McLeod, Christopher J.

Introduction: Although most patients with mitral valve prolapse (MVP) have a benign prognosis, there is a subgroup with bileaflet MVP syndrome (biMVPS) at increased risk of idiopathic ventricular fibrillation (VF). The phenotypic features of this syndrome include myxomatous bileaflet prolapse, complex ventricular ectopy (VE), T-wave inversion in inferolateral ECG leads, and female predominance. The mechanism of ventricular arrhythmia in these patients is unknown. Methods: We reviewed our center’s ablation experience of 14 consecutive patients with biMVPS patients between February 2007 and October 2013 (n=13 female, median [range] age at index ablation 33.8 [21.0 - 58.7] years, left ventricular ejection fraction [EF] 60 [45-67] %, all ≤ moderate mitral regurgitation [MR]). We compared findings from 6 with prior sudden cardiac arrest (SCA) and recurrent ICD shocks for drug refractory VF with 8 who had symptomatic drug-refractory complex VE but without prior SCA. Results: All patients with prior SCA had a predominant VE trigger for the VF. There was no difference between the two groups in EF, MR severity, VE burden, and number of different VE morphologies or foci ablated. Sites of successful VE ablation at index procedure were the LV papillary muscles (PM, n=6 anterior, 6 posterior), fascicular system (n=5 anterior, 4 posterior), mitral annulus (n=2), outflow tracts (3 RVOT, 1 LVOT), and coronary sinus (n=1). All patients had at least one LV papillary or fascicular VE focus. Purkinje origin VE was identified as the VF trigger in 6/6 SCA patients (3 from PM, 3 from LV fascicles) and only 4/8 (none from PM) non-SCA patients (p=0.04). Acute success was seen in 17/19 procedures with no complications. VF storm occurred within 24 hours of ablation in a single patient. At 310 (39 - 2099) days follow-up, 1 SCA patient received a single shock (p=0.031 compared to pre-ablation), and symptoms from VE were reduced in 12/14. Conclusions: BiMVPS is characterized by VE from the LV fascicles and papillary muscles that trigger VF. The VE is invariably multifocal and may also involve the outflow tracts and mitral annulus. Ablation of clinically dominant VE foci alleviates symptoms and reduces the number of VF-terminating ICD shocks.

Background: Transcatheter aortic valve replacement (TAVR) is often complicated by AV block requiring pacing, but whether patients recover AV conduction and whether the need for pacing affects outcomes is unknown. Methods: We retrospectively studied 534 patients who underwent TAVR at Mayo Clinic in Rochester, Minnesota between November 2008 and January 2015. Of these, 115 patients had implantable cardiac devices. Data was collected from subsequent device follow-ups to determine pacemaker dependency and percentage pacing. Results: 44 patients (8.2%) had devices implanted in the immediate post procedural period. The most common indications for implantation were high grade AV block (18 patients) and complete heart block (14 patients). 17/44 (38.6%) patients were pacemaker-dependent at implant and only 4 of these patients were no longer pacemaker-dependent during subsequent followup. The indication for pacing among these four patients was high grade atrio-ventricular block (2 patients), asystole (1 patient) and complete heart block (1). Among non-pacemaker-dependent patients, no significant change in the ventricular pacing percentages was noted over time. Survival was similar between patients who required device implantation post TAVR and those who did not after adjustment for age and gender (HR 0.73 [0.39-1.36], p=ns; figure) Conclusion: Patients requiring pacing after TAVR are often pacemaker-dependent at the time of implant. It is uncommon for patients who are dependent at the time of implant to regain AV conduction, but the need for cardiac pacing is not associated with increased mortality.

Introduction: Mobile thrombi are commonly observed on endovascular leads at the time of catheter ablation. Transseptal puncture poses a risk of paradoxical embolism. We sought to examine the risk of stroke or systemic embolism after transseptal ablation in patients with and without cardiac implantable electronic devices (CIEDs). Methods: Using a large, national administrative claims database we identified 31,720 patients who underwent a catheter ablation requiring transseptal puncture between 1/1/2004 and 9/30/2014. We created two propensity-matched cohorts, matching on age, gender, race, household income, region, Charlson index, CHADS-Vasc score, and year and indication for ablation (5,533 patients with CIEDs and 11,300 patients without devices). Incidence rates (events/100 patient-years) and propensity score-matched cox proportional hazards models (with 95% confidence intervals) were used to estimate risk of stroke, transient ischemic attack, or systemic embolism for patients with or without CIEDs. We also examined the impact of presence of a CIED and oral anticoagulation (OAC) use on risk of stroke or systemic embolism within the matched cohort. Average follow up was 2.1 years. Results: The event rate was 1.5 per 100 person years in patients without device, and 1.9 per 100 person years in patients with device. Among patients not on OAC, presence of a cardiac device was associated with an increased risk of stroke or systemic embolism (HR 1.71 [1.24-2.35], P<0.01) whereas there was no association among patients treated with OAC (0.98 [0.75_1.28], p=ns) (Figure). Conclusions: Cardiac devices are associated with an increased risk of stroke or systemic embolism after transseptal ablation, but this risk is attenuated with post ablation OAC use. Anticoagulation should be considered for all patients with CIEDs post transseptal ablation, regardless of the presence of another compelling indication for anticoagulation.

Background: Rigorous study of ventricular fibrillation (VF) is not feasible in humans. The spatiotemporal characteristics of prolonged VF remain undefined, limiting our understanding of this lethal rhythm. Methods: VF was mapped in 4 canines. The endocardial and epicardial left ventricle (LV) and right ventricle (RV) were sequentially mapped at 0 to 15, 15 to 30, 30 to 45, and 45 to 60 minutes post-induction. Ten consecutive beats were used to determine the average cycle length and regularity index of ventricular and His-Purkinje system signals in discrete regions during each time interval. Results: Average VF time was 58±12 minutes. The shortest ventricular cycle length was present in the RV apical region (70±10 msec) at 0 to 15 minutes and at 15 to 30 minutes (89±31 msec) and LV apical region at 45 to 60 minutes (242±163 msec). The His-Purkinje system cycle length was the shortest at the RV outflow tract (75±3 msec) at 0 to 15 minutes, RV inflow and free wall (89±12 msec) at 15 to 30 minutes, LV apical region (83±14 msec) at 30 to 45 minutes, and inferior and inferolateral LV (145±23 msec) at 45 to 60 minutes. Regularity index was the highest in the RV inflow and free wall (78%) at 0 to 15 minutes, RV apical region (86%) at 15 to 30 minutes, LV septum and epicardial anterior RV (80%) at 30 to 45 minutes, and anterior and anterolateral LV (75%) at 45 to 60 minutes. Conclusions: These data suggest significant regional changes in electrical activity throughout VF in canines. A transition of fastest electrical activity from RV to LV apical regions across VF was observed. These novel insights of the temporal and spatial changes of VF merit further evaluation in diseased hearts to assess for reproducibility of findings.

Introduction: Although the vast majority of mitral valve prolapse (MVP) is benign, women with bileaflet MVP (biMVP), complex ventricular ectopy (VE), and abnormal T waves may comprise the recently described malignant biMVP syndrome. The mechanism of ventricular arrhythmia is unknown. To further characterize the arrhythmic substrate, we reviewed our center’s ablation experience in 6 biMVP patients with prior cardiac arrest and recurrent ICD shocks for drug refractory ventricular fibrillation (VF). Methods and Results: Six women with biMVP (median age 31.5 [range 24.2 - 58.7] years, EF 65 [45 - 67]%, all ≤moderate mitral regurgitation) experienced 6 (3 - 25) appropriate ICD shocks over 4.8 (2.8 - 10.7) years and underwent index ablation between 2/2007 - 10/2013. All had multiple VE morphologies (median 7 [3 - 24]) with variable coupling intervals but with a predominant VE trigger for the VF. A median 2 (1 - 4) VE foci were ablated. Sites of successful ablation of VF-triggering and other dominant VE were left ventricular papillary muscles [PM] (1 anterior, 1 posterior, 1 both), fascicles (1 anterior, 1 posterior), or both (1 both PM and posterior fascicle). Outflow tract VE was also present and targeted (1 left, 1 right)i. Two underwent repeat ablation (288 and 312 days) for recurrent complex VE without shocks, with different foci to the index ablation (1 posterior fascicle, 1 both fascicles). The VF-triggering VE in all patients was confirmed as originating from within the left fascicular system, which in 3/6 was at a papillary muscle. Acute procedural success was seen in all with no complications to date. A VF storm occurred within 24 hours of ablation in a single patient. At follow-up of a mean 662 (47 - 2099) days, 1 patient received a single shock (p=0.03 vs. preablation). Symptomatic VE was reduced in all; while 3/6 continue Class 1c antiarrhythmics and 5/6 have beta blockade. Conclusion: Malignant biMVP syndrome is characterized by fascicular and papillary muscle PVCs that trigger ventricular fibrillation, yet in all patients, the VE is multifocal. Ablation of at least one focus appears to improve symptoms and reduce shocks.

Introduction: Prior cardiac surgery, especially the presence of coronary bypass grafts, is thought to preclude percutaneous epicardial access (EpiAcc) and, due to limited catheter maneuverability, mapping and ablation. The objective of our study was to evaluate the feasibility and safety of EpiAcc in patients with prior cardiac surgery. Methods: We retrospectively analyzed all patients who underwent EpiAcc as part of an ablation procedure between 01/01/2004-06/30/2013 at Mayo Clinic, Rochester, MN. All had documented VT or recurring, symptomatic PVCs. Baseline clinical characteristics and procedural characteristics were collected. Results: Of 162 patients that underwent EpiAcc, 18 had prior cardiac surgery (mean age 61 years, all male). This included 10 CABG, 2 epicardial ICD placement, 5 valve surgery (3 aortic valve, 2 mitral valve), 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 patients (66.7%); the inferior approach was utilized in 78%. Of patients with prior CABG, successful access was attained in 6 (60%). The average procedural time was 441.6 ± 141.3 minutes. Adhesiolysis was required in 10 patients with the sheath, access wire, pigtail catheter or ablation catheter. Intra-procedural coronary angiography was performed in 8 patients. There were a total of 45 VTs/PVCs ablated in 18 patients (average 2.5 ± 1.7), mean cycle length 463.6 ± 95.9ms. Ultimately, 12 patients (66.7%) underwent endocardial only ablation, 1 (5.5%) had epicardial only ablation while 5 (27.8%) had endocardial/epicardial ablation. The procedure was deemed successful in 13 patients (72.2%). Four patients had bleeding complications (pericardial effusion, pericardial hematoma, hemoperitoneum and pericardial tamponade [the latter required repair of the RV wall]). In patients with coronary grafts, there was no evidence of acute graft disruption. Conclusions: Percutaneous epicardial access is feasible in patients with previous cardiac surgery, including CABG. However, adhesiolysis is frequently required. Although the risk of coronary graft injury is low, life-threatening complications may occur.

Introduction: Right ventricular apical (RVA) pacing appears to have detrimental effects on cardiac function and long term outcomes. Right ventricular non-apical (RVNA) pacing, especially in the septal position, has been postulated as an alternative that may lead to less morbidity and mortality. Prior studies have shown conflicting results and been limited by small numbers and short follow-up. We aimed to determine if right ventricular septal lead position was associated with a reduction in long-term mortality compared to RVA lead position. Methods: Patients who underwent dual-chamber pacemaker implantation from 2004 through 2013 were evaluated for right ventricular lead position based on chest radiographs. Lead positions were divided in to apical or non-apical. Non-apical lead positions were subdivided to isolate a septal lead position group. Mortality was compared between these groups. Results: During the study period, 3456 patients underwent dual-chamber pacemaker placement and had images appropriate for lead position evaluation. The group was 53.5% male with a mean age of 74 ± 13 years. RVNA lead position was found in 976 (28.2%) patients, including 243 (7.0%) with a septal position. There was no significant difference in age or prior heart failure diagnosis between groups. Kaplan-Meier survival analysis did not reveal a significant difference in mortality between patients with RVA versus RVNA lead position during 5 year follow-up (p = 0.82). However, septal lead position was associated with a significantly lower mortality compared with RVA position (p = 0.03) (figure). Conclusions: Right ventricular septal lead position is associated with a lower long-term mortality than RVA lead position. This has substantial implications regarding the preferred site for ventricular pacing lead placement.

Introduction: Percutaneous epicardial access (EAc) is increasingly performed as part of VT/PVC ablation, especially in those that have failed prior ablation. We aimed to delineate the outcomes of EAc. Methods: We retrospectively analyzed individuals undergoing EAc for arrhythmia ablation between June 2004 and July 2014. Acute procedural success was defined as elimination/non-inducibility of the clinical arrhythmia after ablation; clinical success was defined as absence of symptoms/arrhythmia. Results: Of 175 patients, 126 (72%) were male with a mean age of 52.8±15.7 years. Eighty-three (47.4%) patients had NICM, 25 (14.3%) had ICM and 34 (19.4%) had normal hearts. Baseline EF was 44±16%. Patients had failed an average of 1.7±1.2 antiarrhythmic drugs; 139 patients (79%) had failed prior endocardial (endo) ablation (average 1.3±1.1). Six (3.4%) had prior EAc and 18 (10.3%) prior cardiac surgery. The indication for ablation was VT or PVC in 113 (64.6%) and 60 (34.3%) patients, respectively. Successful access was obtained in 168 (98%) patients. Anterior access, inferior access, or both, was utilized in 89 (52.7%), 77 (45.6%) and 2 (1.2%) patients, respectively. There were an average of 2.7±2.2 VT/PVCs identified, and 1.6±1.1 ablated. Endo, epicardial (epi) or combined ablation was performed in 58 (33.1%), 14 (8%), and 100 (57.1%) patients, respectively; 3 did not undergo ablation. Procedural success was obtained in 158 of 173 (91.3%) patients for whom data was available. At 12 months, clinical success was maintained in 62% with no difference between endo, epi or combined ablation (figure). Cardiac tamponade requiring repeat EAc occurred in 12 (6.9%) patients. There were no procedural related deaths. Conclusion: Epicardial access is feasible in almost all patients with no prior cardiac surgery, and permits acute procedural success in 91.3% of patients, most of whom had failed previous ablation. Furthermore, complications are relatively infrequent in this complex cohort.

Introduction: Patients with congenital heart disease (CHD) frequently require implantable cardiac devices. Device infection or malfunction may necessitate lead extraction. Extraction may be challenging due to long lead dwell times, anatomic abnormalities, and prior cardiac surgery. Little is known about extraction outcomes in the CHD population. Methods and Results: This retrospective study included 41 CHD patients and 82 age and gender matched controls that underwent lead extractions at two centers between 2001-2014. Only patients with leads older than 12 months were included. There were 79 leads in CHD patients and 150 in controls. Patients with CHD had a mean age of 39±17 years at extraction and on average their leads had been implanted for 81±84 months, this was not significantly different from the control group. Eighty eight percent of CHD patients had 1 or more cardiac surgeries as compared to only 22% of controls (p<0.001). The number of abandoned leads was also significantly different with 16 abandoned leads in the CHD group and 3 in controls (p<0.001). There was no statistically significant difference in extraction techniques between the groups. Complete extraction was achieved in 94% of patients in both groups. There were no CHD group complications. Control group complications included 3 SVC lacerations requiring sternotomy (one was fatal), and 1 ventricular perforations with tamponade requiring sternotomy. None of these patients had a history of cardiac surgery. The average age of leads in patients with a complication was 15.3 years which was older than the mean lead age seen in the CHD and control populations which was 6.75 and 4.6 years respectively. Conclusions: Lead extraction can be safely performed in patients with CHD. Despite anatomic abnormalities and previous cardiac surgery, the outcome of lead extraction in patients with CHD is comparable to controls. Prior cardiac surgery may lower the risk for extraction complications.