Inappropriate Subcutaneous Implantable Cardioverter-defibrillator Shocks-A Rare Case of Triple Counting.

Sudden cardiac death (SCD) caused by ventricular tachyarrhythmias is a significant contributor to cardiovascular deaths worldwide. Implantable cardioverter-defibrillators (ICDs) have shown efficacy in preventing and reducing mortality from SCD, but traditional transvenous ICDs have inherent challenges and drawbacks, such as lead fractures, lead-associated endocarditis, and lead failure. To address these issues, subcutaneous ICDs (S-ICDs) have been developed. S-ICDs lack pacing capacity but are a valid alternative for patients at high risk for infection or with difficult venous access. Pre-implantation screening can help prevent inappropriate device shocks. We present a case in which a patient received inappropriate S-ICD therapy, which was attributed to the triple counting of P-, R-, and T-waves in a patient with sinus rhythm. This is an unusual occurrence, and, to the best of our knowledge, there are only a limited number of case reports documenting inappropriate shocks due to the oversensing of P-waves and T-waves.

Prior Statin vs In-Hospital Statin Usage in Severe COVID-19: Review and Meta-Analysis.

Studies have shown that statins can decrease COVID-19 mortality in hospitalized patients. This paper evaluates these studies and reviews the possible mechanism of how statins modulate COVID-19 severity. Meta-analysis of 31 retrospective studies demonstrated a reduction in mortality rate among statin users (OR 0.69, 95% CI 0.56-0.86, P = 0.0008) (HR 0.83, 95% CI 0.72-0.95, P = 0.0078). Meta-analysis of 8 randomized control studies demonstrated a nonsignificant reduction in mortality (OR 0.90, 95% CI 0.69-1.18, P = 0.461), including 4 studies with medications other than statins, and 4 studies with only statins (OR 0.88, 95% CI 95% CI 0.64-1.21, P = 0.423). Prolonged statin usage decreases the extracellular localization of ACE2, along with statins' immunomodulating effects and reduction of oxidative stress, decreases COVID-19 mortality. Hospitalized patients with COVID-19 should continue statin treatment if previously prescribed, and patients should not be started on statins, as they do not seem to provide any mortality benefit.

Reproducible asystole following vagal nerve stimulator lead replacement: a case report.

BACKGROUND: Vagal nerve stimulation (VNS) is approved therapy for the treatment of intractable epilepsy. The stimulation of either nerve, left or right, is effective. However, due to the anatomic and physiological effects of cardiac innervation, the right vagus nerve is typically avoided in order to minimize the risk of cardiac bradyarrhythmias. The location of the VNS lead contacts on the nerve can also have an effect, namely, more distally placed contacts have been associated with lower risk of cardiac arrhythmias, presumably by avoiding vagal cervical cardiac branches; however, our case demonstrates reproducible asystole despite left sided, distal VNS lead placement. CASE PRESENTATION: We report a 28-year-old male patient with pharmacoresistant generalized clonic-tonic seizures. The VNS therapy with 1.5 mA output and 16% duty cycle drastically reduced his seizure burden for several years. The breakthrough seizures along with stabbing pain episodes at the implantable pulse generator (IPG) site have prompted the VNS lead revision surgery with new lead contacts placed more caudally than the old contacts. However, the intraoperative device interrogation with 1 mA output resulted in immediate asystole for the duration of stimulation and it was reproducible until the output was decreased to 0.675 mA. CONCLUSIONS: Our case highlights the possibility of new severe cardiac bradyarrhythmias following surgical VNS lead replacements even in patients without preoperatively known clinical side effects. We suggest preoperative electrocardiography and cardiology consultation for detected abnormalities for all patients undergoing new VNS implantations, as well as revision surgeries for VNS malfunctions. Intraoperatively, the surgeon and anesthesia team should be vigilant of cardiac rhythms and prepared for the immediate management.

Impact of atrial fibrillation on in-hospital outcomes among hospitalizations for cardiac surgery: an analysis of the National Inpatient Sample.

The short-term impact of atrial fibrillation (AF) on cardiac surgery hospitalizations has been previously reported in cohorts of various sizes, but results have been variable. Using the 2005-2014 National Inpatient Sample, we identified all adult hospitalizations for cardiac surgery using the International Classification of Diseases, Ninth Revision, Clinical Modification as any procedure code and AF as any diagnosis code. We estimated the impact of AF on inpatient mortality, length of stay (LOS), and cost of hospitalization using survey-weighted, multivariable logistic, accelerated failure-time log-normal, and log-transformed linear regressions, respectively. Additionally, we exact-matched AF to non-AF hospitalizations on various confounders for the same outcomes. A total of 1,269,414 hospitalizations were noted for cardiac surgery during the study period. Coexistent AF was found in 44.9% of these hospitalizations. Overall mean age was 65.6 years, 40.9% were female, mean LOS was 11.6 days, and inpatient mortality was 4.5%. Stroke rate was lower in AF hospitalizations (1.8% vs 2.1%, p<0.001). Mortality was lower in the AF (3.9%) versus the non-AF (5%) group (exact-matched OR or emOR=0.48, 95% CI 0.29 to 0.80, p<0.001; 987 matched pairs, n=2423), with similar results after procedural stratification: isolated valve replacement/repair (emOR=0.38, p<0.001), isolated coronary artery bypass graft (CABG) (emOR=0.33, p<0.001), and CABG with valve replacement/repair (emOR=0.55, p<0.001). A 12% increase was seen in LOS in the AF subgroup (exact-matched time ratio=1.12, 95% CI 1.10 to 1.14, p<0.001) among hospitalizations which underwent valve replacement/repair with or without CABG. Hospitalizations for cardiac surgery which had coexistent AF were found to have lower inpatient mortality risk and stroke prevalence but higher LOS and hospitalization costs compared with hospitalizations without AF.

Utilizing the Cool-Down Phenomenon to Differentiate Supraventricular Tachycardias in a Patient with COVID-19 Infection.

A 63-year-old male patient with a history of hypertension, diabetes mellitus type 2, prostate cancer and class two obesity was admitted for encephalopathy. During his hospital stay he developed narrow complex tachycardia and it was difficult to definitively diagnose the underlying arrhythmia. Observation of the cool down phenomenon on telemetry strip allowed us to make the diagnosis of atrial tachycardia and elegantly rule out other causes. We report this interesting case of narrow complex tachycardia.

Direct Oral Anticoagulants Versus Warfarin in Left Ventricular Thrombus: A Systematic Review and Meta-Analysis.

BACKGROUND: There are conflicting results regarding the safety and efficacy of direct oral anticoagulants (DOACs) in the management of left ventricular thrombus (LVT) compared with the vitamin K antagonist warfarin. STUDY QUESTION: What is the safety and efficacy of DOACs in the management of LVT compared with warfarin? DATA SOURCE: Randomized clinical trials and cohort studies in the MEDLINE and Cochrane databases from inception till April 4, 2021. STUDY DESIGN: The present analysis is a systematic review and meta-analysis. Desired outcomes were all-cause mortality, complete resolution of LVT, stroke and systemic emboli, and major bleeding. The risk ratio (RR) of the outcomes and 95% confidence intervals (CIs) were calculated using a random-effects modeling approach. RESULTS: Twelve studies with a total of 2322 patients were included. There was no difference between the 2 interventions in the resolution of LVT [RR 0.97 (CI 0.93-1.02)], stroke and systemic embolism [RR 0.95 (CI 0.63-1.45)], bleeding [RR 1.14 (CI 0.81-1.60)], and all-cause mortality [RR 0.99 (CI 0.67, 1.46)]. CONCLUSIONS: DOACs and warfarin have comparable safety and efficacy outcomes in the management of LVT.

Theophylline in Treatment of COVID-19 Induced Sinus Bradycardia.

This is a retrospective case series of two patients with laboratory-confirmed coronavirus 2 (SARS-CoV-2) infection, presented to the University of Arkansas for Medical Sciences in January 2021. Medical records of these patients were reviewed using the EPIC electronic health record system. Clinical, laboratory, and treatment data were reviewed against periods of bradycardia in each patient. Both of the patients presented with dizziness and presyncope related to sinus bradycardia in which they received treatment with 1 mg of IV atropine and theophylline 200 mg orally. We share these two cases of theophylline treatment in COVID-19 induced sinus bradycardia. The first patient was a 39-year-old female, with a past medical history of polycystic ovarian syndrome, who presented to the emergency department with lightheadedness and dizziness. Two weeks prior to her presentation, she was tested positive for COVID-19 infection that was treated with azithromycin, dexamethasone and aspirin. Upon presentation, her ECG showed sinus bradycardia at a rate of 48 bpm. The second patient, a 21-year-old female with no significant past medical history, presented with presyncope. Three weeks prior to her presentation, she tested positive for COVID-19 infection that was treated symptomatically at her home. Upon presentation, her ECG showed junctional rhythm at a heart rate of 51 bpm.

Oral Anticoagulation Discontinuation Following Catheter Ablation of Typical Atrial Flutter.

Catheter ablation (CA) of typical atrial flutter (AFL) is the preferred treatment for typical AFL due to its excellent long-term success rate. However, current guidelines recommend pursuing oral anticoagulation (OAC) based on established indices of stroke regardless of the perceived success of ablation. We conducted a retrospective study of all patients who underwent typical AFL ablation at our institute from 2011 to 2017. All patients continued OAC for at least six weeks post-CA and underwent 24-hour Holter monitoring. OAC was discontinued if there was no evidence of recurrence at six weeks. In patients with low left ventricular ejection fraction or prior atrial fibrillation episodes, OAC was continued for six months with repeat Holter monitoring at six months. A total of 106 patients were included in our analysis, with a mean age of 64 ± 14 years and 78.3% of whom were male. The mean CHA2DS2-VASc score was 3 ± 1 points. OAC was discontinued by six weeks in 17% and at one year in 55.7% of patients, respectively, but was continued indefinitely in 44.3%. Over a mean follow-up period of 28.6 ± 27.3 months, there was one ischemic stroke in the OAC discontinuation group and no ischemic events in the continued OAC group. There were a total of three major bleeding events, all in the OAC group. In patients undergoing successful AFL ablation, a strategy of OAC discontinuation with close rhythm monitoring appears feasible. The benefit of continued OAC in this cohort may be outweighed by an adverse risk of bleeding. Further studies examining rhythm-guided OAC can minimize unnecessary exposure to long-term anticoagulation.

The sensitivity of graphic trends in differentiating sinus and supraventricular tachycardia.

BACKGROUND: The use of cardiac telemetry in the inpatient setting is widespread and has become integral in managing hospitalized patients. Telemetry is used to monitor patients with brady- and tachyarrhythmias. While most of the focus is on the rhythm strip data, a significant utility remains in analyzing the graphic heart rate trends. We specifically focused on the shape of the curve (rectangle or bell) of the heart rate over time to differentiate sinus tachycardia (ST) and supraventricular tachycardia (SVT). We hypothesized that identifying the shape of the graphic trend would improve the accuracy of diagnosis. METHODS: To demonstrate the simplicity of employing this method for improving the diagnosis of arrhythmia, we had senior medical students evaluate the telemetry strips and graphical trends. We gathered data from the medical student interpretation of 82 strips of in-hospital cardiac telemetry and asked them to differentiate ST and SVT based on the shape of the graphic trend. Each rhythm strip and the graphic trend was interpreted by two clinical cardiac electrophysiology attending physicians and confirmed on a 12­lead electrocardiogram. RESULTS: When students were asked to choose between ST and SVT based on the telemetry rhythm strip without graphic trends, 73% of their answers were correct. Diagnostic accuracy improved to 96% correct with the addition of the graphic trend. Depending on the telemetry rhythm strip alone, sensitivity to detect SVT was 75%, with 68% specificity. With the addition of the graphical trend, sensitivity improved to 98% and specificity 100%. CONCLUSION: Review of graphical trends, specifically the analysis of onset and offset, allows novice ECG readers to improve the ability to distinguish between ST and SVT.

Inappropriate Sinus Tachycardia Following Viral Illness.

A 67-year-old female patient with a past medical history of menopause, migraines, and gastro-esophageal disease presented with palpitation, fatigue, and shortness of breath. One month prior to her presentation, she reported having flu-like symptoms. Her EKG showed sinus tachycardia with no other abnormality. Laboratory findings, along with imaging, showed normal results. The event monitor failed to detect any arrythmias. We report a case of inappropriate sinus tachycardia secondary to viral infection as a diagnosis of exclusion.

Gender differences, outcomes and trends among nonagenarian with atrial fibrillation: insight from National Inpatient Sample database.

BACKGROUND: Nonagenarians (NG), individuals aged ≥ 90 years, constitute an increasing proportion of hospitalizations presenting with atrial fibrillation (AF). However, not much is known about demographics, clinical outcomes, and trends of hospitalizations. Therefore, we analyzed data about hospitalizations and clinical outcomes among NGs with AF over ten years from 2005 to 2014 using a publically available database, the National Inpatient Sample. METHODS: All hospitalizations and major outcomes of subjects ≥ 90 years with a primary diagnosis of AF (ICD-9-CM code 427.31) over a ten-year period were assessed in this study by multivariate logistic regression analysis. RESULTS: There were more females than males (176,268 females, 51,384 males) in this analysis. The number of hospitalizations for AF among NG increased by 50% (17,295 in 2005 to 25,830 in 2014). Males were more likely to undergo cardioversion (6.14% of males vs. 5.06% of females, P < 0.0001). Over this period, in-hospital mortality declined from 3.21% in 2005 to 2.38% in 2014 ( P = 0.0041), with higher in-hospital mortality in males (3.23% in males vs. 2.76% in females, P = 0.0138), mean length of hospitalization decreased from 4.53 days to 4.13 days (P < 0.0001), the prevalence of congestive heart failure fell from 0.48% to 0.23% ( P = 0.0257), and the use of anticoagulation increased from 6.09% to 14.54% (P < 0.0001). In a multivariate analysis, hospital admission on the weekend, Elixhauser comorbidity index, CHA 2DS2VASc score, acute respiratory failure, and the length of hospital stay were associated with a higher risk of in-hospital mortality. CONCLUSIONS: From 2005 to 2014, AF-related hospitalizations among NGs increased, more so in in females population, mortality trends improved, rates of anticoagulation increased, and cardioversions increased. Despite the decreasing trend of in-hospital mortality since 2005, the relatively high mortality rate in males warrants further studies.

Utility of Inferior Lead Q-waveforms in diagnosing Ventricular Tachycardia.

BACKGROUND: Electrocardiogram (ECG) differentiation of wide complex tachycardia (WCT) into ventricular tachycardia (VT) and supraventricular tachycardia with aberration (SVT-A) is often challenging. OBJECTIVE: To determine if the presence of Q-waveforms (QS, Qr, QRs) in the inferior leads (II, III, aVF) can differentiate VT from SVT-A in a WCT compared to Brugada algorithm. We studied 2 inferior lead criteria namely QWC-A where all the inferior leads had a similar Q wave pattern and QWC-B where only lead aVF had a Q-waveform. METHODS: A total of 181 consecutive cases of WCT were identified, digitally separated into precordial leads and inferior leads and independently reviewed by 2 electrophysiologists. An electrocardiographic diagnosis of VT or SVT-A was assigned based on Brugada and inferior lead algorithms. Results were compared to the final clinical diagnosis. RESULTS: VT was the final clinical diagnosis in 24.9% of ECG cohort (45/181); 75.1% (136/181) were SVT-A. QWC-A and QWC-B had a high specificity (93.3% and 82.8%) and accuracy (78.2% and 71.0%), but low sensitivity (33.3% and 35.6%) in differentiating VT from SVT-A. The Brugada algorithm yielded a sensitivity of 82.2% and specificity of 68.4%. Area under the curve in ROC analysis was highest with Brugada algorithm (0.75, 95% CI 0.69-0.81) followed by QWC-A (0.63, 95% CI 0.56-0.70) and QWC-B (0.59, 95% CI 0.52-0.67). CONCLUSION: QWC-A and QWC-B criteria had poor sensitivity but high specificity in diagnosing VT in patients presenting with WCT. Further research combining this simple criterion with other newer diagnostic algorithms can potentially improve the accuracy of the overall diagnostic algorithm.

Supraventricular tachycardia of the sick, a unique entity.

OBJECTIVE: This study explored a unique form of atrioventricular nodal reentrant tachycardia (AVNRT) in which certain acutely ill patients have a first episode of supraventricular tachycardia (SVT) with a short RP interval. METHODS: A retrospective chart review was conducted of patients at a single institution who developed SVT with short RP and yielded 19 patients. RESULTS: None of the 19 patients had a prior history of AVNRT or any other arrhythmia. The mean age was 58 years, the majority of patients were male (13/19), and there was a presence of hypertension (10/19), diabetes mellitus (5/19), hyperlipidemia (7/19), congestive heart failure (2/19), coronary artery disease (3/19), obstructive sleep apnea (2/19), and active cancer (8/19). The reasons for admission were planned surgery (8/19), sepsis (8/19), drug abuse (2/19), and neurological disorder (2/19). The AVNRT either terminated spontaneously or following the administration of adenosine. The patients were treated with amiodarone (12/19), metoprolol (6/19), or diltiazem (1/19). Follow-up (mean: 370 days) details revealed that patients were on amiodarone (3/19), metoprolol (6/19), were not taking any cardiac medication (5/19), or had passed away (5/19). Only 1 patient had a recurrence of AVNRT, and none of the patients required ablation therapy. CONCLUSION: 'AVNRT of the sick' has not been previously described in the medical literature, to our knowledge. It can be successfully treated with medications and the chance of recurrence after resolution of the acute illness is small.

An unusual pacing artifact.

Cardiac implantable electronic devices (CIEDs) are widely used in current practice. Analyzing the electrocardiographic patterns of these devices and having knowledge of artifacts is crucial to appropriate CIED management. A 32-year-old female patient presented at the device clinic for a routine follow-up visit. A dual-chamber pacemaker had been implanted 12 years previously for sinus node dysfunction. An initial 12-lead electrocardiogram (ECG) prompted concern due to a cyclical pattern of multiple, rapid pacing stimulus artifacts. Device interrogation revealed normal overall pacemaker function. Turning the pace gain function of the ECG machine off failed to eliminate the artifact. On review of the past medical history, the patient was found to have a prior diagnosis of congenital central hypoventilation syndrome and pulmonary hypertension, for which she underwent insertion of a diaphragmatic pacemaker. Interrogation of the diaphragmatic pacemaker revealed that the programmed parameters correlated with the frequency of the artifact noted on the ECG. In cardiac pacing, a single stimulus artifact of sufficient threshold can enable myocardial capture. Capturing diaphragmatic pacing, however, requires a train of multiple stimuli above the threshold. Thus, an understanding of the pacing configurations of various electrical devices that can potentially interfere with CIEDs is crucial to appropriate patient management.

Prescription Patterns and Outcomes of Patients With Atrial Fibrillation Treated With Direct Oral Anticoagulants and Warfarin: A Real-World Analysis.

BACKGROUND: Direct oral anticoagulants (DOACs) have been found to be similar or superior to warfarin in reducing ischemic stroke and intracranial hemorrhage (ICH) in patients with atrial fibrillation (AF). We sought to examine the anticoagulation prescription patterns in community since the advent of DOACs and also evaluate the outcomes in terms of gastrointestinal (GI) bleeding, ischemic stroke, and ICH in real-world patients with AF receiving anticoagulation. METHODS: This is a retrospective study comprising patients who were newly diagnosed with nonvalvular AF and were prescribed anticoagulants for stroke prevention. Prescription pattern of the anticoagulants based on CHA2DS2Vasc score was studied. Clinical outcomes of GI bleeding, ischemic stroke, and ICH were analyzed using a multivariate logistic regression model. RESULTS: Of the 2362 patients with AF on anticoagulation, 44.7% were prescribed DOACs. Patients with CHA2DS2VASc score of ≥3 received a prescription for warfarin more often than DOACs (P < .001). Multivariate logistic regression analysis revealed that the incidence of GI bleed (odds ratio [OR]: 0.91, 95% confidence interval [CI]: 0.62-1.35, P = .66) and stroke (OR: 0.77, 95% CI: 0.57-1.05, P = .10) was similar between warfarin and DOAC users. However, there was a trend toward lower ICH in the DOAC group (OR: 0.60, 95% CI: 0.36-1.01, P = .06). CONCLUSIONS: Prescription rate of DOACs for nonvalvular AF has increased significantly, with apixaban being the most commonly used agent. Patients with higher CHA2DS2-VASc score (≥3) are prescribed DOACs less often than warfarin. The reason for this discrepancy is unclear. Given the favorable risk-benefit profile of DOACs, further studies are needed to identify factors that determine anticoagulant selection in patients with AF with high thromboembolic risk.

Coronary artery injury related to catheter ablation of cardiac arrhythmias: A systematic review.

INTRODUCTION: Catheter ablation (CA) has emerged as the preferred modality of treatment for many cardiac arrhythmias. Anatomical sites of ablation are often located in close proximity to coronary arteries. However, the incidence of CA-related coronary injury has not been well studied. We sought to systematically evaluate all cases of CA-related coronary injuries. METHODS AND RESULTS: A PubMed search was conducted from inception until May 1, 2017 using the keywords "coronary artery" and "ablation." We identified 2817 published articles of which 43 articles met our inclusion criteria representing 61 cases of coronary artery injury attributed to CA procedures from 1992 to 2017. Posteroseptal accessory pathway ablation was associated with the highest incidence of coronary injury (35.6% of cases), followed by cavotricuspid isthmus-dependent flutter (19.3%). The right coronary artery was the site of injury in over two-thirds of all reported cases. Coronary injury was detected intraprocedurally in about half of the cases (43.1%), whereas it was a delayed presentation in the other half. Coronary intervention was performed in a third of all cases (32.7%). There were a total of three deaths attributed to coronary artery injury. CONCLUSIONS: Most (91.8%) coronary injuries are a result of anatomic proximity to the site of ablation. Awareness of the relation between coronary artery course and anatomical site of ablation could prevent myocardial damage and improve procedural safety.