ORAL ABSTRACT SESSION: WHO SAID THERE'S NOTHING NEW IN CARDIAC PACING?!

1311
Micra Transcatheter Pacing System: early performance assessment to demonstrate safety for pacemaker dependent patients

Abstract

Introduction: The MicraTM Transcatheter Pacing System (TPS) is a multisite, single arm, worldwide investigational IDE clinical study. The purpose is to evaluate the safety and efficacy of the system and assess long-term device performance. An initial enrollment limitation was that pacemaker-dependent patients be excluded. The data analysis utilized to remove the pacemaker-dependent exclusion requirement is presented.

Methods: At the 1-month follow-up, Medtronic ER-220 custom ambulatory ECG (AECG) recordings were collected until 25 high quality recordings were received. The early safety assessment goal was to demonstrate freedom from ventricular pauses and summarize adverse events. The AECG provides ECG, telemetry EGM, marker channel and supplemental marker data. Thresholds were automatically measured daily by a Ventricular Capture Management (VCM) test and confirmed hourly. The AECG records were manually reviewed in detail for pauses, cardiac cycles <400 ms, and arrhythmias by a technician (JH), and reviewed by scientist (TS) and physician (DGB). The final report was reviewed by the steering committee, data monitoring committee (DMC) and FDA. Again at 6-months, 25 AECG records were collected and examined to verify performance.

Results: There were 67 patients implanted from 3 continents when 25 1-month AECG records were received. The mean age was 76.9 ± 9.5 years. Twenty-four adverse events were reported, 16 of which were considered as procedure-related and/or system-related. None were unanticipated. Electrical results at implant were: Threshold = 0.56 ± 0.32V, R-wave amplitude = 11.6 ± 4.7mV and Impedance = 730 ± 225Ω. AECG results demonstrated freedom from pauses. The VCM test measurements were accurate with a threshold of 0.57 ± 0.36V; thresholds were stable with no evidence of loss of capture. No oversensing was observed. All short cycles were due to PVCs or rapidly conducted atrial fibrillation. Sporadic undersensing of PVCs was observed in 4 patients at 1-month. A sensitivity of 2.0 mV at the 6-month AECG eliminated undersensing events. Three patients had asymptomatic rate response pacing above the lower rate at night (2 due to postural sensitivity, 1 incorrect vector programmed). Postural testing at pre-hospital discharge was recommended in subsequent patients. The steering committee and DMC allowed removal of the exclusion of pacemaker-dependent patients based on the data analysis.

Conclusions: The Micra TPS system demonstrated freedom from ventricular pauses and good safety profile in this study. The FDA approved removal of the pacemaker-dependent restriction in late July 2014.

1312
Micra delivery system perforation risk assessment

Abstract

Background: The Micra™ Transcatheter Pacing System includes a deflectable catheter (DC) designed to navigate from a femoral vein access site to the right ventricular (RV) apex, where it is positioned against the cardiac tissue for deployment of the Micra Transcatheter Pacemaker. In this study three parameters were measured to better understand the risk of perforating the RV with the DC.

Methods: The three measured parameters were the RV perforation force (RVPF), the DC RV tip force (TF), and the push efficiency (PE). The RVPF was assessed by measuring the force required to push the delivery cup through multiple RV locations in 5 transplant quality isolated hearts. The TF was measured with the DC inserted into 7 fresh cadavers in which the right heart and large veins were perfused with warm saline after the anterior rib cage was resected. While a measured force was applied to the handle of the DC, the TF was measured with a force gauge attached to an 18 gauge needle placed through the RV apex into the DC device cup. The PE was the TF divided by the handle force.

Results: The mean PE was 11%. The measured forces are shown in the figure. The average difference between the RVPF and the TF was 13.6 N (18x margin), and the minimum RVPF was 4.1 N higher than the maximum TF (1.8x margin).

Conclusions: The push efficiency of the DC was low, and there was not enough TF generated in any of the cadavers to penetrate any of the 5 hearts tested. There is a significant margin (18X) between the mean TF and the mean RVPF in this test sample.

Measured Forces in Newtons

1313
Permanent His bundle pacing in patients with advanced AV block: feasibility and long term follow-up

Abstract

Introduction: Right ventricular apical pacing induces ventricular dyssynchrony. His bundle pacing (HBP) is a physiological alternative to RV pacing but is technically challenging. We aimed to establish permanent HBP in pts with AV block (B) without routine use of a mapping catheter or back-up RV lead.

Methods: All pts presenting with AVB underwent permanent HBP using Medtronic Select Securetm 3830 pacing lead and a fixed-shaped catheter (C315 HIS). His bundle (HB) was mapped using unipolar recording from the lead tip or by pace-mapping. If HB pacing was not successful after 5 attempts, the lead was placed in RV mid-septum. Mapping catheter or back-up RV lead was not routinely used. Pts were followed at 2 weeks, 2 months and yearly in addition to remote f/u.

Results: One hundred consecutive patients with AVB (age 76±12 yrs; male 62%; AV nodal 46%; Infra-nodal 54%) underwent HBP. HBP was successful in 84 (84%) pts (AV nodal 93%; Infra-nodal 76%). Mean procedure time was 71±21 min, mean fluoroscopy time was 10.7±6 min. Baseline QRS duration 121±29 msec; paced QRSd 134±24 msec. His bundle pacing threshold at implant, 2 weeks, 2 months and last follow-up (19 ±12 months) was 1.30±0.9 V, 1.56±1.0 V, 1.60±1.1 V and 1.64±1.1@ 0.5 msec respectively. Five pts needed lead revision during f/u.

Conclusions: Permanent HBP was successful in 84% of unselected pts with AVB. His bundle mapping catheter or a back-up RV lead was not necessary. Fluoroscopy and procedure times were comparable to conventional pacing. Routine HBP in pts with AVB is safe and feasible.

1314
Clinical benefit of right ventricular mid-septal pacing: 3 years follow-up data of a large consecutive patients cohort

Abstract

Right ventricular apical pacing (RVAP) is known to be deleterious is some patients (pts). Right ventricular mid-septal pacing (RVSP) might be an alternative. Long term data on RVSP are however missing. The present study investigated the feasibility, long term safety and clinical outcomes associated with RVSP.

From 2003 to 2012, primo-implantations of right ventricular leads were preferably screwed in the mid-septum in 453 consecutive pts with Class I or II pacing indications. Successful RVSP implantation was verified by X ray and confirmed by the presence of a narrow positive stimulated QRS in lead D II. Clinical and electrical characteristics were compared between 94 pts with RVAP, 225 pts with RVSP, and 134 pts with intermediate pacing sites (RVXP). Survival status at the end of follow-up was obtained through local administration for all patients.

Baseline characteristics were comparable between groups. Mean age was 76±11 years (range37-93), and 49% were men. Mean EF was 56±11%, and native QRS width was 112±28 msec. After implantation, QRS width increased to 162±28 msec with RVAP, 152±26 msec with RVSP, and 153±34 msec with RVXP. Lead impedance was comparable at 732±188, 737±218, and 748±228 Ohms in the 3 groups. Sensing was 12±10, 11±5, and 11±5 mV. V threshold was 0.64±0.52, 0.59±0.26 and 0.63±0.26 V at 0.5 msec. After a mean follow-up of 3±2.2 years, QRS width increased to 172±22 msec in the RVAP group, 162±24 msec in the RVSP group and 167±28 msec in the RVXP group, lead impedance decreased similarly to 509±150, 499±137, and 508±144 Ohms in the 3 groups. Sensing was 9±5, 9±4, and 9±5 mV. V threshold was 0.82±0.43, 0.77±0.44 and 0.77±0.33 V. During follow-up, heart failure occurred in 21% of pts with RVAP compared with only 14% of RVSP (p=0.14). Occurrence of new AF (7% vs 5%) and strokes (2.2% vs 1.1 %) was comparable between RVAP and RVSP. Kaplan-Meier survival curves showed a 28% relative risk reduction for death from any cause with RVSP at 3 years.

We conclude that RVSP is feasible and safe, does not affect sensing and pacing values over time and might decrease clinical adverse outcomes and mortality in pts where a stable RV septal position was achieved at implant.

1315
Reversal of chronic right ventricular pacing induced adverse structural and electrical remodeling by permanent his bundle pacing

Abstract

Background: His bundle pacing (HBP) is a physiological alternative to RV pacing (P). RVP leads to adverse structural and electrical remodeling. The aim of the study is to assess the feasibility and effects of permanent HBP in patients with longstanding (L) CHB and chronic RVP.

Methods: Permanent HBP was attempted in 15 pts (age 75±10 yrs; men 10; HTN 12, DM 3, CAD 6, AF 8, AVR 1, MVR 2, AVN ablation 3) with L-CHB (mean duration 9±6 yrs, range 2-24 yrs) and chronic RVP. HBP was performed using Medtronic SelectSecure 3830 lead delivered via C315His sheath. Indications for HBP: pacing induced cardiomyopathy (PIC) 6, lead failure 6, infection 3.

Results: HBP was successful in all 15 pts. Ten patients had AV nodal block and 5 had HV block. Mean fluoroscopy duration 12±7 min. Baseline RV paced QRS duration 181±19 ms (152-222 ms); HB paced QRS duration 114±20 ms (85-144 ms). HBP threshold at implant was 1.8±1.3 V @ 0.5 ms; at last f/u (1.6±1 yr) was 1.75±0.9 V @ 0.5 ms. Ventricular sensing amplitude 4.6±4.4 mV (1.2 - 15 mV). LVEF improved from 38% (range 20-49%) at baseline to 51% (45-55%) during follow-up in the 6 pts with PIC. NYHA functional status improved by at least 1 class in 9 of 15 pts. All pts showed evidence for paradoxical acute T wave memory changes with HBP which normalized in 2-6 weeks. Conclusions: Permanent HBP was successful in 15 pts with L-CHB and chronic RVP. Despite long duration of CHB (nodal and infra-nodal), conduction through distal HB and normalization of QRS could be achieved with HBP. Chronic RVP induced electrical (depolarization and repolarization) and structural (LV function) changes could be reversed with HBP.

1316
Cardiovascular and non-cardiovascular adverse events in sinus node disease and AV block with a ventricular pacing minimization mode versus standard DDD: A substudy from the ANSWER randomized trial

Abstract

Background: Ventricular pacing (Vp) has been presumed to promote adverse cardiovascular outcomes. The international randomized ANSWER trial compared the SafeR AAI-DDD changeover mode with a standard DDD setting in a general dual chamber pacemaker population with regard to hospitalizations for heart failure (HF) or atrial fibrillation (AF). This sub-analysis reports the occurrence of cardiovascular (CV) or non-CV adverse events (AE) with or without hospitalization from this study.

Methods: ANSWER is a randomized, multicenter, international trial comparing SafeR, a mode designed to minimize Vp by promoting intrinsic conduction, to standard DDD (AV delay left to physician's discretion). Patients enrolled suffered from sinus node disease (SND), intermittent AV block (AVB) or allegedly permanent AVB. All pts were programmed in SafeR at implant. 1 month after implant, pts were randomized 1:1 to either SafeR or DDD. All AE were blindly adjudicated by a Clinical Event Committee. Treatment groups were compared based on the intention-to-treat principle.

Results: 650 pts were enrolled in 43 centers in 7 countries (72.4±11.2 years, 55.2% males, 52.0% SND, 41.8% intermittent AVB and 6.2% permanent AVB) and implanted with a dual chamber pacemaker. 632 pts were randomized (314 in SafeR and 318 in DDD). Median %Vp was 11.5% in SafeR vs. 93.6% in DDD (p<0.001). After an average follow-up duration of 919±342 days a total of 528 AE (302 non-CV, 226 CV) had occurred in 306 patients (47,1%). CV AE were experienced by significantly less patients with SafeR versus DDD (see table).

Conclusions: CV and non-CV AE are common in a general dual chamber PM population. SafeR is associated with less frequent CV AE compared to DDD.

1317
Complications following cardiac implantable electronic device procedures: results from a 6-month prospective registry

Abstract

Introduction: Complications following cardiac implantable electronic devices (CIED) implantation are an emerging problem because of increasing implant rates, aging and associated comorbidities in the CIED population. We sought to analyze the incidence and clinical predictors of mortality and rehospitalization after CIED procedures.

Methods: Prospective single center registry of all CIED procedures performed from Feb/2011 to Aug/2011. Three groups were studied: initial implants (cohort 1), generator replacement (cohort 2) and transvenous lead replacement or upgrade procedures (cohort 3). All outcomes were adjudicated by an independent events committee. Multivariate logistic regression analysis was performed to identify predictors of mortality and rehospitalization. Kaplan-Meier analysis was used to obtain the probability of mortality and rehospitalization between the three cohorts.

Results: A total of 713 patients were enrolled in the study. Of these, 333, 304 and 76 patients were enrolled in the cohort 1, 2 and 3, respectively. Complications occurred in 7.5% (95% CI, 4.2-9.2) of cohort 1, 1.6% (95% CI, 0.2-3.1) of cohort 2 and in 11.8% (95% CI, 3.7-16.7) of cohort 3 (P= 0.014). In the three cohorts, complications were higher in patients with implantable cardioverter defibrillator (ICD). A total of 75 (10.5%) patients were rehospitalized throughout the study period. Patients from cohort 3 presented higher probability of rehospitalization (P<0.001). Predictors for rehospitalization were: use of ICD devices (OR= 4.2, 2.3-7.7), NYHA FC III/ IV (OR= 1.8, 1.1-3.0) and warfarin use (OR= 1.9, 1.1-3.4). A total of 58 patients (8.1%) died within the first 6 months. Only three deaths were possibly procedure-related. Patients from the cohort 1 presented higher probability of mortality (P= 0.002). Predictors for mortality were: patients older than 80 years old (OR= 2.4, 1.3-4.4), left ventricular ejection fraction (LVEF) lower than 0.40 (OR= 2.2, 1.2-3.9), NYHA FC III/IV (OR= 3.3, 1.8-5.8) and warfarin use (OR= 2.3, 1.3-4.1)

Conclusions: Among patients undergoing CIED procedures, presence of ICD devices, NYHA FC III/IV, warfarin use were predictors of rehospitalization; age, ventricular dysfunction, NYHA FC III/IV, warfarin use were predictors of mortality, in a period of 6-month following the procedure.

1318
Effect on late clinical outcomes of permanent pacemaker implantation after transcatheter aortic valve implantation

Abstract

Purpose: Very few data exist on the clinical impact of permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation. The objective of this study was to assess this impact on late outcomes in a large cohort of patients.

Methods and Results: A total of 401 consecutive patients without prior PPI undergoing transcatheter aortic valve implantation were included and 97 (24.2%) required a PPI within the first 30 days after transcatheter aortic valve implantation, median time 48 hours (24-216 hours) At a mean follow-up of 53.6±39 months, there was a trend to more mortality in patients with PPI (22.9% vs. 14.9%, p= 0.061), but no association was observed between the need for PPI and all-cause mortality (hazard ratio, 1.49; 95% confidence interval, 0.906-2.4601.30; P=0.116), cardiovascular mortality (hazard ratio, 0.69; 95% confidence interval, 0.237-2.022; P=0.520), or rehospitalisation for heart failure (hazard ratio, 1.93; 95% confidence interval, 0.804-4.647; P=0.141).

There were 4 cases of unexpected death (sudden or unknown), all of them in patients without PPI. Patients with new PPI showed a poorer evolution on left ventricular ejection fraction over time. Mean left ventricular ejection fraction increased from 60.7±14 mmHg to 63.4±11 mmHg after TAVI and decreased to 60.6±10 mmHg after 1 year and to 59 ± 6 mmHg after 4 years (p for post-TAVI trend 0.034).

Conclusions: The need for PPI was a frequent complication of transcatheter aortic valve implantation, but it was not associated with any increase in overall or cardiovascular death or rehospitalization for heart failure after a mean follow-up of 4 years. However, new PPI did have a mild negative effect on left ventricular function over time.

1319
Prognostic implication of heart failure with preserved and reduced ejection fraction in patients requiring pacemaker implantation

Abstract

Background: The prognostic implication of HFpEF and HFrEF in patients requiring pacemaker implantation has not been elucidated.

Methods: A total of 982 consecutive patients who have received their first pacemaker implantation from year 2008 to 2013 at 2 centers in Japan were analyzed. Patients lacking left ventricular ejection fraction (LVEF) data were excluded, leading to 826 patients (age 75.7±10.6 years, 50.2% male) left for analysis. Patients were divided into three groups; patients without history of heart failure (no HF group, n=656), patients with history of heart failure with LVEF≥50% (HFpEF group, n=144), and patients with history of heart failure with LVEF<50% (HFrEF group, n=26). The primary endpoint was all cause death.

Results: There were 86 (10.4%) deaths during median follow-up period of 815 days. In Kaplan-Meier analysis, significant difference in prognosis was observed between the groups, with worse prognosis in order of HFrEF group, HFpEF group, and no HF group (Log-rank: P<0.001) (Figure). In multivariate analysis, HFrEF group showed significantly worse prognosis (hazard ratio [HR]: 5.06, 95% confidence interval [CI]: 2.27-12.27, P<0.001) and HFpEF group showed marginally worse prognosis (HR: 1.64, 95% CI: 0.96-2.78, P=0.069) when no HF group was use as a reference even after adjustment by other risk factors. The HFrEF group showed significantly worse prognosis (HR: 3.10, 95% CI: 1.36-7.04, P=0.007) even when HFpEF group was used as a reference.

Conclusion: Prognosis of patients requiring pacemaker implantation is influenced significantly by presence of HFrEF, and marginally by presence of HFpEF. In this patient population, HFrEF has significantly worse prognosis than HFpEF, and may require more aggressive treatment strategies.

1320
Optimized pacing mode for hypertrophic cardiomyopathy. the impact of ECG-fusion during pacing

Abstract

Introduction: ECG-fusion with intrinsic QRS could reduce the benefit of pacing for the reduction of left ventricular outflow tract gradient (LVOTG) in hypertrophic obstructive Cardiomyopathy (HOCM).

Methods: Of 23 symptomatic HOCM symptomatic patients with severe LVOTG included in the study, 21 were successfully implanted with an atrial-synchronous biventricular pacing (AS-BivP) device. Surface ECG were evaluated for the presence of fusion and its effect on LVOTG reduction and outcomes. The evaluation was retrospective in the first 12 patients, after which 11 patients were prospectively included to evaluate the "optimized-pacing" mode by performing atrio-ventricular node ablation (AVNA) to achieve a complete ventricular pre-excitation if fusion was present during AS-BiVP.

Results: Seven (58%) of the first 12 patients had ECG-fusion. After 54±24 months of AS-BivP, the presence of fusion was associated with lower values for reduction of resting LVOTG (30±31% vs 70±30% p=0.117), dynamic LVOTG (39±27% vs 74±26%, p=0.03) and NYHA class (0.7±0.75 vs 1.2±1.3, p=0.64). In the prospectively optimized patients, after 12 months follow-up, the resting LVOTG decreased from 98±39 mmHg to 39±24 mmHg (p=0.008); dynamic LVOTG decreased from 112±38 mmHg to 60±24 mmHg (p=0.013); NYHA class decreased from 2.8±0.4 to 1.7±0.6 (p=0.014); endurance time during constant-work rate cycling exercise increased from 399±148 to 691±249 seconds (p=0.046); QoL improved from 46±22 to 22±20 points (p=0.02) and BNP levels decreased from 318±238 to 152±118 pg/mL (p=0.09). Eight (73%) of them needed AVNA that further decreased LVOTG, from 108±40 baseline to 89±29 after BivP to 54±22 mmHg after AVNA (p=0.003).

Conclusions: As-BivP assuring no EG-fusion by means of AVNA when needed seems to be the optimal pacing mode for LVOTG reduction in HOCM patients.