Background: Machine learning (ML) may improve prediction of atrial fibrillation (AF), but its value compared with traditional models such as Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE-AF) in patients with diabetes remains unclear. Methods: Among 9,307 patients in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) with type 2 diabetes and no prior AF, a random forest (RF) classifier using clinical and metabolic variables was compared with a CHARGE-AF Cox model. Discrimination was assessed by five-fold cross-validated area under receiver operating curve (AUC). Results: Over 6.26 years, 175 patients developed AF. The RF model (AUC = 0.731) performed comparably to CHARGE-AF (AUC = 0.756; p = 0.18). Age, waist circumference, race, total cholesterol, and estimated glomerular filtration rate were the top predictors. Conclusion: ML matched CHARGE-AF performance and revealed distinct predictors supporting personalized AF risk prevention.

Cardiac resynchronization therapy (CRT) can improve heart function and decrease arrhythmic events. We tested whether CRT altered circulating markers of calcium handling and sudden death risk. Circulating cardiac sodium channel messenger RNA (mRNA) splicing variants indicate arrhythmic risk, and a reduction in sarco/endoplasmic reticulum calcium adenosine triphosphatase 2a (SERCA2a) is thought to diminish contractility in heart failure. CRT was associated with a decreased proportion of circulating, nonfunctional sodium channels and improved SERCA2a mRNA expression. Patients without CRT did not have improvement in the biomarkers. These changes might explain the lower arrhythmic risk and improved contractility associated with CRT.

An overview of electroanatomical mapping is described, including its history and current application in treating patients with atrial and ventricular arrhythmias Using a roving catheter in 3D space relative to a fixed reference, electroanatomical mapping provides the electrophysiologist with important location and electrical data to carefully guide catheter ablation procedures Both magnetic-based mapping and impedance based mapping are briefly discussed

BACKGROUND:Because of its technical feasibility and presumed safety benefits, balloon cryoablation is being increasingly employed for pulmonary vein (PV) isolation. While acute isolation has been demonstrated in most patients, little data are available on the chronic durability of cryoballoon lesions. METHODS AND RESULTS:Twelve atrial fibrillation patients underwent PV isolation using either a 23-mm or 28-mm cryoballoon. For each vein, after electrical isolation was verified with the use of a circular mapping cathether, 2 bonus balloon ablation lesions were placed. Gaps in balloon occlusion were overcome using either a spot cryocatheter or a "pull-down" technique. A prespecified second procedure was performed at 8-12 weeks to assess for long-term PV isolation. Acute PV isolation was achieved in all PVs in the patient cohort (n = 48 PVs), using the cryoballoon alone in 47/48 PVs (98%); a "pull-down" technique was employed for 5 PVs (1 right superior pulmonary vein, 2 right inferior pulmonary veins, and 2 left inferior pulmonary veins). The gap in the remaining vein was ablated with a spot cryocatheter. During the second mapping procedure, 42 of 48 PVs (88%) remained isolated. One vein had reconnected in 2 patients, while 2 veins had reconnected in another 2 patients. All PVs initially isolated with the "pull-down" technique remained isolated at the second procedure. CONCLUSIONS:Cryoballoon ablation allows for durable PV isolation with the use of a single balloon. With maintained chronic isolation in most PVs, it may represent a significant step toward consistent and lasting ablation procedures.

Catheter ablation has become one of the primary treatments for symptomatic drug-refractory atrial fibrillation (AF). This procedure can be associated with complications including the risk of injury to structures adjacent to the left atrium (LA), such as the esophagus, the aorta, the left circumflex coronary artery, the bronchial tree, and the phrenic nerve. The objective of this article is to review the above anatomy and assess the ability of imaging to detect the proximity and orientation of these secondary structures in relation to the LA and the pulmonary veins (PVs). Lastly, we will discuss ablation strategies to avoid damage to these secondary structures. The imaging techniques described in this review include computed tomographic (CT) angiography, magnetic resonance angiography, and intracardiac echocardiography (ICE).

Dissociated PV Activity During AF Ablation. Introduction: Pulmonary veins (PV) play an important role in the arrhythmogenesis of atrial fibrillation (AF). Catheter‐based PV isolation is one of the primary treatments for symptomatic drug refractory AF. Following electrical isolation, isolated rhythms in the PV are encountered. The aim of this study was to assess the frequency of postisolation PV activity and classify the different rhythms observed. Methods and Results: This single center prospective study sought to assess the dissociated activity in the PVs following their isolation during AF ablation. In 100 consecutive patients (60 paroxysmal, 40 persistent) undergoing AF ablation, dissociated PV activity was recorded using a multielectrode mapping catheter following antral PV isolation. The dissociated PV activity was classified as (1) silent, (2) isolated ectopic beats, (3) ectopic rhythm, and (4) PV fibrillation. All the PVs were successfully isolated in all the patients. In 91 of 100 patients, there was dissociated activity in at least 1 isolated ipsilateral PV group. There was no significant difference in spontaneous PV activity between patients with paroxysmal and persistent AF (91.7% vs 90%, P = 1.0). Among the 200 isolated ipsilateral PV groups, 64 of 200 (32%) were silent, 86 of 200 (43%) demonstrated isolated ectopic beats, 41 of 200 (20.5%) had ectopic rhythms and 9 of 200 (4.5%) had PV fibrillation. The average cycle length of the PV ectopic rhythm was 2594 ± 966 ms (range 1193–4750 ms). Conclusions: Following PV isolation, a majority of patients demonstrate dissociated activity in at least 1 PV. This finding was evident in patients with both paroxysmal and persistent AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1338‐1343, December 2010)

The Sprint Fidelis® lead has an increased incidence of lead fracture. The manufacturer has recommended programming alerts to preempt lead malfunction due to fracture. The current trigger for an alert is an increase in the right ventricular pacing impedance to greater than 1,000 Ω. Our patient suffered multiple inappropriate implantable cardioverter defibrillator therapies with stable impedance less than 1,000 Ω. This case of lead fracture would not have been detected with these programming alerts. Additional programming measures may detect lead fractures, including changing the lower detection for impedances, arranging for a percentage change in the impedance trend to trigger an alarm, or programming the device to warn if there is an increase in nonphysiologic short R‐R interval counts.

Journal of Cardiovascular ElectrophysiologyVolume 19, Issue 2 p. 221-222 Ablation of Atrial Flutter in a Patient with Situs Inversus Totalis Using Integration of Real-Time Three-Dimensional Electroanatomical Mapping ARASH ARYANA M.D., ARASH ARYANA M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorPATRICK T. ELLINOR M.D., Ph.D., PATRICK T. ELLINOR M.D., Ph.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorRYAN G. ALEONG M.D., RYAN G. ALEONG M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorDAVID M. DONALDSON M.D., DAVID M. DONALDSON M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorWILFRED S. MAMUYA M.D., Ph.D., WILFRED S. MAMUYA M.D., Ph.D. the Cardiology Division of Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USASearch for more papers by this authorJEREMY N. RUSKIN M.D., JEREMY N. RUSKIN M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorMOUSSA C. MANSOUR M.D., MOUSSA C. MANSOUR M.D. Cardiac Arrhythmia ServiceSearch for more papers by this author ARASH ARYANA M.D., ARASH ARYANA M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorPATRICK T. ELLINOR M.D., Ph.D., PATRICK T. ELLINOR M.D., Ph.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorRYAN G. ALEONG M.D., RYAN G. ALEONG M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorDAVID M. DONALDSON M.D., DAVID M. DONALDSON M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorWILFRED S. MAMUYA M.D., Ph.D., WILFRED S. MAMUYA M.D., Ph.D. the Cardiology Division of Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USASearch for more papers by this authorJEREMY N. RUSKIN M.D., JEREMY N. RUSKIN M.D. Cardiac Arrhythmia ServiceSearch for more papers by this authorMOUSSA C. MANSOUR M.D., MOUSSA C. MANSOUR M.D. Cardiac Arrhythmia ServiceSearch for more papers by this author First published: 25 October 2007 https://doi.org/10.1111/j.1540-8167.2007.00987.xCitations: 2 Address for correspondence: Moussa C. Mansour, M.D., Cardiac Arrhythmia Service, Massachusetts General Hospital, GRB–109, 55 Fruit Street, Boston, MA 02114. Fax: 617-724-1241; E-mail: mmansour@partners.org Drs. Ruskin and Mansour serve as consultants to Biosense-Webster Inc. J Cardiovasc Electrophysiol, Vol. 19, pp. 221-222, February 2008. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume19, Issue2February 2008Pages 221-222 RelatedInformation

Background: Intracardiac echocardiography (ICE) can be integrated with pre-procedural CT or MR imaging to direct catheter ablation of atrial fibrillation (AF). Prior work has described ICE imaging of the left atrium (LA) with the ICE probe in the RA, but it is feasible to image the LA from an ICE probe placed directly into the LA via a trans-septal puncture performed for the mapping/ablation procedure. The purpose of this study was to determine whether direct LA imaging with ICE results in improved image integration during AF ablation compared with LA imaging indirectly from the RA. Methods: Twenty-five consecutive patients undergoing an AF ablation procedure with the CARTO-Sound system were studied. A 10 French phased array catheter with an embedded CARTO navigation sensor was employed to provide 2D echocardiogram images of the LA - 13 patients underwent imaging from the RA alone and 12 patients from the LA. The accuracy of the image integration was assessed by the average integration error after surface registration and the requirement to take supplementary electroanatomic mapping points to obtain acceptable image integration. Results: Twenty-five patients (56% paroxysmal AF, average LA size = 42±8 mm, average EF = 63±10 %) were examined. There was no difference in the time or number of ultrasound contours required to create a LA anatomic map with ICE imaging from the RA versus the LA (24±17min vs. 24±25min, P=1.0, 24±16 contours vs. 29±18 contours, P=0.5). The average integration error for all patients was 2.19±0.59mm. Direct LA imaging was associated with improved integration error compared to indirect LA imaging from the RA (1.85±0.33mm versus 2.51±0.62mm, P=0.004). Image integration using RA acquired LA images had a tendency to be less accurate resulting in the primary operator acquiring additional registration points to supplement the registration process (patients requiring additional registration points for registration: 3/12 for LA imaging versus 9/13 for RA imaging of the LA, P=0.05). Conclusion: Direct ICE imaging from within the LA is feasible and associated with improved accuracy of image integration during AF ablation.

BACKGROUND Three-dimensional (3D) reconstruction of the left atrium (LA) can be performed using real-time intracardiac echocardiography (ICE) to facilitate image integration during atrial fibrillation (AF) ablation. Current users of this technology generally image the LA indirectly from the right atrium (RA).OBJECTIVE The purpose of this study was to assess the feasibility and accuracy of image integration with placement of the ICE catheter directly in the LA to visualize the LA.METHODS Thirty consecutive patients undergoing an AF ablation with the CARTO-Sound system were enrolled. A 10-Fr phased-array ICE catheter was used to obtain two-dimensional echocardiographic images of the LA; in 15 patients the ICE probe was placed in the LA, and in 15 patients it was placed only in the RA. Sequential images were obtained and merged with a preacquired computed tomography/magnetic resonance image. The accuracy of image integration was assessed by the value of the average image integration error after surface registration.RESULTS Thirty patients (60% paroxysmal AF, LA size = 42 +/- 7 mm, ejection fraction = 62% +/- 10%) were studied. There was no difference in the time required to create the LA anatomic map and perform image integration with imaging from the LA versus the RA (22 +/- 22 vs. 24 +/- 16 minutes; P = .8). The number of ultrasound contours obtained was also similar (LA = 26 +/- 17 vs. RA = 24 +/- 16; P = .7). The average integration error was less with direct LA imaging (LA = 1.83 +/- 0.32 vs. RA = 2.52 +/- 0.58 mm; P = .0004).CONCLUSION Direct LA imaging with ICE is feasible and results in improved LA visualization and image integration.

In vitro techniques were employed to investigate the mechanisms by which immune complexes are deposited or formed within collagenous tissues from rabbits. In the eighteen different tissues studied, both free antibody and antigen were able to penetrate the tissues and form immune complexes, whereas the preformed immune complexes were almost completely excluded. In vitro studies with long tendons from rabbits revealed: (1) Immune complexes were formed and retained when either the soluble antigen was present prior to antibody exposure or the antibody was present prior to antigen exposure; (2) immune complexes were also formed and retained with cross-reactive antibody; (3) both IgG and IgM formed stable immune complexes in tissue; (4) antigen specific F(ab′)2 was effective in forming insoluble immune complexes with antigen in tissue, whereas antigen specific Fab did not; (5) Fc pretreatment of tissue did not alter the formation or retention of immune complexes; (6) preformed immune complexes were excluded from both normal and antibody-treated tissue.

Summary The production of antibodies in cell cultures from the draining lymph nodes of rabbits injected in the foot pads with two to four different protein antigens was studied. Antibodies against all of the immunizing antigens were produced simultaneously when aliquots of the cells were cultured 4 to 8 weeks after immunization in the absence of further antigen exposure. In vitro exposure to a single immunizing antigen always resulted in an anamnestic response to the added antigen and a general enhancement of antibody production against cross-reactive determinants on other immunizing antigens. However, antibody production against unrelated immunizing antigens was always significantly suppressed by this exposure. This suppression was not the result of antibody feedback and could not be induced unless the unrelated antigen had been used as a priming antigen.