Presence Of Ventricular Tachycardia Research Articles

Association between scar quantification and documented history of ventricular tachycardia in patients with hypertrophic cardiomyopathy

Abstract Background Hypertrophic cardiomyopathy (HCM) is a major risk factor for sudden cardiac death, and it is crucial to accurately identify patients who may benefit from implantable cardioverter defibrillator (ICD) implantation. Therefore, accurate risk stratification remains an unmet clinical need for patients with obstructive (HOCM) and non-obstructive (HNCM) hypertrophic cardiomyopathy. Methods and Aim Consecutive HCM patients were enrolled at a tertiary academic center and underwent cardiac magnetic resonance imaging. We aimed to explore risk factors for a documented history of ventricular tachycardia (VT). Results In total 246 HCM (160 HNCM, 86 HOCM) patients were included in the present analysis. Patients with HOCM and HNCM had similar rates of documented VTs (20.0% vs. 23.2%, p=0.61). However, the HCM-risk-score was significantly lower in HNCM patients (4.56% vs. 3.36%, p=0.003). There was no significant difference in age (53 vs. 57 years, p=0.65), sex (female sex 30% vs. 42%, p=0.14), or echocardiographic parameters, including the maximum outflow tract gradient (59 vs. 67 mmHg, p=0.71), the maximum wall thickness (21 vs. 20 mm, p=0.088), and the left atrial diameter (57 vs. 56 mm, p=0.59), in patients with versus without a history of documented VT. Furthermore, NT-proBNP (1040 vs. 1199 pg/mL, p=0.74) and high sensitivity troponin-T levels (22 vs. 19 ng/L, p=0.38) did not differ between groups. Patients with a history of VT were significantly more likely to have late gadolinium enhancement (LGE, 80% vs 50%, p=0.007) and had a higher percentage of LGE in relation to the left ventricular mass (9.2% vs 3.7%, p=0.001). These findings were consistent in patients with HOCM and HNCM (3.32% vs. 5.72% p=0.085). In an adjusted logistic regression model, the percentage of LGE was independently associated with the presence of VT (Odds ratio 1.27 [95%CI 1.08-1.50]). Conclusion These findings suggest that LGE may be a useful imaging marker for risk assessment in patients with HOCM and HNCM.

Association between metabolic dysfunction-associated fatty liver disease and supraventricular and ventricular tachyarrhythmias in patients with type 2 diabetes

BackgroundCurrently, it remains uncertain whether metabolic dysfunction-associated fatty liver disease (MAFLD) is associated with increased risk of supraventricular and ventricular tachyarrhythmias in people with type 2 diabetes mellitus (T2DM). MethodsWe retrospectively examined the data of 367 ambulatory patients with T2DM who underwent 24-hour Holter monitoring between 2015 and 2022 for clinical indications, and who did not have pre-existing permanent atrial fibrillation (AF), kidney failure or known liver diseases. Paroxysmal supraventricular tachycardia (PSVT), paroxysmal AF and episodes of ventricular tachyarrhythmias (i.e., presence of ventricular tachycardia, >30 premature ventricular complexes per hour, or both) were recorded. The presence and severity of MAFLD was diagnosed by ultrasonography and fibrosis-4 (FIB-4) index. ResultsPatients with T2DM who had MAFLD (n = 238) had a significantly greater prevalence of PSVT (51.7% vs. 38.8%), paroxysmal AF (6.3% vs. 1.3%) and combined ventricular tachyarrhythmias (31.9% vs. 20.2%) compared to their counterparts without MAFLD (n = 129). MAFLD was significantly associated with a greater than two-fold risk of having PSVT (adjusted-odds ratio [OR] 2.04, 95% confidence interval 1.04–4.00) or ventricular tachyarrhythmias (adjusted-OR 2.44, 95%CI 1.16–5.11), after adjusting for age, sex, smoking, alcohol intake, diabetes-related factors, comorbidities, medication use and left ventricular ejection fraction on echocardiography. The risk of supraventricular and ventricular tachyarrhythmias was even greater amongst patients with MAFLD and FIB-4 ≥ 1.3. ConclusionsIn ambulatory patients with T2DM, the presence and severity of MAFLD was strongly associated with an increased risk of supraventricular and ventricular arrhythmias on 24-hour Holter monitoring.

Young Age Onset Multivascular Pathology in a Patient with Severe Dyslipidemia: an Incidental Case or a Particular Type of Familial Hypercholesterolemia?

Abstract Familial hypercholesterolemia (FH) is a genetic disorder that affects about 1 in 250 people and increases the likelihood of having coronary heart disease at a younger age. We present the case of a 55-year-old patient, known with inferior and anterior myocardial infarction treated by percutaneous coronary intervention and coronary artery bypass grafts, Leriche syndrome, aortic abdominal aneurysm, and bilateral renal stents—pathologies with onset at a young age—who was admitted for fast-paced palpitations, accompanied by increased fatigue. The coronarography did not reveal any acute lesions, but the presence of ventricular tachycardia at admission required the implantation of a cardiac defibrillator. Since the patient presented with early onset severe systemic atherosclerosis, with a lipid profile dominated by hypo-HDL, doubled by an apolipoprotein A1 deficiency, we considered the diagnosis of familial hypercholesterolemia. Due to the high-risk profile, the association between a statin and a PCSK9 inhibitor was initiated at discharge. At the 1-month follow-up control, a significant reduction of LDL-C has been achieved, with a simultaneous increase of HDL-C serum levels.

Electrocardiographic Patterns of Depolarization Abnormalities Help to Identify Reduced Left Ventricular Ejection Fraction.

The aim of the study was to investigate the relationship between a decrease in the left ventricular ejection fraction (EF) and traditional ECG signs associated with structural changes of the myocardium (pathological Q wave, ventricular arrhythmias) and relatively new and poorly understood (fragmented QRS complex (fQRS), early repolarization pattern (ERP)) and evaluate their significance for identifying patients with mildly reduced EF (mrEF). The study included 148 patients who were treated and examined at the Almazov Medical Research Center. FQRS, ERP, pathological Q wave, and premature ventricular contractions (PVC) were described in the analysis of the ECG, and the results of echocardiography and statistical data were analyzed: Fisher’s test and chi-square, correlation analysis, and ROC analysis. According to the level of EF, patients were divided into three groups: group 1—patients with low EF (lEF) (less than 40%), group 2—patients with mildly reduced EF (mrEF) (40–49%); group 3—patients with preserved EF (pEF) (more than 50%). In the first group (EF), fQRS was registered in 16 (51.6%) patients, in the mrEF in 16 (18.2%). Pathological Q wave was detected in lEF in 20 (65%), in mrEF in 10 (35%), 15 (18%), in pEF in 15 (18%). The fQRS has been found to be more important in identifying patients with mrEF. In lEF in 2 (6.5%) patients, in mrEF in 2 (6.9%), in pEF in 11 (12.5%). There was no relationship between ERP, the amount of PVC, and the presence of ventricular tachycardia with EF. FQRS is significantly more common occurred with a decrease in EF and may be a marker of a mrEF. Thus, fQRS is associated with mrEF and pay close attention in routine clinical practice to identify patients at high risk of developing systolic dysfunction.

Electrocardiographic signs of impaired depolarization (fragmented QRS, early ventricular repolarization, etc.) as markers of left ventricular systolic dysfunction

Aim. To study the relationship between a decrease in left ventricular (LV) ejection fraction (EF) and conventional electrocardiographic (ECG) signs associated with myocardial structure changes (pathological Q wave, ventricular arrhythmias), and relatively novel and less studied (fragmented QRS (fQRS), early ventricular repolarization (EVR)) and to evaluate their significance for identifying patients with mildly-reduced EF (mrEF).Material and methods. The study included 148 patients who were treated and examined at the Almazov National Medical Research Center. During the ECG analysis, fQRS, EVR, pathological Q wave, and ventricular arrhythmias (VAs) were assessed. Echocardiography data were analyzed. Statistical processing was carried out, including Fisher and chi-squared test, as well as correlation and ROC analysis.Results. Depending on the EF level, patients were divided into three groups: group 1 — patients with reduced EF (rEF) (<40%); group 2 — patients with mrEF (40-49%); group 3 — patients with preserved EF (pEF) (>50%). In the 1st group (with rEF), fQRS was registered in 16 (51,6%) patients, in the 2nd (with mrEF) — in 13 (44,8%), in the 3rd (with EF >50%) — in 16 (18,2%). Pathological Q wave was detected in the 1st group (rEF) in 20 (65%) patients, in the 2nd (mrEF) — in 10 (35%); in the 3rd (pEF) — in 15 (18%) (p<0,001). ROC analysis found that fQRS is more important for identifying patients with mrEF. In the 1st group (rEF), EVR was registered in 2 (6,5%) patients, in the 2nd (pEF) — in 2 (6,9%), in the 3rd (EF>50%) — in 11 (12,5%); the differences were not significant (p=0,5). The relationship of EVR, the number of PVCs and the presence of ventricular tachycardia with EF was not revealed.Conclusion. FQRS is significantly more often observed with a decrease in EF and may be a marker of an mildly-reduced EF. There were no significant correlations between EVR and EF. There was also no relationship between VAs and LV systolic dysfunction.

Risks of Ventricular Tachyarrhythmia and Mortality in Patients with Amyloidosis - A Long-Term Cohort Study.

The presence of ventricular tachycardia (VT) is associated with higher mortality. The annual incidence of VT after a diagnosis of amyloidosis and the associated cardiovascular (CV) outcomes have not been well assessed in a large cohort. A total of 12,139 amyloidosis patients were identified from the Taiwan National Health Insurance Research Database. Non-amyloidosis group was matched 1:1 for age, gender, hypertension, and diabetes mellitus (DM) to the amyloidosis group using a propensity score. Analysis of the risk of CV outcomes was conducted. We also analyzed the incidence of cardiac amyloidosis (CA). The incidence rates of amyloidosis and CA were 6.54 and 0.61 per 100,000 person-years, respectively. Multivariable analysis revealed that the risk of VT was higher in both the amyloidosis [hazard ratio (HR): 7.90; 95% confidence interval (CI): 4.49-13.9] and CA (HR: 153.3, 95% CI: 54.3-432.7) groups. In the amyloidosis group, the risk of heart failure (HF)-related hospitalization, CV death, and all-cause death was also higher. Amyloidosis was associated with a higher CV mortality rate following VT (HR: 1.50; 95% CI: 1.07-2.12). The onset of a new VT event in patients with amyloidosis was associated with HF, DM, chronic liver disease, and anti-arrhythmic drug use. In this nationwide cohort study, the incidence rates of amyloidosis and CA were 6.54 and 0.61 per 100,000 person-years, respectively. The long-term risks of VT and CV mortality were higher in the patients with amyloidosis and CA. The patients with amyloidosis had a poorer prognosis following VT events, highlighting the importance of continuous monitoring in these patients.

Evaluation of ventricular tachycardia inducibility after implementation of a standardized programmed ventricular stimulation protocol in patients with repaired Tetralogy of Fallot

Abstract Introduction The electrophysiologic (EP) evaluation with programmed electrical stimulation (PVS) is generally recommended in patients with repaired Tetralogy of Fallot and additional risk factors for sudden cardiac death. Nevertheless, different PVS protocols have been described. The aim of our study was to evaluate the differences in ventricular tachycardia (VT) inducibility of patients with TOF after the implementation of a standard PVS protocol in the EP laboratory of a Congenital Heart Disease reference center. Methods All patients with repaired TOF who underwent an EP study with PVS between January 2001 and October 2020 were included. The new standardized PVS protocol was performed in 2 ventricular sites (apex and outflow tract) with 3 drive trains (cycle lengths 400, 500 and 600ms) and up to 3 extrastimuli. In absence of VT induction, the protocol was repeated under isoprenaline infusion. This new protocol was implemented since January 2012. Non protocolized PVS studies before 2012 were defined as “Non-standardized”. Baseline clinical information about symptoms and previous arrhythmias was recorded as well as electrocardiogram, echocardiogram and cardiac MRI parameters. Finally, the follow-up events (ICD implantation, sudden cardiac death, global mortality, arrythmias and ICD therapies) were also retrospective recorded. Results A total of 154 EP studies with PVS were performed in 128 patients with repaired TOF. 31 of them were performed before the 1st January 2012 (non-standardized PVS) and 112 were performed with the new standardized protocol. The median follow-up was 6,5 years. Both groups had similar baseline characteristics except LVEF and RVEF, that were lower in the “Non-standardized PVS” group. There were no differences between the ventricular tachycardia inducibility of both protocols (22,3% vs 33,3%; p=0,162). The risk factors for VT inducibility were the QRS length (184,46ms vs 169,34 ms; p=0,038), the RVEF (36,25% vs 43,79; p=0,0007), the presence of ventricular ectopia (VE) (38,5% vs 20,0%; p=0,024) and previous VT (35,9% vs 13,9%; p=0,003). VT induction during EP study was related with ICD implantation (71,8% vs 21,7%, p≤0,001), VT (30,8% vs 20%, p<0,001) and all kind of arrythmias (VT, non-sustained VT, VE and auricular flutter) (41% vs 21,7%, p=0,005) during follow-up. A total of 6 deaths (1 in the group with induced VT and 5 in the group with non-induced VT) were recorded. Conclusions The implementation of a standardized and more complete PVS protocol in patients with repaired TOF has not shown differences in the experience of our center. The risk factors for VT inducibility were the QRS length, the RVEF, the presence of ventricular ectopia and previous VT, which have also been reported as risk factors for sudden cardiac death in previous studies. The presence of VT induction entailed more ICD implantation and more arrythmias at follow-up. Funding Acknowledgement Type of funding sources: None.

Cardiac Magnetic Resonance Imaging and Ventricular Tachycardias Involving the Sinuses of Valsalva in Patients With Nonischemic Cardiomyopathy

The goal of this study was to investigate the relationship between cardiac scar on late gadolinium enhancement cardiac resonance imaging (LGE-CMR) and the presence of ventricular tachycardia (VT) ablation target sites within the sinuses of Valsalva (SV). Patients with idiopathic dilated cardiomyopathy (IDCM) often have scarring involving the basal myocardium, including the SV, allowing targeting of VTs from within the SV. Forty-three consecutive patients with IDCM underwent a VT ablation procedure with pre-procedure LGE-CMR. Retrospectively, scar characteristics were compared between patients with and without VT target sites in the SV. The ratio between SV-related scarring and the total cardiac scarring was defined as the SV scar index: SV-related scarring/total cardiac scarring. VT target sites were identified in the SV in 22 (51%) of 43 patients. LGE-CMR identified peri-aortic scarring involving the SV in 34 patients (79%). Scarring extended to the septum in 26 patients, involved the lateral basal wall in 4, and both areas in 13 patients. Scar volume within the SV was larger in patients with SV-VT targets (1.7 ± 0.9cm3 vs. 0.7 ± 0.6cm3; p<0.0001) compared with other patients. A cutoff scar volume identifying SV-VT targets was 1.23cm3 in the short-axis view (area under the curve 0.82; sensitivity 0.64; specificity 0.91). The SV scar index was significantly greater in patients who had SV-VT target sites (0.33 ± 0.2 vs. 0.09 ± 0.09; p<0.0001). Patients with IDCM undergoing ablation of VT often have peri-aortic scarring visualized on LGE-CMR. Both the presence and the extent of scarring adjacent to the aortic annulus are associated with the presence of VT target sites within the SV.

The Role of Cardiac Magnetic Resonance in Evaluation of Idiopathic Ventricular Arrhythmia in Children.

The aim of the study was to assess the role of cardiovascular magnetic resonance (CMR) in the diagnosis of idiopathic VA in children. This retrospective single-centre study included a total of 80 patients with idiopathic ventricular arrhythmia that underwent routine CMR imaging between 2016 and 2020 at our institution. All patients underwent a 3.0 T scan involving balanced steady-state free precession cine images as well as dark-blood T2W images and assessment of late gadolinium enhancement (LGE). In 26% of patients (n = 21) CMR revealed cardiac abnormalities, in 20% (n = 16) not suspected on prior echocardiography. The main findings included: non-ischemic ventricular scars (n = 8), arrhythmogenic right ventricular cardiomyopathy (n = 6), left ventricular clefts (n = 4) and active myocarditis (n = 3). LGE was present in 57% of patients with abnormal findings. Univariate predictors of abnormal CMR result included abnormalities in echocardiography and severe VA (combination of >10% of 24 h VA burden and/or presence of ventricular tachycardia and/or polymorphic VA). CMR provides valuable clinical information in many cases of idiopathic ventricular arrhythmia in children, mainly due to its advanced tissue characterization capabilities and potential to assess the right ventricle.

Apparent dual exit pathways during ventricular tachycardia recorded by an ICD

Ventricular tachycardia (VT) with dual exit pathways has been demonstrated in many ways. In this respect we found suggestive evidence of dual exit behavior during VT in a patient with an implanted cardioverter-defibrillator. The evaluation was done with continuous recordings of the right ventricular (RV) and left ventricular (LV) electrograms. The recordings documented the varying duration of the LV to RV delay and no change in the RV rate during increases in the LV-RV delay. The unchanged rate ruled out RV participation in the VT circuit. This ruled out the presence of VT with dual exit pathways and provided proof of an unusual RV bystander that did not participate in the VT circuit.

Prognostic value of coupling interval, prematurity index and heart rate variability in Boxer dogs

ABSTRACT: Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC) can experience sudden cardiac death regardless of presence/absence of clinical signs. The aims of this retrospective study were two-fold: 1) to investigate the coupling interval (CI) and prematurity index (PI) of ventricular arrhythmias (VA), and the heart rate variability (HRV) in Boxers, and 2) to evaluate their impact on overall survival time. The first 24-hour Holter 36 client-owned Boxer dogs meeting inclusion/exclusion criteria were evaluated for the number, morphology, site of origin, complexity, CI and PI, of ventricular premature complexes (VPCs), and time domain HRV. The effect on survival was assessed, considering the presence/absence of ventricular tachycardia (VT), and syncope. All-cause mortality was considered as the end-point, with median survival times being obtained by Kaplan-Meier analyses and compared by log-rank test. Polymorphic VPCs were more common in symptomatic dogs than asymptomatic. VPCs in dogs with VT were less premature, due to the influence of heart rate on PI despite comparable CI. The PI and mean heart rate (HRme) were significantly different between VT and non-VT dogs but did not discriminate adequately between groups as standalone tests. Median survival time was shorter in Boxer dogs with VT (463 vs 1645 days, HR: 4.31, P=0.03). The HRV parameters, SDNN and SDANN, were both associated with prognosis. The CI and PI were not demonstrated to be prognostic surrogates in Boxer dogs with VA. HRme≥112bpm is 100% sensitive but only 46% specific for detecting VT in Boxers on the 24-hour Holter. Presence of VT, SDNN≤245ms, or SDANN≤134ms at the time of the first 24-hour Holter was associated with a shorter survival.

Abstract 16621: Holter Monitoring in Patients With Left Ventricular Noncompaction

Introduction: Multiple arrhythmias including ventricular tachycardia (VT) and atrial fibrillation (AF) have been reported in patients with left ventricular noncompaction (LVNC). We sought to determine the frequency of rhythm abnormalities on Holter monitoring, and their association with all-cause mortality, in patients with LVNC. Methods: Imaging databases from 2000-2016 were reviewed to identify patients with LVNC. On transthoracic echocardiography (TTE), LVNC was defined as: end systolic noncompacted: compacted (NC:C) ratio&gt;2 and end diastolic epicardium to trough: epicardium to peak trabeculation (X:Y) ratio&lt;0.5. Holter monitor reports from the medical record were evaluated. VT was defined as ≥3 consecutive beats of ventricular origin. All-cause mortality was obtained from a web-based research and location service (Accurint). We used a proportional hazards model to determine associations of Holter variables with all-cause mortality. Results: Among 340 LVNC patients, Holter reports were available for 177 patients (median age 45 years, interquartile range [IQR] 33-61; 45% females). On TTE, the median NC:C ratio was 2.7 (IQR 2.4-3.2) and X:Y ratio was 0.25 (IQR 0.20-0.28). The median ejection fraction (EF) was 48% (IQR 33-58). 48 patients (27%) had at least one episode of VT (median 4 episodes, IQR 2-4). The median longest duration of VT was 5 beats (IQR 4-9) and maximum rate was 148 beats per minute (IQR: 125-169). PVC burden &gt;5% and 20% was present in 13% and 5% of patients respectively. Patients with EF&lt;50% were more likely to have VT (43% vs 16%, p=0.0003) and PVC burden &gt;5% (19% vs 7%, p=0.03). AF was infrequent (N=5, all persistent). All-cause mortality was 12% over median 6.9 years of follow up (IQR: 3.6-11.3 years). Presence of VT and PVC burden on Holter monitoring were not associated with all-cause mortality (p&gt;0.05). Among patients with VT, the number, longest duration, and fastest rate of VT episodes were not associated with all-cause mortality. Conclusions: Ventricular tachycardia on Holter monitoring is common among patients with LVNC, especially those with a reduced EF. However, the clinical significance of this finding is uncertain, and presence of VT was not associated with long term all-cause mortality.

Anesthetic Management in Radiofrequency Catheter Ablation of Ventricular Tachycardia.

Radiofrequency catheter ablation is increasingly being used to treat patients who have ventricular tachycardia, and anesthesiologists frequently manage their perioperative care. This narrative review is intended to familiarize anesthesiologists with preprocedural, intraprocedural, and postprocedural implications of this ablation. Ventricular tachycardia typically arises from structural heart disease, most often from scar tissue after myocardial infarction. Many patients thus affected will benefit from radiofrequency catheter ablation in the electrophysiology laboratory to ablate the foci of arrhythmogenesis. The pathophysiology of ventricular tachycardia is complex, as are the technical aspects of mapping and ablating these arrhythmias. Patients often have substantial comorbidities and tenuous hemodynamic status, necessitating pharmacologic and mechanical cardiopulmonary support. General anesthesia and monitored anesthesia care, when used for sedation during ablation, can lead to drug interactions and side effects in the presence of ventricular tachycardia, so anesthesiologists should also be aware of potential perioperative complications. We discuss variables that can help anesthesiologists safely guide patients through the challenges of radiofrequency catheter ablation of ventricular tachycardia.

A Review of the Potential Pathogenicity and Management of Frequent Premature Ventricular Contractions.

Very frequent premature ventricular complexes (PVCs) may be a reversible cause of dilated cardiomyopathy. Literature on this largely unrecognized entity has increased in the last 15 years. This paper reviews the literature on the consequences of frequent PVCs on myocardial function and management of PVC-associated cardiomyopathy. The authors reviewed articles published in English before June 2015 describing pathophysiology, risk factors, symptoms, time course, treatment, and outcome of cardiomyopathy associated with PVCs. The search was conducted using Medline and Embase. Keywords included: cardiomyopathy, catheter ablation, antiarrhythmic drug (AAD), pathophysiology, and ventricular premature contractions or synonyms. PVC-associated cardiomyopathy is associated with a high burden of PVC (over 20% of heartbeats). Other risk factors include electrophysiological characteristics, such as PVC QRS width, presence of ventricular tachycardia, retrograde P waves, interpolation, polymorphic PVCs, and longer coupling intervals. Symptoms include palpitations, light-headedness, dyspnea, cough, and dysphagia. The systolic dysfunction and chamber dilatation progress over a few years. Once the PVCs are suppressed by radiofrequency ablation or AADs, the cardiomyopathy usually resolves within 6 months. The pathophysiology remains unknown, but hypotheses mainly include ventricular dyssynchrony resulting in hemodynamic disturbances and abnormalities in calcium handling and oxygen consumption. PVC-associated cardiomyopathy remains a largely unrecognized entity. It is a reversible cause of dilated cardiomyopathy that results from abnormal calcium and oxygen handling within the myocyte, dyssynchrony, and hemodynamic compromise from inefficient heartbeats. Suppression of the PVCs improves myocardial function, cardiac chamber sizes, and patient's symptoms.

Predictors of Sudden Cardiac Death in Doberman Pinschers with Dilated Cardiomyopathy.

BackgroundDoberman Pinschers with dilated cardiomyopathy (DCM) are at high risk of sudden cardiac death (SCD). Risk factors for SCD are poorly defined.AimTo assess cardiac biomarkers, Holter‐ECG, echocardiographic variables and canine characteristics in a group of Doberman Pinschers with DCM dying of SCD and in a DCM control group to identify factors predicting SCD.Methods/AnimalsA longitudinal prospective study was performed in 95 Doberman Pinschers with DCM. Forty‐one dogs died within 3 months after the last cardiac examination (SCD‐group) and were compared to 54 Doberman Pinschers with DCM surviving 1 year after inclusion. Holter‐ECG, echocardiography, measurement of N‐terminal prohormone of brain‐natriuretic peptide (NT‐proBNP), and cardiac Troponin I (cTnI) concentrations were recorded for all dogs.ResultsVolume overload of the left ventricle (left ventricular end‐diastolic volume (LVEDV/BSA) > 91.3 mL/m²) was the single best variable to predict SCD. The probability of SCD increases 8.5‐fold (CI 0.95 = 0.8–35.3) for every 50 mL/m²‐unit increment in LVEDV/BSA. Ejection fraction (EF), left ventricular end‐systolic volume (LVESV/BSA) and NT‐proBNP were highly correlated with LVEDV/BSA (r = −0.63, 0.96, 0.86, respectively). Generated conditional inference trees (CTREEs) revealed that the presence of ventricular tachycardia (VT), increased concentration of cTnI, and the fastest rate (FR) of ventricular premature complexes (VPC) ≥260 beats per minute (bpm) are additional important variables to predict SCD.ConclusionConditional inference trees provided in this study might be useful for risk assessment of SCD in Doberman Pinschers with DCM.

Alternating atrial pacing cycle length during ventricular tachycardia: What is the mechanism?

Case summary A 62-year-old man with a background of ischemic cardiomyopathy and sick sinus syndrome underwent implantation of a cardiac resynchronization therapy defibrillator (CRTD) device (Medtronic Concerto, Minneapolis, MN). Table 1 lists the basic pacing programming of the device. At routine follow-up, a ventricular event was detected that was terminated successfully following 3 antitachycardia pacing therapies. The dot-plot relating to the ventricular event initially demonstrated some variation in the cycle length of the ventricular tachycardia (VT), resulting in V-V intervals drifting above and below the ventricular tachycardia detection interval (VTDI) set at 400 ms (Figure 1). Simultaneous critically short coupled ventricular tracked events during this period of VT were seen in association with those V-V intervals that were just above the VTDI. Careful analysis of the corresponding electrograms also revealed an interesting pattern of atrial pacing with alternating cycle lengths of 680 and 490 ms occurring concurrently in the presence of VT (Figure 2). Further inspection of the episode revealed that once acceleration of the VT occurred with V-V intervals falling consistently below the VTDI, cessation of atrial pacing was seen, followed by the successful detection and subsequent termination of the VT episode with antitachycardia pacing. The questions that arise are as follows. (1) Which algorithm was responsible for the simultaneous critically short coupled ventricular tracked events observed following initiation of VT? (2) Why, despite ongoing VT,

Prognostic Value of 24‐Hour AmbulatoryECG(Holter) Monitoring in Boxer Dogs

Boxer dogs are reported to be predisposed to arrhythmogenic right ventricular cardiomyopathy (ARVC), but the natural history has not been well characterized and inconsistent diagnostic criteria have been applied to identify affected dogs. Echocardiographic examination findings are unremarkable in many affected Boxer dogs, and in these dogs, 24-hour ambulatory ECG (Holter) monitoring often is used for diagnostic and prognostic purposes, despite limited information available relating Holter findings to outcome. Boxers with complex ventricular arrhythmias at initial presentation will have shorter survival times. The objective was to investigate the prognostic value of Holter monitoring in Boxer dogs. One hundred and twenty-two Boxer dogs seen at 3 university referral hospitals. Retrospective study. Survival times were obtained for Boxer dogs evaluated by echocardiography and a 24-hour Holter ECG. Kaplan-Meier survival analysis was used to estimate the median survival time and Cox proportional hazards analysis was used to identify variables independently associated with cardiac mortality. Outcome data were obtained for 122/163 dogs meeting the inclusion criteria. Of the 70 dogs that had died, 45 were considered to have suffered cardiac-related deaths. Median survival was significantly longer in dogs with a left ventricular systolic diameter (LVIDs) ≤ 35 mm compared with those with LVIDs > 35 mm (P < .001). Multivariable analysis in dogs with LVIDs ≤ 35 mm showed that the presence of ventricular tachycardia, age >4.5 years, and male sex were independent predictors of cardiac mortality. Holter monitoring in Boxer dogs provides valuable prognostic information.

Abstract 2126: Therapeutic Evaluation of Corticosteroid Therapy for Ventricular Tachycardia Associated with Cardiac Sarcoidosis -Application of High Resolution Electrocardiography-

Background The outcome of cardiac sarcoidosis (CS) is sometimes fatal. Ventricular tachycardia (VT) is one of the common causes of sudden death in CS patients. In patients with definite diagnosis of CS, corticosteroid therapy should be the absolute indication. However, little is known about the effectiveness for VT. Further, there is no established method for therapeutic evaluation in CS. Thus, we investigated whether or not VT is suppressed following corticosteroid therapy and the utility of Signal Averaged Electrocardiography (SAECG) for therapeutic assessment in CS patients with VT. Methods Fifteen histological proved CS patients presenting with sustained or non-sustained VT were investigated. All of these patients were treated with predonisolone 30mg to 10mg/day, and assessed before and after corticosteroid therapy. All patients underwent SAECG in which the filtered QRS duration (f-QRS), the root mean square voltage of the terminal 40 ms (RMS 40 ) in the filtered QRS complex and the duration of low-amplitude signals &lt; 40μV (LAS 40 ) in the terminal filtered QRS complex were measured. The presence of VT was assessed by Holter monitoring. Results VT was suppressed in 6 patients {VT (−) group} and the remaining 9 patients were not {VT (+) group}. Accumulation of gallium-67 was detected more frequently in VT (−) group than in VT (+) group (66.7% vs. 11.1%, p&lt;0.05). Left ventricular ejection fraction (LVEF) was significantly higher in VT (−) group than that of VT (−) group (54.1+/−20.1 vs 32.8+/−11.7 p&lt;0.05). In VT (−) group, f-QRS and LAS 40 were significantly decreased and RMS 40 was significantly increased compared with those before corticosteroid therapy (f-QRS: 136.3+/−30.6msec vs 116.8+/−25.4msec, p&lt;0.05 LAS 40 : 68.2+/−24.0msec vs 47.8+/−22.9msec, p&lt;0.05 RMS 40 : 7.2+/−3.3 msec vs 13.3+/−7.6msec, p&lt;0.05). However, SAECG parameters did not change significantly in VT (+) group. Conclusions In the early and viable stage of the disease, corticosteroid therapy was effective for VT in CS. Reversible conduction abnormality detected by SAECG might reflect reversible arrhythmogenic substrate for the occurrence of VT. SAECG is useful for therapeutic evaluation of CS patients with VT.

Monitorização eletrocardiográfica ambulatorial por 24-horas em cães com cardiomiopatia dilatada idiopática

Caracterizou-se monitorização eletrocardiográfica ambulatorial por 24 horas (ou monitorização Holter) em cães com cardiomiopatia dilatada idiopática, visando principalmente à detecção de arritmias ventriculares não detectadas pela eletrocardiografia convencional (de repouso). Para tanto, avaliaram-se 40 pacientes com diagnóstico de cardiomiopatia dilatada idiopática, por meio de exame físico e mensuração indireta da pressão arterial, além de exames eletrocardiográfico, ecocardiográfico, radiográfico de tórax e da monitorização Holter. Extra-sístoles ventriculares foram detectadas, por monitorização Holter, em 97,5% dos animais e taquicardia ventricular, em 45%. Não houve correlação entre o número de extra-sístoles ventriculares e a fração de encurtamento. Considerando as manifestações clínicas, apenas houve associação entre presença de taquicardia ventricular e histórico de síncopes. Conclui-se que a incidência de arritmias ventriculares em cães com cardiomiopatia dilatada idiopática é bastante alta, sendo a taquicardia ventricular relativamente freqüente, ocorrendo mais sob a forma não sustentada.

AB50-4: Delayed enhancement MRI can detect arrhythmogenic substrate

We previously reported that myocardial fibrosis with positive delayed-enhancement (DE) was highly associated with presence of ventricular tachycardia (VT) in patients with nonischemic dilated cardiomyopathy. However, it remains still controversial if the DE in the myocardium contributes to the electrophysiological features and is the substrate for arrhythmogenicity.