Ventricular Arrhythmias After Primary Percutaneous Coronary Intervention for STEMI.

Importance: 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). Objective: To evaluate the risk of late VT and VF after primary PCI for STEMI. Design, Setting, and Participants: 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. Main Outcomes and Measures: 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%. Results: 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). Conclusions and Relevance: 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.

Bleeding and Thrombosis in Patients With Out-of-Hospital Ventricular Tachycardia/Ventricular Fibrillation Arrest Treated With Extracorporeal Cardiopulmonary Resuscitation.

BACKGROUND: Extracorporeal cardiopulmonary resuscitation improves outcomes after out-of-hospital cardiac arrest. However, bleeding and thrombosis are common complications. We aimed to describe the incidence and predictors of bleeding and thrombosis and their association with in-hospital mortality. METHODS AND RESULTS: Consecutive patients presenting with refractory ventricular tachycardia/ventricular fibrillation out-of-hospital cardiac arrest between December 2015 and March 2022 who met the criteria for extracorporeal cardiopulmonary resuscitation initiation at our center were included. Major bleeding was defined by the Extracorporeal Life Support Organization's criteria. Adjusted analyses were done to seek out risk factors for bleeding and thrombosis and evaluate their association with mortality. Major bleeding occurred in 135 of 200 patients (67.5%), with traumatic bleeding from cardiopulmonary resuscitation in 73 (36.5%). Baseline demographics and arrest characteristics were similar between groups. In multivariable analysis, decreasing levels of fibrinogen were independently associated with bleeding (adjusted hazard ratio [aHR], 0.98 per every 10 mg/dL rise [95% CI, 0.96-0.99]). Patients who died had a higher rate of bleeds per day (0.21 versus 0.03, P<0.001) though bleeding was not significantly associated with in-hospital death (aHR, 0.81 [95% CI. 0.55-1.19]). A thrombotic event occurred in 23.5% (47/200) of patients. Venous thromboembolism occurred in 11% (22/200) and arterial thrombi in 15.5% (31/200). Clinical characteristics were comparable between groups. In adjusted analyses, no risk factors for thrombosis were identified. Thrombosis was not associated with in-hospital death (aHR, 0.65 [95% CI, 0.42-1.03]). CONCLUSIONS: Bleeding is a frequent complication of extracorporeal cardiopulmonary resuscitation that is associated with decreased fibrinogen levels on admission whereas thrombosis is less common. Neither bleeding nor thrombosis was significantly associated with in-hospital mortality.

Association between survival and number of shocks for pulseless ventricular arrhythmias during pediatric in-hospital cardiac arrest in a national registry.

BACKGROUND: Annually 15,200 children suffer an in-hospital cardiac arrest (IHCA) in the US. Ventricular fibrillation or pulseless ventricular tachycardia (VF/pVT) is the initial rhythm in 10-15% of these arrests. We sought to evaluate the association of number of shocks and early dose escalation with survival for initial VF/pVT in pediatric IHCA. METHODS: Using 2000-2020 data from the American Heart Association's (AHA) Get with the Guidelines®-Resuscitation (GWTG-R) registry, we identified children >48 hours of life and ≤18 years who had an IHCA from initial VF/pVT and received defibrillation. RESULTS: There were 251 subjects (37.7%) who received a single shock and 415 subjects (62.3%) who received multiple shocks. Baseline and cardiac arrest characteristics did not differ between those who received a single shock versus multiple shocks except for duration of arrest and calendar year. The median first shock dose was consistent with AHA dosing recommendations and not different between those who received a single shock versus multiple shocks. Survival was improved for those who received a single shock compared to multiple shocks. However, no difference in survival was noted between those who received 2, 3, or ≥4 shocks. Of those receiving multiple shocks, no difference was observed with early dose escalation. CONCLUSIONS: In pediatric IHCA, most patients with initial VF/pVT require more than one shock. No distinctions in patient or pre-arrest characteristics were identified between those who received a single shock versus multiple shocks. Subjects who received a single shock were more likely to survive to hospital discharge even after adjusting for duration of resuscitation.

Trends in ventricular fibrillation/flutter mortality in US population, 1999 to 2019.

BACKGROUND: The Ventricular fibrillation and flutter (VF/VFL)-related mortality trends in the United States (US) population have not yet been investigated. We aimed to assess the trends of VT/VFL-related mortality from 1999 to 2019 among subjects aged more than 15 years old in the US. METHODS: Data derived from the Centers for Disease Control and Prevention's (CDC) WONDER were analyzed between 1999 and 2019 for VF/VFL-related mortality in subjects aged more than 15 years of age. Adjusted mortality rates (AAMRs) per 100,000 people by year, sex, race and urban-rural status with relative confidence intervals (CIs) were determined. Both the average annual percent change (AAPC) and the annual percent change (APC) with 95% Cis were calculated. RESULTS: Between 1999 and 2019, 242,125 VT/VFL-related deaths occurred in the US. The overall AAMR steadily declined [AAPC -4.4% (95% CI: -4.7 to -4.0, p < .0001)]. Women showed a more pronounced AAMRs decline [AAPC: -4.8% (95% CI: -5.3 to -4.3, p < .0001). AAMR steadily declined in white subjects and in those of other races [AAPC: -4.5 (95% CI: -4.7 to -4.2, p < .0001) and AAPC: -4.3 (95% CI: -5.1 to -3.5, p < .001), respectively]. Conversely, African Americans showed a steadily AMMR decline between 1999 and 2007 [APC: -8.3 (95% CI: -9.2 to -7.3, p < .0001)], followed by a period of stability from 2007 to 2019 (p = .73). A similar decline was observed for the AAMR among subjects living in urban and rural areas. CONCLUSIONS: VT/VFL-related mortality steadily decreased between 1999 and 2019 in US. Despite the encouraging results, further efforts are needed to prevent VF/VFL-related mortality in US subjects.

Defibrillation Strategies for Refractory Ventricular Fibrillation.

BACKGROUND: Despite advances in defibrillation technology, shock-refractory ventricular fibrillation remains common during out-of-hospital cardiac arrest. Double sequential external defibrillation (DSED; rapid sequential shocks from two defibrillators) and vector-change (VC) defibrillation (switching defibrillation pads to an anterior-posterior position) have been proposed as defibrillation strategies to improve outcomes in patients with refractory ventricular fibrillation. METHODS: We conducted a cluster-randomized trial with crossover among six Canadian paramedic services to evaluate DSED and VC defibrillation as compared with standard defibrillation in adult patients with refractory ventricular fibrillation during out-of-hospital cardiac arrest. Patients were treated with one of these three techniques according to the strategy that was randomly assigned to the paramedic service. The primary outcome was survival to hospital discharge. Secondary outcomes included termination of ventricular fibrillation, return of spontaneous circulation, and a good neurologic outcome, defined as a modified Rankin scale score of 2 or lower (indicating no symptoms to slight disability) at hospital discharge. RESULTS: A total of 405 patients were enrolled before the data and safety monitoring board stopped the trial because of the coronavirus disease 2019 pandemic. A total of 136 patients (33.6%) were assigned to receive standard defibrillation, 144 (35.6%) to receive VC defibrillation, and 125 (30.9%) to receive DSED. Survival to hospital discharge was more common in the DSED group than in the standard group (30.4% vs. 13.3%; relative risk, 2.21; 95% confidence interval [CI], 1.33 to 3.67) and more common in the VC group than in the standard group (21.7% vs. 13.3%; relative risk, 1.71; 95% CI, 1.01 to 2.88). DSED but not VC defibrillation was associated with a higher percentage of patients having a good neurologic outcome than standard defibrillation (relative risk, 2.21 [95% CI, 1.26 to 3.88] and 1.48 [95% CI, 0.81 to 2.71], respectively). CONCLUSIONS: Among patients with refractory ventricular fibrillation, survival to hospital discharge occurred more frequently among those who received DSED or VC defibrillation than among those who received standard defibrillation. (Funded by the Heart and Stroke Foundation of Canada; DOSE VF ClinicalTrials.gov number, NCT04080986.).

Myocardial Fibrosis Predicts Ventricular Arrhythmias and Sudden Death After Cardiac Electronic Device Implantation.

BACKGROUND: Increasing evidence supports a link between myocardial fibrosis (MF) and ventricular arrhythmias. OBJECTIVES: The purpose of this study was to determine whether presence of myocardial fibrosis on visual assessment (MFVA) and gray zone fibrosis (GZF) mass predicts sudden cardiac death (SCD) and ventricular fibrillation/sustained ventricular tachycardia after cardiac implantable electronic device (CIED) implantation. METHODS: In this prospective study, total fibrosis and GZF mass, quantified using cardiovascular magnetic resonance, was assessed in relation to the primary endpoint of SCD and the secondary, arrhythmic endpoint of SCD or ventricular arrhythmias after CIED implantation. RESULTS: Among 700 patients (age 68.0 ± 12.0 years), 27 (3.85%) experienced a SCD and 121 (17.3%) met the arrhythmic endpoint over median 6.93 years (IQR: 5.82-9.32 years). MFVA predicted SCD (HR: 26.3; 95% CI: 3.7-3,337; negative predictive value: 100%). In competing risk analyses, MFVA also predicted the arrhythmic endpoint (subdistribution HR: 19.9; 95% CI: 6.4-61.9; negative predictive value: 98.6%). Compared with no MFVA, a GZF mass measured with the 5SD method (GZF5SD) >17 g was associated with highest risk of SCD (HR: 44.6; 95% CI: 6.12-5,685) and the arrhythmic endpoint (subdistribution HR: 30.3; 95% CI: 9.6-95.8). Adding GZF5SD mass to MFVA led to reclassification of 39% for SCD and 50.2% for the arrhythmic endpoint. In contrast, LVEF did not predict either endpoint. CONCLUSIONS: In CIED recipients, MFVA excluded patients at risk of SCD and virtually excluded ventricular arrhythmias. Quantified GZF5SD mass added predictive value in relation to SCD and the arrhythmic endpoint.

Association of a simple SACAF score with bystander witnessed sudden death due to ventricular tachyarrhythmias in a multicenter cohort.

Out-of-hospital cardiac arrest (OHCA) remains a major threat to public health worldwide. OHCA patients presenting initial shockable ventricular tachycardia/ventricular fibrillation (VT/VF) rhythm have a better survival rate. We sought to develop a simple SACAF score to discriminate VT/VF from non-VT/VF OHCAs based on the Taiwan multicenter hospital-based registry database. We analyzed the in- and pre-hospital data, including demographics, baseline comorbidities, response times, automated external defibrillator information, and the 12-lead ECG recording closest to the OHCA event in bystander-witnessed OHCA patients. Among the 461 study patients, male sex (OR 2.54, 95% CI = 1.32-4.88, P = 0.005), age ≤ 65 years (OR 2.78, 95% CI = 1.64-4.70, P < 0.001), cardiovascular diseases (OR 2.97, 95% CI = 1.73-5.11, P < 0.001), and atrial fibrillation (AF) (OR 2.36, 95% CI = 1.17-4.76, P = 0.017) were independent risk factors for VT/VF OHCA (n = 81) compared with non-VT/VF OHCA (n = 380). A composite SACAF score was developed (male Sex, Age ≤ 65 years, Cardiovascular diseases, and AF) and compared with the performance of a modified CHA2DS2-VASc score (Cardiovascular diseases, Hypertension, Age ≥ 75 years, Diabetes, previous Stroke, Vascular disease, Age 65-74 years, female Sex category). The area under the receiver operating characteristic curve (AUC) of the SACAF was 0.739 (95% CI = 0.681-0.797, P < 0.001), whereas the AUC of the modified CHA2DS2-VASc was 0.474 (95% CI = 0.408-0.541, P = 0.464). A SACAF score of ≥ 2 was useful in discriminating VT/VF from non-VT/VF OHCAs with a sensitivity of 0.75 and a specificity of 0.60. In conclusion, the simple SACAF score appears to be useful in discriminating VT/VF from non-VT/VF bystander-witnessed OHCAs and the findings may also shed light on future mechanistic evaluation.

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.

Electrical storm: Prognosis and management.

Electrical storm is present when a cluster of ventricular arrhythmias (VAs) occurs within a short time frame. The most widely accepted definition is 3 or more episodes of VA within a 24-h period, although prognostic risk begins to rise when 2 or more events occur within 3months. Electrical storm often presents as a medical emergency in the form of recurrent implantable cardiac defibrillator (ICD) shocks, recurrent syncope in patients with no ICD or low cardiac output symptoms. Management often requires a multimodality approach including ICD management, pharmacologic therapy, catheter ablation and modulations of the autonomic nervous system. In this article, we review the definition, prognosis and management of electrical storm.

Atrial fibrillation increases the risk of recurrent ventricular tachyarrhythmias in implantable cardioverter defibrillator recipients.

BACKGROUND: Data regarding recurrences of ventricular tachyarrhythmias in implantable cardioverter defibrillator (ICD) recipients according to atrial fibrillation is limited. OBJECTIVE: To assess the prognostic impact of atrial fibrillation on recurrences of ventricular tachyarrhythmias in implantable cardioverter defibrillator recipients. METHODS: A large retrospective registry was used, including all ICD recipients with episodes of ventricular tachycardia or fibrillation from 2002 to 2016. Patients with atrial fibrillation were compared to those without atrial fibrillation. The primary endpoint was first recurrence of ventricular tachyarrhythmias at 5 years. Secondary endpoints comprised recurrences of ICD-related therapies, first cardiac rehospitalization and all-cause mortality at 5 years. Cox regression, Kaplan-Meier and propensity score-matching analyses were applied. RESULTS: A total of 592 consecutive ICD recipients were included (33% with atrial fibrillation). Atrial fibrillation was associated with reduced freedom from recurrent ventricular tachyarrhythmias (42% vs. 50%, log-rank P=0.004; hazard ratio 1.445, 95% confidence interval 1.124-1.858), mainly attributable to recurrent ventricular fibrillation in secondary-preventive ICD recipients. Accordingly, atrial fibrillation was associated with reduced freedom from first appropriate ICD therapies (31% vs. 42%, log-rank P=0.001; hazard ratio 1.598, 95% confidence interval 1.206-2.118). Notably, the primary endpoint of freedom from first episode of recurrent ventricular tachyarrhythmias was still reduced in those with atrial fibrillation compared to those without atrial fibrillation after propensity score matching. Regarding secondary endpoints, patients with atrial fibrillation still showed a trend towards reduced freedom from appropriate ICD therapies. CONCLUSIONS: Atrial fibrillation was associated with increased rates of recurrent ventricular tachyarrhythmias and appropriate device therapies in ICD recipients with ventricular tachyarrhythmias.

Electrical Substrate Ablation for Refractory Ventricular Fibrillation: Results of the AVATAR Study.

[Figure: see text].

Prognostic value of admission serum magnesium in acute myocardial infarction complicated by malignant ventricular arrhythmias.

OBJECTIVES: Although electrolyte abnormalities are related to worse clinical outcomes in patients with acute myocardial infarction (AMI), little is known about the association between admission serum magnesium level and adverse events in AMI patients complicated by out-of-hospital cardiac arrest presenting with malignant ventricular arrhythmias (OHCA-MVA). We investigated the prognostic value of serum magnesium level on admission in these patients. METHODS: We retrospectively analyzed the data of 165 consecutive reperfused AMI patients complicated with OHCA-MVA between April 2007 and February 2020 in our university hospital. Serum magnesium concentration was measured on admission. The primary outcome was in-hospital death. RESULTS: Fifty-four patients (33%) died during hospitalization. Higher serum magnesium level was significantly related to in-hospital death (Fine & Gray's test; p < 0.001). In multivariable logistic regression analyses, serum magnesium level on admission was independently associated with in-hospital death (hazard ratio 2.68, 95% confidence interval 1.24-5.80) even after adjustment for covariates. Furthermore, the incidences of cardiogenic shock necessitating an intra-aortic balloon pump (p = 0.005) or extracorporeal membrane oxygenation (p < 0.001), tracheal intubation (p < 0.001) and persistent vegetative state (p = 0.002) were significantly higher in patients with higher serum magnesium level than in those with lower serum magnesium level. CONCLUSIONS: In reperfused AMI patients complicated by OHCA-MVA, admission serum magnesium level might be a potential surrogate marker for predicting in-hospital death.

Left intraventricular pressure gradient in hypertrophic cardiomyopathy patients receiving implantable cardioverter-defibrillators for primary prevention.

BACKGROUND: Conventional risk factors for sudden cardiac death (SCD) justify primary prevention through implantable cardioverter-defibrillator (ICD) implantation in hypertrophic cardiomyopathy (HCM) patients. However, the positive predictive values for these conventional SCD risk factors are low. Left ventricular outflow tract obstruction (LVOTO) and midventricular obstruction (MVO) are potential risk modifiers for SCD. The aims of this study were to evaluate whether an elevated intraventricular pressure gradient (IVPG), including LVOTO or MVO, is a potential risk modifier for SCD and ventricular arrhythmias requiring ICD interventions in addition to the conventional risk factors among HCM patients receiving ICDs for primary prevention. METHODS: We retrospectively studied 60 HCM patients who received ICDs for primary prevention. An elevated IVPG was defined as a peak instantaneous gradient ≥ 30 mmHg at rest, as detected by continuous-wave Doppler echocardiography. The main outcome was a composite of SCD and appropriate ICD interventions, which were defined as an antitachycardia pacing or shock therapy for ventricular tachycardia or fibrillation. The Cox proportional hazards model was used to assess the relationships between risk factors and the occurrence of SCD and appropriate ICD interventions. RESULTS: Thirty patients met the criteria of elevated IVPG (50%). During the median follow-up period of 66 months, 2 patients experienced SCD, and 10 patients received appropriate ICD interventions. Kaplan-Meier curves showed that the incidence of the main outcome was higher in patients with an IVPG ≥ 30 mmHg than in those without an IVPG ≥ 30 mmHg (log-rank P = 0.03). There were no differences in the main outcome between patients with LVOTO and patients with MVO. The combination of nonsustained ventricular tachycardia (NSVT) and IVPG ≥ 30 mmHg was found to significantly increase the risk of the main outcome (HR 6.31, 95% CI 1.36-29.25, P = 0.02). Five patients experienced ICD implant-related complications. CONCLUSIONS: Our findings showed that a baseline IVPG ≥ 30 mmHg was associated with an increased risk of experiencing SCD or appropriate ICD interventions among HCM patients who received ICDs for primary prevention. Combined with NSVT, which is a conventional risk factor, a baseline IVPG ≥ 30 mmHg may be a potential modifier of SCD risk in HCM patients.

FLNC and MYLK2 Gene Mutations in a Chinese Family with Different Phenotypes of Cardiomyopathy.

Mutations in the sarcomeric protein filamin C (FLNC) gene have been linked to hypertrophic cardiomyopathy (HCM), as they have been determined to increase the risk of ventricular arrhythmia and sudden death. Thus, in this study, we identified a novel missense mutation of FLNC in a Chinese family with HCM, and, interestingly, a second novel truncating mutation of MYLK2 was discobered in one family member with different phenotype.We performed whole-exome sequencing in a Chinese family with HCM of unknown cause. To determine and confirm the function of a novel mutation of FLNC, we introduced the mutant and wild-type gene into AC16 cells (human cardiomyocytes): we then used western blotting to analyze the expression of FLNC in subcellular fractions, and confocal microscope to observe the subcellular distribution of the protein.As per our findings, we were able to identify a novel missense single nucleotide variant (FLNC c.G5935A [p.A1979T]) in the family, which segregates with the disease. FLNC expression levels were observed to be equivalent in both wild-type and p.A1979T cardiomyocytes. However, the expression of the mutant protein has resulted in cytoplasmic protein aggregations, in contrast to wild-type FLNC, which was distributed in the cytoplasm and did not form aggregates. Unexpectedly, a second truncating mutation, NM_033118:exon8:c.G1138T:p.E380X of the MYLK2 gene, was identified in the mother of the proband with dilated cardiomyopathy, which was not found in other subjects.We then identified the FLNC A1979T mutation as a novel pathogenic variant associated with HCM in a Chinese family as well as a second causal mutation in a family member with a distinct phenotype. The possibility that there is more than one causal mutation in cardiomyopathy warrants clinical attention, especially for patients with atypical clinical features.

Machine Learned Cellular Phenotypes in Cardiomyopathy Predict Sudden Death.

RATIONALE: Susceptibility to VT/VF (ventricular tachycardia/fibrillation) is difficult to predict in patients with ischemic cardiomyopathy either by clinical tools or by attempting to translate cellular mechanisms to the bedside. OBJECTIVE: To develop computational phenotypes of patients with ischemic cardiomyopathy, by training then interpreting machine learning of ventricular monophasic action potentials (MAPs) to reveal phenotypes that predict long-term outcomes. METHODS AND RESULTS: We recorded 5706 ventricular MAPs in 42 patients with coronary artery disease and left ventricular ejection fraction ≤40% during steady-state pacing. Patients were randomly allocated to independent training and testing cohorts in a 70:30 ratio, repeated K=10-fold. Support vector machines and convolutional neural networks were trained to 2 end points: (1) sustained VT/VF or (2) mortality at 3 years. Support vector machines provided superior classification. For patient-level predictions, we computed personalized MAP scores as the proportion of MAP beats predicting each end point. Patient-level predictions in independent test cohorts yielded c-statistics of 0.90 for sustained VT/VF (95% CI, 0.76-1.00) and 0.91 for mortality (95% CI, 0.83-1.00) and were the most significant multivariate predictors. Interpreting trained support vector machine revealed MAP morphologies that, using in silico modeling, revealed higher L-type calcium current or sodium-calcium exchanger as predominant phenotypes for VT/VF. CONCLUSIONS: Machine learning of action potential recordings in patients revealed novel phenotypes for long-term outcomes in ischemic cardiomyopathy. Such computational phenotypes provide an approach which may reveal cellular mechanisms for clinical outcomes and could be applied to other conditions.

Cardiac arrhythmias in hospitalized patients with COVID-19: A prospective observational study in the western United States.

Arrhythmias have been reported frequently in COVID-19 patients, but the incidence and nature have not been well characterized. Patients admitted with COVID-19 and monitored by telemetry were prospectively enrolled in the study. Baseline characteristics, hospital course, treatment and complications were collected from the patients' medical records. Telemetry was monitored to detect the incidence of cardiac arrhythmias. The incidence and types of cardiac arrhythmias were analyzed and compared between survivors and non-survivors. Among 143 patients admitted with telemetry monitoring, overall in-hospital mortality was 25.2% (36/143 patients) during the period of observation (mean follow-up 23.7 days). Survivors were less tachycardic on initial presentation (heart rate 90.6 ± 19.6 vs. 99.3 ± 23.1 bpm, p = 0.030) and had lower troponin (peak troponin 0.03 vs. 0.18 ng/ml. p = 0.004), C-reactive protein (peak C-reactive protein 97 vs. 181 mg/dl, p = 0.029), and interleukin-6 levels (peak interleukin-6 30 vs. 246 pg/ml, p = 0.003). Sinus tachycardia, the most common arrhythmia (detected in 39.9% [57/143] of patients), occurred more frequently in non-survivors (58.3% vs. 33.6% in survivors, p = 0.009). Premature ventricular complexes occurred in 28.7% (41/143), and non-sustained ventricular tachycardia in 15.4% (22/143) of patients, with no difference between survivors and non-survivors. Sustained ventricular tachycardia and ventricular fibrillation were not frequent (seen only in 1.4% and 0.7% of patients, respectively). Contrary to reports from other regions, overall mortality was higher and ventricular arrhythmias were infrequent in this hospitalized and monitored COVID-19 population. Either disease or management-related factors could explain this divergence of clinical outcomes, and should be urgently investigated.

Radiofrequency treatment for electrical storm: evolution and monitoring. / Tratamiento con radiofrecuencia de la tormenta eléctrica: evolución y seguimiento.

Introducción y objetivos: La tormenta eléctrica (TE) se caracteriza por episodios repetidos de taquicardia ventricular o fibrilación ventricular relacionados con mal pronóstico a corto y largo plazos. El objetivo fue evaluar la prevalencia, resultados y supervivencia de los pacientes sometidos a tratamiento intervencionista por TE en un centro de referencia. Métodos: Estudio unicéntrico, observacional y retrospectivo. Se revisaron los procedimientos de ablación por TE y se evaluaron las características basales de los pacientes, tipo de procedimiento, mortalidad total, recurrencia de arritmia, mortalidad cardiovascular y necesidad de trasplante. Resultados: Desde enero de 2009 hasta diciembre de 2016 se realizaron 67 procedimientos (38% de complejos: 19% de ablación endoepicárdica, 7.5% de crioablación epicárdica quirúrgica, 3% de simpatectomía, 3% de inyección coronaria con alcohol; 6% de apoyo con oxigenación con membrana extracorpórea) en 41 pacientes (61% de causa isquémica) por TE. La mortalidad intraprocedimiento fue del 1.5%. La mediana de seguimiento fue de 23.5 meses (RIQ, 14.2-52.7). Tras el primer ingreso por TE (uno o varios procedimientos), la mortalidad a un año fue de 9.8%. La incidencia acumulada de trasplante cardiaco por TE fue de 2.4%. En el análisis multivariado, el riesgo de recurrencias arrítmicas o muerte por cualquier causa fue significativamente mayor en pacientes con arritmias clínicas inducibles (HR, 9.03; p = 0.017). Conclusiones: El tratamiento de pacientes con TE, instituido en un centro de referencia y con experiencia, se relacionó con una tasa baja de recurrencia y supervivencia elevada, con una tasa de trasplante cardiaco por TE muy baja. Ante una recurrencia temprana es recomendable practicar un nuevo procedimiento durante el ingreso. Introduction and objective: Electrical storm (ES) is characterized by repeated episodes of ventricular tachycardia or ventricular fibrillation, with poor short and long term prognosis. Our objective was to evaluate the prevalence, results of interventional treatment and survival of patients undergoing interventional treatment for ES in our center. Methods: Retrospective, unicentric and observational study. ES ablation procedures were revised and data regarding baseline characteristics of the patients, type of procedure, total mortality, recurrence of arrhythmia, cardiovascular mortality and the need for transplantation were evaluated. Results: From January 2009 to December 2016, 67 procedures (38% complex procedures: 19% epicardial ablation, 7.5% surgical epicardial crioablation, 3% simpatectomy, 3% coronary alcohol injection, 6% extracorporeal membrane oxygenation support) were performed in 41 patients (61% Ischemic etiology) due to ES. Intraprocedural mortality was 1.5%. The median follow-up was 23.5 months (IQR [14.2-52.7]). After the first admission for ES (one or several procedures), 1-year mortality was 9.8%. The cumulative incidence of cardiac transplantation was 2.4%. The risk of arrhythmic recurrences or death was significantly higher in patients with inducible clinical arrhythmias after ablation (HR: 9.03, p = 0.017). Conclusions: The treatment of patients with ES, performed in a reference center, allows obtaining good rates of recurrence and survival, with very low rates of cardiac transplantation for ES. In the presence of an early recurrence, it is advisable to perform a new procedure during admission.

Tratamiento con radiofrecuencia de la tormenta eléctrica: evolución y seguimiento / Radiofrequency treatment for electrical storm: evolution and monitoring

Resumen Introducción y objetivos: La tormenta eléctrica (TE) se caracteriza por episodios repetidos de taquicardia ventricular o fibrilación ventricular relacionados con mal pronóstico a corto y largo plazos. El objetivo fue evaluar la prevalencia, resultados y supervivencia de los pacientes sometidos a tratamiento intervencionista por TE en un centro de referencia. Métodos: Estudio unicéntrico, observacional y retrospectivo. Se revisaron los procedimientos de ablación por TE y se evaluaron las características basales de los pacientes, tipo de procedimiento, mortalidad total, recurrencia de arritmia, mortalidad cardiovascular y necesidad de trasplante. Resultados: Desde enero de 2009 hasta diciembre de 2016 se realizaron 67 procedimientos (38% de complejos: 19% de ablación endoepicárdica, 7.5% de crioablación epicárdica quirúrgica, 3% de simpatectomía, 3% de inyección coronaria con alcohol; 6% de apoyo con oxigenación con membrana extracorpórea) en 41 pacientes (61% de causa isquémica) por TE. La mortalidad intraprocedimiento fue del 1.5%. La mediana de seguimiento fue de 23.5 meses (RIQ, 14.2-52.7). Tras el primer ingreso por TE (uno o varios procedimientos), la mortalidad a un año fue de 9.8%. La incidencia acumulada de trasplante cardiaco por TE fue de 2.4%. En el análisis multivariado, el riesgo de recurrencias arrítmicas o muerte por cualquier causa fue significativamente mayor en pacientes con arritmias clínicas inducibles (HR, 9.03; p = 0.017). Conclusiones: El tratamiento de pacientes con TE, instituido en un centro de referencia y con experiencia, se relacionó con una tasa baja de recurrencia y supervivencia elevada, con una tasa de trasplante cardiaco por TE muy baja. Ante una recurrencia temprana es recomendable practicar un nuevo procedimiento durante el ingreso.

Abstract Introduction and objective: Electrical storm (ES) is characterized by repeated episodes of ventricular tachycardia or ventricular fibrillation, with poor short and long term prognosis. Our objective was to evaluate the prevalence, results of interventional treatment and survival of patients undergoing interventional treatment for ES in our center. Methods: Retrospective, unicentric and observational study. ES ablation procedures were revised and data regarding baseline characteristics of the patients, type of procedure, total mortality, recurrence of arrhythmia, cardiovascular mortality and the need for transplantation were evaluated. Results: From January 2009 to December 2016, 67 procedures (38% complex procedures: 19% epicardial ablation, 7.5% surgical epicardial crioablation, 3% simpatectomy, 3% coronary alcohol injection, 6% extracorporeal membrane oxygenation support) were performed in 41 patients (61% Ischemic etiology) due to ES. Intraprocedural mortality was 1.5%. The median follow-up was 23.5 months (IQR [14.2-52.7]). After the first admission for ES (one or several procedures), 1-year mortality was 9.8%. The cumulative incidence of cardiac transplantation was 2.4%. The risk of arrhythmic recurrences or death was significantly higher in patients with inducible clinical arrhythmias after ablation (HR: 9.03, p = 0.017). Conclusions: The treatment of patients with ES, performed in a reference center, allows obtaining good rates of recurrence and survival, with very low rates of cardiac transplantation for ES. In the presence of an early recurrence, it is advisable to perform a new procedure during admission.

Long-Term Outcome of the Randomized DAPA Trial.

BACKGROUND: The randomized DAPA trial (Defibrillator After Primary Angioplasty) aimed to evaluate the survival benefit of prophylactic implantable cardioverter defibrillator (ICD) implantation in early selected high-risk patients after primary percutaneous coronary intervention for ST-segment-elevation myocardial infarction. METHODS: A randomized, multicenter, controlled trial compared ICD versus conventional medical therapy in high-risk patients with primary percutaneous coronary intervention, based on one of the following factors: left ventricular ejection fraction <30% within 4 days after ST-segment-elevation myocardial infarction, primary ventricular fibrillation, Killip class ≥2 or TIMI (Thrombolysis in Myocardial Infarction) flow <3 after percutaneous coronary intervention. ICD was implanted 30 to 60 days after MI. Primary end point was all-cause mortality at 3 years follow-up. The trial prematurely ended after inclusion of 266 patients (38% of the calculated sample size). Additional survival assessment was performed in February 2019 for the primary end point. RESULTS: A total of 266 patients, 78.2% males, with a mean age of 60.8±11.3 years, were enrolled. One hundred thirty-one patients were randomized to the ICD arm and 135 patients to the control arm. All-cause mortality was significant lower in the ICD group (5% versus 13%, hazard ratio, 0.37 [95% CI, 0.15-0.95]) after 3 years follow-up. Appropriate ICD therapy occurred in 9 patients at 3 years follow-up (5 within the first 8 months after implantation). After a median long-term follow-up of 9 years (interquartile range, 3-11), total mortality (18% versus 38%; hazard ratio, 0.58 [95% CI, 0.37-0.91]), and cardiac mortality (hazard ratio, 0.52 [95% CI, 0.28-0.99]) was significant lower in the ICD group. Noncardiac death was not significantly different between groups. Left ventricular ejection fraction increased ≥10% in 46.5% of the patients during follow-up, and the extent of improvement was similar in both study groups. CONCLUSIONS: In this prematurely terminated and thus underpowered randomized trial, early prophylactic ICD implantation demonstrated lower total and cardiac mortality in patients with high-risk ST-segment-elevation myocardial infarction treated with primary percutaneous coronary intervention. Registration: URL: https://www.trialregister.nl; Unique identifier: Trial NL74 (NTR105).