.8%) and five patients (2.2%) died mainly due to heart failure. CONCLUSION: S-ICDs were effective at detecting and treating both induced and spontaneous ventricular arrhythmias. Major clinical complications were rare.

A Comprehensive Review of Left Ventricular Summit Ventricular Arrhythmias.

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.

A prospective survey of atrial fibrillation management in Iran: Baseline results of the Iranian Registry of Atrial Fibrillation (IRAF).

BACKGROUND: Atrial fibrillation. (AF) is the most common sustained arrhythmia globally and its prevalence is likely to increase in the next decades as a result of increasing age and co-morbidities. There are no data on demographic features, clinical characteristics, associated comorbidities, and practice patterns of AF in Iran. METHODS: The Iranian Registry of Atrial Fibrillation (IRAF) is a hospital-based prospective survey of AF patients with a 12-month follow-up. Data were collected on a standardized case report form and entered into a web-based electronic database. This paper reports the baseline characteristics of the IRAF cohort. RESULTS: Between February 2018 and March 2020, a total of 1300 patients (57% Male, mean age, 60 ± 14 years) were enrolled. Palpitations were the most common presenting symptom (66%). The most common cardiac comorbidities were hypertension (52%), heart failure (23.7%), and valvular heart disease (21.8%). AF mainly presented as a paroxysmal pattern (44.6%). Seventy-eight percent of the patients with non-valvular AF had CHA2 DS2 -VASc score ≥1 and most (97%) were at low risk for bleeding (HAS-BLED score <3). Rhythm control was given to 55.1% of the patients. Anticoagulation for stroke prevention was provided to 69.5% of the eligible patients, while aspirin was used in 35%. CONCLUSION: The IRAF Registry has provided a systematic collection of contemporary data regarding the management and treatment of AF in Iran. Oral anticoagulant was used in 69.5%, but aspirin use was still common.

Clinical profile and outcome of familial versus non-familial atrial fibrillation.

BACKGROUND: There is paucity of information on clinical characteristics and outcome of patients with familial atrial fibrillation (AF). The present study was aimed to compare clinical profile and outcome of familial AF with those of non-familial AF. METHODS: Between February 2017 and February 2018, we enrolled 738 participants (60% men, median age, 51 years in familial AF vs. 61 years in non-familial AF) from Iranian Registry of AF. All patients were followed for 12 months. Clinical characteristics and main outcome measures for AF patients were obtained from patient's medical records. RESULTS: A positive history of AF in first-degree relative was reported in 15.3% of our AF population. Familial AF group were significantly younger than non-familial group (p = 0.001). Concomitant sinus node dysfunction and cardiomyopathies were more common in familial AF group (p = 0.02, p = 0.004, respectively). Patients with familial AF were also likely to receive cardiac devices and AF catheter ablation (all p < 0.05). However, all-cause mortality and thromboembolic events were similar (all p > 0.05). CONCLUSIONS: Familial AF patients were more likely to have associated rhythm disorders and dilated cardiomyopathies. Cardiac interventions were also more common in familial patients. However, they did not differ significantly in their long-term outcome.

Postoperative antibiotic prophylaxis in the prevention of cardiac implantable electronic device infection.

BACKGROUND: The aim of the present study was to determine whether postprocedural antibiotic reduces the risk of infection related to the cardiac implantable electronic device (CIED) implantations. METHODS: The present investigation is a randomized, prospective, single-blinded controlled trial. All consecutive patients who presented for new CIED implantation, generator replacement, or upgrade were randomized into the following three groups: (A) no antibiotic, (B) intravenous (IV) antibiotic for 1 day, (C) 1 day IV plus 7 days oral antibiotic. Follow-up was performed on 10-12 days; 1, 3, 6 months; and then every 6 months for 2 years. The primary endpoint was any evidence of infection at the generator pocket or systemic infection related to the procedure at short-term (6-month) and long-term (2-year) follow-ups. RESULTS: Of the 450 patients (72 patients with cardiac resynchronization device) included in the study, the primary endpoint of short-term infection was reached in one patient (0.2%) in group A and no patients in groups B and C. The endpoint of long-term infection was reached in nine patients (2%) with equal frequency between three randomized groups (three patients in each group). On multivariable analysis, the only independent predictor of infection was defibrillator implantation (odds ratio, 8.5; 95% confidence interval, 1.6-45). CONCLUSIONS: The results of this prospective study showed no benefit for the postoperative antibiotic for the prevention of CIED infection.

New Insights into Predictors of Cardiac Implantable Electronic Device Infection.

Infection is an important complication of cardiac implantable electronic device procedures. To further study the factors associated with infection, we retrospectively reviewed the records of 3,205 consecutive patients who had undergone de novo or revision cardiac electronic device implantation at our institution from March 2011 through March 2015. We recorded all infections and specified whether they were related to the characteristics of the patient, device, or procedure. To identify predictors of infection, we performed multivariate analysis. Device infections were identified in 85 patients (2.7%), at a mean follow-up time of 27 ± 11 months. The main predictors of device infection were use of an implantable cardioverter-defibrillator or a cardiac resynchronization therapy defibrillator device (odds ratio [OR]=16; 95% CI, 4.14-61.85; P=0.0001), stage 3 chronic kidney disease (OR=9.41; 95% CI, 1.77-50.04; P=0.009), a revision procedure (OR=8.8; 95% CI, 3.37-23.2; P=0.0001), or postoperative hematoma (OR=6.9; 95% CI, 1.58-30.2; P=0.01). We also identified 2 novel predictors of infection: a low body mass index of <20 kg/m2 (OR=1.03; 95% CI, 1.01-1.06; P=0.005), and use of povidone-iodine rather than chlorhexidine-alcohol for topical antisepsis (OR=4.4; 95% CI, 2.01-9.4; P=0.03). We conclude that comorbidities, device characteristics, procedure types, and postoperative noninfective complications all increase the risk of device infection after a cardiac implantable electronic device procedure.

Cryoballoon ablation results and complications in mid-term follow-up of patients with atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia, and its prevalence increases with advancing age. Pulmonary vein isolation is a standard approach in drug refractory paroxysmal AF which could be performed by cryoballoon ablation (CBA). We tried to evaluate its efficacy and safety in Iranian patients with AF. METHODS: From 2015 to 2017, 97 patients with paroxysmal and persistent AF were enrolled in our observational historical cohort study. They were visited 1 and 6 months post-procedure in order to assess the efficacy (recurrence) and safety. Recurrence was defined as 30 seconds of arrhythmia on their 48-hours Holter monitoring. RESULTS: Ninety-seven patients enrolled in the study, 64 (66.0%) of them were men, and their mean age was 55 ± 12 years. Hypertension was reported in 41 patients (42.3%), as the most common cardiac risk factor. 71 patients (73.2%) patients with paroxysmal AF and 15 patients (15.5%) with persistent AF underwent the procedure. After 6 months, recurrence was documented in only 17 patients (17.5%), and 82.5% of the patients were free from the recurrence. Post-procedural complication was detected only in 3 patients (3.1%). CONCLUSION: In our study, the mid-term success and safety of CBA in patients with paroxysmal AF was showed. CBA is a safe and effective method in paroxysmal AF, and even in some cases with persistent AF.

Electrocardiographic patterns in biventricular pacing delivered by second-generation cardiac resynchronization devices.

BACKGROUND: With increasing use of cardiac resynchronization therapy (CRT), treating physicians should be familiar with different electrocardiographic (ECG) patterns of left ventricular (LV) lead and biventricular (BiV) pacing. However, there are a few publications on ECG patterns during BiV pacing. PURPOSE: This study was sought to determine different ECG patterns in patients with BiV pacing. METHODS: Twelve-lead ECGs during BiV pacing (right ventricular leads at apex and LV leads in one of the lateral coronary veins) were analyzed in 181 consecutive patients (121 male; mean age, 62.0 ± 13.5 years) with advanced heart failure and baseline left bundle branch block pattern after at least 6-month of uncomplicated CRT. RESULTS: During BiV pacing, 65% of the patients showed a dominant R wave in V1. There was a right axis deviation in 57% in frontal plane. However, a left superior axis emerged in 34% and normal frontal plane axis in 9%. Sequential BiV pacing (73% vs. 58%, P = 0.04) and pacing from posterolateral coronary vein (80% vs. 60%, p = 0.045) were more likely to present with a dominant R wave in V1. In sequential pacing, AV interval was significantly longer in patients with negative complex in V1 than in those with positive complex (124 ± 21 vs. 116 ± 8.0, p = 0.005). A Q/q wave was detected in 85% of patients in lead I and 78% in lead aVL. CONCLUSIONS: BiV pacing from lateral coronary venous branches and right ventricular apex characteristically presented with dominant R wave in V1, Q/q wave in leads I and aVL, and right or left superior axis. However, a negative complex in V1, QRS axis in other quadrants, and lack of Q/q wave in leads I and aVL did not necessarily indicate a problem.

Assessment of QT and JT Intervals in Patients With Left Bundle Branch Block.

BACKGROUND: Prolongation of the QT interval is considered a risk factor for cardiac adverse events and mortality. Left bundle branch block (LBBB) lengthens the QT interval. The corrected QT interval (QTc) is most likely overestimated because its prolongation is caused by increases in depolarization duration and not in repolarization. OBJECTIVES: In this study, we aimed to apply corrected JT interval (JTc) as an appropriate measure of ventricular repolarization for predicting QTc in a formula. PATIENTS AND METHODS: The study population consisted of 101 patients with sinus rhythm (SR) and narrow QRS complexes (< 120 milliseconds). All patients underwent electrophysiology studies or ablation. A diagnostic catheter was positioned in the right ventricular apex (RVA) to induce LBBB at two different cycle lengths (CLs; 600 and 700 mv). The intrinsic QRS complex, QT time, and JT time were measured during SR and subsequent RVA pacing. The JTc was derived simply by subtracting the QRS duration from the QTc. RESULTS: Stimulation from the RVA increased the QTc from 456.20 ± 38.63 ms to 530.67 ± 47.73 ms at a CL of 600 (P < 0.0001) and to 502.32 ± 47.26 ms at 700 CL (P < 0.0001). JTc showed no significant changes with stimulation from the RVA (102.97 ± 11.35 ms vs. 103.59 ± 10.67 ms, P = 0.24). There was no significant correlation between JTc and QRS complex duration. A significant correlation was seen between QRS and QTc at both CLs. The ROC curve indicated that sensitivity of 80% and specificity of 67% were obtained with JTc duration of 92.6 ms. CONCLUSIONS: Right ventricular pacing increases the QT interval without increasing the JT interval. Our results confirm that JTc, as an index of repolarization, is independent of ventricular depolarization. Therefore, it can be applied for predicting QTc in patients with LBBB.

Complex genetic background in a large family with Brugada syndrome.

The Brugada syndrome (BrS) is an inherited arrhythmia characterized by ST-segment elevation in V1-V3 leads and negative T wave on standard ECG. BrS patients are at risk of sudden cardiac death (SCD) due to ventricular tachyarrhythmia. At least 17 genes have been proposed to be linked to BrS, although recent findings suggested a polygenic background. Mutations in SCN5A, the gene coding for the cardiac sodium channel Nav1.5, have been found in 15-30% of index cases. Here, we present the results of clinical, genetic, and expression studies of a large Iranian family with BrS carrying a novel genetic variant (p.P1506S) in SCN5A. By performing whole-cell patch-clamp experiments using HEK293 cells expressing wild-type (WT) or p.P1506S Nav1.5 channels, hyperpolarizing shift of the availability curve, depolarizing shift of the activation curve, and hastening of the fast inactivation process were observed. These mutant-induced alterations lead to a loss of function of Nav1.5 and thus suggest that the p.P1506S variant is pathogenic. In addition, cascade familial screening found a family member with BrS who did not carry the p.P1506S mutation. Additional next generation sequencing analyses revealed the p.R25W mutation in KCNH2 gene in SCN5A-negative BrS patients. These findings illustrate the complex genetic background of BrS found in this family and the possible pathogenic role of a new SCN5A genetic variant.

Predictors of the atrial fibrillation following catheter ablation of typical atrial flutter.

BACKGROUND: Despite technical refinements and improved long-term efficacy of the ablation procedure for treating AFL (AFL), the subsequent occurrence of AF (AF) following this procedure remains a significant clinical problem. OBJECTIVES: To determine long-term incidence and predictors of AF after catheter ablation of typical AFL. MATERIAL AND METHODS: Between March 2005 and February 2010, a total of 84 consecutive patients who underwent catheter ablation of documented typical AFL were enrolled. RESULTS: Cavotricuspid isthmus ablation was successful in terminating and preventing the re-induction of AFL in all 84 patients (100%). The mean follow-up duration for study was 26± 22 months. During the follow-up period, early AF occurred in 5% after successful catheter ablation of AFL and late AF in 11% of the patients. The clinical variables associated with the occurrence of AF after catheter ablation of AFL were female, a history of AF before AFL ablation, body mass index (BMI), and left atrial abnormality. However, logistic multivariate analysis demonstrated that only BMI was independently associated with the late AF (OR 1.36, 95% CI 1.11-1.70, P = 0.004). CONCLUSIONS: Catheter ablation of flutter circuit will not prevent later manifestation of AF in 16% of the patients undergoing catheter ablation of the typical AFL. BMI was the only independent predictor of AF following catheter ablation of the typical AFL.

Deep sedation in patients undergoing atrioventricular nodal reentry tachycardia ablation.

BACKGROUND: General anesthesia and deep sedation can be used during cardiac EPS to relief pain and provide comfort and immobility, but many electrophysiologists avoid sedation for better arrhythmia induction. OBJECTIVE: To determine anesthesia effects in ablation procedures in adults, we used intravenous anesthetic agents in patients who underwent slow pathway ablation. PATIENTS AND METHODS: One hundred patients who were to undergo radiofrequency catheter ablation were randomly assigned to with and without intravenous anesthesia groups. All patients had palpitation with a documented electrocardiography (ECG) compatible with atrio-ventricular nodal reentrant tachycardia (AVNRT). We used propofol, fentanyl and midazolam for intravenous sedation. Electrophysiological parameters were checked for the two groups and compared before and after the ablation. RESULTS: Electrophysiological parameters were not significantly different in the two groups. In the anesthetic group, patients were more satisfied with the procedure (P value < 0. 001). CONCLUSIONS: Intravenous anesthesia could be done safely in patients who underwent electrophysiological procedures. It had no effect on arrhythmia induction or slow pathway ablation in patients with documented AVNRT.

Evaluation of atrial thrombus formation and atrial appendage function in patients with pacemaker by transesophageal echocardiography.

BACKGROUND: Physiologic pacing is claimed to be superior to ventricular pacing in as much as it entails lower risk of atrial fibrillation, stroke, and atrial remodeling. There are few data on the relation between atrioventricular (AV) synchrony and atrial clot formation. Utilizing transesophageal echocardiography (TEE), this study sought to evaluate the effect of AV synchrony loss on left atrial physiology, atrial stasis, and clot formation. METHODS: We conducted a cross-sectional study on patients with both AV and ventricular pacing with left ventricular ejection fraction (LVEF) >30%. TEE enabled us to explore atrial and pacing leads thrombi and measure left atrial appendage (LAA) flow velocity. RESULTS: A total 72 patients (mean age, 65 +/- 11.7) were enrolled in the study. The pacing mode was VVI in 53% and AV sequential in 47% of patients. LVEF (mean +/- SD; %) was 53.3 +/- 6.2% in ventricular pacing mode and 52.2 +/- 6.6 in physiologic pacing mode. Thrombus formation on pacing lead (<10 mm in 97% of patients) was observed in 32% of all the patients (23% in patients with AV sequential pacing mode and 39% with VVI mode). Left atrial appendage flow velocity (LAA-FV) was significantly higher among the patients with AV sequential pacing mode (49.44 +/- 18 cm/s vs 40.94 +/- 19.4 cm/s, P value = 0.02). LAA-FV >40 cm/s was detected in 60% of the patients, 60% of whom were in physiologic mode. Left atrial size was significantly larger among the patients with VVI pacing mode (42.3 +/- 2.3 mm vs 37.79 +/- 4.5 mm, P = 0.001). Multivariate analysis showed no relation between LAA-FV and age, hypertension, diabetes mellitus, left atrial size, and left ventricular function. Only one patient had right atrial clot. There was no thrombus in the ventricles and atrial appendage. CONCLUSION: Long-term loss of AV synchrony induced by VVI pacing is associated with the impairment of LAA contraction. Thrombus formation in the LAA is not increased by VVI pacing in patients with relatively good left ventricular (LV) function and sinus rhythm.

Multiple arrhythmogenic substrate for tachycardia in a patient with frequent palpitations.

We report a 26-year-old woman with frequent episodes of palpitation and dizziness. Resting electrocardiography showed no evidence of ventricular preexcitation. During electrophysiologic study, a concealed right posteroseptal accessory pathway was detected and orthodromic atrioventricular reentrant tachycardia incorporating this pathway as a retrograde limb was reproducibly induced. After successful ablation of right posteroseptal accessory pathway, another tachycardia was induced using a concealed right posterolateral accessory pathway in tachycardia circuit. After loss of retrograde conduction of second accessory pathway with radiofrequency ablation, dual atrioventricular nodal physiology was detected and typical atrioventricular nodal reentrant tachycardia was repeatedly induced. Slow pathway ablation was done successfully. Finally sustained self-terminating atrial tachycardia was induced under isoproterenol infusion but no attempt was made for ablation. During 8-month follow-up, no recurrence of symptoms attributable to tachycardia was observed.

Coexistence of atrioventricular nodal reentrant tachycardia and idiopathic left ventricular outflow-tract tachycardia.

Double tachycardia is a relatively rare condition. We describe a 21 year old woman with history of frequent palpitations. In one of these episodes, she had wide complex tachycardia with right bundle branch and inferior axis morphology. A typical atrioventricular nodal tachycardia was induced during electrophysiologic study, aimed at induction of clinically documented tachycardia. Initially no ventricular tachycardia was inducible. After successful ablation of slow pathway, a wide complex tachycardia was induced by programmed stimulation from right ventricular outflow tract. Mapping localized the focus of tachycardia in left ventricular outflow tract and successfully ablated via retrograde aortic approach. During 7 month's follow-up, she has been symptom free with no recurrence. This work describes successful ablation of rare combination of typical atrioventricular nodal tachycardia and left ventricular outflow tract tachycardia in the same patient during one session.