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.

Left Atrial Appendage Closure: An Alternative to Anticoagulation for Stroke Prevention in Patients with Kidney Disease.

Anticoagulation to reduce thromboembolic stroke risk due to nonvalvular atrial fibrillation in ESKD is associated with increased bleeding. There is an existing debate in ESKD centers around the pros and cons of anticoagulation. We propose percutaneous left atrial appendage occlusion as a third alternative to balance thrombosis and bleeding risks in this high-risk population.

Major adverse cardiac events in symptomatic women with non-obstructive CAD on coronary CTA: pooled analysis from PROMISE and SCOT-HEART.

The presence of non-obstructive coronary artery disease (CAD) on coronary computed tomography angiography (CTA) has been associated with the occurrence of major adverse cardiac events (MACE). However, factors associated with the development of MACE in symptomatic women with non-obstructive CAD on coronary CTA have not been fully elucidated. We sought to examine the influence of risk factors and coronary artery calcification on MACE in symptomatic women with non-obstructive CAD on coronary CTA. Women from PROMISE and SCOT-HEART trials with none or non-obstructive CAD on coronary CTA comprised the study cohort. Baseline characteristics and clinical presentation were assessed. Survival analysis using Kaplan-Meier curves was done to compare outcomes stratified by the atherosclerotic cardiovascular disease (ASCVD) risk score and the Agatston score. The primary endpoint was a composite of all-cause mortality, myocardial infarction, and revascularization. 2597 women had non-obstructive CAD or normal coronary CTA, with a median follow-up of 32 months. Compared to women without MACE, women with MACE had lower high-density lipoprotein cholesterol (HDL-C) levels and higher mean ASCVD risk scores. Further, women with non-obstructive CAD and ASCVD ≥ 7.5% had higher risk of MACE than those with ASCVD < 7.5% [3.2% vs. 1.1%, adjusted HR (aHR) of 3.1 (95% CI 1.32, 7.23), P-value 0.009]. The Agatston calcium score, on the other hand, was not independently associated with MACE among this population of symptomatic women. Symptomatic women with non-obstructive CAD on coronary CTA are at higher risk for MACE, with the ASCVD risk score being independently associated with the occurrence of adverse events.

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.

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.

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.

His-bundle pacing: A novel treatment for left bundle branch block-mediated cardiomyopathy.

BACKGROUND: Chronic left bundle branch block (LBBB) can lead to LBBB-mediated cardiomyopathy from left ventricular dysynchrony. His-bundle pacing (HBP) results in direct electrical synchrony using the native His-Purkinje system, providing a novel treatment for this cardiomyopathy. OBJECTIVE: To assess the feasibility of HBP for cardiac resynchronization therapy (CRT) in LBBB-mediated cardiomyopathy patients. METHODS: Retrospective database review was conducted on patients who underwent CRT by the HBP capable provider at Indiana University Health and Eskenazi Hospital from August 2015 to August 2017. A subset of patients who met the predefined syndrome criteria of LBBB-mediated cardiomyopathy who underwent HBP were identified. Clinical, echocardiographic, and electrocardiographic variables were extracted at baseline and follow-up. RESULTS: Nine patients had cardiomyopathy and LBBB. Among those two were lost to follow-up. Seven patients were included in the analysis. The average time from device implantation to the last follow-up was 14.5 months. Left ventricular ejection fraction improved on average from 25% to 50% (p = .0001). The left ventricular end-systolic dimension decreased from 47 to 37 mm (p = .003) and the left ventricular end-diastolic dimension decreased from 55 to 48 mm (p = .03). QRS duration with HBP-CRT decreased from 152 to 115 ms. New York Heart Association classification improved from an average of 2.7-2. CONCLUSION: HBP is a viable technique for pursuing CRT in patients with LBBB-mediated cardiomyopathy.

Left Bundle Branch Block-Induced Cardiomyopathy in a Transplanted Heart Treated With His Bundle Pacing.

A 70-year-old male with prior orthotopic heart transplant developed left bundle branch block followed by new-onset left ventricular systolic dysfunction. He underwent His bundle pacing for cardiac resynchronization therapy with complete normalization of his ejection fraction. This is the first reported case of left bundle branch block-induced cardiomyopathy in a transplanted heart. (Level of Difficulty: Advanced.).

Mapping and Ablation of Ventricle Arrhythmia in Patients with Left Ventricular Assist Devices.

Ventricular arrhythmias (VA) constitute well-known problems in patients with left ventricular assist devices (LVADs), with incidence ranging from 18% to as high as 52%. Catheter ablation has become a common therapeutic intervention to treat drug-refractory VA, particularly with the increase and more widespread use of durable LVADs to bridge patients to transplantation or as destination therapy. In this article, we focus on etiology, mechanisms, periprocedural management, and mapping and ablation techniques in patients with LVADs and VA.

His Bundle Pacing in Heart Failure-Concept and Current Data.

PURPOSE OF REVIEW: His bundle pacing (HBP) has continued to emerge as a viable alternative to both right ventricular pacing (RVP) and cardiac resynchronization therapy. In recent years, a considerable amount of research has been published with regard to using HBP to treat congestive heart failure (CHF) and this article presents a concise yet comprehensive review of this literature. RECENT FINDINGS: Studies have demonstrated that HBP is useful for CHF patients who are non-responders to biventricular pacing (BiVP) or have a history of previously failed coronary sinus lead placement, right/left bundle branch block cardiomyopathy, or pacing-induced cardiomyopathy. Additionally, HBP is useful in patients with an indication for pacing who are expected to have a RVP burden exceeding 20%. The theoretical benefit of utilizing the native His Purkinje system to excite cardiac tissue is appealing as it can result in true cardiac resynchronization. Limited studies have shown its benefit in reducing heart failure symptoms and improving cardiac function. Larger randomized clinical trials and further investments into developing better technologies are highly desired to make its clinical use sustainable in the long run.

How to Perform His Bundle Pacing: Tools and Techniques.

Recently, permanent His bundle pacing (HBP) has emerged as a viable pacing strategy for chronic ventricular pacing. It allows for recruitment of the native His Purkinje system thereby preventing pacing-induced ventricular dyssynchrony seen in traditional right ventricular pacing. Current tools allow for relatively good success rates for implantation. Understanding the various responses to HBP is crucial for long-term success. With better tools and unique pacing and sensing algorithms designed specifically for this form of pacing, HBP is likely to increase as a tool for long-term pacing therapy.

Subvalvular aortic stenosis: a review of current literature.

Subvalvular aortic stenosis (SAS) is one of the common adult congenital heart diseases, with a prevalence of 6.5%. It is usually diagnosed in the first decade of life. Echocardiography is the test of choice to diagnose SAS. Surgical correction is the best treatment modality, and the prognosis is usually excellent. In this review, we describe the pathophysiology, diagnosis, prognosis, and management of SAS with a focus on different pathophysiologic mechanisms, diagnostic approach, and prognosis of the disease by reviewing the current literature.

Significance of inferior wall ischemia in non-dominant right coronary artery anatomy.

AIM: To investigate the relationship of inferior wall ischemia on myocardial perfusion imaging in patients with non-dominant right coronary artery anatomy. METHODS: This was a retrospective observational analysis of consecutive patients who presented to the emergency department with primary complaint of chest pain. Only patients who underwent single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) were included. Patients who showed a reversible defect on SPECT MPI and had coronary angiography during the same hospitalization was analyzed. Patients with prior history of coronary artery disease (CAD) including history of percutaneous coronary intervention and coronary artery bypass graft surgerys were excluded. True positive and false positive results were identified on the basis of hemodynamically significant CAD on coronary angiography, in the same territory as identified on SPECT MPI. Coronary artery dominance was determined on coronary angiography. Patients were divided into group 1 and group 2. Group 1 included patients with non-dominant right coronary artery (RCA) (left dominant and codominant). Group 2 included patients with dominant RCA anatomy. Demographics, baseline characteristics and positive predictive value (PPV) were analyzed for the two groups. RESULTS: The mean age of the study cohort was 57.6 years. Sixty-one point seven percent of the patients were males. The prevalence of self-reported diabetes mellitus, hypertension and dyslipidemia was 36%, 71.9% and 53.9% respectively. A comparison of baseline characteristics between the two groups showed that patients with a non-dominant RCA were more likely to be men. For inferior wall ischemia on SPECT MPI, patients in study group 2 had a significantly higher PPV, 32/42 (76.1%), compared to patients in group 1, in which only 3 out of the 29 patients (10.3%) had true positive results (P value < 0.001 Z test). The difference remained statistically significant even when only patients with left dominant coronary system (without co-dominant) were compared to patients with right dominant system (32/40, 76.1% in right dominant group, 3/19, 15.8% in left dominant group, P value < 0.001 Z test). There was no significant difference in mean hospital stay, re-hospitalization, and in-hospital mortality between the two groups. CONCLUSION: The positive predictive value of SPECT MPI for inferior wall ischemia is affected by coronary artery dominance. More studies are needed to explain this phenomenon.