Asirvatham, Samuel J

BackgroundEndocardial ablation of atrial ganglionated plexi (GP) has been described for treatment of atrial fibrillation (AF). Our objective in this study was to develop percutaneous epicardial GP ablation in a canine model using novel energy sources and catheters.MethodsPhase 1: The efficacy of several modalities to ablate the GP was tested in an open chest canine model (n = 10). Phase 2: Percutaneous epicardial ablation of GP was done in six dogs using the most efficacious modality identified in phase 1 using two novel catheters.ResultsPhase 1: Direct current (DC) in varying doses (blocking [7–12 μA], electroporation [300–500 μA], ablation [3,000–7,500 μA]), radiofrequency ablation (25–50 W), ultrasound (1.5 MHz), and alcohol (2–5 mL) injection were successful at 0/8, 4/12, 5/7, 3/8, 1/5, and 5/7 GP sites. DC (500–5,000 μA) along with alcohol irrigation was tested in phase 2. Phase 2: Percutaneous epicardial ablation of the right atrium, oblique sinus, vein of Marshall, and transverse sinus GP was successful in 5/6 dogs. One dog died of ventricular fibrillation during DC ablation at 5,000 μA. Programmed stimulation induced AF in six dogs, preablation and no atrial arrhythmia in three, flutter in one, and AF in one postablation. Heart rate, blood pressure, effective atrial refractory period, and local atrial electrogram amplitude did not change significantly postablation. Microscopic examination showed elimination of GP, and minimal injury to atrial myocardium.ConclusionPercutaneous epicardial ablation of GP using DC and novel catheters is safe and feasible and may be used as an adjunct to pulmonary vein isolation in the treatment of AF in order to minimize additional atrial myocardial ablation.

Background Hyper‐ and hypokalemia are clinically silent, common in patients with renal or cardiac disease, and are life threatening. A noninvasive, unobtrusive, blood‐free method for tracking potassium would be an important clinical advance. Methods and Results Two groups of hemodialysis patients (development group, n=26; validation group, n=19) underwent high‐resolution digital ECG recordings and had 2 to 3 blood tests during dialysis. Using advanced signal processing, we developed a personalized regression model for each patient to noninvasively calculate potassium values during the second and third dialysis sessions using only the processed single‐channel ECG . In addition, by analyzing the entire development group's first‐visit data, we created a global model for all patients that was validated against subsequent sessions in the development group and in a separate validation group. This global model sought to predict potassium, based on the T wave characteristics, with no blood tests required. For the personalized model, we successfully calculated potassium values with an absolute error of 0.36±0.34 mmol/L (or 10% of the measured blood potassium). For the global model, potassium prediction was also accurate, with an absolute error of 0.44±0.47 mmol/L for the training group (or 11% of the measured blood potassium) and 0.5±0.42 for the validation set (or 12% of the measured blood potassium). Conclusions The signal‐processed ECG derived from a single lead can be used to calculate potassium values with clinically meaningful resolution using a strategy that requires no blood tests. This enables a cost‐effective, noninvasive, unobtrusive strategy for potassium assessment that can be used during remote monitoring.

Dysrhythmias and Death in BiMVPIntroductionBileaflet mitral valve prolapse (BiMVP) is common among survivors of otherwise unexplained sudden cardiac death, but prognostic implications of BiMVP are unknown. This study evaluated whether patients with BiMVP are at higher risk for ventricular dysrhythmias, ICD placement, or death compared to controls with either single‐leaflet mitral valve prolapse (SiMVP) or no mitral valve prolapse (MVP).Methods and ResultsThis retrospective, matched cohort study included 18,786 patients who underwent echocardiography at Mayo Clinic between June 1990 and September 2014. The study included three cohorts: BiMVP, SiMVP, and controls without MVP. We assessed rates of ventricular dysrhythmias, ICD placement, and all‐cause mortality between groups. BiMVP was associated with higher rates of ventricular tachycardia compared to SiMVP and controls (adjusted HR 1.48 [1.14–1.92], P = 0.003 and 1.40 [1.04–1.88], P = 0.026, respectively); however, there were no statistically significant differences in rates of ventricular fibrillation/cardiac arrest or ICD placement between groups. BiMVP was associated with a lower rate of all‐cause mortality compared to SiMVP and controls (adjusted HR 0.86 [0.79–0.94], P = 0.0008, and 0.55 [0.50–0.60], P < 0.0001, respectively).ConclusionAlthough BiMVP is associated with ventricular tachycardia, it is not associated with an increased risk of cardiac arrest/ventricular fibrillation or ICD implantation and is, paradoxically, associated with a better survival compared to SiMVP or matched controls. The findings suggest that, despite its association with ventricular tachycardia, BiMVP in the absence of other risk factors does not seem to portend a poor prognosis at the population level.

Background There is significant practice variation in oral anticoagulation ( OAC ) use following catheter ablation for atrial fibrillation. It is not clear whether the risk of cardioembolism increases after discontinuation of OAC following catheter ablation. Methods and Results We identified 6886 patients within a large national administrative claims database who underwent catheter ablation for atrial fibrillation between January 1, 2005, and September 30, 2014. We assessed the effect of time off of OAC by CHA 2 DS 2 ‐ VAS c score (after adjusting for other comorbidities) on risk of cardioembolism, using Cox proportional hazards models. There was an increase in the use of non–vitamin K OAC after ablation from 0% in 2005 to 69.8% in 2014. OAC discontinuation was high, with only 60.5% and 31.3% of patients remaining on OAC at 3 and 12 months, respectively. The rate of discontinuation was higher in low‐risk patients (82% versus 62.5% at 12 months for CHA 2 DS 2 ‐ VAS c 0–1 versus ≥2, respectively; P <0.001). Stroke occurred in 1.4% of patients with CHA 2 DS 2 ‐ VAS c ≥2 and 0.3% of those with CHA 2 DS 2 ‐ VAS c 0 or 1 over the study follow‐up. The risk of cardioembolism in the first 3 months after ablation was increased among those with any time off OAC (hazard ratio 8.06 [95% CI 1.53–42.3], P <0.05). The risk of cardioembolism beyond 3 months was increased with OAC discontinuation among high‐risk patients (hazard ratio 2.48 [95% CI 1.11–5.52], P <0.05) but not low‐risk patients. Conclusion The overall risk of stroke in postablation patients is low; however, OAC discontinuation after ablation is common and is associated with increased risk of cardioembolism for all patients within the first 3 months and for high‐risk patients in the long term. Continuing OAC for at least 3 months in all patients and indefinitely in high‐risk patients appears to be the safest strategy.

Background— Transvenous lead removal (TLR) has made significant progress with respect to innovation, efficacy, and safety. However, limited data exist regarding trends in use and adverse outcomes outside the centers of considerable experience for TLR. The aim of our study was to examine use patterns, frequency of adverse events, and influence of hospital volume on complications. Methods and Results— Using the Nationwide Inpatient Sample, we identified 91 890 TLR procedures. We investigated common complications including pericardial complications (hemopericardium, cardiac tamponade, or pericardiocentesis), pneumothorax, stroke, vascular complications (consisting of hemorrhage/hematoma, incidents requiring surgical repair, and accidental arterial puncture), and in-hospital deaths described with TLR, defining them by the validated International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code. We specifically assessed in-hospital death (2.2%), hemorrhage requiring transfusion (2.6%), vascular complications (2.0%), pericardial complications (1.4%), open heart surgery (0.2%), and postoperative respiratory failure (2.4%). Independent predictors of complications were female sex and device infections. Hospital volume was not independently associated with higher complications. There was a significant rise in overall complication rates over the study period. Conclusions— The overall complication rate in patients undergoing TLR was higher than previously reported. Female sex and device infections are associated with higher complications. Hospital volume was not associated with higher complication rates. The number of adverse events in the literature likely underestimates the actual number of complications associated with TLR.