Munger, Thomas M.

BackgroundAlthough sudden death (SD) is a rare complication after atrioventricular junction (AVJ) ablation and permanent pacemaker implantation, the risk factors leading to this SD remain unknown. The purpose of this study was to investigate SD and its risk factors after ablate‐and‐pace strategy for rate control in atrial fibrillation (AF) patients during long‐term follow‐up.HypothesisMethodsFrom January 2005 to December 2009, we enrolled into this study 517 AF patients with AVJ ablation and right ventricular pacemaker implantation. Patients were divided into 2 groups, SD and non‐SD. Cox proportional hazards models were used to assess potential risk factors for overall mortality and SD.ResultsDuring a mean follow‐up of 25.8 ± 18.6 months (range, 3 days to 63.8 months), 53 patients died (15 with SD). Cox proportional hazards models showed that the presence of congestive heart failure, New York Heart Association functional class, chronic renal failure, and nonsustained ventricular tachycardia were risk factors that predicted overall mortality. For SD, the presence of dilated cardiomyopathy and mitral stenosis were associated risk factors. SD was exclusively seen in patients who had narrow QRS complex or right bundle branch block prior to AVJ ablation and pacemaker implantation; SD was not seen in any patient with preexisting complete left bundle branch block.ConclusionsDilated cardiomyopathy, mitral stenosis, and baseline QRS morphology should be examined as potential risk factors for SD after AVJ ablation and pacemaker implantation.

BackgroundMany patients with atrial fibrillation (AF) or atrial flutter (Aflutter) have concomitant sinus node dysfunction (SND). Ablation may result in injury to the sinus node complex or its blood supply resulting in sinus arrest and need for temporary pacing. We sought to characterize patients who develop acute SND (ASND) during/immediately after AF/Aflutter ablation.MethodsWe performed a retrospective analysis of AF/Aflutter ablation patients between January 1, 2010 and February 28, 2015 to characterize those who required temporary pacemaker (TPM) implantation due to ASND (sinus arrest, sinus bradycardia <40 beats/min, or junctional rhythm with hemodynamic compromise) following atrial ablation.ResultsOf 2,151 patients, eight patients (<0.5%) with ASND manifesting as sinus arrest (n = 2), severe sinus bradycardia (n = 2), and junctional rhythm with hemodynamic compromise (n = 4) were identified (all male, age 66 ± 9.9 years, 4/8 [50%] persistent AF). AF ablation was performed in four, atypical Aflutter in one, and AF/Aflutter in three patients. The ablation set consisted of: pulmonary vein (PV) isolation (n = 6), roof line ablation (n = 6), mitral annulus‐left inferior PV line ablation (n = 5), left atrial appendage‐mitral annulus ablation (n = 1), cavotricuspid isthmus ablation (n = 5), and isolation or ablation near the superior vena cava (SVC, n = 4). Patients with peri‐SVC ablation were more likely to develop ASND (P = 0.03). All patients received TPM; six received permanent pacemaker before discharge, performed 3.5 days postablation (range 2–6 days). At 3‐month device interrogation, all patients were atrially paced >50%.ConclusionASND is a rare complication of atrial ablation. It may be more common when peri‐SVC ablation is performed and may necessitate permanent pacemaker implantation.

Background Atrial fibrillation (AF) is a common, growing, and costly medical condition. We aimed to evaluate the impact of a management algorithm for symptomatic AF that used an emergency department observation unit on hospital admission rates and patient outcomes. Methods and Results This retrospective cohort study compared 563 patients who presented consecutively in the year after implementation of the algorithm, from July 2013 through June 2014 (intervention group), with 627 patients in a historical cohort (preintervention group) who presented consecutively from July 2011 through June 2012. All patients who consented to have their records used for chart review were included if they had a primary final emergency department diagnosis of AF . We observed no significant differences in age, sex, vital signs, body mass index, or CHADS 2 (congestive heart failure, hypertension, age, diabetes mellitus, and prior stroke or transient ischemic attack) score between the preintervention and intervention groups. The rate of inpatient admission was significantly lower in the intervention group (from 45% to 36%; P <0.001). The groups were not significantly different with regard to rates of return emergency department visits (19% versus 17%; P =0.48), hospitalization (18% versus 16%; P =0.22), or adverse events (2% versus 2%; P =0.95) within 30 days. Emergency department observation unit admissions were 40% ( P <0.001) less costly than inpatient hospital admissions of ≤1 day's duration. Conclusions Implementation of an emergency department observation unit AF algorithm was associated with significantly decreased hospital admissions without increasing the rates of return emergency department visits, hospitalization, or adverse events within 30 days.

ObjectivesTo determine the frequency and predictors of pericardial effusion following epicardial sheath removal.BackgroundPericardial effusion can occur following cardiac surgical or interventional procedures including percutaneous epicardial access (EpiAcc), which is increasingly used as part of electrophysiology ablation procedures.MethodsA retrospective analysis of the Mayo Clinic comprehensive electronic medical record was performed from all patients who underwent planned EpiAcc as part of an electrophysiology ablation procedure between January 1, 2004 and June 30, 2013.ResultsOf 144 patients (mean age 51.3 ± 15.5 years, 68% male) who underwent planned EpiAcc as part of an electrophysiology ablation (95.8% pericardial access success rate), seven (4.9%) developed a postoperative pericardial effusion requiring repeat EpiAcc. Inferior access was utilized in 74 (51.4%) patients. Patients with pericardial effusion tended to be younger (41.1 years vs 51.8 years, P = 0.08) and were more likely to have undergone inferior approach access (85.7% vs 49.6%, P = 0.06) than those who did not develop postoperative pericardial effusion. Seventy‐one percent of patients with postoperative pericardial effusion versus 32.1% of patients without postoperative pericardial effusion had a preprocedure ejection fraction ≥55% (P = 0.03). There were no procedural‐related deaths, and no difference in mortality between groups.ConclusionsPostoperative pericardial effusion requiring repeat access/drainage was relatively infrequent, occurring in 4.9% of patients shortly after epicardial procedures. While the majority occur early and therefore require close observation, some patients may present in a delayed manner.

Background— Prior cardiac surgery, especially the presence of coronary artery bypass grafts, is thought to preclude percutaneous epicardial access (EpiAcc) and, therefore, mapping and ablation. We evaluated the feasibility and safety of EpiAcc in patients with a prior cardiac operation. Methods and Results— We retrospectively analyzed all patients who underwent EpiAcc for ablation for ventricular tachycardia or symptomatic premature ventricular complexes between 2004 and 2013 at Mayo Clinic, Rochester, MN. Of 162 patients who underwent EpiAcc, 18 had prior cardiac surgery (median age, 64 years, all men). This included 10 coronary artery bypass grafts, 2 epicardial implantable cardioverter defibrillator placement, 5 valve surgery, 2 septal myectomy, 1 aortic arch replacement, 1 myocardial bridge unroofing, and 1 myocardial perforation repair (3 patients had multiple procedures). Access was successful in 12 of 18; the inferior approach was used in 78%. Successful access was achieved in 6 of 10 patients with prior coronary artery bypass grafts. Adhesiolysis was required in 10 patients with the sheath, access wire, and pigtail or ablation catheter. Intraprocedural coronary angiography was performed in 8 patients. A total of 45 ventricular tachycardias/premature ventricular complexes were ablated. Thirteen patients underwent endocardial-only ablation, 2 had epicardial-only ablation, whereas 3 had endocardial–epicardial ablation. Ablation was deemed successful in 13 of 18 patients. Four patients had bleeding complications (pericardial effusion, pericardial hematoma, hemoperitoneum, and pericardial tamponade). In patients with coronary grafts, there was no evidence of acute graft disruption. Conclusions— Percutaneous EpiAcc is feasible in patients with previous cardiac surgery, including coronary artery bypass grafts. However, adhesiolysis is frequently required. Although the risk of coronary graft injury is low, life-threatening complications may occur.

Arrhythmogenic Substrate of Ventricular Arrhythmias at the AMCIntroductionCatheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown.MethodsProcedural records of 528 consecutive patients undergoing ablation of VA at Mayo Clinic, Rochester, MN, were reviewed. The electrocardiographic and electrophysiologic characteristics of patients with successful ablation at the AMC were analyzed to characterize the underlying arrhythmogenic substrate.ResultsOf the 21 patients (mean age 53.2 ± 13.4 years, 47.6% male) who underwent ablation of VA at the AMC with acute success, prepotentials (PPs) were found at the ablation sites preceding the ventricular electrogram (VEGM) during arrhythmias in 13 (61.9%) patients and during sinus rhythm in 7 (53.8%) patients. VAs with PPs were associated with a significantly higher burden of premature ventricular complexes (PVCs; 26.1 ± 10.9% vs. 14.9 ± 10.1%, P = 0.03), shorter VEGM to QRS intervals (9.0 ± 28.5 milliseconds vs. 33.1 ± 8.8 milliseconds, P = 0.03), lower pace map scores (8.7 ± 1.6 vs. 11.4 ± 0.8, P = 0.001), and a trend toward shorter V‐H intervals during VA (32.1 ± 38.6 milliseconds vs. 76.3 ± 11.1 milliseconds, P = 0.06) as compared to those without PP. A strong and positive correlation was found between V‐H interval and QRS duration during arrhythmia in those with PPs (B = 2.11, R2 = 0.97, t = 13.7, P < 0.001) but not in those without PPs.ConclusionLocal EGM characteristics and relative activation time of the His bundle suggest the possibility of conduction tissue as the origin for VA arising from the fibrous AMC. Specific identification and targeting of PPs when ablating VAs at this location may improve procedural success.

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.

Epicardial Access and ObesityIntroductionPercutaneous epicardial access for ablative therapies is an increasingly common technique utilized for refractory ventricular arrhythmias. There are, however few known data on obesity and complication rates associated with this procedure.Methods and ResultsWe retrospectively reviewed the charts of subjects undergoing epicardial access at Mayo Clinic between January 2004 and June 2013. Baseline clinical and echocardiographic data were collected for each subject, who was then classified into body mass index (BMI) categories as underweight, normal weight, overweight, and obese based on a BMI of <18.5, 18.5–24.99, 25–29.99, and ≥30, respectively. Events and complications were recorded, and procedural and clinical success rates were determined.There was no statistically significant difference in access approach, procedural or clinical outcomes, or complications among the BMI categories. Note that 95.1%, 91.7%, and 93.1% derived procedural success among the normal weight, overweight, and obese categories, respectively (P value = 0.81). Similarly, there was no difference in clinical outcomes with success rates of 68.3%, 66.7%, and 75.9% between the respective groups (P value = 0.54). At 5 years, there was a trend toward increased mortality among obese individuals (28.8%) compared to normal weight (8.8%) and overweight (9.8%) patients (P value = 0.139).ConclusionPercutaneous epicardial access, mapping, and ablation can be performed in obese individuals with similar outcomes to those of lower weight category. Obesity should not preclude the use of percutaneous epicardial access when clinically indicated.

ECG Lead I and Outflow Tract ArrhythmiaIntroductionOutflow tract ventricular arrhythmia (OTVA) can be complicated to target for ablation when originating from either the periaortic or pulmonary valve (PV) region. Both sites may present with a small R wave in lead V1. However, the utility of lead I in distinguishing these arrhythmia locations is unknown.Methods and ResultsThirty‐six consecutive patients (mean age 41 ± 14 years, 13 male) underwent catheter ablation for OTVA. OTVA origin was determined from intracardiac electrogram tracings and electroanatomic maps. Observers blinded to results measured QRS waveform amplitude and duration from standard 12‐lead ECG tracings. Measurements with highest diagnostic performance were modeled into an algorithm. Sites of successful ablation were anterior right ventricular outflow tract (RVOT; n = 6), posterior RVOT (n = 4), PV (n = 18), and right coronary cusp (RCC; n = 8). Highest performing surface ECG discriminators were from lead I to V1 vectors: RCC, lead I R wave ≥ 1.5 mV, and V1 R wave ≥2.0 mV (sensitivity 87%, specificity 93%); PV, V1 R wave > 0 mV, and lead I R/(R+S) ≤ 0.75 (sensitivity 78%, specificity 72%); anterior RVOT, V1 R wave = 0 mV, and lead I R/(R+S) <0.4 (sensitivity 67%, specificity 97%); posterior RVOT, V1 R wave > 0 mV, and lead I R/(R+S) > 0.75 (sensitivity 75%, specificity 84%). Sequential algorithmic application of these criteria resulted in an overall accuracy of 72% in predicting site of OTVA origin.ConclusionsA relatively large R wave in lead I is seen with RCC origin but not PV origin. A sequential algorithm has limited but potentially significant value beyond assessment of lead I in approaching OTVA.