Polymorphic ventricular tachycardia and cardiac arrest from abiraterone-induced hypokalemia: a case report.

BACKGROUND: Polymorphic ventricular tachycardia (PMVT) is an unstable and often fatal cardiac tachyarrhythmia. While there are many causes of this rhythm, including electrolyte imbalances, ischemia, and genetic disorders, iatrogenic etiologies are important to recognize. Abiraterone is an androgen synthesis antagonist effective in treating prostate cancer, but here we describe a case of severe hypokalemia secondary to abiraterone resulting in polymorphic ventricular tachycardia and cardiac arrest. While this is a potential adverse effect of the medication, severe hypokalemia causing polymorphic ventricular tachycardia and cardiac arrest, as seen in our patient's case, has not been described. CASE PRESENTATION: A 78-year-old African-American man with history of prostate cancer presents with polymorphic ventricular tachycardia and cardiac arrest. After resuscitation, he was found to be severely hypokalemic and refractory to large doses of repletion. Evaluation of secondary causes of hypokalemia identified the likely culprit to be adverse effects from prostate cancer treatment. CONCLUSION: A broad differential diagnosis for polymorphic ventricular tachycardia is essential in identifying and treating patients presenting in this rhythm. Here we present a case of iatrogenic polymorphic ventricular tachycardia secondary to oncologic treatment.

An inherited life-threatening arrhythmia model established by screening randomly mutagenized mice.

Inherited arrhythmia syndromes (IASs) can cause life-threatening arrhythmias and are responsible for a significant proportion of sudden cardiac deaths (SCDs). Despite progress in the development of devices to prevent SCDs, the precise molecular mechanisms that induce detrimental arrhythmias remain to be fully investigated, and more effective therapies are desirable. In the present study, we screened a large-scale randomly mutagenized mouse library by electrocardiography to establish a disease model of IASs and consequently found one pedigree that exhibited spontaneous ventricular arrhythmias (VAs) followed by SCD within 1 y after birth. Genetic analysis successfully revealed a missense mutation (p.I4093V) of the ryanodine receptor 2 gene to be a cause of the arrhythmia. We found an age-related increase in arrhythmia frequency accompanied by cardiomegaly and decreased ventricular contractility in the Ryr2I4093V/+ mice. Ca2+ signaling analysis and a ryanodine binding assay indicated that the mutant ryanodine receptor 2 had a gain-of-function phenotype and enhanced Ca2+ sensitivity. Using this model, we detected the significant suppression of VA following flecainide or dantrolene treatment. Collectively, we established an inherited life-threatening arrhythmia mouse model from an electrocardiogram-based screen of randomly mutagenized mice. The present IAS model may prove feasible for use in investigating the mechanisms of SCD and assessing therapies.

Evaluation of cardiac arrhythmia in pediatric patients with Left Ventricular Assist Device (L-VAD).

OBJECTIVE: Pediatric heart failure is an important cause of morbidity and mortality in childhood. Left ventricular assist devices (L-VAD) are used for bridging to transplantation in patients with indications for heart transplantation. PATIENTS AND METHODS: The children included in the study were patients who underwent implantation of an L-VAD due to advanced heart failure at Ege University Faculty of Medicine Hospital between January 2009 and January 2023. RESULTS: Of the 33 patients who underwent L-VAD implantation, 16 (48.5%) were female and 17 (51.5%) were male. The median age at surgery was 13 years (IQR, 9.5-15). The median weight was 44 kg (IQR, 25.65-52), the median height was 158 cm (IQR, 134.5-168.5), and the median body surface area was 1.37 m2 (IQR, 0.95-1.51). All patients who underwent L-VAD implantation had an echocardiographic diagnosis of dilated cardiomyopathy. The patients underwent a median of 16 (IQR, 9-21) ECGs, and the median number of 24-hour Holter ECGs obtained was 3 (IQR, 2-5). Arrhythmias that occurred after L-VAD implantation were classified as atrial and ventricular. Ventricular arrhythmia included ventricular tachycardia (VT) lasting for more than 30 seconds (sustained VT), VT lasting for less than 30 seconds (nonsustained VT), and ventricular fibrillation. Atrial arrhythmias included atrial flutter, atrial fibrillation, supraventricular tachycardia, and atrial ectopic tachycardia. During the follow-up, atrial or ventricular arrhythmias were observed in 11 (33%) patients. The most common rhythm disturbances before L-VAD implantation were ventricular arrhythmias, while after the surgery, atrial arrhythmias were found to be the most frequent. A total of 5 patients underwent cardioversion (n=2) or defibrillation (n=3) due to arrhythmia. CONCLUSIONS: In patients undergoing L-VAD implantation, rhythm disorders that could normally lead to hemodynamic instability are frequently encountered. In these rhythm disorders, medical therapy should be attempted before resorting to cardioversion or defibrillation, and subsequently, more aggressive treatment methods should be considered.

Impact of ventricular tachycardia ablation in subcutaneous implantable cardioverter defibrillator carriers: a multicentre, international analysis from the iSUSI project.

AIMS: Catheter ablation (CA) of ventricular tachycardia (VT) has become an important tool to improve clinical outcomes in patients with appropriate transvenous implantable cardioverter defibrillator (ICD) shocks. The aim of our analysis was to test whether VT ablation (VTA) impacts long-term clinical outcomes even in subcutaneous ICD (S-ICD) carriers. METHODS AND RESULTS: International Subcutaneous Implantable Cardioverter Defibrillator (iSUSI) registry patients who experienced either an ICD shock or a hospitalization for monomorphic VT were included in this analysis. Based on an eventual VTA after the index event, patients were divided into VTA+ vs. VTA- cohorts. Primary outcome of the study was the occurrence of a combination of device-related appropriate shocks, monomorphic VTs, and cardiovascular mortality. Secondary outcomes were addressed individually. Among n = 1661 iSUSI patients, n = 211 were included: n = 177 experiencing ICD shocks and n = 34 hospitalized for VT. No significant differences in baseline characteristics were observed. Both the crude and the yearly event rate of the primary outcome (5/59 and 3.8% yearly event rate VTA+ vs. 41/152 and 16.4% yearly event rate in the VTA-; log-rank: P value = 0.0013) and the cardiovascular mortality (1/59 and 0.7% yearly event rate VTA+ vs. 13/152 and 4.7% yearly event rate VTA-; log-rank P = 0.043) were significantly lower in the VTA + cohort. At multivariate analysis, VTA was the only variable remaining associated with a lower incidence of the primary outcome [adjusted hazard ratio 0.262 (0.100-0.681), P = 0.006]. CONCLUSION: In a real-world registry of S-ICD carriers, the combined study endpoint of arrhythmic events and cardiovascular mortality was lower in the patient cohort undergoing VTA at long-term follow-up. CLINICALTRIALS.GOV IDENTIFIER: NCT0473876.

Management of patients with an electrical storm or clustered ventricular arrhythmias: a clinical consensus statement of the European Heart Rhythm Association of the ESC-endorsed by the Asia-Pacific Heart Rhythm Society, Heart Rhythm Society, and Latin-American Heart Rhythm Society.

Electrical storm (ES) is a state of electrical instability, manifesting as recurrent ventricular arrhythmias (VAs) over a short period of time (three or more episodes of sustained VA within 24 h, separated by at least 5 min, requiring termination by an intervention). The clinical presentation can vary, but ES is usually a cardiac emergency. Electrical storm mainly affects patients with structural or primary electrical heart disease, often with an implantable cardioverter-defibrillator (ICD). Management of ES requires a multi-faceted approach and the involvement of multi-disciplinary teams, but despite advanced treatment and often invasive procedures, it is associated with high morbidity and mortality. With an ageing population, longer survival of heart failure patients, and an increasing number of patients with ICD, the incidence of ES is expected to increase. This European Heart Rhythm Association clinical consensus statement focuses on pathophysiology, clinical presentation, diagnostic evaluation, and acute and long-term management of patients presenting with ES or clustered VA.

Vericiguat suppresses ventricular tachyarrhythmias inducibility in a rabbit myocardial infarction model.

BACKGROUND: The VICTORIA trial demonstrated a significant decrease in cardiovascular events through vericiguat therapy. This study aimed to assess the potential mechanisms responsible for the reduction of cardiovascular events with vericiguat therapy in a rabbit model of myocardial infarction (MI). METHODS: A chronic MI rabbit model was created through coronary artery ligation. Following 4 weeks, the hearts were harvested and Langendorff perfused. Subsequently, electrophysiological examinations and dual voltage-calcium optical mapping studies were conducted at baseline and after administration of vericiguat at a dose of 5 µmol/L. RESULTS: Acute vericiguat therapy demonstrated a significant reduction in premature ventricular beat burden and effectively suppressed ventricular arrhythmic inducibility. The electrophysiological influences of vericiguat therapy included an increased ventricular effective refractory period, prolonged action potential duration, and accelerated intracellular calcium (Cai) homeostasis, leading to the suppression of action potential and Cai alternans. The pacing-induced ventricular arrhythmias exhibited a reentrant pattern, attributed to fixed or functional conduction block in the peri-infarct zone. Vericiguat therapy effectively mitigated the formation of cardiac alternans as well as the development of reentrant impulses, providing additional anti-arrhythmic benefits. CONCLUSIONS: In the MI rabbit model, vericiguat therapy demonstrates anti-ventricular arrhythmia effects. The vericiguat therapy reduces ventricular ectopic beats, inhibiting the initiation of ventricular arrhythmias. Furthermore, the therapy successfully suppresses cardiac alternans, preventing conduction block and, consequently, the formation of reentry circuits.

Cryocure-VT: the safety and effectiveness of ultra-low-temperature cryoablation of monomorphic ventricular tachycardia in patients with ischaemic and non-ischaemic cardiomyopathies.

AIMS: The ultra-low-temperature cryoablation (ULTC) ablation system using -196°C N2 cryogen has been reported to create lesions with freeze duration-dependent depth titratable to over 10 mm with minimum attenuation by scar. Cryocure-VT (NCT04893317) was a first-in-human clinical trial evaluating the safety and efficacy of a novel, purpose-built ULTC catheter in endocardial ablation of scar-dependent ventricular tachycardias (VTs). METHODS AND RESULTS: This prospective, multi-centre study enrolled patients referred for de novo or second ablations of recurrent monomorphic VT of both ischaemic and non-ischaemic aetiologies. Primary safety and efficacy endpoints of the study were freedom from device- or procedure-related major adverse events (MAEs) up to 30 days post-ablation, acute non-inducibility of clinical VTs at the end of the procedure, and freedom from sustained VT or implantable defibrillator intervention at 6 months. Ultra-low-temperature cryoablation was performed in 64 patients (age 67 ± 11 years, 78% ischaemic, ejection fraction = 35 ± 10%) at 9 centres. The primary acute effectiveness endpoint was achieved in 94% (51/54) of patients in whom post-ablation induction was attempted. There were no protocol-defined MAEs; four procedure-related serious adverse events resolved without clinical sequelae. At 6-month follow-up, 38 patients (60.3%) remained VT-free, and freedom from defibrillator shock was 81.0%, with no significant difference between ischaemic and non-ischaemic cohorts. In 47 patients with defibrillator for at least 6 months prior to the ablation, the VT burden was reduced from median of 4, inter-quartile range (IQR, 1-9) to 0, IQR (0-2). CONCLUSION: In this first-in-human multi-centre experience, endocardial ULTC ablation of monomorphic VT appears safe and effective in patients with both ischaemic-cardiomyopathy and non-ischaemic-cardiomyopathy. CLINICAL TRIAL REGISTRATION: NCT04893317.

Non-paroxysmal junctional tachycardia complicating disseminated intravascular coagulation during massive surgical hemorrhage: A case report.

RATIONALE: Non-paroxysmal junctional tachycardia (NPJT) is a self-limiting supraventricular tachycardia associated with primary heart disease, cardiac surgery, digitalis toxicity, and metabolic or electrolyte imbalances. However, NPJT caused enhanced normal automaticity even in the absence of structural heart disease can be fatal if not managed properly. PATIENT CONCERNS: A 74-year-old hypertensive female patient was scheduled for transureteroureterostomy and right ureteroneocystostomy under general anesthesia. DIAGNOSIS: The patient developed NPJT without visible P wave and severe hypotension due to adrenergic stimulation in response to massive hemorrhage during surgery. INTERVENTIONS: NPJT with hypotension was initially converted to sinus rhythm with normotension with administration of adenosine and esmolol. However uncontrolled surgical hemorrhage and administration of large dose of vasopressors eventually perpetuated NPJT refractory to antiarrhythmic drugs. OUTCOMES: Despite intravenous fluid resuscitation and massive transfusion, the patient was deteriorated hemodynamically due to uncontrolled bleeding and persistent NPJT, which resulted in hypovolemic shock and fatal disseminated intravascular coagulation (DIC). LESSONS: NPJT can occur by enhanced automaticity due to increased catecholamine during severe surgical hemorrhage. Although NPJT is generally self-limiting, it can be refractory to antiarrhythmic agents and accelerate hypotension if the surgical bleeding is uncontrolled. Therefore, aggressive management of the primary pathologic condition is crucial for the management of NPJT and hemodynamic collapse even in the absence of structural heart disease.

Discrimination between ventricular tachycardia and wide-QRS preexcited tachycardia.

BACKGROUND: To develop a new algorithm to differentiate ventricular tachycardia (VT) from preexcited tachycardia (pre-ET) according to left bundle branch block (LBBB) and right bundle branch block (RBBB) patterns. METHODS: This study included 67 electrocardiograms (ECGs) with VT and 63 ECGs with pre-ET, collected from our hospital and through PubMed. Of those, 64 were allocated to the derivation cohort and the rest to the validation cohort. The diagnoses of the ECGs were confirmed using an electrophysiological study. Parameters and classifiers from prior algorithms along with the propagation speeds in the early portion of the QRS complex (initial deflection index) in leads V1, V6, aVR, II, and III were manually measured. The performance of the new algorithm was compared with that of prior algorithms. RESULTS: The initial deflection index in lead III was the strongest predictor of pre-ET in LBBB-pattern wide-QRS tachycardia (p = 0.003, AUC 0.805). The initial deflection index in lead V1 was the most powerful predictor of pre-ET in RBBB-pattern wide-QRS tachycardia (p = 0.001, AUC 0.848). Compared to earlier algorithms, those using the initial deflection indexes: lead III in LBBB patterns (cutoff value >0.3) and lead V1 in RBBB patterns (cutoff value ≤0.48), demonstrated superior performance in screening VT, with AUC values of 0.828. The initial deflection indexes proved effective as discriminators between VT and pre-ET in the validation cohort. CONCLUSIONS: In LBBB-pattern wide-QRS tachycardia, the early propagation speed of pre-ET was faster than that in VT. Conversely, in RBBB-pattern wide-QRS tachycardia, it was slower.

RV1+RV3 Index to Differentiate Idiopathic Ventricular Arrhythmias Arising From Right Ventricular Outflow Tract and Aortic Sinus of Valsalva: A Multicenter Study.

BACKGROUND: This study aimed to investigate the predictive value of parameters of every precordial lead and their combinations in differentiating between idiopathic ventricular arrhythmias (IVAs) from the right ventricular outflow tract and aortic sinus of Valsalva (ASV). METHODS AND RESULTS: Between March 1, 2018, and December 1, 2021, consecutive patients receiving successful ablation of right ventricular outflow tract or ASV IVAs were enrolled. The amplitude and duration of the R wave and S wave were measured in every precordial lead during IVAs. These parameters were either summed, subtracted, multiplied, or divided to create different indexes. The index with the highest area under the curve to predict ASV IVAs was developed, compared with established indexes, and validated in an independent prospective multicenter cohort. A total of 150 patients (60 men; mean age, 45.3±16.4 years) were included in the derivation cohort. The RV1+RV3 index (summed R-wave amplitude in leads V1 and V3) had the highest area under the curve (0.942) among the established indexes. An RV1+RV3 index >1.3 mV could predict ASV IVAs with a sensitivity of 95% and a specificity of 83%. Its predictive performance was maintained in the validation cohort (N=109). In patients with V3 R/S transition, an RV1+RV3 index >1.3 mV could predict ASV IVAs, with an area under the curve of 0.892, 93% sensitivity, and 75% specificity. CONCLUSIONS: The RV1+RV3 index is a simple and novel criterion that accurately differentiates between right ventricular outflow tract and ASV IVAs. Its performance outperformed established indexes, making it a valuable tool in clinical practice.

Clinical Decision Support Requirements for Ventricular Tachycardia Diagnosis Within the Frameworks of Knowledge and Practice: Survey Study.

BACKGROUND: Ventricular tachycardia (VT) diagnosis is challenging due to the similarity between VT and some forms of supraventricular tachycardia, complexity of clinical manifestations, heterogeneity of underlying diseases, and potential for life-threatening hemodynamic instability. Clinical decision support systems (CDSSs) have emerged as promising tools to augment the diagnostic capabilities of cardiologists. However, a requirements analysis is acknowledged to be vital for the success of a CDSS, especially for complex clinical tasks such as VT diagnosis. OBJECTIVE: The aims of this study were to analyze the requirements for a VT diagnosis CDSS within the frameworks of knowledge and practice and to determine the clinical decision support (CDS) needs. METHODS: Our multidisciplinary team first conducted semistructured interviews with seven cardiologists related to the clinical challenges of VT and expected decision support. A questionnaire was designed by the multidisciplinary team based on the results of interviews. The questionnaire was divided into four sections: demographic information, knowledge assessment, practice assessment, and CDS needs. The practice section consisted of two simulated cases for a total score of 10 marks. Online questionnaires were disseminated to registered cardiologists across China from December 2022 to February 2023. The scores for the practice section were summarized as continuous variables, using the mean, median, and range. The knowledge and CDS needs sections were assessed using a 4-point Likert scale without a neutral option. Kruskal-Wallis tests were performed to investigate the relationship between scores and practice years or specialty. RESULTS: Of the 687 cardiologists who completed the questionnaire, 567 responses were eligible for further analysis. The results of the knowledge assessment showed that 383 cardiologists (68%) lacked knowledge in diagnostic evaluation. The overall average score of the practice assessment was 6.11 (SD 0.55); the etiological diagnosis section had the highest overall scores (mean 6.74, SD 1.75), whereas the diagnostic evaluation section had the lowest scores (mean 5.78, SD 1.19). A majority of cardiologists (344/567, 60.7%) reported the need for a CDSS. There was a significant difference in practice competency scores between general cardiologists and arrhythmia specialists (P=.02). CONCLUSIONS: There was a notable deficiency in the knowledge and practice of VT among Chinese cardiologists. Specific knowledge and practice support requirements were identified, which provide a foundation for further development and optimization of a CDSS. Moreover, it is important to consider clinicians' specialization levels and years of practice for effective and personalized support.

Comparison of continuous 24-hour and 14-day ECG monitoring for the detection of cardiac arrhythmias in patients with ischemic stroke or syncope.

BACKGROUND: Previous studies show that using 12-lead electrocardiogram (ECG) or 24-h ECG monitor for the detection of cardiac arrhythmia events in patients with stroke or syncope is ineffective. HYPOTHESIS: The 14-day continuous ECG patch has higher detection rates of arrhythmias compared with conventional 24-h ECG monitoring in patients with ischemic stroke or syncope. METHODS: This cross-sectional study of patients with newly diagnosed ischemic stroke or syncope received a 24-h ECG monitoring and 14-day continuous cardiac monitoring patch and the arrhythmia events were measured. RESULTS: This study enrolled 83 patients with ischemic stroke or syncope. The detection rate of composite cardiac arrhythmias was significantly higher for the 14-day ECG patch than 24-h Holter monitor (69.9% vs. 21.7%, p = .006). In patients with ischemic stroke, the detection rates of cardiac arrhythmias were 63.4% for supraventricular tachycardia (SVT), 7% for ventricular tachycardia (VT), 5.6% for atrial fibrillation (AF), 4.2% for atrioventricular block (AVB), and 1.4% for pause by 14-day ECG patch, respectively. The significant difference in arrhythmic detection rates were found for SVT (45.8%), AF (6%), pause (1.2%), AVB (2.4%), and VT (9.6%) by 14-day ECG patch but not by 24-h Holter monitor in patients with ischemic stroke or syncope. CONCLUSIONS: A 14-day ECG patch can be used on patients with ischemic stroke or syncope for the early detection of AF or other cardiac arrhythmia events. The patch can be helpful for physicians in planning medical or mechanical interventions of patients with ischemic stroke and occult AF.

Diagnosis and Management of Paroxysmal Supraventricular Tachycardia.

Importance: Paroxysmal supraventricular tachycardia (PSVT), defined as tachyarrhythmias that originate from or conduct through the atria or atrioventricular node with abrupt onset, affects 168 to 332 per 100 000 individuals. Untreated PSVT is associated with adverse outcomes including high symptom burden and tachycardia-mediated cardiomyopathy. Observations: Approximately 50% of patients with PSVT are aged 45 to 64 years and 67.5% are female. Most common symptoms include palpitations (86%), chest discomfort (47%), and dyspnea (38%). Patients may rarely develop tachycardia-mediated cardiomyopathy (1%) due to PSVT. Diagnosis is made on electrocardiogram during an arrhythmic event or using ambulatory monitoring. First-line acute therapy for hemodynamically stable patients includes vagal maneuvers such as the modified Valsalva maneuver (43% effective) and intravenous adenosine (91% effective). Emergent cardioversion is recommended for patients who are hemodynamically unstable. Catheter ablation is safe, highly effective, and recommended as first-line therapy to prevent recurrence of PSVT. Meta-analysis of observational studies shows single catheter ablation procedure success rates of 94.3% to 98.5%. Evidence is limited for the effectiveness of long-term pharmacotherapy to prevent PSVT. Nonetheless, guidelines recommend therapies including calcium channel blockers, ß-blockers, and antiarrhythmic agents as management options. Conclusion and Relevance: Paroxysmal SVT affects both adult and pediatric populations and is generally a benign condition. Catheter ablation is the most effective therapy to prevent recurrent PSVT. Pharmacotherapy is an important component of acute and long-term management of PSVT.

Acute myocardial infarction revealed by recurrent ventricular tachyarrhythmias detected by remote monitoring.

Remote monitoring (RM) of cardiac implantable electronic devices (CIED) represented a major improvement in clinical practice and has been used with multiple indications. Many parameters monitored on a daily basis by current CIED can indeed assist in clinical practice (eg, decompensated heart failure) by providing the patient with optimal timing for anticipated outpatient visit or urgent medical care. Recognition of acute myocardial infarction (AMI) is not usually considered among the capabilities of RM. We present the case of an AMI occurring without any ischaemic symptoms but associated with recurrent ventricular tachyarrhythmias effectively treated by multiple interventions of the implantable cardioverter defibrillator and promptly detected by RM personnel, who recommended the patient to quickly access to the emergency department where diagnosis and revascularization of an otherwise untreated myocardial infarction was performed.

Automated isochronal late activation mapping for substrate characterization in patients with repaired tetralogy of Fallot.

AIMS: Slow conduction (SC) anatomical isthmuses (AIs) are the dominant substrate for monomorphic ventricular tachycardia (VT) in patients with repaired tetralogy of Fallot (rTF). This study aimed to evaluate the utility of automated propagational analysis for the identification of SC-AI in patients with rTF. METHODS AND RESULTS: Consecutive rTF patients undergoing VT substrate characterization were included. Automated isochronal late activation maps (ILAM) were obtained with multielectrode HD Grid Catheter. Identified deceleration zones (DZs) were compared with both SC-AI defined by conduction velocity (CV) (<0.5 m/s) and isthmuses of induced VT for mechanistic correlation. Fourteen patients were included (age 48; p25-75 35-52 years; 57% male), 2 with spontaneous VT and 12 for risk stratification. Nine VTs were inducible in seven patients. Procedure time was 140 (p25-75 133-180) min and mapping time 29.5 (p25-75 20-37.7) min, using a median of 2167 points. All the patients had at least one AI by substrate mapping, identifying a total of 27 (11 SC-AIs). Isochronal late activation maps detected 10 DZs mostly in the AI between ventricular septal defect and pulmonary valve (80%). Five patients had no DZs. A significant negative correlation between number of isochrones/cm and CV was observed (rho -0.87; P < 0.001). Deceleration zones correctly identified SC-AI (90% sensitivity; 100% specificity; 0.94 accuracy) and was related to VT inducibility (P = 0.006). Deceleration zones co-localized to the critical isthmus of induced VTs in 88% of cases. No complications were observed. CONCLUSION: Deceleration zones displayed by ILAM during sinus rhythm accurately identify SC-AIs in rTF patients allowing a safe and short-time VT substrate characterization procedure.

Enhancing the accuracy of shock advisory algorithms in automated external defibrillators during ongoing cardiopulmonary resuscitation using a cascade of CNNEDs.

Delivery of continuous cardiopulmonary resuscitation (CPR) plays an important role in the out-of-hospital cardiac arrest (OHCA) survival rate. However, to prevent CPR artifacts being superimposed on ECG morphology data, currently available automated external defibrillators (AEDs) require pauses in CPR for accurate analysis heart rhythms. In this study, we propose a novel Convolutional Neural Network-based Encoder-Decoder (CNNED) structure with a shock advisory algorithm to improve the accuracy and reliability of shock versus non-shock decision-making without CPR pause in OHCA scenarios. Our approach employs a cascade of CNNEDs in conjunction with an AED shock advisory algorithm to process the ECG data for shock decisions. Initially, a CNNED trained on an equal number of shockable and non-shockable rhythms is used to filter the CPR-contaminated data. The resulting filtered signal is then fed into a second CNNED, which is trained on imbalanced data more tilted toward the specific rhythm being analyzed. A reliable shock versus non-shock decision is made when both classifiers from the cascade structure agree, while segments with conflicting classifications are labeled as indeterminate, indicating the need for additional segments to analyze. To evaluate our approach, we generated CPR-contaminated ECG data by combining clean ECG data with 52 CPR samples. We used clean ECG data from the CUDB, AFDB, SDDB, and VFDB databases, to which 52 CPR artifact cases were added, while a separate test set provided by the AED manufacturer Defibtech LLC was used for performance evaluation. The test set comprised 20,384 non-shockable CPR-contaminated segments from 392 subjects, as well as 3744 shockable CPR-contaminated samples from 41 subjects with coarse ventricular fibrillation (VF) and 31 subjects with rapid ventricular tachycardia (rapid VT). We observed improvements in rhythm analysis using our proposed cascading CNNED structure when compared to using a single CNNED structure. Specifically, the specificity of the proposed cascade of CNNED structure increased from 99.14% to 99.35% for normal sinus rhythm and from 96.45% to 97.22% for other non-shockable rhythms. Moreover, the sensitivity for shockable rhythm detection increased from 90.90% to 95.41% for ventricular fibrillation and from 82.26% to 87.66% for rapid ventricular tachycardia. These results meet the performance thresholds set by the American Heart Association and demonstrate the reliable and accurate analysis of heart rhythms during CPR using only ECG data without the need for CPR interruptions or a reference signal.

[Whether to implant a defibrillator or not? The Possibility of Using the MADIT-ICD Benefit Score Calculator in Real Practice].

AIM: To study the predictive capabilities of the MADIT-ICD Benefit Score calculator in assessing the benefit of implantable cardioverter defibrillator (ICD) placement for the primary prevention of sudden cardiac death (SCD). MATERIAL AND METHODS: This study included 388 patients with NYHA II-IV functional class chronic heart failure (CHF) with a left ventricular ejection fraction (LVEF) ≤35 % who underwent ICD placement for the primary prevention of SCD. Patients were followed up for two years to record the endpoints of first-time paroxysmal sustained ventricular tachyarrhythmia (VT) or non-arrhythmic death. RESULTS: According to the results of calculation with the MADIT-ICD Benefit Score calculator, 276 (71 %) patients had a high risk of VT (score ≥7) and 150 (39 %) had a high risk of non-arrhythmic death (score ≥3). 336 (94%) patients would benefit from an ICD: 148 (38 %) with a high level of probability and 218 (56 %) with a medium level of probability. According to the incidence of endpoints, VT episodes predominated in the low-ICD benefit group (36%), while the high-ICD benefit group had a relatively high incidence of non-arrhythmic death (12%). CONCLUSION: The results obtained for a cohort of Russian patients with CHF and reduced LVEF indicated that the use of the MADIT-ICD Benefit Score in routine clinical practice does not improve the stratification of SCD risk compared to the traditional approach to selecting patients with CHF for ICD based on the LVEF value.