Background: Fragmented QRS (fQRS) complex on a 12-lead electrocardiogram (ECG) is reportedly associated with myocardial scar or fibrosis in patients with structural heart disease. In healthy persons, however, the prevalence, underlying mechanisms, and clinical implications of fQRS remain unknown. Methods: In this prospective study, the routine 12-lead resting ECGs of 1500 consecutive healthy adults (707 male, age [38 ± 12] years) were independently screened for fQRS by two ECG readers. fQRS was defined as ≥1 additional deflection or notching within the QRS complex, including the peak of the R-wave or the nadir of S-wave, in at least two continuous leads. Results: fQRS was identified in 76 participants (5.1%) in a mean of (2.3 ± 0.7) leads, most commonly inferior leads (86.8%, 66/76), followed by precordial leads (13.2%, 10/76). Longer QRS duration and left deviation of the frontal QRS axis of ≤30° were identified as independent predictors of fQRS. In addition, fQRS in the precordial leads covered the QRS transition lead (from R/S <1 to R/S >1) in all ten participants. Sixteen healthy volunteers who were found to have fQRS underwent late gadolinium enhancement–cardiac magnetic resonance scanning, which revealed no myocardial fibrosis, scar, or other abnormalities. Conclusions: fQRS is not rare in healthy adults. The underlying mechanisms of fQRS in healthy adults seem to be mainly related to left axis deviation (especially deviations ≤30°), rather than myocardial scar or fibrosis.

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The impact of coronavirus disease 2019 (COVID-19) infection is immeasurable. As we continue to learn about the presentation and complications of this infection, we begin to understand that COVID-19 is associated with multiorgan involvement. Bradycardia is one of cardiac complications that occur frequently in patients with COVID-19 infection. This clinical case is one approach to further understand the mechanism of COVID-19–induced dysautonomia causing bradycardia, through overstimulation of parasympathetic nervous system. Routine physical rehabilitation had improved the symptoms.

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Background: The practice of antibiotic prophylaxis for permanent pacemaker implantation varied widely in the real world of clinical practice due to no guidelines. The present study aims to investigate the use of antibiotic prophylaxis peri- and postimplantation of pacemaker in China. Materials and Methods: A total of 141 adult heart centers performing device implantation were asked using an E-mail or paper questionnaire to collect data regarding the use of antibiotics before or at implantation and duration of postimplantation. Subsequent telephone calls and E-mails were used to ascertain dubious data if necessary. Results: The final analysis included 135 centers (95.7% of total contacted) covering 7 main geographic regions of China. One hundred and twenty-six of the 135 centers (93.3%) used prophylactic antibiotics peri- and postimplantation. Among these centers, 107 centers (84.9%) selected first- or second-generation cephalosporins. In 100 centers (79.4%) of those used systemic antibiotics, an initial dose was given 0.5–2 h before surgery. With respect to duration of antibiotics administration, 99 centers of those used prophylactic antibiotics (78.6%) continued antibiotic therapy for 24–72 h while only 10 centers (7.9%) just administrated a single dose of antimicrobial agent before commencement of a procedure. Forty-eight of the 135 centers (35.6%) used intrapocket antibiotics at implantation, and gentamicin was the most commonly used antimicrobial agent (in 39/48 centers). Conclusion: Although the administration of prophylactic antibiotics before permanent pacemaker implantation has been implemented widely and routinely, our results showed that some electrophysiological centers still used no systemic antibiotic prophylaxis before or at the implantation. A significant difference exists in the timing, duration, and type of antibiotics use. Clinical trial evidence are required to guide optimal antibiotic prophylaxis for device implantation.

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Multifocal atrial tachycardia (MAT) is a cardiac rhythm disorder frequently diagnosed in elderly patients affected by several comorbidities. However, MAT can be observed also in younger ages as an incidental finding or in association with heart and lung diseases. MAT is characterized by heart rate >100 beats/min and at least three different P waves when compared to sinus P wave. Recent guidelines recommend the use of beta-blockers and verapamil for rate control and ongoing management of MAT. Unfortunately, electrical cardioversion and antiarrhythmic drugs have been demonstrated not always effective in MAT treatment. Intravenous magnesium seems a promising therapy in restoring sinus rhythm in patients who developed MAT. Moreover, in the last years, innovative strategies such as atrioventricular junction modification, ablate and pace approach, and electrophysiological isolation of firing sites have been successfully tested as curative treatment in selected cases of MAT resistant to drug therapy.

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Sudden cardiac death (SCD) is the leading cause of death in adults worldwide. Coronary heart disease is the underlying reason for most of the patients with SCD, including acute coronary syndrome and chronic ischemic heart disease. Revascularization is an important treatment technology for coronary heart disease, which includes percutaneous coronary intervention and surgical coronary artery bypass grafting. However, according to the recommended guidelines, even with the use of secondary prevention strategies such as medication treatment and a complete revascularization, there are still a great number of patients who have reduced left ventricular ejection fraction, heart failure, and ventricular arrhythmia at different stages in the course of disease. SCD remains to be a serious challenge in the long-term management of ischemic heart disease patients who have had revascularization. Here, we focus on broader issues of concerns to provide more insights by comprehensive recommendations for the clinical treatment of coronary artery disease after revascularization for SCD prevention.

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Scientific growth in the field of magnetic resonance imaging (MRI) and cardiac devices has been exponential in recent decades. Cardiac implantable electronic devices due to their ferromagnetic constituents in leads and device body have always been an issue if patients need MRI. MRI is relatively safe. Recent introduction of changes in leads and device body constituents renders them less ferromagnetic, making MRI less frightening to a certain extent. Simultaneously, there is increasing research interest in MRI. Not only anatomy and pathology but also physiology of cardiac and nervous structures can be imaged. It is estimated that 53%–64% of intracardiac defibrillator (ICD) patients will require an MRI determination over a 10-year time horizon, highlighting the importance of MRI-conditional devices for this patient population. In this article, we briefly describe evolution and current status of conditioning of cardiac devices to make them MRI-friendly and briefly discuss where we are in terms of our physician role with respect to MRI-conditional devices.

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Purposes: There are few vector-based electrocardiogram (ECG) algorithms to differentiate ventricular tachycardia (VT) and premature ventricular complexes (PVCs) originating from the septum (SP) or free wall (FW) in the right ventricular outflow tract (RVOT). Methods: One hundred and twenty-one patients (mean age 41 ± 13 years; 62% female) underwent mapping and ablation of symptomatic PVC or VT with left bundle branch block morphology. Inferior axis and precordial lead transition zone ≥V3 on the ECG were analyzed retrospectively. Ablation was highly successful on the 95 SP patients and among 26 cases in the FW group. The ECG morphology of VT/PVC was analyzed to derive a novel algorithm to localize VT origin within the RVOT. A VT/PVC QRS axis ≥90° or an R wave amplitude ratios ≥1 in leads II and III predicted a septal origin. If neither of these characteristics were present, the following criteria were each given a score of 1: VT/PVC QRS axis <85;°, leads II and III R wave amplitude ratio <0;.88, QRS duration in lead III ≥155 ms, and QRS duration ≥155 ms in lead aVL. A cumulative score of ≥2 predicted an FW origin whereas a total score of <2; predicted an SP origin. A prospective analysis in 99 patients was used to confirm the significance of the algorithm. Results: Retrospective analysis showed that the new algorithm predicted an SP origin with an overall sensitivity, specificity, and positive predictive values of 95.2%, 88%, and 96.3%, respectively. Prospective analysis showed that the new algorithm predicted RVOT-SP origin with a sensitivity, specificity, and positive predictive values of 97.5%, 88.9%, and 97.5%, respectively. Conclusion: The new vector-based ECG algorithm can differentiate septal from FW sites of origin in the RVOT with a high sensitivity, specificity, and positive predictive values.

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Brugada syndrome is an arrhythmogenic disease associated with sudden cardiac death due to ventricular arrhythmias. The risk stratification of patients without previous cardiac arrest remains the most controversial issue, especially for asymptomatic individuals, in Brugada syndrome. We review the recent data of several clinical, electrocardiographic, and electrophysiological parameters proposed for risk stratification. A history of documented fatal ventricular arrhythmias or aborted sudden cardiac death and/or arrhythmogenic syncope is a predictor of arrhythmic events, whereas the prognostic value of a familial history of sudden cardiac death and the presence of an SCN5A mutation are not well defined. On the electrocardiographic features, the spontaneous type 1 electrocardiogram (ECG) is associated with the risk for arrhythmic events in most of the studies, whereas early repolarization and fragmented QRS increases the risk in some studies. Late potentials using signal-averaged ECG and microscopic T-wave alternans indicate some available results in small studies that should be validated. The prognostic value of programmed electrical stimulation during electrophysiological study as a risk marker also remains controversial. A less aggressive protocol of programmed electrical stimulation may be preferable for risk stratification in the Brugada syndrome patients without previous cardiac arrest. Multiparametric approaches evaluating specific clinical factors and ECG may improve risk stratification.

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Tilt was used physiologically, 1930s–1970s, becoming a clinical diagnostic test for syncope in 1980s. Tilt has been criticized recently for failing to discriminate between reflex and more sinister syncope. Studies on possible benefit of pacing for older reflex syncope patients (2012–2014) yielded unexpected results. Patients with electrocardiogram implantable loop recorder (ILR) documented asystole and negative tilt, despite history strongly suggestive of reflex syncope, did well with pacing having syncope recurrence similar to that in paced His-Purkinje disease, while those with identical ILR findings and positive tilt did little better than those without pacing. These findings prompted explanation. The hypothesis hinged on tilt revealing a hypotensive/vasodepressor tendency rather than defining vasovagal syncope. Support was drawn from literature demonstrating good test sensitivity and specificity but no clinical value in arrhythmic, unexplained, or structural cardiovascular disease syncope. Further, in carotid sinus syndrome, another reflex syncope, the same pattern of disappointing pacing results was seen when tilt was positive but lack of syncope when tilt was negative. Thus, rethinking tilt testing is required to portray it in reflex, arrhythmic, unexplained, and cardiovascular syncope as having value in demonstrating risk of recurrence rather than being diagnostic. Its value in diagnosis of orthostatic hypotension (immediate/delayed), psychogenic pseudosyncope, and postural orthostatic tachycardia remains important and unchanged. The hypothesis has additional implications for management of hypertensive patients with syncope where medication may exacerbate symptoms requiring reduction/discontinuation. Tilt testing has greater value now than that claimed at its 1986 introduction.

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Background: Entirely leadless pacemakers (LPMs) address limitations of conventional pacemakers that include complications related to the pacing leads, their connections, and pacemaker pockets. The aim of this study was to describe early implantation experience and clinical efficacy of LPM. Methods: A total of eight patients received an LPM (Micra™ Transcatheter Pacing System, Medtronic plc, Minneapolis, MN, USA). LPM was transvenously deployed using a 23 F sheath, and actively fixed by 4 nitinol tines. Results: On average, the patients were 74.3 ± 8.1 years, and 50% were female. All had indications for a ventricular demand (VVI) pacemaker, and ejection fraction was 66.4% ±7.4%. Except for one patient, all were implanted from the right femoral vein. The LPM was deployed either at the right ventricular apex (63%) or at the septum (37%). At implantation, pacing threshold at 0.24 ms was 0.69 ± 0.35 V, and R wave was 8.1 ± 2.9 mV. Successful pacing sites were reached at a median of 1 attempt (range 1–3), and the mean procedure and fluoroscopic times were 74 ± 19 min and 11.0 ± 5.8 min, respectively. 50% were on uninterrupted anticoagulation, and there were no acute complications including groin hematoma. Both pacing threshold and R wave improved at 1 month compared to acute implant value (0.46 ± 0.11 V and 14.5 ± 5.6 mV, respectively, P< 0.05 compared with implant). Between 1 and 3 months follow-up, there was no change in pacing or sensing threshold. The average percentage of ventricular pacing was 65% ± 26%. The intracardiac accelerometer was activated in 3/8 patients, and the satisfactory rate response profile during activity of daily living was achieved. Battery longevity was estimated to be more than 8 years in all patients. Conclusion This study documents excellent implantation success of the Micra™ LPM with stable pacing and sensing and satisfactory rate response profile.

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Purpose: This study aimed to investigate the intermediate- and short-term effects of transcatheter secundum atrial septal defect (ASD) closure on cardiac electric remodeling in children and adults. Methods: Fifty patients with secundum ASD referred for possible transcatheter device closure were subjected to history taking, proper physical examination, electrocardiographic assessment, and transthoracic echocardiographic examination and were evaluated before the ASD closure, 1 day, 3 months, and 6 months after closure. Results: During the 6-month follow-up, electrocardiographic parameters of remodeling were improved. P dispersion decreased from 49.73 ± 9.01 ms to 30.53 ± 5.08 ms (P = 0.004), QT dispersion decreased from 67.60 ± 5.31 to 51.13 ± 5.73 ms (P = 0.003), QRS duration decreased from 134.40 ± 4.97 ms to 116.20 ± 3.47 ms (P = 0.002), and PR interval decreased from 188.87 ± 6.06 ms to 168.00 ± 6.16 ms (P = 0.002). Electric remodeling was associated with remodeling of the cardiac chambers. At the end of follow-up, the right ventricular (RV) end-diastolic dimension decreased from 25.67 ± 5.50 mm to 17.80 ± 2.70 mm (P = 0.001) the left ventricular end-diastolic dimension increased from 33.17 ± 6.44 mm to 37.53 ± 5.15 mm (P = 0.002), mean pulmonary artery pressure decreased from 16.97 ± 3.37 mmHg to 9.22 ± 1.37 mmHg (P = 0.000), and RV systolic pressure decreased from 30.77 ± 4.69 mmHg to 18.8 ± 2.11 mmHg. After 6 months, 93.3% of the patients had normal RV size. Conclusion: Transcatheter ASD device closure leads to a significant improvement in the right-sided chambers' dimension and function and can reverse electrical changes in atrial and ventricular myocardium in children and adults after correcting hemodynamic status in short- and intermediate-term follow-up.

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This collaborative statement from the International Society for Holter and Noninvasive Electrocardiology/Heart Rhythm Society (HRS)/European Heart Rhythm Association/Asia-Pacific HRS describes the current status of mobile health (mHealth) technologies in arrhythmia management. The range of digital medical tools and heart rhythm disorders that may be applied to and clinical decisions that may be enabled is discussed. The facilitation of comorbidity and lifestyle management (increasingly recognized to play a role in heart rhythm disorders) and patient self-management are novel aspects of mHealth. The promises of predictive analytics but also operational challenges in embedding mHealth into routine clinical care are explored.

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Sudden cardiac death (SCD) is the leading cause of cardiovascular mortality and a major international health problem, with an estimated 3.7 million deaths occurring annually, accounting for approximately 15%–20% of all deaths worldwide. The implantable cardiac defibrillator (ICD) is an effective treatment of SCD and has had a major impact on outcomes. However, this therapy has been largely used in patients with left ventricular dysfunction. A changing epidemiology of SCD with fewer patients having marked reductions in left ventricular ejection fraction (LVEF) has renewed the focus on identifying other high risk populations. This article summarizes the current understanding of the diverse clinical, genetic, racial, electrocardiographic and imaging techniques available to detect patients most at risk. Despite many identified risk factors, no single predictor has been shown to have sufficient predictive value to be used to guide preventative therapy and reduce mortality. More recent effort has been directed towards combining markers to define a risk profile for identifying high risk cohorts.

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Background: Elective direct current cardioversion (DCCV) has traditionally been performed by physicians in the United States. A few recent reports from the United Kingdom suggested that a specialist nurse-led service for elective DCCV of persistent atrial fibrillation was feasible. This practice has not been reported in the United States previously. Several years ago, we introduced a program where specially trained advanced practice providers (APPs) (physician assistants and nurse practitioners) assisted by an anesthesiology team, performed elective DCCV in patients with atrial fibrillation and atrial flutter, without direct cardiologist supervision. Methods: Upon receiving approval from the Institutional Review Board, we conducted a retrospective analysis of 447 consecutive DCCVs electively performed by APPs, for atrial fibrillation or atrial flutter, at Regions Hospital between 12/2006 and 10/2010. Transient deep sedation was administered by an anesthesiology team. The cohort was evaluated for procedural success and safety. Results: The procedural success rate was 92% (412/447). The incidence of procedural related adverse events, requiring immediate intervention, was 0.2% (1/447). This patient required emergent temporary pacing catheter insertion followed by a permanent pacemaker implantation at a later date. There were no other procedure-related complications and no thromboembolic events. A comparison with fifty elective cardioversions performed by cardiologists during the same period found no statistical difference in procedural success rates or complications. Conclusion: Under deep sedation administered by anesthesiology service, elective DCCV of atrial fibrillation and atrial flutter performed by well-trained APPs, without direct cardiologist supervision, is feasible and does not compromise patient safety.

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Background: In this work, a deep learning method is proposed to identify the types of arrhythmia. Methods: The 12-lead electrocardiogram signal is first denoised by filters to eliminate the baseline drift and the myoelectric interference. Then, the filtered signal is sliced into beats and sent to a deep neural network, which contains four convolutional layers, two gated recurrent unit layers, and one full-connected layer. Features in both the spatial domain and the time-frequency domain can be extracted implicitly by the deep neural network, instead of being extracted manually. Results: On the test split of the dataset, our neural network model achieves an accuracy of 98.15%. Among the accuracies for the four types of arrhythmia, respectively, the lowest one is 96% and the highest is 99%. Our model is must better than a baseline support vector machines classifier, with a test accuracy of 73.54%. Conclusion: The results give a supportive evidence to make our model clinically applicable to assist physicians in diagnosing certain diseases.

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Four decades of progress in understanding the electrogenesis, clinical value and recording methods of the epsilon wave have been achieved since it was first recognized in 1977. According to the new 2010 Task Force criteria, epsilon waves are a major criterion in the diagnosis of arrhythmogenic right ventricular dysplasia. Epsilon waves can be observed in the right precordial leads when a relevant intramyocardial conduction defect is present in the right ventricle. In this paper, we summarize the progress, challenge, and controversies in the definition of epsilon waves.

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In recent years, silent atrial fibrillation (AF) has acquired broad interest in the neurologic and cardiovascular communities. Silent AF has been associated with similar morbidity and mortality as symptomatic AF and with similar rates of silent embolic events. In current clinical practice, AF remains mostly underdiagnosed, and 25% of patients with AF-associated cardioembolic stroke have not been previously diagnosed with AF. Silent AF detection methods include pulse palpation, ambulatory external electrocardiographic recordings, insertable cardiac monitors, and previously implanted cardiac devices with atrial lead. The increased interest is being directed toward detection of silent AF. Whether this will imply better outcomes for patients remains to be demonstrated.

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Atrial fibrillation is independently associated with an increased risk of thromboembolic stroke. While anticoagulants decrease this risk, they also carry a substantial risk of bleeding. Most left atrial thrombi arise from the left atrial appendage (LAA), which has led to several investigations into surgical and percutaneous methods of LAA exclusion for stroke reduction. The PubMed database was queried, and over 400 articles were considered for inclusion in this review. Of the surgical methods of LAA exclusion, complete excision is the most effective. Other methods, including ligation and stapling, may be incomplete and associated with left atrial thrombus formation. Surgical LAA exclusion has been commonly performed during mitral valve surgery although it has not been shown to prevent stroke in many retrospective studies. In patients unable to take warfarin, several percutaneous LAA exclusion devices have been studied, including the PLAATO system, Amplatzer Cardiac Plug (ACP), Watchman device, and Lariat. Both the ACP and Watchman have shown a significant stroke reduction and improved procedural safety with greater experience. The Lariat ligates the LAA using a combined endocardial and epicardial approach but is currently associated with substantial procedural risks. With better patient selection for the different options of LAA exclusion, thromboembolic stroke protection can be maximized with fewer complication risks.

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Pulmonary vein isolation (PVI) is the established cornerstone in catheter ablation for atrial fibrillation (AF). The traditional point-to-point ablation by focal radiofrequency (RF) catheter to achieve PVI was technically challenging, and the outcome remained suboptimal despite advancement in three-dimensional electroanatomical mapping systems and steerable sheaths. Different catheter designs including contact force, balloon-based catheters with other energy sources (cryothermal and laser energies), and circular RF catheters have been developed to make the ablation procedure more user-friendly and PVI more durable. Adjunctive techniques including detection of dormant conduction by adenosine triphosphate injection and pace-capture-guided ablation have also been studied to improve the durability of PVI and thus reduce the AF recurrence rate.

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The cardiovascular side effects of older antidepressants and neurolepts are well known. These drugs inhibit the cardiac Na⁺, Ca²⁺, and K⁺ channels often leading to life-threatening arrhythmia. Selective serotonin receptor inhibitor antidepressants and new antipsychotics were introduced to overcome the toxicity of older generation drugs. These drugs have gained popularity owing to their fewer side-effect profiles. However, several case reports have revealed the arrhythmogenic effect of these drugs as well as orthostatic hypotension, especially in those receiving cardiac medications. We report a case of a 65-year-old male who experienced junctional rhythm during the treatment of his acute manic episode with quetiapine and returned to normal sinus rhythm after discontinuing the medication.

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The need for transvenous lead extraction (TVL) is increasing. Unfortunately, many patients with indications for extraction go without appropriate care. There are multiple barriers to patients receiving TVL. These include a knowledge deficit, a lack of adequate training, a lack of appropriate tools, and a lack of resources. In this paper, we will review these barriers and offer some potential solutions. Hopefully, in the near future, all patients that require TVL will be appropriately referred and the resources and training will allow safe and effective treatment.

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