Early Ventricular Fibrillation Research Articles

The Rate of Success of CPR in Patients Suffering from Cardiac Arrest in Patients Admitted in CCU in Cardiology Department Ayub Medical Teaching Institute

Cardiopulmonary resuscitation (CPR) is an essential procedure used to treat patients who are in cardiac arrest, particularly in the Critical Care Unit (CCU). Objective: To assess the success rate of CPR admitted to the CCU, revealing insight on the effectiveness of current resuscitation techniques. Methods: This retrospective study was conducted at Department of Cardiology Ayub Medical Teaching Institute, Abbottabad, between 13th April 2023 to 30th November 2023, 110 patients had cardiac arrest while in the intensive care unit. Data were gathered and examined on patient demographics, pre-existing comorbidities, time to start CPR, duration of CPR, and results. CPR success was defined as a sustained restoration of spontaneous circulation (ROSC) for at least 20 minutes. Results: This study included 110 cardiac patients. Most patients (68.18%) were male. Hypertension was the most common comorbidity at 72.7%. CPR started on average 4.8 minutes late, with a 1.2-minute standard deviation. The average CPR time was 18.2 minutes, with a 5.6-minute SD. After cardiac arrest, 60 (54.5%) patients began CPR within 5 minutes. Another subgroup found 96.0% CPR success in 25 (22.7%) ventricular fibrillation patients. Then occurred ventricular tachycardia (80.0%), pulseless electrical activity (76.0%), and asystole (68.9%). These data suggest that CPR works better in ventricular fibrillation patients. Conclusions: This research sheds light on cardiac arrest CCU patients' demographics, care, and outcomes. The data show that early CPR and ventricular fibrillation detection and treatment improve outcomes for these individuals.

The significance of early-onset malignant arrhythmias in ST-elevation myocardial infarction patients treated with primary percutaneous coronary intervention and their relationship with biomarkers

Background/Aim. Patients who were treated with primary percutaneous coronary intervention (pPCI) and survived ventricular tachycardia (VT) and ventricular fibrillation (VF) in the first 48 hrs after ST-elevation myocardial infarction (STEMI) had, in most investigations, a similar long-term prognosis of the outcome, compared to those patients who did not have VT and VF during the first 48 hrs after STEMI. The aim of the study was to determine the association of myocardial infarction markers: creatine kinase-MB fraction (CK-MB), heart failure marker ? B-type natriuretic peptide (BNP), and systemic inflammation factor ? C-reactive protein (CRP) with early VT and VF onset, in relation to patient mortality during the first six months after STEMI. Methods. The retrospective study included 971 patients with STEMI treated with pPCI for ten years. VF and sustained VT (sVT) were detected outside of the hospital and during the first 48 hrs of hospitalization. Results. During the first 4 8 hrs from admission, 1 08 ( 11.1%) patients had life-threatening arrhythmias, of which 75 (69.4%) had VF, and 33 (30.6%) had sVT and were treated with direct current ? DC shock and intravenous amiodarone. Intrahospital mortality was significantly higher in patients with VF/sVT in the first 48 hrs compared to patients without VF/sVT (14.8% vs. 5.7%, p = 0.001). BNP level had higher accuracy in the prediction of six-month death than the maximum blood level of CRP in patients without VF/sVT after 48 hrs. However, in patients with early-onset malignant arrhythmias, BNP showed a lower level of accuracy in predicting the six-month mortality, a s did the CRP values, which had almost the same level of accuracy. Admission glycemia had a much lower predictive value in both groups of patients compared to BNP and C RP [ 0.705 ( 0.628? 0.781), p < 0.001 and 0.662 (0.521?0.803), p = 0.046, respectively]. In either of the groups, maximum CK-MB levels were not significant in predicting the six-month all-cause mortality. Conclusion. Our study indicates that STEMI patients with early onset of VF and sVT, treated with pPCI, with a high BNP level, have a statistically significantly higher mortality rate compared to patients with a lower BNP level.

Immediate, early and late ventricular fibrillation complicating acute myocardial infarction: insights from a real life registry

Abstract Background Conflicting data exist on the prognosis of ventricular fibrillation (VF) based on its timing in relation to coronary occlusion in acute myocardial infarction (AMI). Purpose To describe the patient profile and prognostic impact of VF during AMI according to its time of occurrence. Methods Data from three nationwide French cohorts carried out 5 years apart from 2005 to 2015 were analysed (FAST-MI program). All consecutive patients with AMI (STEMI and Non-STEMI) over a 1-month period were enrolled and followed 5 years. The present analysis focused on patients who presented with VF according to its time of occurrence defined as: immediate (out-of-hospital cardiac arrest), early (<48h at admission) and late (≥48h after admission). Results Out of 13 125 patients admitted for AMI (66±14 years, 71% men, 52% ST-elevation myocardial infarction-STEMI), 406 (3.1%) presented with VF including 205 immediate (50.5%), 147 early (36.2%) and 54 late (13.3%) VF episodes. Immediate and early VF were most frequent during STEMI (respectively 2.3% and 1.8% vs. 0.8% and 0.4% in non-STEMI, p<0.001), while late VF incidence was as frequent in ST-elevation and non-STEMI (0.5% vs 0.4%, p value). The proportion of immediate, early and late VF in AMI were similar in 2005, 2010 and 2015. Patients with immediate (61.6±13.2 yo) or early (62.4±14.2 yo) VF were younger than those with no VF (66.1±14.1 yo, p<0.001) while patients with late VF patients were the oldest (70.5±13.6 yo). LVEF was lower in patients with early (48±10%) or late (48±13%), compared with patients without VF (52±11%) or those with immediate VF (51±12%) (p<0.001). In-hospital mortality was particularly high in patients who developed immediate (24.9%) and late (37.0%) VF, intermediate in early VF patients (10.9%) and lowest in non-VF patients (3.0%) (p<0.001). Among patients alived at hospital discharge, and compared with patients with no VF (4.2%), the six-month mortality was considerably increased in the late VF subgroup (17.6%, adjusted HR: 6.04 [2.69-13.58], P<0.001), moderately increased in immediate VF (5.2%, HR:2.15 [1.06-4.34, P=0.03) ) and did not differ in early VF (1.5%, HR: 0.52 [0.13-2.11 P=0.36). At five years, mortality was also significantly higher in patients with late VF (38.2%, adjusted HR 1.72 [1.01-2.91]), with no significant difference between immediate, early, and non VF patients (14.2%, 11.5% and 19.3% respectively). Conclusions Patients with immediate, early and late VF during AMI do present with significantly different profiles. Still, only late VF (≥48h after admission) was associated with poorer outcome after the index hospitalisation, especially within the initial 6 months. By contrast with current guidelines based on relatively old data from the 2000s in secondary prevention in ischemic or non-ischemic settings, the extent to which patients with late VF would benefit from rapid cardioverter defibrillator implantation is questionable.3 months survival after VF in AMI5 year survival after VF in AMI

C2 DIFFERENT CLINICAL PREDICTORS OF EARLY AND LATE PRIMARY VENTRICULAR FIBRILLATION: RESULTS OF THE PREDESTINATION STUDY

Abstract Introduction Few studies evaluated risk factors for primary ventricular fibrillation (VF) before reperfusion during a first acute myocardial infarction (AMI). Important parameters such as kalemia, blood pressure (BP) and heart rate (HR) at presentation were rarely considered. Furthermore, potential differences according to the time elapsed between symptoms onset and VF onset have never been investigated. Objectives to evaluate predictors of primary VF in the PREDESTINATION (PRImary vEntricular fibrillation and suDden dEath during a firST myocardIal iNfArcTION) study cohort also differentiating between early (<60 min from symptoms onset) and late (>60 min) VF. Early VF is more likely to cause sudden death (SD) before medical services arrival. Patients and Methods PREDESTINATION is a prospective, multicenter, case–control (1:2 age– and sex–matched) study enrolling patients aged 18–80 years with a first AMI, either complicated (cases) or not (controls) by primary VF before reperfusion. Results 1478 patients were analysed: mean age was 59 years, 83% were male, 36% cases. The multivariate analysis (logistic regression) on the whole population (c–statistic= 0.74) identified 8 independent predictors of primary VF: atrial fibrillation as presenting rhythm (OR 4.61), kalemia ≤3.5 mEq/L (OR 2.8), HR at presentation ≥90 bpm (OR 2.25), first–degree family history of SD (OR 2.08), anterior infarct site (OR 1.54), physical inactivity (OR 1.59), systolic BP at presentation (OR 0.98 for each mmHg), and first–degree family history of coronary artery disease/myocardial infarction (OR 0.71). The time elapsed between symptoms onset and VF was known for 405 cases (184 early and 221 late VF). There were 6 predictors of early VF, with loss of significance of physical inactivity and of family history of coronary artery disease/infarction, and an increase in the OR of family history of SD to 2.85 (95% CI: 1.6–5.08), and in the c–statistic of the model to 0.80. Among the 6 predictors of late VF, on the other hand, anterior site of AMI and family history of SD were not confirmed (c–statistic of the model 0.7). Conclusions The present study identified 8 independent predictors of primary VF. First–degree family history of SD is a powerful independent predictor of early VF, but not of late VF, suggesting that genetic predisposition plays a determining role only in early–onset VF cases and therefore the advisability of a specific genetic investigation in these patients.

Prolonged repolarization in the early phase of ischemia is associated with ventricular fibrillation development in a porcine model.

Background: Repolarization prolongation can be the earliest electrophysiological change in ischemia, but its role in arrhythmogenesis is unclear. The aim of the present study was to evaluate the early ischemic action potential duration (APD) prolongation concerning its causes, expression in ECG and association with early ischemic ventricular fibrillation (phase 1A VF). Methods: Coronary occlusion was induced in 18 anesthetized pigs, and standard 12 lead ECG along with epicardial electrograms were recorded. Local activation time (AT), end of repolarization time (RT), and activation-repolarization interval (ARIc) were determined as dV/dt minimum during QRS-complex, dV/dt maximum during T-wave, and rate-corrected RT-AT differences, respectively. Patch-clamp studies were done in enzymatically isolated porcine cardiomyocytes. IK(ATP) activation and Ito1 inhibition were tested as possible causes of the APD change. Results: During the initial period of ischemia, a total of 11 pigs demonstrated maximal ARIc prolongation >10ms at 1 and/or 2.5min of occlusion (8 and 6 cases at 1 and 2.5min, respectively) followed by typical ischemic ARIc shortening. The maximal ARIc across all leads was associated with VF development (OR 1.024 95% CI 1.003-1.046, p = 0.025) and maximal rate-corrected QT interval (QTc) (B 0.562 95% CI 0.346-0.775, p < 0.001) in logistic and linear regression analyses, respectively. Phase 1A VF incidence was associated with maximal QTc at the 2.5min of occlusion in ROC curve analysis (AUC 0.867, p = 0.028) with optimal cut-off 456ms (sensitivity 1.00, specificity 0.778). The pigs having maximal QTc at 2.5min more and less than 450ms significantly differed in phase 1A VF incidence in Kaplan-Meier analysis (log-rank p = 0.007). In the patch-clamp experiments, 4-aminopyridine did not produce any effects on the APD; however, pinacidil activated IK(ATP) and caused a biphasic change in the APD with initial prolongation and subsequent shortening. Conclusion: The transiently prolonged repolarization during the initial period of acute ischemia was expressed in the prolongation of the maximal QTc interval in the body surface ECG and was associated with phase 1A VF. IK(ATP) activation in the isolated cardiomyocytes reproduced the biphasic repolarization dynamics observed in vivo, which suggests the probable role of IK(ATP) in early ischemic arrhythmogenesis.

Early Ventricular Fibrillation Prediction Based on Topological Data Analysis of ECG Signal

Early ventricular fibrillation (VF) prediction is critical for prevention of sudden cardiac death, and can improve patient survival. Generally, electrocardiogram (ECG) signal features are extracted to predict VF, a process which plays an important role in prediction accuracy. Therefore, this study first proposes a novel feature based on topological data analysis (TDA) to improve the accuracy of early ventricular fibrillation prediction. Firstly, the heart activity is regarded as a cardiac dynamical system, which is described by phase space reconstruction. Then the topological structure of the phase space is characterized with persistent homology, and its statistical features are further extracted and defined as TDA features. Finally, 60 subjects (30 VF, 30 healthy) from three public ECG databases are used to validate the prediction performance of the proposed method. Compared to heart rate variability features and box-counting features, TDA features achieve a superior accuracy of 91.7%. Additionally, the three types of features are combined as fusion features, achieving the optimal accuracy of 95.0%. The fusion features are then ranked, and the first seven components are all from the TDA features. It follows that the proposed features provide a significant effect in improving the predictive performance of early VF.

Distinct spectral dynamics of implanted cardiac defibrillator signals in spontaneous termination of polymorphic ventricular tachycardia and fibrillation in patients with electrical and structural diseases.

To determine the spectral dynamics of early spontaneous polymorphic ventricular tachycardia and ventricular fibrillation (PVT/VF) in humans. Fifty-eight self-terminated and 173 shock-terminated episodes of spontaneously initiated PVT/VF recorded by Medtronic implanted cardiac defibrillators (ICDs) in 87 patients with various cardiac pathologies were analyzed by short fast Fourier transform of shifting segments to determine the dynamics of dominant frequency (DF) and regularity index (RI). The progression in the intensity of DF and RI accumulations further quantified the time course of spectral characteristics of the episodes. Episodes of self-terminated PVT/VF lasted 8.6 s [95% confidence interval (CI): 8.1-9.1] and shock-terminated lasted 13.9 s (13.6-14.3) (P < 0.001). Recordings from patients with primarily electrical pathologies displayed higher DF and RI values than those from patients with primarily structural pathologies (P < 0.05) independently of ventricular function or antiarrhythmic drug therapy. Regardless of the underlying pathology, the average DF and RI intensities were lower in self-terminated than shock-terminated episodes [DF: 3.67 (4.04-4.58) vs. 4.32 (3.46-3.93) Hz, P < 0.001; RI: 0.53 (0.48-0.56) vs. 0.63 (0.60-0.65), P < 0.001]. In a multivariate analysis controlled by the type of pathology and clinical variables, regularity remained an independent predictor of self-termination [hazard ratio: 0.954 (0.928-0.980)]. Receiver operating characteristic (ROC) curve analysis of DF and RI intensities demonstrated increased predictability for self-termination in time with 95% CI above the 0.5 cut-off limit at about t = 8.6 s and t = 6.95 s, respectively. Consistent with the notion that fast organized sources maintain PVT/VF in humans, reduction of frequency and regularity correlates with early self-termination. Our findings might help generate ICD methods aiming to reduce inappropriate shock deliveries.

Role of Purkinje-muscle junction in early ventricular fibrillation in a porcine model: Beyond the trigger concept.

The role of the Purkinje network in triggering ventricular fibrillation (VF) has been studied; however, its involvement after onset and in early maintenance of VF is controversial. We studied the role of the Purkinje-muscle junctions (PMJ) on epicardial-endocardial activation gradients during early VF. In a healthy, porcine, beating-heart Langendorff model [control, n = 5; ablation, n = 5], simultaneous epicardial-endocardial dominant frequent mapping was used (224 unipolar electrograms) to calculate activation rate gradients during the onset and early phase of VF. Selective Purkinje ablation was performed using Lugol's solution, followed by VF re-induction and mapping and finally, histological evaluation. Epicardial activation rates were faster than endocardial rates for both onset and early VF. After PMJ ablation, activation rates decreased epicardially and endocardially for both onset and early VF [Epi: 9.7 ± 0.2 to 8.3 ± 0.2 Hz (p <.0001) and 10.9 ± 0.4 to 8.8 ± 0.3 Hz (p < .0001), respectively; Endo: 8.2 ± 0.3 Hz to 7.4 ± 0.2 Hz (p < .0001) and 7.0 ± 0.4 Hz to 6.6 ± 0.3 Hz (p = .0002), respectively]. In controls, epicardial-endocardial activation rate gradients during onset and early VF were 1.7 ± 0.3 Hz and 4.5 ± 0.4 Hz (p < .001), respectively. After endocardial ablation of PMJs, these gradients were reduced to 0.9 ± 0.3 Hz (onset VF, p < .001) and to 2.2 ± 0.3Hz (early VF, p <.001). Endocardial-epicardial Purkinje fiber arborization and selective Purkinje fiber extinction after only endocardial ablation (not with epicardial ablation) was confirmed on histological analysis. Beyond the trigger paradigm, PMJs determine activation rate gradients during onset and during early maintenance of VF.

Border zone repolarization duration as a predictor of early ischemic ventricular fibrillation

Ventricular fibrillation (VF) is a dangerous complication of acute myocardial infarction. Within an episode of acute ischemia, VFs are clustered into early (1A) and delayed (1B) phases based on different mechanisms. Our previous work demonstrated that prolonged repolarization duration in the border zone predisposed to VF development. A prolongation of action potential duration in the affected area is a frequent though not inevitable change at the very beginning of ischemia. However, the role of this phenomenon in arrhythmogenesis is unclear. The objective of the present study was to evaluate an association between early (1A phase) VF with repolarization duration in the border zone in an experimental porcine myocardial infarction model.Myocardial ischemia was induced in 19 anesthetized domestic pigs by ligation of the left anterior descending (n=9) or left circumflex (n=10) coronary arteries. Epicardial mapping was done with a 64‐lead epicardial array placed on the affected area with adjacent regions. Recordings were done in the baseline state and during ischemia with a custom‐designed system (16 bits; bandwidth 0.05 to 1000 Hz; sampling rate 4000 Hz). Local activation time (AT) and end of repolarization time (RT) were measured in each epicardial lead as the instants of a dV/dt minimum during QRS‑complex and dV/dt maximum during T‑wave, respectively. Activation‐repolarization interval (ARI, a surrogate for action potential duration) was taken as a rate‐corrected difference between RT and AT. Dispersion of repolarization (DOR) was calculated as a difference between the latest and earliest RTs throughout all recorded epicardial leads.Ten early VF episodes developed during first minutes of ischemia (1‐8 min). In logistic regression analysis, VF incidence was associated with ARI duration in the border zone (regression coefficient 1.02, 95% CI 1.003‐1.037, p=0.023), but not DOR (regression coefficient 1.005, 95%CI 0.990‐1.021, p=0.508) during first ten minutes of ischemia. In multivariate logistic regression analysis (baseline ARI duration vs the fact of ARI prolongation), VF incidence was associated only with the baseline ARI duration (regression coefficient 1.025, 95%CI 1.007‐1.044, p=0.005).Our data demonstrated the role of the prolonged repolarization duration in the development of 1A phase VF, which was independent of DOR and related to its baseline duration. Since the border zone is by definition at least partly accessible for blood flow, it may present a target for VF prevention therapy in a setting of acute myocardial ischemia.

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.

Sometimes Late Is Better Than Never: Implantation of a Cardioverter Defibrillator Years after an Acute Myocardial Infarction —Case Report

Abstract Sustained ventricular arrhythmias that occur early post-myocardial infarction (MI) are generally considered epiphenomena of the MI and are not consistently associated with long-term prognosis. The lack of association with long-term prognosis is more clearly established for early ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PVT). Sustained monomorphic ventricular tachycardia (SMVT), even when it occurs early, however, may reflect a permanent arrhythmic substrate1. Patients with COVID-19 have a high risk of thromboembolic events, and the virus has also been shown to have extensive effects on the cardiovascular system2,3,4. A 62-year-old woman, recently hospitalized for COVID-19 pneumonia, was brought to the emergency department with pulseless SMVT having been successfully resuscitated in the prehospital setting. The patient has a history of an old MI treated with thrombolysis and percutaneous coronary intervention (PCI) that was complicated with early SMVT, but with preserved left ventricular function and without heart failure. The patient underwent implantation of a cardioverter defibrillator (ICD). During the hospitalization, she developed dyspnea and was diagnosed with minor pulmonary embolism. It may be appropriate to consider early SMVT as a predictor of adverse late outcomes that would necessitate rigorous follow-up and maybe an early invasive primary prevention strategy. This case also reflects the possibility of long-term cardiac involvement and increased thromboembolic risk in patients recovering from COVID-19.

Human Plasma Metabolomics Identify 9-cis-retinoic Acid and Dehydrophytosphingosine Levels as Novel biomarkers for Early Ventricular Fibrillation after ST-elevated Myocardial Infarction

ABSTRACT The relevant metabolite biomarkers for risk prediction of early onset of ventricular fibrillation (VF) after ST-segment elevation myocardial infarction (STEMI) remain unstudied. Here, we aimed to identify these imetabolites and the important metabolic pathways involved, and explore whether these metabolites could be used as predictors for the phenotype. Plasma samples were obtained retrospectively from a propensity-score matched cohort including 42 STEMI patients (21 consecutive VF and 21 non-VF). Ultra-performance liquid chromatography and mass spectrometry in combination with a comprehensive analysis of metabolomic data using Metaboanalyst 5.0 version were performed. As a result, the retinal metabolism pathway proved to be the most discriminative for the VF phenotype. Furthermore, 9-cis-Retinoic acid (9cRA) and dehydrophytosphingosine proved to be the most discriminative biomarkers. Biomarker analysis through receiver operating characteristic (ROC) curve showed the 2-metabolite biomarker panel yielding an area under the curve (AUC) of 0.836. The model based on Monte Carlo cross-validation found that 9cRA had the greatest probability of appearing in the predictive panel of biomarkers in the model. Validation of model efficiency based on an ROC curve showed that the combination model constructed by 9cRA and dehydrophytosphingosine had a good predictive value for early-onset VF after STEMI, and the AUC was 0.884 (95% CI 0.714–1). Conclusively, the retinol metabolism pathway was the most powerful pathway for differentiating the post-STEMI VF phenotype. 9cRA was the most important predictive biomarker of VF, and a plasma biomarker panel made up of two metabolites, may help to build a potent predictive model for VF.

Relation of Early Monomorphic Ventricular Tachycardia to Long-Term Mortality in ST-Elevation Myocardial Infarction

Early ventricular tachycardia (VT) and ventricular fibrillation (VF) are associated with increased in-hospital mortality but do not influence the long-term prognosis in ST-elevation myocardial infarction (STEMI). Recent data advocate a differential approach to the type of arrhythmia and indicate long-term mortality hazard associated with monomorphic VT. We aimed to evaluate the prognostic value of early monomorphic VT compared to nonmonomorphic VT/VF in a nonselected cohort of STEMI patients. Consecutive STEMI patients admitted for primary percutaneous coronary intervention from 2007 to 2010 were included. Clinical characteristics were obtained from the Swedish national SWEDEHEART registry. The occurrence and type of early VT/VF were verified in medical records. All-cause mortality 8 years after STEMI was assessed using the Swedish Cause of Death Register. A total of 2,277 STEMI patients were included (age 66 ± 12 years, 70% male), among them 35 (1.5%) with early monomorphic VT and 115 (5.1%) with nonmonomorphic VT/VF. Patients with monomorphic VT had similar clinical characteristics compared to those with nonmonomorphic VT/VF. In total, 22 patients (63%) with monomorphic VT and 43 (37%) with nonmonomorphic VT/VF died by 8 years of follow-up (p=0.011). Monomorphic VT was associated with a higher risk of all-cause mortality compared to nonmonomorphic VT/VF in univariate analysis (HR 2.03, 95% CI 1.21 to 3.39, p=0.007) and after adjustment for age and history of myocardial infarction (MI) (HR 1.74, 95% CI 1.02 to 2.97, p=0.041). Early monomorphic VT in STEMI is associated with a higher risk of all-cause mortality compared to nonmonomorphic VT/VF and deserves further studies to refine risk stratification strategies.

Prognosis of the non-ST elevation myocardial infarction complicated with early ventricular fibrillation at higher age

Early ventricular fibrillation (EVF) predicts mortality in ST-segment elevation myocardial infarction (STEMI) patients. Data are lacking about prognosis and management of non-ST-segment elevation myocardial infarction (NSTEMI) EMI with EVF, especially at higher age. In the daily clinical practice, there is no clear prognosis of patients surviving EVF. The present study aimed to investigate the risk factors and factors influencing the prognosis of NSTEMI patients surviving EVF, especially at higher age. Clinical data, including 30-day and 1-year mortality of 6179 NSTEMI patients, were examined; 2.44% (n=151) survived EVF and were further analyzed using chi-square test and uni- and multivariate analyses. Patients were divided into two age groups below and above the age of 70 years. Survival time was compared with Kaplan-Meier analysis. EVF was an independent risk factor for mortality in NSTEMI patients below (HR: 2.4) and above the age of 70 (HR: 2.1). Mortality rates between the two age groups of NSTEMI patients with EVF did not differ significantly: 30-day mortality was 24% vs 40% (p=0.2709) and 1-year mortality was 39% vs 55% (p=0.2085). Additional mortality after 30 days to 1 year was 15% vs 14.6% (p=0.9728). Clinical characteristics of patients with EVF differed significantly from those without in both age groups. EVF after revascularization—within 48 h—had 11.2 OR for 30-day mortality above the age of 70. EVF in NSTEMI was an independent risk factor for mortality in both age groups. Invasive management and revascularization of NSTEMI patients with EVF is highly recommended. Closer follow-up and selection of patients (independent of age) for ICD implantation in the critical first month is essential.

Prognosis and clinical characteristics of patients with early ventricular fibrillation in the 6-week guideline-offered time period: is it safe to wait 6 weeks with the assessment? (results from the VMAJOR-MI Registry)

The most common, potentially fatal complication following an acute myocardial infarction (AMI) is early ventricular fibrillation (EVF). According to the guidelines, the assessment of implanting an implantable cardioverter defibrillator (ICD) is sufficient 6 weeks after the event, in patients with reduced left ventricular ejection fraction (LVEF), regardless of VF. The present study aimed to evaluate the 6-week prognosis of patients surviving an EVF. We divided the patients in two group based on their general condition at the time they left the hospital. We investigated the clinical characteristics of patients discharged in good general health but still dying within 6 weeks. The present study comprised 12,270 patients with AMI following their primary revascularization in the first 12 h of symptom onset. Five hundred and forty-seven of them suffered EVF due to the AMI. Clinical and 6-week mortality data were examined. Poor general condition correlates with multiple comorbidities, higher troponin levels, more severe complications after the event. Patients leaving in good condition thought to be low risk, from dying. But low LVEF, high blood sugar, high cardiac biomarker level, poor renal function elevates the risk of dying within 6 weeks. However, there is no difference in clinical characteristics between EVF- cases and EVF+ cases in good condition who dies within 6 weeks. According to our study we can select patients who are safe in the critical 6-week period and those who need closer follow-up despite leaving in good general condition.

Melatonin Prevents Early but Not Delayed Ventricular Fibrillation in the Experimental Porcine Model of Acute Ischemia.

Antiarrhythmic effects of melatonin have been demonstrated ex vivo and in rodent models, but its action in a clinically relevant large mammalian model remains largely unknown. Objectives of the present study were to evaluate electrophysiological and antiarrhythmic effects of melatonin in a porcine model of acute myocardial infarction. Myocardial ischemia was induced by 40-min coronary occlusion in 25 anesthetized pigs. After ischemia onset, 12 animals received melatonin (4 mg/kg). 48 intramyocardial electrograms were recorded from left ventricular wall and interventricular septum (IVS). In each lead, activation time (AT) and repolarization time (RT) were determined. During ischemia, ATs and dispersion of repolarization (DOR = RTmax − RTmin) increased reaching maximal values by 3–5 and 20–25 min, respectively. Ventricular fibrillation (VF) incidence demonstrated no relations to redox state markers and was associated with increased DOR and delayed ATs (specifically, in an IVS base, an area adjacent to the ischemic zone) (p = 0.031). Melatonin prevented AT increase in the IVS base, (p < 0.001) precluding development of early VF (1–5 min, p = 0.016). VF occurrence in the delayed phase (17–40 min) where DOR was maximal was not modified by melatonin. Thus, melatonin-related enhancement of activation prevented development of early VF in the myocardial infarction model.

Early repolarization in the inferolateral leads predicts the presence of vasospastic angina: a novel predictor in patients with resting angina.

An association between early repolarization and ventricular fibrillation has recently been reported in patients with vasospastic angina (VSA). However, no studies have clarified whether the presence of early repolarization can predict VSA. Participants comprised 286 patients (136 males) with clinically suspected VSA who underwent intracoronary provocation tests using acetylcholine or ergonovine. Patients were divided into a VSA group [n = 94, positive provocation test as induction of coronary arterial spasm (>90% stenosis)] and a non-VSA group (n = 192). Detailed early repolarization data were compared between groups. The VSA group showed a higher frequency of smokers (28.7%) than the non-VSA group (17.2%; P = 0.02). On baseline 12-lead ECG, early repolarization (defined as a J-point elevation ≥0.1 mV from baseline in both or either of inferolateral leads) was found in 39 patients (inferior leads, n = 27; inferolateral leads, n = 12). Early repolarization was found more frequently in the VSA group (28.7%) than in the non-VSA group (6.2%, P < 0.01). Multivariate analysis revealed early repolarization as an independent predictor of VSA (odds ratio, 5.22; 95% confidence interval, 2.41-11.2; P < 0.01). Early repolarization pattern features including inferior lead, higher amplitude, notched type and horizontal/descending ST segments were associated with increased risk of VSA. In patients with resting chest pain, early repolarization was a predictor of VSA that could be particularly related to the inferior lead, higher amplitude, notched type and horizontal/descending ST segment.

Effect of flunarizine on defibrillation outcomes and early refibrillation in a canine model of prolonged ventricular fibrillation

New Findings What is the central question of this study? Can successful electrical shock in combination with a delayed after‐depolarization (DAD) blocker suppress early refibrillation episodes following long duration ventricular fibrillation (LDVF)? What is the main finding and its importance? Flunarizine significantly reduced the activation of LDVF and early ventricular fibrillation (VF) recurrence following LDVF, suggesting that DADs potentially contribute to refibrillation in prolonged VF. Thus, DAD inhibition can be used as an adjunctive therapy for electrical defibrillation to treat prolonged VF and suppress refibrillation following LDVF. This study attempts to detect changes in the defibrillation threshold (DFT) at different stages of ventricular fibrillation (VF) (short duration VF, SDVF; long duration VF, LDVF) and during early refibrillation following successful defibrillation of LDVF by giving flunarizine, a blocker of delayed after‐depolarizations (DADs). Twelve beagles were divided into two groups (the control group, n = 6; and the flunarizine group, n = 6). Two 64‐electrode basket catheters were deployed into the left and the right ventricles for global endocardium mapping. The DFTs of SDVF and LDVF were determined at 20 s and 7 min, respectively, after VF induction in each group. Any refibrillation episodes were recorded within 15 min after the first successful defibrillation of LDVF. In the flunarizine group, the SDVF‐DFT values before and after the drug were not significantly different. The 7 min LDVF‐DFTs were markedly reduced by 26% (P < 0.05, the control group) and 38% (P < 0.01, the flunarizine group) compared to the 20 s SDVF‐DFTs within each group. The difference between SDVF‐DFT and LDVF‐DFT after flunarizine was larger than that in the control group (213 ± 65 vs. 120 ± 84 V, P < 0.05). The number of refibrillation episodes per animal (1.3 ± 1.0) following successful defibrillation of LDVF after flunarizine was 48% of that in controls (2.7 ± 2.0, P < 0.05). The effect of flunarizine on SDVF‐DFT and LDVF‐DFT indicates that the role of DADs in the defibrillation mechanism may differ as VF continues. Flunarizine significantly reduced early VF recurrence following LDVF, suggesting that DADs potentially contribute to refibrillation in a canine model of prolonged VF.

Twenty-five year trends (1986-2011) in hospital incidence and case-fatality rates of ventricular tachycardia and ventricular fibrillation complicating acute myocardial infarction

Long-term trends in the incidence rates (IRs) and hospital case-fatality rates (CFRs) of ventricular tachycardia (VT) and ventricular fibrillation (VF) among patients hospitalized with acute myocardial infarction (AMI) have not been recently examined. We used data from 11,825 patients hospitalized with AMI at all 11 medical centers in central Massachusetts on a biennial basis between 1986 and 2011. Multivariable adjusted logistic regression modeling was used to examine trends in hospital IRs and CFRs of VT and VF complicating AMI. The median age of the study population was 71 years, 57.9% were men, and 94.7% were white. The hospital IRs declined from 14.3% in 1986/1988 to 10.5% in 2009/2011 for VT and from 8.2% to 1.7% for VF. The in-hospital CFRs declined from 27.7% to 6.9% for VT and from 49.6% to 36.0% for VF between 1986/1988 and 2009/2011, respectively. The IRs of both early (<48 hours) and late VT and VF declined over time, with greater declines in those of late VT and VF. The incidence rates of VT declined similarly for patients with either an ST-segment elevation myocardial infarction (STEMI) or non-STEMI, whereas they only declined in those with VF and a STEMI. The hospital IRs and CHRs of VT and VF complicating AMI have declined over time, likely because of changes in acute monitoring and treatment practices. Despite these encouraging trends, efforts remain needed to identify patients at risk for these serious ventricular arrhythmias so that preventive and treatment strategies might be implemented as necessary.

Endocardial Activation Drives Activation Patterns During Long-Duration Ventricular Fibrillation and Defibrillation.

Understanding the mechanisms that drive ventricular fibrillation is essential for developing improved defibrillation techniques to terminate ventricular fibrillation (VF). Distinct organization patterns of chaotic, regular, and synchronized activity were previously demonstrated in VF that persisted over 1 to 2 minutes (long-duration VF [LDVF]). We hypothesized that activity on the endocardium may be driving these activation patterns in LDVF and that unsuccessful defibrillation shocks may alter activation patterns. The study was performed using a 64-electrode basket catheter on the left ventricle endocardium and 54 6-electrode plunge needles inserted into the left ventricles of 6 dogs. VF was induced electrically, and after short-duration VF (10 seconds) and LDVF (7 minutes), shocks of increasing strengths were delivered every 10 seconds until VF was terminated. Endocardial activation patterns were classified as chaotic (varying cycle lengths and nonsynchronous activations), regular (highly repeatable cycle lengths), and synchronized (activation that spreads rapidly over the endocardium with diastolic periods between activations). The results showed that the chaotic pattern was predominant in early VF, but the regular pattern emerges as VF progressed. The synchronized pattern only emerged occasionally during late VF. Failed defibrillation shocks changed chaotic and regular activation patterns to synchronized patterns in LDVF but not in short-duration VF. The regular and synchronized patterns of activation were driven by rapid activations on the endocardial surface that blocked and broke up transmurally, leading to an endocardial to epicardial activation rate gradient as LDVF progressed.