This collection highlights some of the case reports from 2021 published in the cardiac rhythmology section. Cardiac Rhythmology aims to advance the understanding of underlying mechanisms, diagnosis and treatment of arrhythmias and conduction disturbances. The latter includes sinus node disease, inter- and intra-atrial blocks, AV block, and bundle branch block. Among the former are included premature atrial and ventricular beats, atrial tachycardias, supra-ventricular tachycardias, and ventricular arrhythmias. Case reports aim to highlight unique cases of patients that present with an unexpected/unusual diagnosis, treatment outcome, or clinical course.?Case reports provide insight into the differential diagnosis, decision making, and clinical management of unusual cases and are a valuable educational tool.

The University of Hong Kong

Frontiers in Cardiovascular Medicine

Cardiac Rhythmology

Cardiac Rhythmology Case Reports: Abnormal ECG and beyond

A 12-lead surface electrocardiogram (ECG) is an essential initial investigation for most cardiac conditions, both for establishing the diagnosis and facilitating management. Moreover, ECG also provides a wide array of clinical information, from physiological condition and homeostasis to active and past cardio-pulmonary pathologies. Clinicians might occasionally be tempted to solely rely on ECG findings for making diagnoses. Nevertheless, it is essential to go beyond ECG findings and perform a holistic clinical assessment, including detailed history taking, meticulous physical examination, and adjunct investigation, including blood tests, echocardiography, and other imaging modalities, as well as invasive investigations, to guide proper clinical management. The approach of going beyond ECG abnormality identification to whole-patient care was well-exemplified by the authors who contributed to this case report Research Topic on interesting ECG findings in Frontier in Cardiovascular Medicine.We curated two illustrative case reports related to pre-procedural planning and post-procedural complications with intriguing ECG findings. <a href="https://doi.org/10.3389/fcvm.2021.659821">Luo et al.</a> showcased the management of a pediatric patient with refractory atrial tachycardia despite anti-arrhythmic medications, and complicated with tachycardia-mediated cardiomyopathy. Pre-procedural ECG suggested that the atrial tachycardia originated from the right atrial appendage with a negative P wave in lead V1 and a positive towering P wave in the inferior leads. Using a three-dimensional electroanatomical mapping system, the atrial tachycardia foci was indeed localized at the apex of the right atrial appendage. As the atrial tachycardia could not be terminated after extensive catheter-based endocardial radiofrequency ablation, the authors switched to a thoracoscopic approach and performed clamp radiofrequency ablation using bipolar radiofrequency ablation forceps to the base of right atrial appendage. Atrial tachycardia was successfully terminated with no recurrence during the next 3 months of follow up. With resolution of atrial tachycardia accompanied by guideline-directed medical therapy, the left ventricular systolic function of this patient improved from 31 to 60%. In another interesting case report, <a href="https://doi.org/10.3389/fcvm.2021.744079">Zheng et al.</a> reported a rare post-procedural complication after left bundle branch area pacing (LBBP). Since the introduction of LBBP in 2017 (<a href="#B1">1</a>), this novel pacing technique has been increasingly utilized as an alternative approach to his bundle pacing for physiologic conductive system pacing, as LBBP has a high implant success rate and preserves left ventricular function compared to conventional right ventricular sites pacing in recent observational studies (<a href="#B2">2</a>, <a href="#B3">3</a>). Nonetheless, there are limited data on the short- and long-term safety of this novel LBBP approach. <a href="https://doi.org/10.3389/fcvm.2021.744079">Zheng et al.</a> reported a patient with chest pain, non-specific ST-segment depression on ECG, and markedly elevated troponin level 1 hour after LBBP. Careful examination with transthoracic echocardiography by the authors revealed swollen interventricular septum and the computer tomography angiography (CTA) confirmed the presence of a septal hematoma. It was postulated that the hematoma resulted from inadvertent injury to one of the septal perforating arterial branches. The patient was conservatively treated, and a serial imaging 1 month later showed resolution of the hematoma.It is well-known that patients with acute medical or surgical illnesses may also manifest abnormal ECG findings despite having no definite cardiac pathology. Some of these ECG changes may mimic acute coronary syndrome; for instance, ST segment changes were not uncommon among patients with ischemic or hemorrhagic stroke (<a href="#B4">4</a>). It has been proposed that those ECG abnormalities can be mediated by changes in autonomic nervous system activity, secondary to underlying systemic or intracranial pathologies, without necessarily implicating underlying cardiac disease. It may sometimes be challenging for clinicians to accurately determine whether acute cardiac complications are present that warrant urgent investigation and intervention. <a href="https://doi.org/10.3389/fcvm.2021.742740">Cao et al.</a> reported a middle-aged woman with Guillain Barre Syndrome, who complained of multiple pain over chest, back, and limbs. ECG showed transient T-wave inversion over lead I, aVL, and from V2 to V4. Cardiac injury biomarkers and echocardiography were both normal. Underlying coronary artery disease was initially considered less likely as the patient had no known cardiovascular risk factors, and Guillain Barre Syndrome was known to be associated with ECG changes. In a retrospective study involving 96 patients with Guillain Barre Syndrome, ECG abnormalities were present in 50% of the patients, with 12.5% having ST-T changes (<a href="#B5">5</a>). Despite the patient's relatively low probability of having coronary artery disease, the authors proceeded to arrange a CT coronary angiogram based on clinical suspicions, as the patient had recurrent chest pain. A critical stenosis was found to be present in the left anterior descending artery, and the patient subsequently underwent coronary revascularization procedure. In another case report, <a href="https://doi.org/10.3389/fcvm.2021.741253">Long et al.</a> described an elderly woman presented with acute pancreatitis with diffuse abdominal tenderness. She had no chest pain, but ECG showed ST-segment elevation over inferior leads. It was uncertain whether the ECG changes reflected true coronary pathology or were merely the ECG changes associated with acute pancreatitis. In a small case series, it was reported that up to 55% of patients with pancreatitis had abnormal ECG findings (<a href="#B6">6</a>), and ECG findings mimicking ST-elevated myocardial infarction have also been reported in case reports as well (<a href="#B7">7</a>). It was critical to distinguish between true acute coronary syndrome and non-specific ECG changes secondary to pancreatitis because it had significant implications in downstream management strategies. Acute coronary syndrome would require prescription of anti-thrombotic mediations, which confers additional bleeding risk to the patient with pancreatitis. On the other hand, missing the opportunity to arrange timely interventional or pharmacological therapy for acute coronary syndrome would compromise cardiac outcome. The authors eventually arranged echocardiography and CTA, which confirmed that the patient had critical stenosis over the left anterior descending artery and right coronary artery.We congratulate the above authors for publication of those enlightening case reports, which demonstrated the importance of careful analysis and interpretation of ECG, which subsequently resulted in appropriate further investigation and treatment of underlying conditions.C-KW and H-FT wrote manuscript and revised the manuscript critically for important intellectual content. Both authors have read and approved the final version of the manuscript to be published.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Editorial: Cardiac rhythmology case reports: Abnormal ECG and beyond

Background: Both acute pancreatitis and acute myocardial infarction (AMI) are rapidly progressive and frequently fatal diseases that can be interrelated and lead to a vicious cycle for further problems. The concomitant occurrence of AMI and acute pancreatitis is rare but critical, and efficient diagnosis and treatment of such patients are challenging.Case Summary: We reported an uncommon case of abnormal ECG findings in a 63-year-old woman with acute pancreatitis. The patient exhibited increased biomarkers of myocardial injury, such as creatine kinase-MB (CK-MB) and troponin T, as well as ST segment elevation in inferior leads II, III, and aVF. Both of these have been previously observed in patients with acute abdomen in the absence of ST-segment elevation myocardial infarction (STEMI), including pancreatitis. In addition, lacking complaints of chest pain or tightness was also supportive of this idea. Echocardiography indicated abnormalities in the functioning of the left inferior posterior wall segments and decreased overall systolic function of the left ventricle with a 51% ejection fraction. Eventually, AMI was diagnosed after coronary computed tomography angiography (CCTA) showing critical stenosis of the right coronary artery and left anterior descending artery segments. The patient was urgently transferred to intensive care unit and was treated with anticoagulation, antiplatelet aggregation, lipid-lowering and other palliative drugs.Conclusion: Concomitant acute pancreatitis and AMI are often considered to be critical conditions with a poor prognosis. Therefore, it is important to rapidly identify this condition and consider transferring patients for multidisciplinary supportive care.

Background: Both acute pancreatitis and acute myocardial infarction (AMI) are rapidly progressive and frequently fatal diseases that can be interrelated and lead to a vicious cycle for further problems. The concomitant occurrence of AMI and acute pancreatitis is rare but critical, and efficient diagnosis and treatment of such patients are challenging.Case Summary: We reported an uncommon case of abnormal ECG findings in a 63-year-old woman with acute pancreatitis. The patient exhibited increased biomarkers of myocardial injury, such as creatine kinase-MB (CK-MB) and troponin T, as well as ST segment elevation in inferior leads II, III, and aVF. Both of these have been previously observed in patients with acute abdomen in the absence of ST-segment elevation myocardial infarction (STEMI), including pancreatitis. In addition, lacking complaints of chest pain or tightness was also supportive of this idea. Echocardiography indicated abnormalities in the functioning of the left inferior posterior wall segments and decreased overall systolic function of the left ventricle with a 51% ejection fraction. Eventually, AMI was diagnosed after coronary computed tomography angiography (CCTA) showing critical stenosis of the right coronary artery and left anterior descending artery segments. The patient was urgently transferred to intensive care unit and was treated with anticoagulation, antiplatelet aggregation, lipid-lowering and other palliative drugs.Conclusion: Concomitant acute pancreatitis and AMI are often considered to be critical conditions with a poor prognosis. Therefore, it is important to rapidly identify this condition and consider transferring patients for multidisciplinary supportive care.

Case Report: Abnormal ECG in a Patient With Acute Pancreatitis

Background: Guillain–Barré syndrome (GBS) is an acute immune-mediated disorder in the peripheral nervous system (PNS) characterized by symmetrical limb weakness, sensory disturbances, and clinically absent or decreased reflexes. Pantalgia and dysautonomia, including cardiovascular abnormalities, are common findings in the spectrum of GBS. It is usually challenging to distinguish GBS-related electrocardiogram (ECG) abnormities and chest pain from acute coronary syndrome (ACS) in patients with GBS due to the similar clinical symptom and ECG characteristics. Here, we present a case of GBS complicating ACS.Case Summary: A 37-year-old woman with a 2-month history of GBS presented to the emergency department due to pantalgia. The ECG showed a pattern of transitional T-wave inversion in the leads I, aVL, and V2 through V4 and shortly returned to normal, which appeared several times in a short time, but lab testing was unremarkable. Then, a further coronary computed tomography angiography (CTA) revealed the presence of critical stenosis of the left anterior descending artery, leading to the diagnosis of ACS. During the follow-up, she suffered from a non-ST-elevation myocardial infarction and accepted revascularization of the left anterior descending artery in the second week after discharge.Conclusion: Guillain–Barré syndrome could accompany chest pain and abnormalities on ECG. Meanwhile, it is essential to bear in mind that “GBS-related ECG abnormalities and chest pain” is a diagnosis of exclusion that can only be considered after excluding coronary artery disease, especially when concomitant chest pain, despite being a common presentation of pantalgia, occurs.

Background: Guillain–Barré syndrome (GBS) is an acute immune-mediated disorder in the peripheral nervous system (PNS) characterized by symmetrical limb weakness, sensory disturbances, and clinically absent or decreased reflexes. Pantalgia and dysautonomia, including cardiovascular abnormalities, are common findings in the spectrum of GBS. It is usually challenging to distinguish GBS-related electrocardiogram (ECG) abnormities and chest pain from acute coronary syndrome (ACS) in patients with GBS due to the similar clinical symptom and ECG characteristics. Here, we present a case of GBS complicating ACS.Case Summary: A 37-year-old woman with a 2-month history of GBS presented to the emergency department due to pantalgia. The ECG showed a pattern of transitional T-wave inversion in the leads I, aVL, and V2 through V4 and shortly returned to normal, which appeared several times in a short time, but lab testing was unremarkable. Then, a further coronary computed tomography angiography (CTA) revealed the presence of critical stenosis of the left anterior descending artery, leading to the diagnosis of ACS. During the follow-up, she suffered from a non-ST-elevation myocardial infarction and accepted revascularization of the left anterior descending artery in the second week after discharge.Conclusion: Guillain–Barré syndrome could accompany chest pain and abnormalities on ECG. Meanwhile, it is essential to bear in mind that “GBS-related ECG abnormalities and chest pain” is a diagnosis of exclusion that can only be considered after excluding coronary artery disease, especially when concomitant chest pain, despite being a common presentation of pantalgia, occurs.

Case Report: Abnormal ECG and Pantalgia in a Patient With Guillain–Barré Syndrome

Background: Left bundle branch pacing (LBBP) is a novel physiological pacing and previous studies have confirmed the feasibility and safety of it. The incidence of complications in LBBP is relatively low as reported. Here we present a case of interventricular septal hematoma complicating LBBP lead implantation.Case summary: LBBP was achieved for treatment of high-grade atrioventricular block in a 67-year-old female. Chest pain began 1 h after implantation when the electrocardiogram showed ST-T changes. Then bedside echocardiography confirmed the formation of interventricular septal hematoma. Urgent coronary angiography showed the contrast agent retention and overflow in the interventricular septum. The symptom was relieved half an hour later. Echocardiogram performed 2 h later revealed the size of the hematoma was the same as before. The electrocardiography, coronary angiography and CTA confirmed the resolution of the hematoma at 1-month follow-up. Pacing parameters and cardiac function remained stable during 6-month follow-up.Conclusion: This is the first reported case describing the clinic features and management of interventricular septum hematoma complicating LBBP. The importance of routine echocardiograms after implantation for identifying the hematoma should be highlighted.

Background: Left bundle branch pacing (LBBP) is a novel physiological pacing and previous studies have confirmed the feasibility and safety of it. The incidence of complications in LBBP is relatively low as reported. Here we present a case of interventricular septal hematoma complicating LBBP lead implantation.Case summary: LBBP was achieved for treatment of high-grade atrioventricular block in a 67-year-old female. Chest pain began 1 h after implantation when the electrocardiogram showed ST-T changes. Then bedside echocardiography confirmed the formation of interventricular septal hematoma. Urgent coronary angiography showed the contrast agent retention and overflow in the interventricular septum. The symptom was relieved half an hour later. Echocardiogram performed 2 h later revealed the size of the hematoma was the same as before. The electrocardiography, coronary angiography and CTA confirmed the resolution of the hematoma at 1-month follow-up. Pacing parameters and cardiac function remained stable during 6-month follow-up.Conclusion: This is the first reported case describing the clinic features and management of interventricular septum hematoma complicating LBBP. The importance of routine echocardiograms after implantation for identifying the hematoma should be highlighted.

Case Report: Interventricular Septal Hematoma Complicating Left Bundle Branch Pacing Lead Implantation

Atrial tachycardia originating from the right atrial appendage has a higher probability of failure of catheter ablation. Here we report a case of a 13-year-old boy with incessant tachycardia, complicated by heart enlargement, and heart failure. Electrophysiological examination showed that atrial tachycardia (AT) originated from the apex of the right atrial appendage, and endocardial catheter ablation was ineffective. After thoracoscopic approach, the right atrial appendage was successfully ablated with bipolar radiofrequency ablation forceps, atrial tachycardia was terminated and sinus rhythm was restored. Within 3 months since the patient was discharged from the hospital, no arrhythmia occurred and the heart structure returned to normal. Thus, thoracoscopic clamp radiofrequency ablation may be a reasonable choice for young patients with atrial tachycardia originated from the right atrial appendage when transendocardial ablation is not effective.

Atrial tachycardia originating from the right atrial appendage has a higher probability of failure of catheter ablation. Here we report a case of a 13-year-old boy with incessant tachycardia, complicated by heart enlargement, and heart failure. Electrophysiological examination showed that atrial tachycardia (AT) originated from the apex of the right atrial appendage, and endocardial catheter ablation was ineffective. After thoracoscopic approach, the right atrial appendage was successfully ablated with bipolar radiofrequency ablation forceps, atrial tachycardia was terminated and sinus rhythm was restored. Within 3 months since the patient was discharged from the hospital, no arrhythmia occurred and the heart structure returned to normal. Thus, thoracoscopic clamp radiofrequency ablation may be a reasonable choice for young patients with atrial tachycardia originated from the right atrial appendage when transendocardial ablation is not effective.

Case Report: Application of Thoracoscopic Clamp Radiofrequency Ablation on Atrial Tachycardia Originating From Right Atrial Appendage After Catheter Ablation Failure