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Cardiovascular AND Tachycardia, ventricular, [keywords]
- Complex Excitation Dynamics Underlie Polymorphic Ventricular Tachycardia in a Transgenic Rabbit Model of LQT1. [JOURNAL ARTICLE]
- Heart Rhythm 2014 Oct 3.
Long QT syndrome type 1 (LQT1) is a congenital disease arising from a loss of function in the slowly activating delayed potassium current (IKs) that causes early afterdepolarizations (EADs) and polymorphic ventricular tachycardia (pVT).We investigated the mechanisms underlying pVT using a transgenic rabbit model of LQT1.Hearts were perfused retrogradely, and action potentials were recorded using a voltage-sensitive dye and CMOS cameras.Bolus injection of isoproterenol (140 nM) induced pVT initiated by focal excitations from the RV (n=16 out of 18 pVTs). After the pVT is initiated, complex focal excitations occur in both RV and LV that cause oscillations of the QRS complexes in the ECGs, consistent with the recent proposal of multiple shifting foci caused by EAD chaos. Moreover, the action potential upstroke in pVT showed a bimodal distribution, demonstrating the coexistence of two types of excitation that interact to produce complex pVT. Namely, Na(+) current (INa)-mediated fast conduction and L-type Ca(2+) current (ICa)-mediated slow conduction co-exist, manifesting as pVT. Addition of 2 μM TTX to reduce INa converted pVT into monomorphic VT. Reducing late INa in computer simulation converted pVT into a single dominant reentry, agreeing with experimental results.Our study demonstrates that pVT in LQT1 rabbits is initiated by focal excitations from the RV and is maintained by multiple shifting foci in both ventricles. Moreover, the wave conduction in pVT exhibits bi-excitability, i.e., fast wavefronts driven by INa and slow wavefronts driven by ICa co-exist during pVT.
- Use of a Novel Fragmentation Map to Identify the Substrate for Ventricular Tachycardia in Post Infarction Cardiomyopathy. [JOURNAL ARTICLE]
- Heart Rhythm 2014 Oct 3.
Substrate ablation is commonly performed in patients with post-infarction cardiomyopathy and ventricular tachycardia (VT). Recognition of fragmented and late potentials during sinus rhythm is a tedious process subject to operator fatigue.The purpose of this study was to assess the value of automated analysis to quantify electrogram fragmentation and to determine the relationship of fragmented regions to the VT isthmus.Detailed left ventricular (LV) mapping was performed in 2 groups: 1) 14 patients with previous myocardial infarction and tolerated VT and 2) 14 controls with structurally normal hearts. In patients with VT, mid-isthmus sites were identified using entrainment mapping. Sinus rhythm endocardial LV electrograms underwent time and frequency domain analysis and were displayed as fragmentation or frequency maps. The region of fractionated electrograms and their relation to the VT isthmus sites was determined.Cutoffs for abnormal electrogram fragmentation were ventricular fractionation index (VFl) ≥7 and FFT ratio ≥14%, respectively. In the time domain, the left ventricular surface area with fractionated electrograms was significantly smaller than the total scar surface area (27.3 ± 7.1% vs. 42.1±12.3%, p<0.001), yet contained 100% of VT isthmus sites. In the frequency domain, areas of abnormal fractionation occupied 9.7 ± 6.9% of total LV surface area and included only 60% of the VT isthmus sites.Automated electrogram fractionation analysis represent an objective tool to rapidly quantify electrogram fragmentation and guide substrate based ablation of VT. Empiric ablation of these regions may be a new strategy for substrate guided VT ablation.
- Reduced Risk for Inappropriate Implantable Cardioverter-Defibrillator Shocks With Dual-Chamber Therapy Compared With Single-Chamber Therapy: Results of the Randomized OPTION Study (Optimal Anti-Tachycardia Therapy in Implantable Cardioverter-Defibrillator Patients Without Pacing Indications). [JOURNAL ARTICLE]
- JACC Heart Fail 2014 Sep 25.
The OPTION (Optimal Anti-Tachycardia Therapy in Implantable Cardioverter-Defibrillator Patients Without Pacing Indications) trial sought to compare long-term rates of inappropriate shocks, mortality, and morbidity between dual-chamber and single-chamber settings in implantable cardioverter-defibrillators (ICDs) patients.The use of dual-chamber ICDs potentially allows better discrimination of supraventricular arrhythmias and thereby reduces inappropriate shocks. However, it may lead to detrimental ventricular pacing.This prospective multicenter, single-blinded trial enrolled 462 patients with de novo primary or secondary prevention indications for ICD placement and with left ventricular ejection fractions ≤40% despite optimal tolerated pharmacotherapy. All patients received atrial leads and dual-chamber defibrillators that were randomized to be programmed either with dual-chamber or single-chamber settings. In the dual-chamber setting arm, the PARAD+ algorithm, which differentiates supraventricular from ventricular arrhythmias, and SafeR mode, to minimize ventricular pacing, were activated. In the single-chamber setting arm, the acceleration, stability, and long cycle search discrimination criteria were activated, and pacing was set to VVI 40 beats/min. Ventricular tachycardia detection was required at rates between 170 and 200 beats/min, and ventricular fibrillation detection was activated above 200 beats/min.During a follow-up period of 27 months, the time to the first inappropriate shock was significantly longer in the dual-chamber setting arm (p = 0.012, log-rank test), and 4.3% of patients in the dual-chamber setting group compared with 10.3% in the single-chamber setting group experienced inappropriate shocks (p = 0.015). Rates of all-cause death or cardiovascular hospitalization were 20% for the dual-chamber setting group and 22.4% for the single-chamber setting group and satisfied the pre-defined margin for equivalence (p < 0.001).Therapy with dual-chamber settings for ICD discrimination combined with algorithms for minimizing ventricular pacing was associated with reduced risk for inappropriate shock compared with single-chamber settings, without increases in mortality and morbidity. (Optimal Anti-Tachycardia Therapy in Implantable Cardioverter-Defibrillator [ICD] Patients Without Pacing Indications [OPTION]; NCT00729703).
- Is CRT pro-arrhythmic? A comparative analysis of the occurrence of ventricular arrhythmias between patients implanted with CRTs and ICDs. [Journal Article]
- Front Physiol 2014.:334.
Aim and Hypothesis: Despite the proven symptomatic and mortality benefit of cardiac resynchronization therapy (CRT), there is anecdotal evidence it may be pro-arrhythmic in some patients. We aimed to identify if there were significant differences in the incidence of ventricular arrhythmias (VAs) in patients undergoing CRT-D and implantable cardioverter-defibrillators (ICD) implantation for primary prevention indication. We hypothesized that CRT is unlikely to be pro-arrhythmic based on the positive mortality and morbidity data from large randomized trials.A retrospective analysis of device therapies for VA in a primary prevention device cohort was performed. Patients with ischemic (IHD) and non-ischemic (DCM) cardiomyopathy and ICD or CRT+ICD devices (CRT-D) implanted between 2005 and 2007 without prior history of sustained VA were included for analysis. VA episodes were identified from stored electrograms and defined as sustained (VT/VF) if therapy [anti-tachycardia pacing (ATP) or shocks] was delivered or non-sustained (NSVT) if not. Of a total of 180 patients, 117 (68% male) were in the CRT-D group, 42% IHD, ejection fraction (EF) 24.5 ± 8.2% and mean follow-up 23.9 ± 9.8 months. 63 patients (84% male) were in the ICD group, 60% IHD, EF 27.7 ± 7.2% and mean follow-up 24.6 ± 10.8 months. Overall, there was no significant difference in the incidence of VA (35.0 vs. 38.1%, p = 0.74), sustained VT (21.3 vs. 28.5%, p = 0.36) or NSVT (12.8 vs. 9.5%, p = 0.63) and no significant difference in type of therapy received for VT/VF: ATP (68 vs. 66.6%, p = 0.73) and shocks (32 vs. 33.3%, p = 0.71) between the CRT-D and ICD groups, respectively.In patients with cardiomyopathy receiving CRT-D and ICDs for primary prophylaxis, there was no significant difference in the incidence of VA. From this single center retrospective analysis, there is no evidence to support cardiac resynchronization causing pro-arrhythmia.
- Transapical myectomy and surgical cryoablation for refractory ventricular tachycardia due to hypertrophic cardiomyopathy with apical aneurysm. [JOURNAL ARTICLE]
- Eur J Cardiothorac Surg 2014 Oct 1.
Ventricular tachycardia (VT) associated with midventricular hypertrophic cardiomyopathy and apical aneurysm is rare, but is frequently refractory to medical therapy. We report a case of a 44-year old man with incessant VT despite undergoing catheter ablation in the neck of a left ventricular apical aneurysm. Resection of a hypertrophied midventricular muscle through an apical incision and surgical cryoablation of the aneurysm border from the epicardial and endocardial surface were performed successfully. The patient was well without ventricular arrhythmic events at 2 years postoperatively.
- Magnetic Resonance Imaging for Identifying Patients with Cardiac Sarcoidosis and Preserved or Mildly Reduced Left Ventricular Function at Risk of Ventricular Arrhythmias. [JOURNAL ARTICLE]
- Circ Arrhythm Electrophysiol 2014 Sep 29.
-The purpose of this study was to assess whether delayed enhancement (DE) on magnetic resonance imaging (MRI) is associated with ventricular tachyarrhythmia (VT/VF) or death in patients with cardiac sarcoidosis (CS) and left ventricular ejection fraction (LVEF) >35%.-51 patients with CS and LVEF>35% underwent DE-MRI. DE was assessed by visual scoring and quantified with the full-width at half-maximum method. The patients were followed for 48.0±20.2 months. 32 of 51 patients (63%) had DE. Forty patients had no prior history of VT (primary prevention cohort). Among those, 3 patients developed VT and two patients died. DE was associated with risk of VT/VF or death (p=0.0032 for any DE, and p<0.0001 for right ventricular DE). The positive predictive values of the presence of any DE, multifocal DE, and right ventricular DE for death or VT/VF at mean follow-up of 48 months were 22%, 48%, and 100%, respectively. Among the 11 patients with a history of VT prior to the MRI, 10 patients had subsequent VTs, one of whom died.-RV DE in patients with CS is associated with a risk of adverse events in patients with CS and preserved ejection fraction in the absence of a prior history of VT. Patients with DE and a prior history of VT have a high VT recurrence rate. Patients without DE on MRI have a very low risk of VT.
- Efficacy of Anti-Tachycardia Pacing for Terminating Fast Ventricular Tachycardia in Japanese Implantable Cardioverter Defibrillator Patients. [JOURNAL ARTICLE]
- Circ J 2014 Sep 27.
Background:Anti-tachycardia pacing (ATP) delivered by implantable cardioverter defibrillators (ICD) safely avoids painful shocks with minimum risk of tachycardia acceleration. The etiology of ventricular tachycardia (VT) in those studies, however, was predominantly coronary artery disease (CAD). Patient etiology differs by geography and could affect ATP efficacy rate. The primary objective of this study was to examine how often the first ATP therapy terminates fast VT (FVT) in Japanese ICD patients with regional etiologies.Methods and Results:Seven hundred and fifteen patients received ICD or cardiac resynchronization therapy defibrillator with the function of ATP during capacitor charging. The primary endpoint was the first ATP success rate for terminating FVT with cycle length 240-320 ms. During a mean follow-up of 11.3 months, 888 spontaneous VT episodes were detected, including 276 FVT (31.1%) in 42 patients. The first-ATP success rate for FVT in the overall group (41% CAD, 59% non-CAD including 23% idiopathic VT) was 62.1% (61.7% adjusted). Success rate was not different between non-CAD and CAD patients (61.4% adjusted and 57.5% adjusted, respectively, P=0.75). Eight FVT episodes (2.9%) accelerated after the first ATP attempt, all of which were terminated by subsequent device therapy (additional ATP or shock).Conclusions:ATP efficacy for FVT was similar between ICD patients with and without CAD etiology.
- Atrial Fibrillation and Its Association With Sudden Cardiac Death. [JOURNAL ARTICLE]
- Circ J 2014 Sep 26.
Evidence is emerging to indicate that atrial fibrillation (AF) is independently associated with an increased risk of sudden cardiac death (SCD). This association has been consistently observed in specific patient subgroups such as patients with myocardial infarction (MI), heart failure, and hypertension, and importantly, in the general population. Data from studies of implantable cardioverter-defibrillator recipients suggest that the rapid and irregular rhythm of AF and the short-long-short cycles that are highly prevalent in AF increase susceptibility to ventricular tachycardia and ventricular fibrillation. An alternative explanation for the association between AF and SCD includes confounding or mediation by shared risk factors such as coronary artery disease and heart failure. Possible risk factors for SCD in patients with AF include black race, left ventricular hypertrophy, history of MI, and diabetes. Additional research is needed to confirm the inherent proarrhythmic nature of AF, identify patients' characteristics or clinical conditions that potentiate SCD risk, and define effective SCD prevention strategies for patients with AF.
- Early Referral for Ablation of Scar-Related Ventricular Tachycardia Is Associated with Improved Acute and Long Term Outcomes: Results from the Heart Center of Leipzig Ventricular Tachycardia Registry. [JOURNAL ARTICLE]
- Circ Arrhythm Electrophysiol 2014 Sep 27.
-The effects of time to referral for catheter ablation (CA) of scar-related ventricular tachycardia (VT) on acute success, VT recurrence and cardiac mortality are unclear.-We investigated 300 patients after CA of sustained VT. CA was performed within 30 days after the first documented VT in 75 (25%) patients (group 1); between 1 month and 1 year in 84 (28%) patients (group 2); and more than 1 year after the first VT occurrence in 141 (47%) patients (group 3). The end points were non-inducibility of any VT after CA (acute success), VT-recurrence and cardiac mortality after 2 years. Acute success was achieved in 66 (88%) patients in group 1; 68 (81%) in group 2, and in 99 (70.2%) in group 3 (p=0.008). During the 2-years follow-up period, VT recurred in 28 (37.3%) patients in group 1; 52 (61.9%) patients in group 2; and 91 (64.5%) patients in group 3 (p<0.0001). Recurrence-free survival was higher in group 1, as compared to group 2 (HR=1.85; p=0.009) and group 3 (HR=2.04; p=0.001). No survival difference was observed between groups 1 and 2 (HR=0.85; p=0.68), and groups 1 and 3 (HR=1.13; p=0.73). Beta-blocker therapy, VT of ischemic origin, and complete success were associated with VT-free survival. VT recurrence (HR=1.91; p=0.037) predicted cardiac mortality.-CA of scar-related VT performed within 30 days after the first documented VT was associated with improved acute and long-term success. VT recurrence, but not the early referral for CA, was associated with cardiovascular mortality.
- Epidemiology, pathophysiology, and in-hospital management of pulmonary edema: data from the Romanian Acute Heart Failure Syndromes registry. [JOURNAL ARTICLE]
- J Cardiovasc Med (Hagerstown) 2014 Sep 23.
The objective of this study was to evaluate the clinical presentation, inpatient management, and in-hospital outcome of patients hospitalized for acute heart failure syndromes (AHFS) and classified as pulmonary edema (PE).The Romanian Acute Heart Failure Syndromes (RO-AHFS) study was a prospective, national, multicenter registry of all consecutive patients admitted with AHFS over a 12-month period. Patients were classified at initial presentation by clinician-investigators into the following clinical profiles: acute decompensated HF, cardiogenic shock, PE, right HF, or hypertensive HF.RO-AHFS enrolled 3224 patients and 28.7% (n = 924) were classified as PE. PE patients were more likely to present with pulmonary congestion, tachypnea, tachycardia, and elevated systolic blood pressure and less likely to have peripheral congestion and body weight increases. Mechanical ventilation was required in 8.8% of PE patients. PE patients received higher doses (i.e. 101.4 ± 27.1 mg) of IV furosemide for a shorter duration (i.e. 69.3 ± 22.3 hours). Vasodilators were given to 73.6% of PE patients. In-hospital all-cause mortality (ACM) in PE patients was 7.4%, and 57% of deaths occurred on day one. Increasing age, concurrent acute coronary syndromes, life-threatening ventricular arrhythmias, elevated BUN, left bundle branch block, inotrope therapy, and requirement for invasive mechanical ventilation were independent risk factors for ACM.In this national registry, the PE profile was found to be a high-acuity clinical presentation with distinctive treatment patterns and a poor short-term prognosis. Advances in the management of PE may necessitate both the development of novel targeted therapies as well as systems-based strategies to identify high-risk patients early in their course.