McLeod, Christopher J.

BackgroundThis case‐series highlights strategies used for successful epicardial access in challenging cases.Percutaneous epicardial access has become a valuable tool for mapping and ablating arrhythmias. However, this technique can be especially difficult in certain circumstances and is frequently avoided.MethodsAll cases of epicardial access for ablation from our institution were reviewed searching for exceptionally difficult cases in patients with complex pericardial and thoracic anatomy. The successful strategies are characterized in this report.ResultsAmong 144 patients who underwent an epicardial ablation procedure between January 2004 and June 2013, four required unconventional approaches for epicardial access for ventricular tachycardia ablation. Two patients (one with previous cardiac surgery and one with prior pericardial effusion) had substantial fibrous pericardial adhesions with no virtual pericardial space and required adhesiolysis. One patient, status postpartial colectomy, underwent computed tomography‐guided intercostal epicardial access due to the presence of bowel throughout the subdiaphragmatic space in the upper abdomen. The fourth patient had partial congenital absence of the pericardium and underwent epicardial access through the creation of a subxiphoid window. All epicardial accesses were successful and performed without major complication.ConclusionsWith precise procedural planning and cardiac imaging, percutaneous epicardial access is feasible even in patients with significant anatomical challenges.

RVOT Atypical VariantsBackgroundRight ventricular outflow tract (RVOT) arrhythmias are a common form of ventricular tachycardia (VT) in patients with structurally normal heart. The underlying mechanism is due to triggered activity. Mapping and ablation is relatively straightforward targeting the earliest point of activation. Previously reported causes of difficult ablation in the RVOT region include under recognized right ventricular cardiomyopathy/sarcoidosis, presence of endocavitary structures, close proximity to the coronary vasculature, and origin from non‐RVOT structures.Methods and ResultsWe identified all patients undergoing PVCs/sustained RVOT VT ablation from January 2013 to December 2013. This included 33 patients. Of these, we identified procedures that were considered difficult despite a single morphology arrhythmia being targeted and no underlying cardiomyopathy present. Difficulty was specifically considered when ablation at the earliest site of activation was not successful and eventual successful ablation was at a distance of greater than 15 mm from the early activation site. We identified 3 patients (n = 3, 100% male) with evidence of reentrant arrhythmia based on slow conduction zones necessary for the tachycardia/arrhythmia, mid diastolic signals during VT or preceding bigeminal PVCs, pace mapping from the site abnormal signals reproducing the arrhythmia morphology but with prominent conduction delay, the entire cycle length of the tachycardia or coupling interval for the PVCs being mapping, or based on reset characteristics.ConclusionIn patients with atypical forms of RVOT VT, careful mapping and ablation of the myocardial sleeves near the pulmonic valve can eliminate the arrhythmia.

Background and Purpose— Several accepted algorithms exist to characterize the risk of thromboembolism in atrial fibrillation. We performed a comparative analysis to assess the predictive value of 9 such schemes. Methods— In a longitudinal community-based cohort study from Olmsted County, Minnesota, 2720 residents with atrial fibrillation were followed up for 4.4±3.6 years±SD from 1990 to 2004. Risk factors were identified using a diagnostic index integrated with the electronic medical record. Thromboembolism and cardiovascular event data were collected and analyzed. Results— We identified 350 validated thromboembolic events in our cohort. Multivariable analysis identified age >75 years (odds ratio, 2.08; P <0.0001), female sex (odds ratio, 1.45; P =0.0015), history of hypertension (odds ratio, 3.07; P <0.0001), diabetes mellitus (odds ratio, 1.58; P =0.0003), and history of heart failure (odds ratio, 1.50; P =0.0102) as significant predictors of clinical thromboembolism. The Stroke Prevention in Atrial Fibrillation (SPAF; hazard ratio, 2.75; c =0.659), CHADS 2 -revised (hazard ratio, 3.48; c =0.654), and CHADS 2 -classical (hazard ratio, 2.90; c =0.653) risk schemes were most accurate in risk stratification. The low-risk cohort within the CHA 2 DS 2 -VASc scheme had the lowest event rate among all low-risk cohorts (0.11 per 100 person-years). Conclusions— A direct comparison of 9 risk schemes reveals no profound differences in risk stratification accuracy for high-risk patients. Accurate prediction of low-risk patients is perhaps more valuable in determining those unlikely to benefit from oral anticoagulation therapy. Among our cohort, CHA 2 DS 2 -VASc performed best in this purpose.