Impact of omitting the intravenous heparin bolus on outcomes of leadless pacemaker implantation.

BACKGROUND: Early guidance recommended a bolus of intravenous heparin at the beginning of leadless pacemaker (LP) implantation procedures. However, due to concern about bleeding complications, more recent practice has tended toward omitting the bolus and only running a continuous heparin infusion through the introducer sheath. The impact of omitting the heparin bolus on procedural outcomes is not clear. METHODS: We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. The decision to bolus with heparin was at operator discretion. RESULTS: Among 621 LP implants, 326 received an intravenous heparin bolus, 243 did not, and 52 patients were excluded because heparin bolus status could not be confirmed. There was a trend toward more frequent omission of the heparin bolus with more recent implants. Median follow-up after LP implant was 14.3 (interquartile range [IQR]: 8.4-27.9) months. There was no difference between heparin bolus and no bolus groups in the number of device deployments/recaptures (1.42 ± 0.81 vs. 1.31 ± 0.66, p = .15). Implant-related adverse events were also similar between heparin bolus and no bolus groups: access-site hematoma requiring intervention (7 vs. 5, p = .99), pseudoaneurysm (1 vs. 1, p = .99), cardiac perforation (1 vs. 1, p = .99), intraprocedural device thrombus formation (2 vs. 4, p = .41), 30-day rehospitalization (21 vs. 15, p = .98), and 30-day all-cause mortality (16 vs. 14, p = .70). There was one additional nonfatal cardiac perforation in a patient who was excluded due to unknown heparin bolus status. Regarding device electrical parameters between heparin bolus and no bolus groups, there were no significant differences at the time of implant: pacing capture threshold 0.5 ± 0.4 vs. 0.5 ± 0.3, p = .10; pacing impedance 739.9 ± 226.4 vs. 719.1 ± 215.4, p = .52; R wave sensing 11.7 ± 5.7 vs. 12.0 ± 5.4, p = .34). Long-term device performance was also similar between groups. CONCLUSION: Omission of the systemic heparin bolus at the time of LP implantation appears safe in appropriately selected patients. Heparin bolus may still be considered in long cases requiring multiple device deployments or in patients at high risk for thrombotic complications.

Long-term performance of single-connector (DF4) implantable defibrillator leads.

AIMS: Single-connector (DF4) defibrillator leads have become the predominantly implanted transvenous implantable cardioverter-defibrillator lead. However, data on their long-term performance are derived predominantly from manufacturer product performance reports. METHODS AND RESULTS: We reviewed medical records in 5289 patients with DF4 leads between 2011 and 2023 to determine the frequency of lead-related abnormalities. We defined malfunction as any single or combination of electrical abnormalities requiring revision including a sudden increase (≥2×) in stimulation threshold, a discrete jump in high-voltage impedance, or sensing of non-physiologic intervals or noise. We documented time to failure, predictors of failure, and management strategies. Mean follow-up after implant was 4.15 ± 3.6 years (median = 3.63), with 37% of leads followed for >5 years. A total of 80 (1.5%) leads demonstrated electrical abnormalities requiring revision with an average time to failure of 4 ± 2.8 years (median = 3.5). Of the leads that malfunctioned, 62/80 (78%) were extracted and replaced with a new lead and in the other 18 cases, malfunctioned DF4 leads were abandoned, and a new lead implanted. In multivariable models, younger age at implant (OR 1.03 per year; P < 0.001) and the presence of Abbott/St. Jude leads increased the risk of malfunction. CONCLUSION: DF4 defibrillator leads demonstrate excellent longevity with >98.3% of leads followed for at least 5 years still functioning normally. Younger age at implant and lead manufacturer are associated with an increased risk of DF4 lead malfunction. The differences in lead survival between manufacturers require further investigation.

Outcomes of leadless pacemaker implantation after cardiac surgery and transcatheter structural valve interventions.

INTRODUCTION: Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions. METHODS: This retrospective study included patients who received a Micra VR (MicraTM MC1VR01) or Micra AV (MicraTM MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up. RESULTS: A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 ± 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 ± 1.1 years: 1.6 ± 1.3 years for the Micra VR group and 0.8 ± 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% ± 37.2% postprocedure vs. 47.7% ± 40.6% at last follow-up, p < .001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% ± 10.6% vs. 51.5% ± 11.2% p < .001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% ± 11.9% vs. 48.8% ± 11.9%, p = .003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% ± 9.0% vs. 54.6% ± 9.7%, p = .06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction. CONCLUSION: Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort.

Safety of same-day discharge after lead extraction procedures.

BACKGROUND: Same-day discharge (SDD) after cardiovascular procedures is rapidly gaining ground. OBJECTIVE: We sought to evaluate the safety of SDD after transvenous lead extraction (TLE). METHODS: We performed a retrospective chart review of patients who underwent elective TLE between January 2020 and October 2021 at our institution. The primary outcome was SDD, and major procedural complications and readmissions within 30 days of the procedure were secondary outcomes. RESULTS: In this analysis of 111 patients who underwent elective TLE, 80 patients (72%) were discharged on the same day (SDD group) while 31 patients (28%) stayed overnight (overnight group). Lead malfunction was the most common indication for TLE in both groups. Patients in the overnight group were more likely to have a lead dwell time of ≤10 years than those in the SDD group (38.7% vs 20% of all leads in each group; P = .042), have laser sheaths used for extraction and a higher number of leads extracted. No major complications were reported in both groups. In a multivariate analysis, lower body mass index and the use of laser sheath during TLE were predictors of overnight stay. Patients who underwent a procedure using advanced extraction techniques were 3.5 times more likely to stay overnight (95% confidence interval 1.27-9.78; P = .016). CONCLUSION: In appropriately selected patients undergoing elective lead extraction, SDD is feasible and safe. Higher body mass index, fewer extracted leads, shorter lead dwell times (<10 years), and less frequent use of laser-powered extraction sheaths were associated with an increased likelihood of SDD.

Arrhythmic Effects of Cannabis in Ischemic Heart Disease.

Rationale: Cannabis use is increasing worldwide, especially among older individuals at risk for chronic ischemic heart disease (IHD). However, little is known about the arrhythmic effects of cannabis use in IHD. Accordingly, we prospectively assessed the relationship between cannabis use, heart rate (HR), and arrhythmias in healthy age-matched controls and subjects with IHD. Methods: Healthy controls (n=37, 57% men) and subjects with IHD (myocardial infarction ≥3 months ago; n=24, 58% men) who used cannabis wore a Zio® (iRhythm Technologies) monitor for 14 days. Noncannabis using ischemic subjects (n=35, 51% males) wore Zio monitors for standard clinical indications. Baseline HR was compared with average HR measured for 4 h following consumption and changes in HR and frequency of arrhythmias were correlated with cannabis use. Results: In controls, HR increased 20 min (4.99±6.7 bpm, p=0.08) after use, then declined 4 h following use (-7.4±7.7, p<0.001). Conversely, subjects with IHD showed minimal HR increase (1.6±3.9 bpm) and blunted HR decline (-3.4±5.6 bpm, p<0.001). Supraventricular tachycardia (SVT) (29.7% vs. 58.3%; p=0.04) and nonsustained ventricular tachycardia (NSVT) (5.6% vs. 47.8%, p=0.01) were the most frequently occurring arrhythmias in controls and IHD subjects, respectively. Incidence of SVT decreased as cannabis use increased in both groups. Conversely, NSVT tended to increase with increased use in controls, and was significantly more prevalent in IHD. However, overall arrhythmia burden did not differ between cannabis users and nonusers with IHD. Conclusion: Our findings demonstrate that chronic cannabis use is associated with only mild HR changes, which are blunted in IHD. In addition, our data suggest that among cannabis users, arrhythmias are more frequent in IHD subjects that in healthy subjects.

Differences in mode of death between men and women receiving implantable cardioverter-defibrillators or cardiac resynchronization therapy in the MADIT trials.

BACKGROUND: Studies have reported sex differences in outcomes following implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy-defibrillator (CRT-D) implantation. However, little is known about sex differences with regard to mode of death or device efficacy following ICD or CRT-D implantation. OBJECTIVES: The purpose of this study was to investigate whether sex influenced mode of death or device efficacy in ICD and CRT-D subjects enrolled in the MADIT (Multicenter Automatic Defibrillator Implantation Trial) studies (MADIT-II, MADIT-CRT, and MADIT-RIT). METHODS: The combined MADIT cohort consisted of 3038 men and 1000 women with ischemic cardiomyopathy (ICM) or nonischemic cardiomyopathy (NICM), left ventricular ejection fraction ≤30%; New York Heart Association functional class I-III heart failure who received ICD or CRT-D. Mode of death was divided into cardiac and noncardiac causes, reviewed by independent adjudication committees. RESULTS: A total of 295 men and 66 women died (9.7% vs 6.6%; P =.003) during 26 months. The most common cause of death was nonarrhythmic cardiac death in men (n = 121 [41%]) and noncardiac death in women (n = 22 [33%]). All-cause mortality and cardiac deaths were 1.5- to 2.0-fold higher in men vs women with ICM but similar for those with NICM after adjustment for covariates. ICD efficacy was similar in men and women, resulting in a 50% reduction in all-cause mortality. CRT-D was more effective at reducing all-cause and cardiac death in women than men. CONCLUSION: Mode of death differs between sex and is dependent on the underlying cardiac substrate. Compared to women, cardiac death is higher in men with ICM but similar in those with NICM. ICDs are equally effective at reducing mortality in both men and women. However, CRT-D may be more effective at reducing mortality in women.

Competing risks in patients with primary prevention implantable cardioverter-defibrillators: Global Electrical Heterogeneity and Clinical Outcomes study.

BACKGROUND: Global electrical heterogeneity (GEH) is associated with sudden cardiac death in the general population. Its utility in patients with systolic heart failure who are candidates for primary prevention (PP) implantable cardioverter-defibrillators (ICDs) is unclear. OBJECTIVE: The purpose of this study was to investigate whether GEH is associated with sustained ventricular tachycardia/ventricular fibrillation leading to appropriate ICD therapies in patients with heart failure and PP ICDs. METHODS: We conducted a multicenter retrospective cohort study. GEH was measured by spatial ventricular gradient (SVG) direction (azimuth and elevation) and magnitude, QRS-T angle, and sum absolute QRST integral on preimplant 12-lead electrocardiograms. Survival analysis using cause-specific hazard functions compared the strength of associations with 2 competing outcomes: sustained ventricular tachycardia/ventricular fibrillation leading to appropriate ICD therapies and all-cause death without appropriate ICD therapies. RESULTS: We analyzed 2668 patients (mean age 63 ± 12 years; 624 (23%) female; 78% white; 43% nonischemic cardiomyopathy; left ventricular ejection fraction 28% ± 11% from 6 academic medical centers). After adjustment for demographic, clinical, device, and traditional electrocardiographic characteristics, SVG elevation (hazard ratio [HR] per 1SD 1.14; 95% confidence interval [CI] 1.04-1.25; P = .004), SVG azimuth (HR per 1SD 1.12; 95% CI 1.01-1.24; P = .039), SVG magnitude (HR per 1SD 0.75; 95% CI 0.66-0.85; P < .0001), and QRS-T angle (HR per 1SD 1.21; 95% CI 1.08-1.36; P = .001) were associated with appropriate ICD therapies. Sum absolute QRST integral had different associations in infarct-related cardiomyopathy (HR 1.29; 95% CI 1.04-1.60) and nonischemic cardiomyopathy (HR 0.78; 95% CI 0.62-0.96) (Pinteraction = .022). CONCLUSION: In patients with PP ICDs, GEH is independently associated with appropriate ICD therapies. The SVG vector points in distinctly different directions in patients with 2 competing outcomes.

Right ventricular function and cardiopulmonary performance among patients with heart failure supported by durable mechanical circulatory support devices.

BACKGROUND: Patients with continuous-flow left ventricular assist devices (CF-LVADs) experience limitations in functional capacity and frequently, right ventricular (RV) dysfunction. We sought to characterize RV function in the context of global cardiopulmonary performance during exercise in this population. METHODS: A total of 26 patients with CF-LVAD (aged 58 ± 11 years, 23 males) completed a hemodynamic assessment with either conductance catheters (Group 1, n = 13) inserted into the right ventricle to generate RV pressure‒volume loops or traditional Swan‒Ganz catheters (Group 2, n = 13) during invasive cardiopulmonary exercise testing. Hemodynamics were collected at rest, 2 sub-maximal levels of exercise, and peak effort. Breath-by-breath gas exchange parameters were collected by indirect calorimetry. Group 1 participants also completed an invasive ramp test during supine rest to determine the impact of varying levels of CF-LVAD support on RV function. RESULTS: In Group 1, pump speed modulations minimally influenced RV function. During upright exercise, there were modest increases in RV contractility during sub-maximal exercise, but there were no appreciable increases at peak effort. Ventricular‒arterial coupling was preserved throughout the exercise. In Group 2, there were large increases in pulmonary arterial, left-sided filling, and right-sided filling pressures during sub-maximal and peak exercises. Among all participants, the cardiac output‒oxygen uptake relationship was preserved at 5.8:1. Ventilatory efficiency was severely abnormal at 42.3 ± 11.6. CONCLUSIONS: Patients with CF-LVAD suffer from limited RV contractile reserve; marked elevations in pulmonary, left-sided filling, and right-sided filling pressures during exercise; and severe ventilatory inefficiency. These findings explain mechanisms for persistent reductions in functional capacity in this patient population.

Relationship between device-detected burden and duration of atrial fibrillation and risk of ischemic stroke.

BACKGROUND: Wider availability of continuous rhythm monitoring has made feasible the incorporation of metrics of atrial fibrillation (AF) burden and duration into the decision to initiate anticoagulation. However, the relationship between thresholds of burden and duration and underlying risk factors at which anticoagulation should be considered remains unclear. OBJECTIVE: The purpose of this study was to evaluate the relationships of these metrics with each other and the outcome of stroke/transient ischemic attack (TIA). METHODS: We identified patients with cardiovascular implantable electronic devices (CIEDs) with atrial leads who had at least 1 interrogation in 2016 demonstrating nonpermanent AF and were not receiving oral anticoagulation (OAC). We evaluated the relationship between burden (ie, percentage of time spent in AF), the longest single episode of AF, and risk factors (ie, CHA2DS2-VASc score) in predicting risk of stroke/TIA. RESULTS: The study included 384 patients with mean follow-up of 3.2 ± 0.8 years and incidence of stroke/TIA of 14.8% during follow-up (∼4.6% per year). The burden of AF and the duration of longest episode demonstrated a significant positive correlation to each other but not CHA2DS2-VASc score. Importantly, although the CHA2DS2-VASc score was predictive of stroke/TIA, neither burden nor duration was associated with stroke/TIA. CONCLUSION: Among patients with CIED-detected AF not receiving OAC, the amount of AF (measured by either burden or duration) does not seem to significantly impact stroke risk, whereas CHA2DS2-VASc score does. These data suggest that among patients with CIED-detected AF, once AF occurs, stroke risk seems to be predominantly driven by underlying risk factors.

New insights into resting and exertional right ventricular performance in the healthy heart through real-time pressure-volume analysis.

KEY POINTS: Despite growing interest in right ventricular form and function in diseased states, there is a paucity of data regarding characteristics of right ventricular function - namely contractile and lusitropic reserve, as well as ventricular-arterial coupling, in the healthy heart during rest, as well as submaximal and peak exercise. Pressure-volume analysis of the right ventricle, during invasive cardiopulmonary exercise testing, demonstrates that that the right heart has enormous contractile reserve, with a three- or fourfold increase in all metrics of contractility, as well as myocardial energy production and utilization. The healthy right ventricle also demonstrates marked augmentation in lusitropy, indicating that diastolic filling of the right heart is not passive. Rather, the right ventricle actively contributes to venous return during exercise, along with the muscle pump. Ventricular-arterial coupling is preserved during submaximal and peak exercise in the healthy heart. ABSTRACT: Knowledge of right ventricular (RV) function has lagged behind that of the left ventricle and historically, the RV has even been referred to as a 'passive conduit' of lesser importance than its left-sided counterpart. Pressure-volume (PV) analysis is the gold standard metric of assessing ventricular performance. We recruited nine healthy sedentary individuals free of any cardiopulmonary disease (42 ± 12 years, 78 ± 11 kg), who completed invasive cardiopulmonary exercise testing during upright ergometry, while using conductance catheters inserted into the RV to generate real-time PV loops. Data were obtained at rest, two submaximal levels of exercise below ventilatory threshold, to simulate real-world scenarios/activities of daily living, and maximal effort. Breath-by-breath oxygen uptake was determined by indirect calorimetry. During submaximal and peak exercise, there were significant increases in all metrics of systolic function by three- to fourfold, including cardiac output, preload recruitable stroke work, and maximum rate of pressure change in the ventricle (dP/dtmax ), as well as energy utilization as determined by stroke work and pressure-volume area. Similarly, the RV demonstrated a significant, threefold increase in lusitropic reserve throughout exercise. Ventricular-arterial coupling, defined by the quotient of end-systolic elastance and effective arterial elastance, was preserved throughout all stages of exercise. Maximal pressures increased significantly during exercise, while end-diastolic volumes were essentially unchanged. Overall, these findings demonstrate that the healthy RV is not merely a passive conduit, but actively participates in cardiopulmonary performance during exercise by accessing an enormous amount of contractile and lusitropic reserve, ensuring that VA coupling is preserved throughout all stages of exercise.

Analysis of Outcomes in 8304 Patients Undergoing Lead Extraction for Infection.

Background Patients undergoing lead extraction for infected devices have worse outcomes compared with those with noninfected devices. We assessed predictors of in-hospital mortality and procedure-related major adverse events (MAEs) in a large cohort undergoing lead extraction. Methods and Results Deidentified hospital records procedure from 7 states between 1994 and 2013 were aggregated and International Classification of Disease, Ninth Revision (ICD-9) procedure codes were used to identify hospital records reporting lead extraction. MAEs included death, cardiac tamponade, hemothorax, and need for emergent cardiac surgery. Predictors of in-hospital MAEs for infected compared with noninfected leads were identified using multivariate regression. Associations between outcomes and specific microbe were also assessed. In total, 57 220 discharges specified lead extraction. Infected leads accounted for the minority of total lead extractions compared with fractured leads (16.1 versus 59.8%, 25.7% not reported). There were 3298 MAEs (5.8%) including 980 deaths (1.7%). Multivariate predictors of MAE included black race, atrial fibrillation, anemia, heart failure, and admission via either hospital transfer or emergency department versus home (all P<0.001). Infected leads were associated with an increased risk of death (4.6% versus 0.9%, P<0.001) compared with leads with fracture only. Among patients with microbial data, staphylococcal infection was most common, whereas streptococcal infection was associated with the worst outcomes. Conclusions Patients undergoing extraction of infected leads have higher in-hospital mortality and adverse events compared with noninfected leads. Streptococcus, anemia, and heart failure are predictors of adverse outcomes.

Follow-Up After Catheter Ablation of Papillary Muscles and Valve Cusps.

OBJECTIVES: The goal of this study was to determine the impact of catheter ablation in the region of papillary muscles (PMs) and valvular cusps (VC) on mitral, tricuspid, or aortic valve function. BACKGROUND: Ventricular arrhythmias arising from PMs and VCs often require extensive catheter ablation. Little is known regarding the risk of valve dysfunction after radiofrequency catheter ablation of such arrhythmias. METHODS: A retrospective analysis was completed for 149 PM and VC VT/premature ventricular contraction (PVC) ablations from 2008 to 2018 at our institution. Patient and procedural details were collected for VT and PVC ablation cases involving PMs and VCs with available echocardiographic data pre-ablation and post-ablation (within 6 months). Degree of valvular regurgitation (VR) was graded from 0 (none) to 4 (severe), and significant valvular dysfunction was defined as a 2+ change in VR. RESULTS: Of 149 radiofrequency catheter ablation cases, there were 84 (56%) aortic valve cusp ablations, 60 (40%) left ventricular PM ablations, and 5 (3%) right ventricular PM ablations. There were no statistically significant differences between pre-ablation and post-ablation VR severity (p = 0.33). No patients had a 2+ grade change in VR severity when pre-ablation and post-ablation echocardiograms were compared. There were no significant sequelae requiring intervention in the post-ablation period. On follow-up of 36 ± 9 months, for those with a change in VR, the severity had improved to baseline or remained stable. CONCLUSIONS: Despite often-times extensive ablation on and around valvular networks, risk of longstanding or permanent valvular dysfunction after VT/PVC ablation is rare.

Electrophysiologic testing for diagnostic evaluation and risk stratification in patients with suspected cardiac sarcoidosis with preserved left and right ventricular systolic function.

INTRODUCTION: While cardiac sarcoidosis (CS) carries a risk of ventricular arrhythmias (VAs) and sudden cardiac death (SCD), risk stratification of patients with CS and preserved left ventricular/right ventricular (LV/RV) systolic function remains challenging. We sought to evaluate the role of electrophysiologic testing and programmed electrical stimulation of the ventricle (EPS) in patients with suspected CS with preserved ventricular function. METHODS: One hundred twenty consecutive patients with biopsy-proven extracardiac sarcoidosis and preserved LV/RV systolic function underwent EPS. All patients had either probable CS defined by an abnormal cardiac positron emission tomography or cardiac magnetic resonance imaging, or possible CS with normal advanced imaging but abnormal echocardiogram (ECG), SAECG, Holter, or clinical factors. Patients were followed for 4.5 ± 2.6 years for SCD and VAs. RESULTS: Seven of 120 patients (6%) had inducible ventricular tachycardia (VT) with EPS and received an implantable cardioverter defibrillator (ICD). Three patients (43%) with positive EPS later had ICD therapies for VAs. Kaplan-Meier analysis stratified by EPS demonstrated a significant difference in freedom from VAs and SCD (P = 0.009), though this finding was driven entirely by patients within the cohort with probable CS (P = 0.018, n = 69). One patient with possible CS and negative EPS had unrecognized progression of the disease and unexplained death with evidence of CS at autopsy. CONCLUSIONS: EPS is useful in the risk stratification of patients with probable CS with preserved LV and RV function. A positive EPS was associated with VAs. While a negative EPS appeared to confer low risk, close follow-up is needed as EPS cannot predict fatal VAs related to new cardiac involvement or disease progression.

Ambulatory Rhythm Monitoring to Detect Late High-Grade Atrioventricular Block Following Transcatheter Aortic Valve Replacement.

BACKGROUND: High-grade atrioventricular block (H-AVB) is a well-described in-hospital complication of transcatheter aortic valve replacement (TAVR). Delayed high-grade atrioventricular block (DH-AVB) has not been systematically studied among outpatients post-TAVR, using latest-generation TAVR technology and in the early post-TAVR discharge era. OBJECTIVES: The purpose of this study was to assess utility of ambulatory event monitoring (AEM) in identifying post-TAVR DH-AVB and associated risk factors. METHODS: Patients without pre-existing pacing device undergoing TAVR at the University of Colorado Hospital from October 2016 to March 2018, and who did not require permanent pacemaker implantation pre-discharge, were discharged with 30-day AEM to assess for DH-AVB (≥2 days post-TAVR). Clinical and follow-up data were collected and compared among those without incident H-AVB. RESULTS: Among 150 consecutive TAVR patients without a prior pacing device, 18 (12%) developed H-AVB necessitating permanent pacemaker <2 days post-TAVR, 1 died pre-discharge, and 13 declined AEM; 118 had 30-day AEM data. DH-AVB occurred in 12 (10% of AEM patients, 8% of total cohort) a median of 6 days (range 3 to 24 days) post-TAVR. DH-AVB versus non-AVB patients were more likely to have hypertension and right bundle branch block (RBBB). Sensitivity and specificity of RBBB in predicting DH-AVB was 27% and 94%, respectively. CONCLUSIONS: DH-AVB is an underappreciated complication of TAVR among patients without pre-procedure pacing devices, occurring at rates similar to in-hospital, acute post-TAVR H-AVB. RBBB is a risk factor for DH-AVB but has poor sensitivity, and other predictors remain unclear. In this single-center analysis, AEM was helpful in expeditious identification and treatment of 10% of post-TAVR outpatients. Prospective study is needed to clarify incidence, risk factors, and patient selection for outpatient monitoring.

Esophageal position, measured luminal temperatures, and risk of atrioesophageal fistula with atrial fibrillation ablation.

BACKGROUND: Despite improvement in catheter ablation for atrial fibrillation (AF), ability to recognize and prevent esophageal injury remains challenging. We hypothesized that esophageal course may impact esophageal heating, as measured through ablation, and thereby, risk of injury. METHODS: We evaluated all patients undergoing first-time AF ablation with preprocedural computed tomography (CT) imaging from 2014 to 2016 at our institution, focusing on esophageal position at the left atrial (LA)/pulmonary vein junction. Esophageal luminal temperatures (ELTs) were analyzed by esophageal course. In exploratory work by investigation of published reports of atrioesophageal fistula (AEF), we evaluated for a relationship between esophageal course and risk of AEF. RESULTS: Of 68 patients, 48.5% had midline, 36.8% leftward, and 14.7% rightward esophageal positions. Of 20 patients (29% of cohort) with esophageal confinement-defined as a midline or leftward position relative to the LA, vertebrae, and aorta, with luminal distortion-14 had leftward position. No significant differences in patient or procedure characteristics were noted between confinement and nonconfinement cohorts. The average peak ELT was significantly higher in those with confinement (36.9°C vs 36.2°C, P < 0.05) and confinement with a left-sided esophagus (37.1°C vs 36.2°C, P < 0.05). There was a significant correlation between esophageal confinement and risk of AEF (odds ratio [OR]: 2.7, 95% confidence interval [CI]: 1.2-6.2, P < 0.01). CONCLUSION: Approximately one-third of patients undergoing AF ablation display leftward esophageal course along the ablation zone on preprocedure CT imaging, with a significant portion exhibiting esophageal confinement. In those with confinement, higher peak ELTs are noted with ablation. Esophageal confinement may be a risk factor for development of AEF.

Significance of leukocytosis prior to cardiac device implantation.

INTRODUCTION: Infection remains a dreaded complication after cardiac implanted electronic device (CIED) placement. The prognostic value of the preoperative white blood cell (WBC) count, in the absence of other signs of infection, at time of CIED placement as a predictor of postoperative infection, has not been previously examined. METHODS: The study population included 1,247 consecutive device implantations over a 4-year period that met inclusion criteria. The association between preoperative WBC count and resultant infection postoperatively was examined. Early infection was defined as definite infection of the pocket or lead system or development of systemic infection identified <60 days after implantation. Preoperative WBC counts were obtained within 48 hours of the procedure. RESULTS: Baseline characteristics of the population studied were mean age of 65 years, 66% men, and 72% Caucasian. Pacemakers, implantable cardioverter defibrillators (ICDs), and biventricular ICDs were implanted in 41%, 44%, and 15%, respectively. Average procedure time was 174 minutes ± 80. Of 1,247 device implantations, there were 10 infections (0.8%). Mean preprocedure WBC count in those diagnosed with infection was 8.1 × 103 /uL (range 5-11.7) and in those without infection was 7.8 × 10(3)/uL (range 2.3-29) (P = 0.73). Cases resulting in infection demonstrated minimal change in WBC count (mean +5.5 ± 26.5%). There was no statistically significant difference in preprocedure WBC count between the two groups (P = 0.7). Regardless of preprocedural WBC, no patients had other signs and symptoms of infection at time of device implantation. CONCLUSION: As an isolated finding, an elevated preprocedure WBC should not delay the implantation of an indicated device.

Acute isoproterenol leads to age-dependent arrhythmogenesis in guinea pigs.

Sudden cardiac death from ventricular arrhythmias is more common in adult patients with with heart failure compared with pediatric patients with heart failure. We identified age-specific differences in arrhythmogenesis using a guinea pig model of acute ß-adrenergic stimulation. Young and adult guinea pigs were exposed to the ß-adrenergic agonist isoproterenol (ISO; 0.7 mg/kg) for 30 min in the absence or presence of flecainide (20 mg/kg), an antiarrhythmic that blocks Na+ and ryanodine channels. Implanted cardiac monitors (Reveal LINQ, Medtronic) were used to monitor heart rhythm. Alterations in phosphorylation and oxidation of ryanodine receptor 2 (RyR2) were measured in left ventricular tissue. There were age-specific differences in arrhythmogenesis and sudden death associated with acute ß-adrenergic stimulation in guinea pigs. Young and adult guinea pigs developed arrhythmias in response to ISO; however, adult animals developed significantly more premature ventricular contractions and experienced higher arrhythmia-related mortality than young guinea pigs treated with ISO. Although there were no significant differences in the phosphorylation of left ventricular RyR2 between young and adult guinea pigs, adult guinea pigs exposed to acute ISO had significantly more oxidation of RyR2. Flecainide treatment significantly improved survival and decreased the number of premature ventricular contractions in young and adult animals in association with lower RyR2 oxidation. Adult guinea pigs had a greater propensity to develop arrhythmias and suffer sudden death than young guinea pigs when acutely exposed to ISO. This was associated with higher oxidation of RyR2. The incidence of sudden death can be rescued with flecainide treatment, which decreases RyR2 oxidation. NEW & NOTEWORTHY Clinically, adult patients with heart failure are more likely to develop arrhythmias and sudden death than pediatric patients with heart failure. In the present study, older guinea pigs also showed a greater propensity to arrhythmias and sudden death than young guinea pigs when acutely exposed to isoproterenol. Although there are well-described age-related cardiac structural changes that predispose patients to arrhythmogenesis, the present data suggest contributions from dynamic changes in cellular signaling also play an important role in arrhythmogenesis.

Repeat ablation of refractory ventricular arrhythmias in patients with nonischemic cardiomyopathy: Impact of midmyocardial substrate and role of adjunctive ablation techniques.

INTRODUCTION: Multiple ablations are often necessary to manage ventricular arrhythmias (VAs) in nonischemic cardiomyopathy (NICM) patients. We assessed characteristics and outcomes and role of adjunctive, nonstandard ablation in repeat VA ablation (RAbl) in NICM. METHODS AND RESULTS: Consecutive NICM patients undergoing RAbl were analyzed, with characteristics of the last VA ablations compared between those undergoing 1 versus multiple-repeat ablations (1-RAbl vs. >1RAbl), and between those with or without midmyocardial substrate (MMS). VA-free survival was compared. Eighty-eight patients underwent 124 RAbl, 26 with > 1RAbl, and 26 with MMS. 1-RAbl and > 1-RAbl groups were similar in age (57 ± 16 vs. 57 ± 17 years; P = 0.92), males (76% vs. 69%; P = 0.60), LVEF (40 ± 17% vs. 40 ± 18%; P = 0.96), and amiodarone use (31% vs. 46%, P = 0.22). One-year VA freedom between 1-RAbl vs. > 1RAbl was similar (82% vs. 80%; P = 0.81); adjunctive ablation was utilized more in >1RAbl (31% vs. 11%, P = 0.02), and complication rates were higher (27% vs. 7%, P = 0.01), most due to septal substrate and anticipated heart block. >1-RAbl patients had more MMS (62% vs. 16%, P < 0.01). Although MMS was associated with worse VA-free survival after 1-RAbl (43% vs. 69%, P = 0.01), when >1RAbl was performed, more often with nonstandard ablation, VA-free survival was comparable to non-MMS patients (85% vs. 81%; P = 0.69). More RAbls were required in MMS versus non-MMS patients (2.00 ± 0.98 vs. 1.16 ± 0.37; P < 0.001). CONCLUSION: For NICM patients with recurrent, refractory VAs despite previous ablation, effective arrhythmia control can safely be achieved with subsequent ablation, although >1 repeat procedure with adjunctive ablation is often required, especially with MMS.