Impact of early ventricular tachycardia ablation in patients with an implantable cardioverter-defibrillator: An updated systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: There is limited information on whether early catheter ablation (CA) for ventricular tachycardia (VT) is associated with better outcomes compared with alternative strategies in patients with implantable cardioverter-defibrillator (ICD). OBJECTIVE: The purpose of this article was to assess the efficacy of early VT CA in patients with ICD. METHODS: EMBASE, PubMed, and Cochrane were searched from inception to April 2022. Randomized controlled trials comparing the efficacy of early VT CA with control groups, both in patients with ICD, were included in the analysis. Data on effect estimates in individual studies were extracted and combined via random effects meta-analysis using the DerSimonian and Laird method, a generic inverse variance strategy. RESULTS: Nine randomized controlled trials with 1106 patients (n = 1018, 92.1% with ischemic cardiomyopathy and n = 88, 7.9% with nonischemic cardiomyopathy) were evaluated. VT CA was associated with reduced VT recurrences (odds ratio [OR] 0.64; P = .007), appropriate ICD shocks (OR 0.53; P = .002), ICD therapies (OR 0.54; P = .002), and cardiovascular hospitalization (OR 0.67; P = .004). However, no significant differences were observed in terms of mortality rate, heart failure hospitalization, and quality of life between the early VT CA and control groups. CONCLUSION: Early CA was beneficial in reducing VT burden and ICD therapies. However, it did not affect mortality rate and quality of life. Since most patients in the included studies presented with ischemic cardiomyopathy, further studies on nonischemic cardiomyopathy should be conducted to validate if early CA has similar outcomes.

Social Media Influence Does Not Reflect Scholarly or Clinical Activity in Real Life.

BACKGROUND: Social media has become a major source of communication in medicine. We aimed to understand the relationship between physicians' social media influence and their scholarly and clinical activity. METHODS: We identified attending US electrophysiologists on Twitter. We compared physician Twitter activity to (1) scholarly publication record (h-index) and (2) clinical volume according to Centers for Medicare and Medicaid Services. The ratio of observed versus expected (obs/exp) Twitter followers was calculated based on each scholarly (K-index) and clinical activity. RESULTS: We identified 284 physicians, with mean Twitter age of 5.0 (SD, 3.1) years and median 568 followers (25th, 75th: 195, 1146). They had a median 34.5 peer-reviewed articles (25th, 75th: 14, 105), 401 citations (25th, 75th: 102, 1677), and h-index 9 (25th, 75th: 4, 19.8). The median K-index was 0.4 (25th, 75th: 0.15, 1.0), ranging from 0.0008 to 29.2. The median number of electrophysiology procedures was 77 (25th, 75th: 0, 160) and evaluation and management visits 264 (25th, 75th: 59, 516) in 2017. The top 1% electrophysiologists for followers accounted for 20% of all followers, 17% of status updates, had a mean h-index of 6 (versus 15 for others, P=0.3), and accounted for 1% of procedural and evaluation and management volumes. They had a mean K-index of 21 (versus 0.77 for others, P<0.0001) and clinical obs/exp follower ratio of 17.9 and 18.1 for procedures and evaluation and management (P<0.001 each, versus others [0.81 for each]). CONCLUSIONS: Electrophysiologists are active on Twitter, with modest influence often representative of scholarly and clinical activity. However, the most influential physicians appear to have relatively modest scholarly and clinical activity.

Long-Term Population-Based Cerebral Ischemic Event and Cognitive Outcomes of Direct Oral Anticoagulants Compared With Warfarin Among Long-term Anticoagulated Patients for Atrial Fibrillation.

Direct oral anticoagulants (DOACs) have been used in clinical practice in the United States for the last 4 to 6 years. Although DOACs may be an attractive alternative to warfarin in many patients, long-term outcomes of use of these medications are unknown. We performed a propensity-matched analysis to report patient important outcomes of death, stroke/transient ischemic attack (TIA), bleeding, major bleeding, and dementia in patients taking a DOAC or warfarin. Patients receiving long-term anticoagulation from June 2010 to December 2014 for thromboembolism prevention with either warfarin or a DOAC were matched 1:1 by index date and propensity score. Multivariable Cox hazard regression was performed to determine the risk of death, stroke/TIA, major bleed, and dementia by the anticoagulant therapy received. A total of 5,254 patients were studied (2,627 per group). Average age was 72.4 ± 10.9 years, and 59.0% were men. Most patients were receiving long-term anticoagulation for AF management (warfarin: 96.5% vs DOAC: 92.7%, p <0.0001). Rivaroxaban (55.3%) was the most commonly used DOAC, followed by apixaban (22.5%) and dabigatran (22.2%). The use of DOACs compared with warfarin was associated with a reduced risk of long-term adverse outcomes: death (p = 0.09), stroke/TIA (p <0.0001), major bleed (p <0.0001), and bleed (p = 0.14). No significant outcome variance was noted in DOAC-type comparison. In the AF multivariable model patients taking DOAC were 43% less likely to develop stroke/TIA/dementia (hazard ratio 0.57 [CI 0.17, 1.97], p = 0.38) than those taking warfarin. Our community-based results suggest better long-term efficacy and safety of DOACs compared with warfarin. DOAC use was associated with a lower risk of cerebral ischemic events and new-onset dementia.

Pulmonary vein isolation for atrial fibrillation in the postpneumonectomy population: a feasibility, safety, and outcomes study.

BACKGROUND: Pulmonary vein isolation (PVI) of the remnant pulmonary vein (PV) stumps in pneumonectomy patients has not been well characterized. METHODS: This is a multicenter observational study of patients with a remnant PV stump after pneumonectomy. Consecutive patients with a history of pneumonectomy and who had undergone RF ablation for drug refractory AF were identified from the AF database at the participating institutions. RESULTS: There were 15 patients in whom pneumonectomy was performed, for resection of tumors in 10, infection in 4, and bullae in 1 patient and who underwent RF ablation for AF. The mean age was 63 ± 7 years. The stumps were from the right lower PV in 5, left upper PV in 5, left lower PV in 3, and right upper PV in 2 patients. All the PV stumps were electrically active with PV potentials and 9 (60%) of them had triggered activity. PVI was performed in 14 and focal isolation in 1 patient. At 1-year follow-up, 80% were free of AF, off of antiarrhythmic medications. CONCLUSION: PV stumps in AF patients with previous pneumonectomy are electrically active and are frequently the sites of active firing. Isolation of these PV stumps can be accomplished safely and effectively using catheter ablation with no practical concern for PV stenosis or compromising PV stump integrity.

Adjuvant antiarrhythmic therapy in patients with implantable cardioverter defibrillators.

The risk of sudden cardiac death from ventricular fibrillation or ventricular tachycardia in patients with cardiomyopathy related to structural heart disease has been favorably impacted by the wide adaptation of implantable cardioverter defibrillators (ICDs) for both primary and secondary prevention. Unfortunately, after ICD implantation both appropriate and inappropriate ICD therapies are common. ICD shocks in particular can have significant effects on quality of life and disease-related morbidity and mortality. While not indicated for primary prevention of ICD therapies, beta-blockers and antiarrhythmic drugs are a cornerstone for secondary prevention of them. This review will summarize our current understanding of adjuvant antiarrhythmic drug therapy in ICD patients. The review will also discuss the roles of nonantiarrhythmic drug approaches that are used in isolation and in combination with antiarrhythmic drugs to reduce subsequent risk of ICD shocks.

Increasing time between first diagnosis of atrial fibrillation and catheter ablation adversely affects long-term outcomes.

BACKGROUND: Many patients who develop atrial fibrillation (AF) will experience a worsening of their arrhythmia over time. The optimal time to proceed with catheter ablation during the disease course is unknown. Further, whether delays in treatment will negatively influence outcomes is unknown. OBJECTIVE: The purpose of this study was to examine the impact of delay in treatment after the first clinical diagnosis of AF on ablation-related outcomes. METHODS: A total of 4535 consecutive patients who underwent an AF ablation procedure that had long-term established care within an integrated health care system were evaluated. Recursive partitioning was used to determine categories associated with changes in risk from the time of first AF diagnosis to first AF ablation: 1: 30-180 (n = 1152), 2: 181-545 (n = 856), 3: 546-1825 (n = 1326), and 4: >1825 (n = 1201) days. Outcomes evaluated include 1-year AF recurrence, stroke, heart failure hospitalization, and death. RESULTS: With increasing time to treatment, surprisingly patients were older (1: 63.7 ± 11.1, 2: 62.6 ± 11.8, 3: 66.4 ± 10.2, 4: 67.6 ± 9.7; P <.0001) and had more hypertension (1: 53.0%, 2: 59.0%, 3: 53.8%, 4: 39.0%; P <.0001). For each strata of time increase, there was a direct increase of 1-year AF recurrence (1: 19.4%, 2: 23.4%, 3: 24.9%, 4: 24.0%: P trend = .02). After adjustment, clinically significant differences in risk of recurrent AF were found when compared to the 30-180 day time category: 181-545: odds ratio (OR) = 1.23, P = .08; 546-1825: OR = 1.27, P = .02; and >1825: OR = 1.25, P = .05. No differences were observed for 1-year stroke among the groups. Death (1: 2.1%, 2: 3.9%, 3: 5.7%, 4: 4.4%: P trend = .001) and heart failure hospitalization (1: 2.6%, 2: 4.1%, 3: 5.4%, 4: 4.4%; P trend = .009) rates at 1 year were higher in the most delayed groups. CONCLUSION: Delays in treatment with catheter ablation impact procedural success rates independent of temporal changes to the AF subtype at ablation.

Efficacy and safety of ventricular tachycardia ablation with mechanical circulatory support compared with substrate-based ablation techniques.

AIMS: Catheter ablation of ventricular tachycardia (VT) can be limited by haemodynamic instability. In these cases, substrate-based ablation is typically performed. An alternative is to perform activation and entrainment mapping during VT supported by a percutaneous left ventricular assist device (pVAD). We sought to compare the complication and success rates of pVAD-assisted VT ablation with scar-based techniques. METHODS AND RESULTS: Thirteen consecutive patients with haemodynamically unstable VT underwent pVAD-assisted ablation (pVAD group) and were retrospectively compared with 18-matched patients undergoing a substrate-based VT ablation (non-pVAD group). There was no significant difference in age or ejection fraction between the groups although pVAD patients tended to have more shocks in the preceding months. Procedure times were longer for the pVAD group. The number of monomorphic VTs induced was greater in the pVAD group (3.2 vs. 1.6, P= 0.04); however, after ablation, there was no difference in inducibility between the pVAD and non-pVAD group (10 of 13 vs. 12 of 18; 77 vs. 67%, P = 0.69). There was no difference in acute complications including stroke or death. At 9 ± 3 months, 1-year freedom from implantable cardioverter-defibrillator (ICD) shocks/therapies for sustained VT were similar (P= 0.96). In multivariable analysis, the absence of atrial fibrillation (hazard ratio=0.15, P= 0.04) was associated with a lower incidence of ICD shocks. CONCLUSIONS: In high-risk patients, pVAD-assisted VT ablation guided by activation and entrainment mapping is a feasible alternative to substrate mapping and allows outcomes comparable to substrate mapping.

Hypokalemia during the cooling phase of therapeutic hypothermia and its impact on arrhythmogenesis.

BACKGROUND: Mild to moderate therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) as the presenting rhythm. This approach entails the management of physiological variables which fall outside the realm of conventional critical cardiac care. Management of serum potassium fluxes remains pivotal in the avoidance of lethal ventricular arrhythmia. METHODS: We retrospectively analyzed potassium variability with TH and performed correlative analysis of QT intervals and the incidence of ventricular arrhythmia. RESULTS: We enrolled 94 sequential patients with OHCA, and serum potassium was followed intensively. The average initial potassium value was 3.9±0.7 mmol l(-1) and decreased to a nadir of 3.2±0.7 mmol l(-1) at 10 h after initiation of cooling (p<0.001). Eleven patients developed sustained polymorphic ventricular tachycardia (PVT) with eight of these occurring during the cooling phase. The corrected QT interval prolonged in relation to the development of hypothermia (p<0.001). Hypokalemia was significantly associated with the development of PVT (p=0.002), with this arrhythmia being most likely to develop in patients with serum potassium values of less than 2.5 mmol l(-1) (p=0.002). Rebound hyperkalemia did not reach concerning levels (maximum 4.26±0.8 mmol l(-1) at 40 h) and was not associated with the occurrence of ventricular arrhythmia. Furthermore, repletion of serum potassium did not correlate with the development of ventricular arrhythmia. CONCLUSIONS: Therapeutic hypothermia is associated with a significant decline in serum potassium during cooling. Hypothermic core temperatures do not appear to protect against ventricular arrhythmia in the context of severe hypokalemia and cautious supplementation to maintain potassium at 3.0 mmol l(-1) appears to be both safe and effective.

Warfarin knowledge in patients with atrial fibrillation: implications for safety, efficacy, and education strategies.

BACKGROUND: Multiple factors influence warfarin metabolism and can significantly affect the risk of adverse events. The extent to which patients understand the modifiable factors that impact on warfarin safety and efficacy is unclear. METHODS: A 52-item questionnaire related to knowledge of warfarin was administered to patients with atrial fibrillation in a face-to-face interview with a dietitian. Results were compiled based on five categories: general warfarin knowledge, compliance, drug interactions, herbal or vitamin interactions, and diet. RESULTS: 100 patients were surveyed. Stroke risk factors included hypertension (57%), heart failure (36%), age >75 years (33%), diabetes (22%), and prior stroke/transient ischemic attack (29%). The majority were either high-school (49%) or college graduates (27%). Ten (10%) had a stroke while on warfarin, 11 (11%) had a blood transfusion, and 26 (26%) had at least one fall. The percentages correct for questionnaire items in the five categories were as follows: general knowledge (62%), compliance (71%), drug interactions (17%), herbal or vitamin interactions (7%), and diet (23%). Neither education level nor duration of therapy correlated with warfarin knowledge. Patients at highest risk of stroke had very low knowledge scores in general. DISCUSSION: Patients on warfarin have a poor general understanding of the medication, particularly those at highest risk of stroke.

Image integration using intracardiac ultrasound and 3D reconstruction for scar mapping and ablation of ventricular tachycardia.

BACKGROUND: Ablation of ventricular tachycardia (VT) reduces implantable cardioverter defibrillator shocks. Intracardiac ultrasound (ICE) can visualize and quantify the function of all left ventricular wall segments. We thus hypothesized that ICE could identify scar tissue and provide a guide to facilitate substrate-guided VT ablation. METHODS: Eighteen patients underwent VT ablation with real time ICE mapping from the right atrium and ventricle with online 3D-image reconstruction of scar segments. The left ventricle was also scar mapped by traditional electroanatomic mapping (CARTO) for comparison. Images from these 2 scar mapping techniques were compared to each other as well as to a preprocedure transthoracic echocardiogram. RESULTS: The average age was 65 +/- 12 years and 12 (67%) were male (15 [83%] had ischemic cardiomyopathy). Two patients (12%) had recurrence of their clinical VT (1 remained on an antiarrhythmic medication, the other had a repeat ablation) over a follow-up of 127 +/- 33 days. No periprocedural or long-term adverse events occurred. A total of 248 wall segments were analyzed. All 3 modalities were concordant in scar identification in 193 (78%) segments. The ICE segments correlated with the electroanatomic map in 213 (86%) segments versus 198 (80%), which correlated with transthoracic echocardiography and electroanatomic mapping (P = 0.046). Specifically, the ICE wall motion scores were closer to the electroanatomic mapping in the basal segments and showed a higher accuracy in ischemic heart disease. CONCLUSION: These data demonstrate that real time ICE images provide accurate chamber geometries and scar boundaries of the left ventricle. These scar borders were more accurate than transthoracic echocardiography and illustrate the feasibility of ICE for substrate-based ablation for VT.

Mechanisms and utility of discrete great arterial potentials in the ablation of outflow tract ventricular arrhythmias.

BACKGROUND: Outflow tract ventricular tachycardia originating above the semilunar valves has been reported in a small number of studies. Discrete potentials in the great arteries (above the semilunar valves) have been rarely described in patients undergoing electrophysiology evaluation and radiofrequency ablation for ventricular arrhythmias. The mechanisms of these discrete potentials in the great arteries and the utility of such potentials in guiding radiofrequency ablation are unknown. METHODS AND RESULTS: Twelve patients with outflow tract ventricular arrhythmia originating above the semilunar valves with discrete arterial potentials were studied. The clinical characteristics, properties of the arterial potentials, electrophysiological evaluation and ablation, and short- and long-term outcomes were reviewed. Of the twelve patients, 8 (67%) were women. The patients' average age was 41+/-14 years. The average ejection fraction was 0.52+/-0.16 (range: 0.16 to 0.75). Contact mapping in the great artery demonstrated discrete near-field electrograms that were separate from far-field ventricular electrograms in all patients (8 above the pulmonary valve and in 4 the aortic valve). One or more of the following electrophysiological characteristics, supportive of an arrhythmogenic substrate, were observed in 10 of 12 patients: (1) A fixed or reproducibly variable pattern of discrete potential-ventricular arrhythmia relationship was present at baseline or during pacing; (2) the discrete potential-ventricular electrogram relationship during sinus rhythm was the reverse of that during the ventricular arrhythmia; (3) during sustained ventricular tachycardia, spontaneous variation of the ventricular (V-V) cycle length was preceded by a similar variation of arterial spike potential-spike potential cycle length; and (4) ablation guided by the discrete arterial potential successfully eliminated the clinical arrhythmia. Ablation was successful in these patients. In the remaining 2 patients, the potentials were believed to be bystanders. Over 10+/-4 months (range: 5 to 32 months) of follow-up, there have been no recurrences of the premature ventricular complex or ventricular arrhythmia. CONCLUSIONS: Discrete potentials are present in the great arteries of a select group of patients with outflow tract ventricular tachycardia originating above the semilunar valves. When an arrhythmogenic relationship can be demonstrated, discrete potentials are useful in guiding ablation within the great vessels, despite significant anatomic complexity.