Risk Of Ventricular Fibrillation Research Articles

T-wave Peak-to-End Changes Quantified by Time-Warping Predicts Ventricular Fibrillation in a Porcine Myocardial Infarction Model.

The T-peak-to-T-end ( Tpe) interval has shown potential in predicting ventricular arrhythmic risk. It is an appealing index to be measured during ischemia since it is less influenced by ST-segment changes than the early part of the T wave. A time-warping-based index, derived from a spatially transformed PCA lead, [Formula: see text], quantifying changes in the Tpe morphology, has previously demonstrated utility in tracking repolarization changes induced by a 5-minute ischemia model in humans. The value of [Formula: see text] as a predictor of ventricular fibrillation (VF) episodes is assessed in a porcine model of myocardial ischemia with ischemia maintained for 40 minutes. From 32 pigs undergoing a coronary occlusion, pre-occlusion and occlusion ECG recordings from 10 pigs suffering a VF episode after 10 min of occlusion (Delayed VF) and 16 that did not had any episode during the recording were analyzed. The [Formula: see text] series was measured by comparing Tpe morphologies at different stages of the occlusion relative to the peak-to-end morphology of a baseline T-wave. During baseline, [Formula: see text] remained stationary with an intra-recording median [IQR] value of 1.60 [1.33] ms. During artery occlusion, [Formula: see text] followed a well-marked gradual increasing trend as ischemia progressed, reaching a median of 14.58 [17.72] ms. [Formula: see text] averages were significantly higher ( ) in the VF group than in the Non-VF group at time intervals 0-5, 5-10, 10-15, 15-20, 20-25 min after occlusion onset and at 10-15, 5-10 and 5-0 minutes prior to VF episode, with median values of 12.5, 18.8, 26.8, 24.0, 31.0, 18.6, 25.0 and 28.8 vs 6.3, 7.6, 8.0, 7.8, 7.8, 8.5, 7.2 and 6.0 ms, respectively. The [Formula: see text] interval was also significantly higher in the VF group at all analyzed time periods, but with a lower significance level. Pigs with maximum [Formula: see text] ≥ 20.0 ms and [Formula: see text] ≥ 85.4 ms had significantly higher risk for VF occurring in the early 5-10 minutes interval, with 90.0%/75.0% and 80.0%/69.0% sensitivity/specificity, respectively. Univariate Cox analysis yielded hazard ratios of 12.5 for [Formula: see text] vs 5.5 for [Formula: see text]. The time-warping-based index, [Formula: see text], is a stronger VF predictor than [Formula: see text] during ischemia in a porcine model, advising for further clinical exploration studies in humans.

Defibrillation of Atrial Fibrillation is not Associated with Increased Risk of Ventricular Fibrillation – The VCD-Trial (Clinical Trial of Electrical Therapy for Atrial Fibrillation using R-wave Guided Cardioversion Versus Defibrillation)

Background: Because of a possible risk of induction of Ventricular Fibrillation (VF) by defibrillation of atrial fibrillation (AF) postulated by LOWN and coworkers, synchronized cardioversion is used worldwide. This prospective, randomized study assessed the efficacy and safety between R-wave controlled cardioversion and defibrillation of AF at 2 study centers in Cologne, Germany. Hypothesis: Defibrillation is not significantly different from cardioversion primarily in the occurrence of VF or sustained Ventricular Tachycardia (VT) and secondarily in restoring sinus rhythm, inducing non-sustained VT, asystole, or bradycardia. Methods: 146 patients at an outpatient practice and 122 at the university hospital were randomized to cardioversion (n = 140) or defibrillation (n = 124). Results: Cardioversion was successful in 92.1% of cases and defibrillation in 87.1%. The difference in efficacy was not statistically significant. In n = 1 patients receiving defibrillation, VF occurred after the first shock (200J) and immediate defibrillation (200J) restored sinus rhythm. In the n = 1 case, asystole occurred during cardioversion which terminated spontaneously. In n = 1 patients cardioverted and n = 2 who were defibrillated, sinus bradycardia occurred requiring Atropine in two cases. There were no thromboembolic events within 10 days. N = 9 patients reverted to AF within two hours. No patients died. Conclusion: Electrical conversion of AF can be performed with similar results and low risk with both R-wave-triggered cardioversion and defibrillation. In particular, defibrillation with higher energies (> 100J) can be performed as effectively and safely without a statistically significant increased risk of VF or VT. There was no difference in efficacy and risk between electrotherapy performed in the outpatient and inpatient settings.

Ventricular Arrhythmias After Primary Percutaneous Coronary Intervention for STEMI

Currently, mortality risk for patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) with an uncomplicated postprocedure course is low. Less is known regarding the risk of in-hospital ventricular tachycardia (VT) and ventricular fibrillation (VF). To evaluate the risk of late VT and VF after primary PCI for STEMI. This cohort study included adults aged 18 years or older with STEMI treated with primary PCI between January 1, 2015, and December 31, 2018, identified in the US National Cardiovascular Data Registry Chest Pain-MI Registry. Data were analyzed from April to December 2020. Multivariable logistic regression was used to evaluate the risk of late VT (≥7 beat run of VT during STEMI hospitalization ≥1 day after PCI) or VF (any episode of VF≥1 day after PCI) associated with cardiac arrest and associations between late VT or VF and in-hospital mortality in the overall cohort and a cohort with uncomplicated STEMI without prior myocardial infarction or heart failure, systolic blood pressure less than 90 mm Hg, cardiogenic shock, cardiac arrest, reinfarction, or left ventricular ejection fraction (LVEF) less than 40%. A total of 174 126 eligible patients with STEMI were treated with primary PCI at 814 sites in the study; 15 460 (8.9%) had VT or VF after primary PCI, and 4156 (2.4%) had late VT or VF. Among the eligible patients, 99 905 (57.4%) at 807 sites had uncomplicated STEMI. The median age for patients with late VT or VF overall was 63 years (IQR, 55-73 years), and 75.5% were men; the median age for patients with late VT or VF with uncomplicated STEMI was 60 years (IQR, 53-69 years), and 77.7% were men. The median length of stay was 3 days (IQR, 2-7 days) for the overall cohort with late VT or VF and 3 days (IQR, 2-4 days) for the cohort with uncomplicated STEMI with late VT or VF. The risk of late VT or VF was 2.4% (overall) and 1.7% (uncomplicated STEMI). Late VT or VF with cardiac arrest occurred in 674 patients overall (0.4%) and in 117 with uncomplicated STEMI (0.1%). LVEF was the most significant factor associated with late VT or VF with cardiac arrest (adjusted odds ratio [AOR] for every 5-unit decrease ≤40%: 1.67; 95% CI, 1.54-1.85). Late VT or VF events were associated with increased odds of in-hospital mortality in the overall cohort (AOR, 6.40; 95% CI, 5.63-7.29) and the cohort with uncomplicated STEMI (AOR, 8.74; 95% CI, 6.53-11.70). In this study, a small proportion of patients with STEMI treated with primary PCI had late VT or VF. However, late VT or VF with cardiac arrest was rare, particularly in the cohort with uncomplicated STEMI. This information may be useful when determining the optimal timing for hospital discharge after STEMI.

The Effects of Silymarin on Calcium Chloride-Induced Arrhythmia in Male Rat.

Antioxidants play an important role in protecting cardiac arrhythmias. Silymarin, strong antioxidant, is effective in reducing the complications caused by arrhythmias. This study was conducted to determine the effect of silymarin on the prevention and treatment of calcium chloride-induced arrhythmia. In total, 48 male rats were randomly divided into six groups: the first control group for acute administration received intravenous injection of 0.2 mL of dimethylsulfoxide, a cosolvent, immediately after induction of arrhythmia; the second control group for chronic administration, daily gavage of dimethylsulfoxide for 2 weeks before induction of arrhythmia; acute silymarin group, 100 mg/kg intravenous, immediately after the occurrence of arrhythmia; chronic silymarin group, daily gavage of 50 mg/kg for 2 weeks before induction of arrhythmia; amiodarone standard treatment, 5 mg/kg intravenous, immediately after induction of arrhythmia; and quinidine standard treatment, 10 mg/kg intravenous, immediately after induction of arrhythmia. Calcium chloride (140 mg/kg, i.v.) was used to induce arrhythmia. Electrocardiogram was recorded and monitored by PowerLab™ system. The incidence rates of premature ventricular beat (PVB), ventricular tachycardia (VT), and ventricular fibrillation (VF) were calculated. The antiarrhythmic effect of silymarin was observed with a significant decrease in the incidence of premature ventricular beat (22.56 ± 1.04%, P < 0.001), ventricular tachycardia (34.150 ± 1.59%, P < 0.001), and ventricular fibrillation (24.31 ± 1.02%, P < 0.001) compared with the control group (100%). These effects were comparable to antiarrhythmic drugs such as quinidine (29.23% ± 1.24%, 52.23% ± 1.13%, 66.31% ± 1.81%) and amiodarone (22.91% ± .72%, 41.09% ± 1.66%, 61.59% ± 1.11%). Silymarin exerts a potent antioxidant effect, thereby mitigating the risk of VT, VF, and PVC.

Complex repolarization dynamics in ex vivo human ventricles are independent of the restitution properties.

The mechanisms of transition from regular rhythms to ventricular fibrillation (VF) are poorly understood. The concordant to discordant repolarization alternans pathway is extensively studied; however, despite its theoretical centrality, cannot guide ablation. We hypothesize that complex repolarization dynamics, i.e. oscillations in the repolarization phase of action potentials with periods over two of classic alternans, is a marker of electrically unstable substrate, and ablation of these areas has a stabilizing effect and may reduce the risk of VF. To prove the existence of higher-order periodicities in human hearts. We performed optical mapping of explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Signals recorded from the right ventricle endocardial surface were processed to detect global and local repolarization dynamics during rapid pacing. A statistically significant global 1:4 peak was seen in three of six hearts. Local (pixel-wise) analysis revealed the spatially heterogeneous distribution of Periods 4, 6, and 8, with the regional presence of periods greater than two in all the hearts. There was no significant correlation between the underlying restitution properties and the period of each pixel. We present evidence of complex higher-order periodicities and the co-existence of such regions with stable non-chaotic areas in ex vivo human hearts. We infer that the oscillation of the calcium cycling machinery is the primary mechanism of higher-order dynamics. These higher-order regions may act as niduses of instability and may provide targets for substrate-based ablation of VF.

Abstract 15511: Predictors of Polymorphic Ventricular Tachycardia and Ventricular Fibrillation in Patients With Stress Cardiomyopathy

Introduction: Polymorphic ventricular tachycardia (PVT) and ventricular fibrillation (VF) are life-threatening complications of stress cardiomyopathy (SCM) that occur in 2-10% of patients with SCM. Hypothesis: To identify which social and medical factors are associated with an increased risk of PVT and VF in patients with SCM. Methods: All consecutive patients meeting the InterTAK (international takotsubo) diagnostic criteria for stress cardiomyopathy at the Hennepin County Medical Center between January 1 st , 2010, and December 31 st , 2022, were identified from electronic medical records. Logistic regression was used to estimate the odds ratios (OR). The receiver operating characteristic curve (ROC) was plotted to identify the best QTc cutoff at admission to predict ventricular arrhythmia. Results: A total of 296 patients were included in the study, of which 27 (9.1%) experienced PVT/VF. Baseline demographics, including gender, race, and age at diagnosis, were similar to patients without PVT/VF (median age 61 years, and 66.7% were females). Patients with PVT/VF were more likely to have a history of stimulant use (22.2% vs. 8.2%, OR =3.20 p =0.023), apical (Takotsubo) variant stress cardiomyopathy (78% vs.56%, OR=2.69 p=0.038), and an ejection fraction (EF) of less than 30% on admission (63% vs. 41.5%, OR=2.39 p=0.032) ( Table 1 ). Admission QTc interval cut-off value of 490 msec had the highest sensitivity and specificity in predicting the risk of ventricular arrhythmia (AUC=0.687). Notably, all PVT/VF events occurred within 17 hours of hospital admission. Conclusion: Nealy 1 in 10 patients with SCM had life-threatening ventricular arrhythmia. The presence of severe LV systolic dysfunction, recent stimulant use, apical variant SCM, or prolonged QTc &gt; 490 msec is associated with the occurrence of PVT/VF, with the first day of hospital admission being an especially high-risk period.

Early prediction of ventricular fibrillation using electrocardiographic characteristics in prehospital suspected ST-segment elevation myocardial infarction: a case-control study.

Our objective was to determine characteristics of electrocardiograms (ECG) that predict ventricular fibrillation (VF) among prehospital patients with suspected ST-segment elevation myocardial infarction (STEMI) in Québec. We performed a matched case-control study of prehospital adult suspected with STEMI. Patients in case group (STEMI/VF+) were matched with controls (STEMI/VF-) for age and sex and then compared for ECG characteristics, including ST-segment elevations (STE) and depressions (STD), duration of interval complexes, general characteristics, and several calculated variables. Logistic regression was used to measure the association between ECG characteristics and VF development. Overall, 310 prehospital patients with suspected STEMI were included in the analysis (case group, n = 155; control group, n = 155). We confirmed that the presence of TW-pattern complex (OR 7.0, 95% CI 1.55-31.58), premature ventricular contraction (PVC) (OR 5.5, 95% CI 2.04-14.82), and STE in V2-V6 (OR 3.8, 95% CI 1.21-11.74) were electrocardiographic predictors of VF. We also observed that STD in V3-V5 (OR 6.5, 95% CI 1.42-29.39), atrial fibrillation (AF) ≥ 100 beats per minute (bpm) (OR 6.3, 95% CI 1.80-21.90), the combination of STE in V4 and V5, and STD in II, III and aVF (OR 4.8, 95% CI 1.01-22.35), and the presence of STD in ≥ 6 leads (OR 4.2, 95% CI 1.33-13.13) were also associated with VF development. Finally, simultaneous association of 2 (OR 2.3, 95% CI 1.13-4.06) and 3 (OR 11.6, 95% CI 3.22-41.66) predictors showed significant association with VF. In addition to some already known predictors, we have identified several ECG findings associated with the development of VF in patients with suspected STEMI. Early identification of patients with STEMI at increased risk of VF should help EMS providers anticipate adverse events and encourage use of defibrillation pads.

Impact of Neuroeffector Adrenergic Receptor Polymorphisms on Incident Ventricular Fibrillation During Acute Myocardial Ischemia.

Background Cardiac adrenergic receptor gene polymorphisms have the potential to influence risk of developing ventricular fibrillation (VF) during ST-segment-elevation myocardial infarction, but no previous study has comprehensively investigated those most likely to alter norepinephrine release, signal transduction, or biased signaling. Methods and Results In a case-control study, we recruited 953 patients with ST-segment-elevation myocardial infarction without previous cardiac history, 477 with primary VF, and 476 controls without VF, and genotyped them for ADRB1 Arg389Gly and Ser49Gly, ADRB2 Gln27Glu and Gly16Arg, and ADRA2C Ins322-325Del. Within each minor allele-containing genotype, haplotype, or 2-genotype combination, patients with incident VF were compared with non-VF controls by odds ratios (OR) of variant frequencies referenced against major allele homozygotes. Of 156 investigated genetic constructs, 19 (12.2%) exhibited significantly (P<0.05) reduced association with incident VF, and none was associated with increased VF risk except for ADRB1 Gly389 homozygotes in the subset of patients not receiving β-blockers. ADRB1 Gly49 carriers (prevalence 23.0%) had an OR (95% CI) of 0.70 (0.49-0.98), and the ADRA2C 322-325 deletion (Del) carriers (prevalence 13.5%) had an OR of 0.61 (0.39-0.94). When present in genotype combinations (8 each), both ADRB1 Gly49 carriers (OR, 0.67 [0.56-0.80]) and ADRA2C Del carriers (OR, 0.57 [0.45- 0.71]) were associated with reduced VF risk. Conclusions In ST-segment-elevation myocardial infarction, the adrenergic receptor minor alleles ADRB1 Gly49, whose encoded receptor undergoes enhanced agonist-mediated internalization and β-arrestin interactions leading to cardioprotective biased signaling, and ADRA2C Del322-325, whose receptor causes disinhibition of norepinephrine release, are associated with a lower incidence of VF. Registration URL: https://clinicaltrials.gov; Unique identifier: NCT00859300.

Risk stratification of ventricular fibrillation in patients with symptomatic Brugada syndrome using pharmacological tests.

Brugada syndrome (BrS), which is characterized by J-point elevation in right precordial leads of a 12-lead electrocardiogram, is associated with the occurrence of ventricular fibrillation (VF). However, risk stratification of VF in patients with BrS remains challenging. The aim of this study was to identify a risk predictor of VF in patients with BrS using pharmacological tests. Twenty-one consecutive patients with BrS and a history of documented spontaneous VF (n = 16) or syncope presumed to be caused by lethal ventricular arrhythmia (n = 5) were enrolled. J-wave changes in response to intravenous verapamil, propranolol, and pilsicainide were separately assessed. During the median follow-up period of 86.0 months, 8 patients had VF recurrence (recurrence group) and 13 patients did not have VF recurrence (non-recurrence group). Intravenous propranolol injection induced significant J-wave augmentation (i.e., increase in amplitude >0.1 mV) in the inferior and/or lateral leads in the recurrence group compared to the non-recurrence group (p = .048 and p = .015, respectively). Kaplan-Meier analysis revealed that VF recurrence is significantly higher in patients with BrS and J-wave augmentation due to intravenous propranolol than in patients without J-wave augmentation (p = .014). The study results show that propranolol-induced J-wave augmentation is involved in the risk of VF in patients with BrS. The results suggest that early repolarization patterns in response to pharmacological tests may be useful for risk stratification of VF in patients with symptomatic BrS.

Atrial fibrillation is associated with an increased risk of ventricular arrhythmias and sudden death in patients with pacemakers and implantable cardioverter defibrillators (ICDs)

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial fibrillation (AF) has been linked to an increase in the risk of ventricular arrhythmias. Purpose We aimed to investigate whether AF is associated with an increased risk of ventricular tachycardia (VT), ventricular fibrillation (VF) and sudden death (SD) in patients with cardiac implantable electronic devices (CIEDs). Methods All patients hospitalised in France between 2011 and 2020 with a history of pacemakers (PPMs) and implantable cardioverter defibrillator (ICD) were identified from the French National database. Patients with a prior history of VT, VF and SD were excluded. Results A total of 701,195 patients were identified. Of these, 581,781 (90.1%) patients had PPMs and 63,726 (9.9%) had ICDs. In the PPM group, 248046 (42.6%) had AF and 333735 (57.4%) had no AF. After multivariable analysis, predictors for VT, VF and SD included sex, diabetes, heart failure, history of pulmonary oedema, valve disease, dilated cardiomyopathy, coronary artery disease (CAD), AF, vascular disease, intracranial bleeding, smoking, dyslipidaemia, alcohol related disorders, lung disease, chronic kidney disease (CKD), thyroid disorders, inflammatory diseases, anaemia, poor nutrition, cognitive impairment, previous cancer and frailty. The incidence of VT, VF and SD was higher in patients with AF (1.47%/year) compared to those without AF (0.94%/year), with the risk significantly elevated in the former group, hazard ratio (HR) 1.554 (confidence interval (CI) 1.508-1.601). After adjustment for confounders (Figure 1), AF was still associated with a significantly increased risk of VT, VF and SD, HR 1.236 (CI 1.198-1.276) in patients with PPMs. This was further demonstrated through a 1:1 propensity score matched (PSM) analysis (n=200977 in each group) where the risk of incident outcomes was significantly higher in PPM patients with AF, HR 1.230 (1.187-1.274), compared to those without AF. In the ICD group, 20965 (32.9%) had AF and 42761 (67.1%) had no history of AF. Predictors of VT, VF and SD after multivariable analysis included age, sex, diabetes mellitus, heart failure, valve disease, CAD, previous percutaneous coronary intervention, vascular disease, AF, CKD, liver disease and frailty. Incidence of VT, VF and SD was higher in ICD patients with AF (5.30%/ year) compared to those without AF (4.21%/year), with a significantly higher risk, HR 1.261 (CI 1.204-1.320). After adjustment for confounders, this elevated risk was still significant HR 1.167 (1.111-1.226) (Figure 1). 1:1 PSM analysis (n=18349 in each group) demonstrated this further with a significantly elevated risk in ICD patients with AF, compared to ICD patients without AF, HR 1.134 (CI 1.071-1.200). Conclusion Our findings suggest that patients with PPM and ICD with concurrent AF are at a higher risk of VT, VF and sudden death compared to patients with PPM and ICD who do not have AF.

Atrial fibrillation is associated with an increased risk of ventricular arrhythmias and sudden death in the general population

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial fibrillation (AF) has been linked to an increase in the risk of ventricular arrhythmias. Purpose We aimed to investigate whether AF is associated with an increased risk of ventricular tachycardia (VT), ventricular fibrillation (VF) and sudden death (SD). Methods Hospitalised patients from 2013 with and without AF were identified from the French National database and included if they had at least 5 years of follow-up. Results Over a median follow-up period of 5.4 years (interquartile range (IQR) 5.0-5.8 years), a total of 3345638 patients were identified. Of these, 312226 had AF and 3033412 did not have AF. After multivariable analysis, the predictors significantly associated with VT, VF and SD included age, sex, hypertension, diabetes mellitus, heart failure, history of pulmonary oedema, valve disease, dilated cardiomyopathy, coronary artery disease, vascular disease, AF, smoking, dyslipidaemia, obesity, alcohol related diagnoses, chronic kidney disease, lung disease, liver disease, inflammatory diseases, anaemia, previous cancer, poor nutrition, cognitive impairment, and frailty. The incidence of VT, VF and SD was higher in those with AF compared to those without AF (2.23%/year vs. 0.56%/year). AF was associated with a higher risk of incident outcomes compared to no AF, hazard ratio (HR) 3.657 (confidence interval (CI) 3.604-3.711). After adjustments were made for confounders (Figure 1), this increased risk was still significant HR 1.167 (CI 1.111-1.226). A 1:1 propensity score matched analysis was also performed (n=289,332 in each group), demonstrating the significantly increased risk of ventricular arrhythmias and SD in patients with AF compared to those without AF, HR 1.339 (CI 1.313-1.366). Conclusion The findings from our study AF indicate that AF is associated with an increased risk of VT, VF and sudden death in the general population.

Clinical risk factors associated with ventricular fibrillation during first ST-elevation myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 research and innovation programme under acronym ESCAPE-NET, registered under grant agreement No 733381 Introduction Sudden cardiac death (SCD) remains a major public health issue. Most cases in the general population are caused by ischemic heart disease, and often occur in patients without known ischemic heart disease. The assessment of risk factors may point to novel causal pathways or new targets for intervention and risk prediction of SCD. Objective The aim of this study was to evaluate the effect of family history of sudden death, prior history of atrial fibrillation (AF), and anterior infarct location on ECG on the development of ventricular fibrillation (VF) during first ST-elevation myocardial infarction (STEMI). Methods We performed individual participant data meta-analyses of three European case-control studies including first STEMI patients (aged 18-80 years) with VF (cases) and without VF (controls) before revascularization (GEVAMI, AGNES, and PREDESTINATION). Analyses were done using fixed-effect, inverse variance weighted meta-analysis and multivariable logistic regression. Potential confounding variables were identified using causal diagrams and missing data were handled with multiple imputation for each cohort separately. Results We included 1664 cases and 2497 controls (median age (IQR) = 59 (51-67) years, 20% females) in the analyses. After adjusting for potential confounding, we found an independent and additive association between the three exposures and VF (see picture): for family history of sudden death odds ratio (OR) 1.59 (95% confidence interval: 1.37-1.85), for AF OR 2.41 (1.49-3.89), and for anterior myocardial infarction OR 1.50 (1.32-1.71). Further investigation indicated increased effect of family history with multiple sudden deaths in the family, a stronger effect of AF on VF developing within the first minutes of symptoms, and the effect of anterior infarctions being modified by enzymatically determined infarct size. The three risk factors showed an additive effect: with one factor present OR 1.59 (1.38-1.84), two factors OR 2.41 (1.95-2.99), and all three factors OR 5.49 (1.43-21.1). Complete case analysis gave similar results for all analyses. Conclusions Family history of sudden death, history of AF, and anterior infarct location with significant interaction with enzymatic infarct size were all independently and additively associated with an increased risk of VF in patients with a first STEMI.

Incidence of life-threatening events in children with Wolff-Parkinson-White syndrome: Analysis of a large claims database.

Previous estimates of life-threatening event (LTE) risk in Wolff-Parkinson-White (WPW) syndrome are limited by selection bias inherent to tertiary care referral-based cohorts. This analysis sought to measure LTE incidence in children with WPW syndrome in a large contemporary representative population. A retrospective cohort study was conducted using claims data from the IBM MarketScan Research Databases, evaluating subjects with WPW syndrome (age 1-18 years) from any encounter between January 1, 2013, and December 31, 2018. Subjects with congenital heart disease and cardiomyopathy were excluded. The primary outcome was diagnosis of ventricular fibrillation (VF); a composite outcome, LTE, was defined as occurrence of VF and/or cardiac arrest. VF and LTE rates were compared to matched representative controls without WPW syndrome (3:1 ratio). The prevalence of WPW syndrome was 0.03% (8733/26,684,581) over a median follow-up of 1.6 years (interquartile range 0.7-2.9 years). Excluding congenital heart disease/cardiomyopathy, 6946 subjects were analyzed. An LTE occurred in 49 subjects (0.7%), including VF in 20 (0.3%). The incidence of VF was 0.8 events per 1000 person-years, and the incidence of LTE was 1.9 events per 1000 person-years. There were no occurrences of VF in controls; the rate of LTE was 70 times higher in subjects with WPW syndrome (0.7%; 95% confidence interval 0.5%-0.9%) than in controls (0.01%; 95% confidence interval 0%-0.02%). The use of a large claims data setallowed for an evaluation of VF and LTE risk in an unselected pediatric population with WPW syndrome. The observed range of 0.8-1.9 events per 1000 person-years is consistent with prior reports from selected populations. A comparison of event rates to matched controls confirms and quantifies the significant elevation in VF and LTE risk in pediatric WPW syndrome.

The development of ventricular fibrillation as a complication of pericardiectomy in 16 dogs

To describe the clinical characteristics, perioperative protocols, and outcomes in dogs diagnosed with ventricular fibrillation (VF) while undergoing pericardiectomy. Retrospective, multi-institutional study. Sixteen client-owned dogs. Cases were accrued through a listserve request posted to 3 subspecialty veterinary societies. Dogs were included if they developed VF during a pericardiectomy performed through an open or thoracoscopic approach. Data collected included signalment, history and physical examination, surgical approach, histopathology, treatment, and outcome. Indications for pericardiectomy included idiopathic chylothorax (n=7), neoplasia (4), idiopathic pericardial effusion (4), and foreign body granuloma (1). Surgical approaches included thoracoscopy (12), intercostal thoracotomy (3) and median sternotomy (1). Electrosurgical devices were used to complete at least part of the pericardiectomy in 15 of 16 dogs. Ventricular fibrillation appeared to be initiated during electrosurgical use in 8/15 dogs. However, in 5/15 dogs it was not obviously associated with electrosurgical use. In 3/16 dogs the timing of initiation of VF was unclear. In 7/16 dogs, cardiac arrhythmias were noted prior to the development of VF. Fourteen of 16 dogs died from intraoperative VF. In most dogs ventricular fibrillation was a fatal complication of pericardiectomy. Ventricular fibrillation might be associated with the use of electrosurgical devices and cardiac manipulation during pericardiectomy although a causal link could not be established from the data in this study. Surgeons must be aware of the risk of VF during pericardial surgery. Electrosurgery might need to be used judiciously during pericardiectomy, particularly in dogs exhibiting cardiac arrythmias.

Association of early repolarization pattern and ventricular fibrillation in patients with vasospastic angina: A systematic review and meta-analysis.

BackgroundAn early repolarization (ER) pattern is a risk factor for ventricular fibrillation (VF) in patients with vasospastic angina (VSA) caused by a coronary artery spasm. However, its detailed characteristics and prognostic value for VF remain unclear. Thus, we investigated the relationship between ER and VF in patients with VSA.HypothesisThe ER pattern is associated with VF in patients with VSA.MethodsIn this systematic review and meta‐analysis, we searched PubMed, Embase, Cochrane Library, and Web of Science databases for eligible studies published between January 2011 and December 2020; 8 studies with 1761 patients were included in the final analysis.ResultsThe ER pattern significantly predicted adverse cardiovascular events (ACEs) and VF (odds ratio [OR] = 5.13, 95% confidence interval [95% CI]: 3.16–8.35, p < .00001 and OR = 5.20, 95% CI: 3.05–8.87, p < .00001). The presence of ER in the inferior leads increased the VF risk (OR = 7.80, 95% CI: 4.04–15.05, p < .00001), regardless of the J‐point morphology or type of ST‐segment elevation in the ER pattern. A horizontal/descending ST‐segment elevation was significantly associated with VF in patients with or without an ER pattern during a coronary spasm (OR = 2.28, 95% CI: 1.07–4.88, p = .03). However, obstructive coronary artery disease was unrelated to the ER pattern (OR = 0.82, 95% CI: 0.27–2.53, p = .73).ConclusionsAn ER pattern is significantly associated with an increased risk of ACE in patients with VSA. An inferior ER pattern with horizontal/descending ST‐segment elevation confers the highest risk for VF during VSA onset. Nevertheless, the ER pattern is not associated with obstructive coronary artery disease.

Atrial fibrillation is associated with increased risk of lethal ventricular arrhythmias

Atrial fibrillation (AF) is associated with various major adverse cardiac events such as ischemic stroke, heart failure, and increased overall mortality. However, its association with lethal ventricular arrhythmias such as ventricular tachycardia (VT), ventricular flutter (VFL), and ventricular fibrillation (VF) is controversial. We conducted this study to determine whether AF can increase the risk of VT, VFL, and VF. We utilized the Korean National Health Insurance Service database for this nationwide population-based study. This study enrolled people who underwent a nationwide health screen in 2009 for whom clinical follow-up data were available until December 2018. Primary outcome endpoint was the occurrence of VT, VFL, or VF in people who were and were not diagnosed with new-onset AF in 2009. We analyzed a total of 9,751,705 people. In 2009, 12,689 people were diagnosed with new-onset AF (AF group). The incidence (events per 1000 person-years of follow-up) of VT, VFL, and VF was 2.472 and 0.282 in the AF and non-AF groups, respectively. After adjustment for covariates, new-onset AF was associated with 4.6-fold increased risk (p < 0.001) of VT, VFL, and VF over 10 years of follow-up. The risk of VT, VFL, and VF was even higher if identification of AF was based on intensified criteria (≥ 2 outpatient records or ≥ 1 inpatient record; hazard ratio = 5.221; p < 0.001). In conclusion, the incidence of VT, VFL, and VF was significantly increased in people with new-onset AF. The potential risk of suffering lethal ventricular arrhythmia in people with AF should be considered in clinical practice.

Impact of Atrial Fibrillation on Hospitalization Outcomes of Heart Failure in Patients ≥ 60 Years with Implantable Cardioverter Defibrillator

The impact of atrial fibrillation (AF) on the hospitalization outcomes in patients ≥ 60 years of age with implantable cardioverter defibrillators (ICD) is not well studied. We queried the National Inpatient Sample database for all patients aged ≥ 60 who had a history of ICD placement, and were admitted with a primary diagnosis of heart failure (HF) during the years 2016-2017. Patients were stratified into 2 groups based on their history of AF. The primary outcome of the study was all-cause in-hospital mortality. Secondary outcomes included cardiogenic shock, myocardial infarction (MI), ventricular fibrillation (VF), stroke and acute kidney injury (AKI). The association between different age strata and outcomes was investigated. The hospitalization outcomes were modeled using logistic regression. A total of 178,045 patients were included, of whom 56.2% had AF. AF correlated with increased mortality (A-OR 1.22 (95% CI: 1.06-1.4), p=0.005), cardiogenic shock (A-OR 1.21 (95%CI: 1.08-1.36), p<0.001), AKI (A-OR 1.12 (95%CI: 1.06-1.17), p<0.001 and lower risk for MI (A-OR 0.79 (95% CI: 0.68-0.9), p<0.001. There was no correlation between AF and risk for VF or stroke. A significant correlation between AF and higher risk for mortality, cardiogenic shock and AKI was demonstrated in ages≤ 75, ≤ 75, and ≤ 80 years, respectively. In contrast, a significant correlation between AF and lower risk for MI is only demonstrated at age > 70 years. We conclude that AF is an independent predictor for increased all-cause in-hospital mortality and cardiogenic shock. Such risk is influenced by age.

Predicting Ventricular Fibrillation Through Deep Learning

Ventricular fibrillation (VF) is a type of cardiac arrhythmia. This chaotic cardiac electrical activity results in heart quivering instead of normal pumping. To date, early cardiopulmonary resuscitation (CPR) and defibrillation are the only effective VF treatment. Acute myocardial infarction is the most common cause of VF, and cardiomyopathy, myocarditis, electrolyte imbalance, cardiotoxic medication, and even ion channel abnormality can cause VF. Physicians have attempted to identify specific patterns in electrocardiography (ECG) that might predict VF in the short term. For example, ST segment changes might imply coronary artery occlusion with myocardial ischemia, increasing VF risk. However, in most cases, VF occurs abruptly without any early warning. Machine learning is used to extract information usually neglected by the human brain. In deep learning, a cascade of multiple layers of processing is used to extract features. Machine learning is used to classify different types and outcomes of cardiac arrhythmias that are difficult to recognize directly. In this study, we developed a new deep learning method to predict the onset of VF. ECG from MIT-BIH databases were used as the training and validation data sets; the prediction results showed that the proposed two-dimensional short-time Fourier transform (2D STFT)/continuous wavelet transform (CWT) convolutional neural network (CNN) model can reach a recall of 99% and an accuracy of 97%. We also compared the proposed 2D model with 1D and 2D time-domain CNN models. The results showed that the 1D CNN and 2D time-domain models can achieve an accuracy of 60.5% and 56%, respectively.

Cardiac sympathectomy and spinal cord stimulation attenuate reflex-mediated norepinephrine release during ischemia preventing ventricular fibrillation.

The purpose of this study was to define the mechanism by which cardiac neuraxial decentralization or spinal cord stimulation (SCS) reduces ischemia-induced ventricular fibrillation (VF). Direct measurements of norepinephrine (NE) levels in the left ventricular interstitial fluid (ISF) by microdialysis, in response to transient (15-minute) coronary artery occlusion (CAO), were performed in anesthetized canines. Responses were studied in animals with intact neuraxes and were compared with those in which the intrathoracic component of the cardiac neuraxes (stellate ganglia) or the intrinsic cardiac neuronal (ICN) system was surgically delinked from the central nervous system and those with intact neuraxes with preemptive SCS (T1-T3). With intact neuraxes, animals with exaggerated NE release due to CAO were at increased risk for VF. During CAO, there was a 152% increase in NE when the neuraxes were intact compared with 114% following stellate decentralization and 16% following ICN decentralization. During SCS, CAO NE levels increased by 59%. Risk for CAO-induced VF was 38% in controls, 8% following decentralization, and 11% following SCS. These data indicate that ischemia-related afferent neuronal transmission differentially engages central and intrathoracic sympathetic reflexes and amplifies sympathoexcitation. Differences in regional ventricular NE release are associated with increased risk for VF. Surgical decentralization or SCS reduced NE release and VF.

Effect of Potent P2Y12 Inhibitors on Ventricular Arrhythmias and Cardiac Dysfunction in Coronary Artery Disease: A Systematic Review and Meta-Analysis.

Background Previous studies have shown that P2Y12 receptor inhibitors might prevent ventricular arrhythmias and cardiac dysfunction in patients with coronary artery disease. However, few studies have focused on comparison of the efficacy of novel oral potent P2Y12 receptor inhibitors with clopidogrel on these outcomes. Methods and Results We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) that were published in electronic databases of MEDLINE, EMBASE, Cochrane Central Register of Clinical Trials, and ClinicalTrials.gov before June 20, 2018. We compared the effect of prasugrel and ticagrelor with clopidogrel on outcomes of ventricular tachycardia (VT), ventricular fibrillation (VF), heart failure (HF), and cardiogenic shock (CS). Data were combined using both the fixed-effects models and the random-effects models, and the heterogeneity was assessed with the I2 statistic. Nine RCTs (6 with prasugrel and 3 with ticagrelor) with 45,227 patients were included. Patients receiving prasugrel were associated with a lower risk of combined VT and VF (rate ratio [RR]: 0.72, 95% confidence interval [CI]: 95% CI: 0.52-0.99, p=0.043), as well as combined HF and CS (RR: 0.81, 95% CI: 0.70-0.94, p=0.005), compared with clopidogrel. Patients receiving ticagrelor were also associated with a reduced risk of VT and VF (RR: 0.85, 95% CI: 0.72-1.02, p=0.077), although without statistical significance, but not of HF and CS (RR: 0.96, 95% CI: 0.81-1.13, p=0.620). Conclusions This meta-analysis of RCTs shows that, compared with clopidogrel, novel oral P2Y12 inhibitors, especially prasugrel, might have better effect on improving ventricular rhythm and cardiac function.