Noncentrifugal activation patterns in focal RVOT PVC/VT: New insights from high density multielectrode mapping.

BACKGROUND: Activation from an automatic focus is thought to show centrifugal spread. In patients with premature ventricular complex/ventricular tachycardia (PVC/VT) from the right ventricular outflow tract (RVOT), the presence of preferential conduction and epicardial connections could however also lead to noncentrifugal wavefront propagation. OBJECTIVE: To study endocardial activation in RVOT PVC/VT using high-resolution 3D activation mapping. METHODS: Consecutive patients with frequent idiopathic PVC/VT were studied. High-resolution 3D activation maps were acquired using a multielectrode mapping catheter (Orion, Rhythmia, Boston Scientific). Noncentrifugal activation was defined as a pattern of wavefront propagation which does not show uniform propagation in all directions from one focus. Patients without sustained ablation success and patients with a left-sided PVC origin or with insufficient map density were excluded from the analysis. RESULTS: Sixteen patients (44% female) with a median age of 54 years (interquartile range [IQR], 47-64) and a median PVC burden of 19% (IQR, 15-27) were studied. High-resolution activation maps consisting of a median number of 1863 mapping points (IQR, 1195-2463 points) demonstrated a centrifugal activation in 6/16 (38%) and a noncentrifugal activation in 10/16 (62%). When comparing patients with centrifugal and noncentrifugal activation, patients with centrifugal activation were older (p = .01), but no differences were found in age, gender, QRS duration of the PVC's and sites of origin in the RVOT. No procedural complications occurred. CONCLUSIONS: High-resolution multielectrode mapping demonstrates the presence of noncentrifugal activation patterns in some of the patients with idiopathic RVOT PVC/VT. This may indicate the presence of preferential conduction and or epicardial/intramural connections in the outflow tract.

Mechanical Circulatory Support During Catheter Ablation of Ventricular Tachycardia: Indications and Options.

Mapping of scar-related ventricular tachycardia (VT) in structural heart disease is fundamentally driven by identifying the critical isthmus of conduction that supports re-entry in and around myocardial scar. Mapping can be performed using activation and entrainment techniques during VT, or by substrate mapping performed in stable sinus or paced rhythm. Activation and entrainment mapping requires the patient to be in continuous VT, which may not be haemodynamically tolerated, or, if tolerated, may lead to adverse sequelae related to impaired end organ perfusion. Mechanical circulatory support (MCS) devices may facilitate haemodynamic stability and preserve end organ perfusion during sustained VT to permit mapping for long periods. Available options for haemodynamic support include an intra-aortic balloon pump (IABP), TandemHeart left atrial to femoral artery bypass system (CardiacAssist Inc., Pittsburgh, PA, USA), Impella left ventricle (LV) to aorta flow-assist system (Abiomed, Danvers, MA, USA), and extracorporeal membrane oxygenation (ECMO); the bypass and assist devices provide far better augmentation of cardiac output than IABP. MCS has potential key advantages including maintenance of vital organ perfusion, reduction of intra-cardiac filling pressures, reduction of LV volumes, wall stress, and myocardial consumption of oxygen, and improvement of coronary perfusion during prolonged periods of VT induction and/or mapping. Observational studies show MCS allows for longer duration of mapping, and increased likelihood of VT termination, without an increased risk of peri-procedural mortality or VT recurrence in follow-up, despite being used in a significantly sicker cohort of patients. However, MCS has increased risk of complications related to vascular access, bleeding, thromboembolic risk, mapping system interference, increase procedural complexity and increased cost. Acute haemodynamic decompensation occurs in ∼11% of patients undergoing VT ablation, and is associated with increased mortality. Prospectively identifying patients at risk of acute haemodynamic decompensation in the peri-procedural period may allow prophylactic MCS. Although observational studies of MCS in patients at high risk of haemodynamic decompensation are encouraging, its benefit needs to be proven in randomised trials. This review will summarise the indication for MCS, forms of MCS, procedural outcomes, complications and utility of MCS during VT ablation.

Prevalence of cardiac sarcoidosis in patients presenting with monomorphic ventricular tachycardia.

INTRODUCTION: Sarcoidosis is a granulomatous disease of unknown etiology, which involves the heart in 5-25% of cases. Although ventricular tachycardia (VT) has been reported as the first presentation of sarcoidosis, its prevalence has not previously been investigated. In this prospective study, we sought to systematically investigate the prevalence of cardiac sarcoidosis (CS) in patients presenting with monomorphic VT (MMVT) and no previous history of sarcoidosis. METHODS: Consecutive patients presenting with MMVT to a tertiary care center were screened for inclusion. Patients with idiopathic VT, VT secondary to coronary artery disease, or prior diagnosis of sarcoidosis were excluded. Included patients underwent F-18-fluorodeoxyglucose positron emission tomography (PET) scan. In subjects with PET scanning suggestive of active myocardial inflammation, histological diagnosis was confirmed through extracardiac or endomyocardial biopsy (EMB). RESULTS: A total of 182 patients presented to our institution with VT between February 2010 and September 2012 and 14 subjects met inclusion criteria. Within this group, six of 14 (42%) patients had abnormal PET scans suggesting active myocardial inflammation. Four of the six patients had tissue biopsies that were diagnostic of sarcoidosis; the remaining two patients had guided EMB indicating nonspecific myocarditis. Atrioventricular block was observed in three of four (75%) patients with CS and none in 10 of the others (P = 0.022). Three of the four patients had pulmonary sarcoidosis and one patient had isolated CS. All four patients were treated with corticosteroids. CONCLUSION: In this prospective study, four of 14 (28%) patients presenting with MMVT (without idiopathic VT, ischemic VT, or known sarcoidosis) had CS as the underlying etiology. Clinicians should consider screening for CS in patients with unexplained MMVT.

Degenerating regenerating torsades de pointes.

Ventricular fibrillation (VF) commonly ends in death. Isolated case reports describe the uncommon occurrence of spontaneous termination of VF. Torsades de pointes (TdP), a peculiar form of polymorphic ventricular tachycardia associated with a prolonged QT interval on the surface electrocardiogram, most often spontaneously terminates and then returns to the underlying rhythm. Here, we present an unusual case of TdP degenerating into VF, reorganizing into TdP, and then spontaneously terminating. Our case suggests that the mechanisms underlying the maintenance of TdP and VF are not dissimilar. The precipitants to this event and the likely mechanisms operative are discussed.

Cardiac resynchronization therapy: expanding clinical indications and refining patient selection.

PURPOSE OF REVIEW: Cardiac resynchronization therapy (CRT) can reduce morbidity and mortality in patients with heart failure. However, a proportion of patients do not respond to CRT. This review addresses important clinical questions regarding patient selection for CRT. RECENT FINDINGS: Three recent large randomized trials show that CRT reduces morbidity and mortality in patients with New York Heart Association (NYHA) functional class II heart failure. Observational studies and a recent meta-analysis suggest that patients with NYHA III heart failure and atrial fibrillation may benefit from CRT. However, atrioventricular node ablation should be considered in this population to ensure greater than 92% biventricular pacing. Data from clinical trials do not support the use of CRT in patients with baseline right bundle branch block (RBBB). SUMMARY: Careful selection of CRT candidates is vital to improve patient outcomes and reduce exposure to unnecessary complications. This review summarizes recent data on the selection of CRT candidates, with emphasis on patients with NYHA I and II heart failure, atrial fibrillation and RBBB.

Greater response to cardiac resynchronization therapy in patients with true complete left bundle branch block: a PREDICT substudy.

AIMS: Cardiac resynchronization therapy (CRT) benefits patients with heart failure and a wide QRS complex. Still, one-third derive no clinical benefit and a majority of patients demonstrate no objective improvement of left ventricular (LV) function. Left bundle branch block (LBBB) is a strong predictor of response to CRT. We evaluated whether absence of electrocardiogram (ECG) markers of residual left bundle (LB) conduction in guideline-defined LBBB predicted a greater response to CRT. METHODS AND RESULTS: An r wave ≥1 mm in lead V1 (r-V1) and/or a q wave ≥1 mm in lead aVL (q-aVL) was used to identify patients with residual LB conduction. Forty patients with a wide QRS were prospectively enrolled and subdivided into three groups: complete LBBB (cLBBB), LBBB without r-V1 or q-aVL (n = 12); LBBB with residual LB conduction (rLBBB), LBBB with r-V1 and/or q-aVL (n = 15); and non-specific intraventricular conduction delay (IVCD), (n = 13). Following CRT: mean change in left ventricular ejection fraction was 11.9 ± 11.9% in cLBBB, 3.8 ± 5.4% in rLBBB (P= 0.045), and 2.5 ± 4.4% in IVCD (P= 0.02 cLBBB vs. IVCD); mean reduction in left ventricular end-systolic volume was 26.4 ± 39.2% in cLBBB, 14.3 ± 22.9% in rLBBB (P= 0.35), and 5.6 ± 17.3% in IVCD (P= 0.11 cLBBB vs. IVCD); mean change in native QRS duration was -8.0 ± 11.0 ms in cLBBB, -0.8 ± 8.24 ms in rLBBB (P= 0.07), and 0.15 ± 8.0 ms in IVCD (P= 0.048 cLBBB vs. IVCD). CONCLUSION: In patients with guideline-defined LBBB, the absence of ECG markers of residual LB conduction was predictive of a greater improvement in LV function with CRT.

Anticoagulation bridging around device surgery: compliance with guidelines.

BACKGROUND: Current guidelines recommend bridging anticoagulation in patients undergoing cardiac rhythm device surgery with a "moderate to high risk" of thromboembolism. Patients at "low risk" are advised to stop oral anticoagulation without bridging to the procedure. This study examines real world adherence to accepted guidelines and the clinical sequelae of nonadherence. METHODS: We performed a review of all patients undergoing device surgery receiving chronic anticoagulation over a prespecified time period of 14 months. Patients were classified per American College of Chest Physician guidelines as "moderate/high risk" or "low risk" of thromboembolism. We then compared perioperative management of anticoagulation to guideline recommendations and assessed the rate of perioperative bleeding and thromboembolism. RESULTS: One hundred and twenty-nine patients were included in this study. Sixty-two (48%) were classified as "moderate/high risk" and 67 (52%) "low risk." In the "moderate/high risk" group 47/62 (76%) received perioperative anticoagulation but only 25/62 (40%) were bridged both pre- and postprocedure or maintained on uninterrupted warfarin. In the "low risk" group, 22/67 (33%) received bridging therapy. Device pocket hematoma or perioperative bleeding occurred in 10/129 (8%) with 4/10 receiving inappropriate bridging for a calculated low risk of thromboembolism. There were no perioperative thromboembolisms. CONCLUSIONS: Our study identified significant underutilization of bridging, particularly in the postoperative period, in patients at "moderate/high risk" of thromboembolism. Conversely, bridging was overused in "low risk" patients and associated with bleeding complications. Physicians should be urged to follow current expert guidelines in regard to bridging anticoagulation for cardiac rhythm device surgery. (PACE 2012;35:1480-1486).

Psychological adjustment in ICD patients living with advisory fidelis leads.

UNLABELLED: Psychological Adjustment and Fidelis ICD Leads. INTRODUCTION: Implantable cardioverter defibrillators (ICD) advisory notices present treatment dilemmas for physicians and patients. On one side, the risk of device malfunction and the likely severity of clinical sequelae have to be estimated. This estimate has to be weighed against the risks of surgery to replace the advisory component. It is unclear whether there is important psychological morbidity associated with living with an ICD under advisory and whether this should be factored into decision making. The study had 2 objectives: (1) to examine whether there is adverse psychological adjustment when an ICD is under advisory, and (2) to assess the psychological sequel of advisory ICD component malfunction. METHODS: This study focused on the Sprint Fidelis advisory. All patients in our practice who still had an in service Medtronic Fidelis lead were included in the study. Three groups were compared: advisory group but no fracture (n = 249), advisory group with lead fracture (n = 24), and a control group (n = 143). For both objectives, we used a general anxiety and depression instrument and also device-specific measures of psychological well being. RESULTS AND CONCLUSIONS: First, there was no evidence of differences in the psychological functioning of patients at risk of ICD lead malfunction compared to a control group. Second, patients who had experienced an ICD lead fracture had adverse psychological morbidity compared to control patients, and this appeared, primarily, to be related to receiving inappropriate shock(s) at the time of the fracture.

Prevalence and risk factors for cervical and lumbar spondylosis in interventional electrophysiologists.

UNLABELLED: INTRODUCTION: The volume and complexity of interventional electrophysiology procedures have increased greatly over the last 20 years. Anecdotal reports from Canada and elsewhere have suggested an important prevalence of neck and back problems in interventional electrophysiologists. METHODS AND RESULTS: To quantify the scope of neck and back problems, we surveyed 70 interventional electrophysiologists in Canada using an electronic survey with in person and email reminders. We also surveyed an age- and gender-matched group of noninterventional cardiologists. We received responses from a total of 58 of 70 interventional electrophysiologists (response rate 82.8%). There was a significantly higher prevalence of cervical spondylosis among electrophysiologists compared to matched noninterventional cardiologists (20.7% compared to 5.5%, P = 0.033). There was a trend for increased prevalence of lumbar spondylosis (25.9% compared to 16.7%, P = 0.298). Among electrophysiologists, those with cervical spondylosis were older (49.83 ± 10.48 years compared to 44.57 ± 9.20, P = 0.092) and had worked in the specialty for longer in comparison to unaffected physicians (19.67 ± 10.06 years compared to 13.37 ± 8.97 years, P = 0.039). All other variables including gender, height, weight, BMI, type of lead, weekly average lead time, and % of time standing in electrophysiology laboratory were not different. On multivariable analysis there were no independent predictors of disease. CONCLUSIONS: There is a significant increased prevalence of cervical spondylosis among interventional electrophysiologists. Programs to improve ergonomics and minimize time spent wearing lead are needed. The same vigilance that is used to ensure radiation safety in the laboratory should be applied to create ergonomic safety.

Predictors of fracture risk of a small caliber implantable cardioverter defibrillator lead.

INTRODUCTION: The Sprint Fidelis 6949 implantable cardioverter defibrillator (ICD; Medtronic Inc., Minneapolis, MN, USA) lead has a high rate of fracture. Identification of predictors of subsequent fracture is useful in decision making about lead replacement and for future lead design. We sought to determine if there are clinical, procedural, or radiological features associated with a greater risk of subsequent lead fracture. METHODS: Patients with Sprint Fidelis 6949 lead fractures (Fracture group) were identified from our institutional database. Each patient in the Fracture group was matched to two controls, immediately preceeding and succeeding Sprint Fidelis 6949 implant. Clinical and procedural characteristics were compared. Chest radiographs performed 2 weeks after ICD implant were reviewed by an observer blinded to outcomes. The following features were assessed: ICD tip location, lead slack, kinking of the lead body (> or =90 degrees ), and presence of lead "crimping" within the anchoring sleeve. RESULTS: Twenty-six patients with Sprint Fidelis 6949 lead fractures were identified and were matched to 52 control patients. On univariate analysis, a higher left ventricular ejection fraction (LVEF), prior ipsilateral device implant, history of prior ICD lead fracture, and noncephalic venous access were associated with risk of lead fracture. On multivariate analysis, a higher LVEF was the only independent predictor of lead fracture (P = 0.006). Radiological features were similar between the two groups. CONCLUSIONS: In this study, a higher LVEF was associated with a greater risk of lead fracture in patients with Sprint Fidelis 6949 ICD leads. Radiographic features did not predict subsequent risk of lead fracture in our population. (PACE 2010; 437-443).

Clinically Significant Pocket Hematoma Increases Long-Term Risk of Device Infection: BRUISE CONTROL INFECTION Study.

BACKGROUND: The BRUISE CONTROL trial (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial) demonstrated that a strategy of continued warfarin during cardiac implantable electronic device surgery was safe and reduced the incidence of clinically significant pocket hematoma (CSH). CSH was defined as a post-procedure hematoma requiring further surgery and/or resulting in prolongation of hospitalization of at least 24 h, and/or requiring interruption of anticoagulation. Previous studies have inconsistently associated hematoma with the subsequent development of device infection; reasons include the retrospective nature of many studies, lack of endpoint adjudication, and differing subjective definitions of hematoma. OBJECTIVES: The BRUISE CONTROL INFECTION (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial Extended Follow-Up for Infection) prospectively examined the association between CSH and subsequent device infection. METHODS: The study included 659 patients with a primary outcome of device-related infection requiring hospitalization, defined as 1 or more of the following: pocket infection; endocarditis; and bloodstream infection. Outcomes were verified by a blinded adjudication committee. Multivariable analysis was performed to identify predictors of infection. RESULTS: The overall 1-year device-related infection rate was 2.4% (16 of 659). Infection occurred in 11% of patients (7 of 66) with previous CSH and in 1.5% (9 of 593) without CSH. CSH was the only independent predictor and was associated with a >7-fold increased risk of infection (hazard ratio: 7.7; 95% confidence interval: 2.9 to 20.5; p < 0.0001). Empiric antibiotics upon development of hematoma did not reduce long-term infection risk. CONCLUSIONS: CSH is associated with a significantly increased risk of infection requiring hospitalization within 1 year following cardiac implantable electronic device surgery. Strategies aimed at reducing hematomas may decrease the long-term risk of infection. (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial [BRUISE CONTROL]; NCT00800137).

Isolated cardiac sarcoidosis: establishing the diagnosis with electroanatomic mapping-guided endomyocardial biopsy.

Diagnosing isolated cardiac sarcoidosis can be challenging, and requires a high index of suspicion. We report a case of a young woman who presented with sustained ventricular tachycardia, intermittent atrioventricular block and epsilon wave on electrocardiogram. Although the patient fulfilled Task Force criteria for arrhythmogenic right ventricular cardiomyopathy, sarcoidosis was suspected because of the presence of intermittent atrioventricular block. As illustrated in this report, the use of electroanatomic mapping-guided endomyocardial biopsy can be decisive in achieving the diagnosis and is a valuable approach in cases of suspected isolated cardiac sarcoidosis.

Cardiac resynchronization therapy in patients with left ventricular systolic dysfunction and right bundle branch block: a systematic review.

BACKGROUND: Whether patients with right bundle branch block (RBBB) benefit from cardiac resynchronization therapy (CRT) is unclear. OBJECTIVE: The purpose of this study was to systematically review the published data from randomized clinical trials of CRT on the outcomes in patients with baseline RBBB. METHODS: Randomized controlled trials of CRT in heart failure and left ventricular systolic dysfunction were identified from MEDLINE (1950-2010), EMBASE (1980-2010, week 45), Cochrane Controlled Trials Register (2009), Cochrane Database of Systematic Reviews, National Institutes of Health Clinical Trials.gov database. RESULTS: A total of 112 references were retrieved. Four publications from five studies reported data on patients with RBBB and were included in this investigation, with 259 patients randomized to CRT and 226 randomized to non-CRT. None of the available data showed more favorable outcomes (soft or hard) in patients with CRT. CONCLUSION: None of the available data showed more favorable outcomes with CRT in patients with RBBB. A meta-analysis of RBBB patients from the major CRT trials is urgently needed. Results of the meta-analysis can direct further research, perhaps indicating a need for randomized trials in RBBB. Physicians and patients should be aware of the likely reduced benefit form CRT in patients with RBBB, and this should be factored into decision making. However, until more data are available it is too early to change guidelines.