Angela Naperkowski

Permanent His-bundle pacing is feasible, safe, and superior to right ventricular pacing in routine clinical practice

BACKGROUNDnRight ventricular pacing (RVP) has been associated with heart failure and increased mortality. His-bundle pacing (HBP) is more physiological but requires a mapping catheter or a backup right ventricular lead and is technically challenging.nnnOBJECTIVEnWe sought to assess the feasibility, safety, and clinical outcomes of permanent HBP in an unselected population as compared to RVP.nnnMETHODSnAll patients requiring pacemaker implantation routinely underwent attempt at permanent HBP using the Select Secure (model 3830) pacing lead in the year 2011 delivered through a fixed-shaped catheter (C315 HIS) at one hospital and RVP at the second hospital. Patients were followed from implantation, 2 weeks, 2 months, 1 year, and 2 years. Fluoroscopy time (FT), pacing threshold (PTh), complications, heart failure hospitalization, and mortality were compared.nnnRESULTSnHBP was attempted in 94 consecutive patients, while 98 patients underwent RVP. HBP was successful in 75 patients (80%). FT was similar (12.7 ± 8 minutes vs 10 ± 14 minutes; median 9.1 vs 6.4 minutes; P = .14) and PTh was higher in the HBP group than in the RVP group (1.35 ± 0.9 V vs 0.6 ± 0.5 V at 0.5 ms; P < .001) and remained stable over a 2-year follow-up period. In patients with >40% ventricular pacing (>60% of patients), heart failure hospitalization was significantly reduced in the HBP group than in the RVP group (2% vs 15%; P = .02). There was no difference in mortality between the 2 groups (13% in the HBP group vs 18% in the RVP group; P = .45).nnnCONCLUSIONnPermanent HBP without a mapping catheter or a backup right ventricular lead was successfully achieved in 80% of patients. PTh was higher and FT was comparable to those of the RVP group. Clinical outcomes were better in the HBP group than in the RVP group.

PERMANENT HIS BUNDLE PACING IS FEASIBLE AND SUPERIOR TO RIGHT VENTRICULAR PACING IN ROUTINE CLINICAL PRACTICE

Right Ventricular pacing (RVP) has been associated with ventricular dyssynchrony, heart failure (HF) and increased mortality. His Bundle pacing (HBP) is a more physiological alternative but requires a mapping catheter, a back-up RV lead and can be technically challenging. We compared procedural and

Electrophysiologic Insights Into Site of Atrioventricular Block: Lessons From Permanent His Bundle Pacing

OBJECTIVESnThis study sought to report the feasibility of permanent His bundle pacing (HBP) in patients with advanced atrioventricular block (AVB) and electrophysiological observations into site of block in patients with infranodal AVB.nnnBACKGROUNDnHBP is a physiological alternative to right ventricular pacing. Historic studies have reported a low incidence of intra-His AVB. Recent studies of permanent HBP reported limited success in patients with infranodal AVB.nnnMETHODSnConsecutive patients with advanced AVB underwent permanent HBP using Medtronic 3830 lead (Minneapolis, Minnesota) and a fixed-shaped catheter (C315 His). The HB was mapped using unipolar recording from thexa0lead tip or by pace mapping. Success of HBP, type of AVB, and pacing outcomes were documented. Patients were followed at 2 weeks, 2 months, and then yearly.nnnRESULTSnA total of 100 patients with advanced AVB (age 75 ± 12 years; male 62%; AV nodal 46%; infranodal 54%) underwent permanent HBP. HBP was successful in 84 patients (84%; AV nodal 93%, infranodal 76%). Mean procedure time was 71 ± 21 min, mean fluoroscopy time was 11 ± 6 min. Baseline QRS duration was 122 ± 27 ms; paced QRSdxa0was 124 ± 22 ms. The HB pacing threshold at implant, 2 weeks, 2 months, and last follow-up (19 ± 12 months; range: 6 toxa046 months) was 1.3 ± 0.9 V, 1.6 ± 1.0 V, 1.6 ± 1.1 V, and 1.7 ± 1.0 V at 0.5 ms, respectively. Five patients required lead revision.nnnCONCLUSIONSnPermanent HBP was successful in 84% of unselected patients with AVB. His-Purkinje conduction could be normalized in 76% of patients with infranodal block, suggesting intra-His block. Incidence of infra-His AVB was low (24%) in this series. Routine HBP in patients with AVB is feasible and safe for at least up to 18 months.

Permanent His-bundle pacing as an alternative to biventricular pacing for cardiac resynchronization therapy: A multicenter experience

BACKGROUNDnCardiac resynchronization therapy (CRT) using biventricular pacing (BVP) is effective in patients with heart failure, bundle branch block (BBB), or right ventricular pacing. Permanent His-bundle pacing (HBP) has been reported as an alternative option for CRT.nnnOBJECTIVEnThe purpose of this study was to assess the feasibility and outcomes of HBP in CRT eligible or failed patients.nnnMETHODSnHBP was attempted as a rescue strategy in patients with failed left ventricular lead or nonresponse to BVP (group I), or as a primary strategy in patients with AV block, BBB, or high ventricular pacing burden as an alternative to BVP (group II) in patients with indications for CRT. Implant characteristics, New York Heart Association functional class, and echocardiographic data were assessed in follow-up.nnnRESULTSnHBP was successful in 95 of 106 patients (90%): 30 in group I and 65 in group II. Mean age was 71 ± 12 years and 30% were female, with BBB in 45%, paced rhythm in 39%, and AV block in 16%. His capture and BBB correction thresholds were 1.4 ± 0.9 V and 2.0 ± 1.2 V at 1 ms, respectively. During mean follow-up of 14xa0months, both groups demonstrated significant narrowing of QRS from 157 ± 33 ms to 117 ± 18 ms (P = .0001), increase in left ventricular ejection fraction from 30% ± 10% to 43% ± 13% (Pxa0=xa0.0001), and improvement in New York Heart Association functional class from 2.8 ± 0.5 to 1.8 ± 0.6 (P = .0001) with HBP. Lead-related complications occurred in 7 patients.nnnCONCLUSIONnPermanent HBP is a promising alternative for CRT. HBP may be considered as a rescue strategy for failed BVP and may be a reasonable primary alternative to BVP for CRT.

Assessment of exit block following pulmonary vein isolation: Far-field capture masquerading as entrance without exit block

BACKGROUNDnComplete electrical isolation of pulmonary veins (PVs) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of the patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block, and this may appear as persistent conduction from PV to left atrium (LA).nnnOBJECTIVEnTo facilitate accurate assessment of exit block.nnnMETHODSnTwenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block by using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed, pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs.nnnRESULTSnAll 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins: mean age 58 ± 9 years; paroxysmal atrial fibrillation 40%; hypertension 70%, diabetes mellitus 30%, coronary artery disease 15%; left ventricular ejection fraction 55% ± 10%; LA size 42 ± 11 mm. Despite entrance block, exit block was absent in only 16% of the PVs, suggesting persistent PV to LA conduction. FFC of LA appendage was noted in 38% of the left superior PVs. FFC of the superior vena cava was noted in 30% of the right superior PVs. The mean pacing threshold for FFC was 7 ± 4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block.nnnCONCLUSIONSnFFC of LA appendage or superior vena cava can masquerade as persistent PV to LA conduction. A careful assessment for PV capture at decreasing pacing output is essential to exclude FFC.

Adenosine facilitates dormant conduction across cavotricuspid isthmus following catheter ablation.

BACKGROUNDnRecurrence of trans-isthmus conduction following catheter ablation of common right atrial flutter (AFL) has been reported to be as high as 15%-31% at 3 months with invasive follow-up. Intravenous adenosine has previously been shown to facilitate acute, transient reconnection of pulmonary veins following catheter ablation of atrial fibrillation.nnnOBJECTIVEnTo determine whether intravenous adenosine can facilitate dormant trans-isthmus conduction after achieving bidirectional conduction block (BDB) with catheter ablation.nnnMETHODSnThirty-two patients underwent radiofrequency catheter ablation of cavotricuspid isthmus (CTI) for common right AFL at 2 institutions. Once persistent BDB was achieved for 30 minutes and during isoproterenol infusion, 18 mg of intravenous adenosine was injected during coronary sinus pacing. Evidence for transient reconduction across the isthmus was observed. Additional ablation lesions were performed, and adenosine infusion was repeated to reassess for dormant conduction.nnnRESULTSnThirty-two (men 81%, hypertension 72%, coronary artery disease 15%, congestive heart failure 25%, diabetes mellitus 30%, left atrial size 42 ± 11 mm, left ventricular ejection fraction 51% ± 10%) patients underwent ablation of CTI. BDB was achieved in 30 of the 32 patients. Following adenosine infusion, transient reconduction was observed in 7 of the 30 patients (23%) for 10-45 seconds. Following additional ablation lesions, persistent BDB could be achieved in all 7 patients without evidence for reconduction with repeat adenosine infusion. During a mean follow-up of 19 ± 12 months, only 1 of 30 patients (3%) had clinical recurrence of AFL. None of the patients with transient reconduction after adenosine developed symptomatic recurrence of AFL.nnnCONCLUSIONSnAdenosine infusion can facilitate dormant conduction across CTI following catheter ablation. Persistent BDB can be achieved with additional ablation. Adenosine challenge with additional ablation may improve long-term clinical outcome.

Clinical Outcomes of His Bundle Pacing Compared to Right Ventricular Pacing

BACKGROUNDnRight ventricular pacing (RVP) is associated with heart failure and increased mortality. His bundle pacing (HBP) is a physiological alternative to RVP.nnnOBJECTIVESnThis study sought to evaluate clinical outcomes of HBP compared to RVP.nnnMETHODSnAll patients requiring initial pacemaker implantation between October 1, 2013, and December 31, 2016, were included in the study. Permanent HBP was attempted in consecutive patients at 1 hospital and RVP at a sister hospital. Implant characteristics, all-cause mortality, heart failure hospitalization (HFH), and upgrades to biventricular pacing (BiVP) were tracked. Primary outcome was the combined endpoint of death, HFH, or upgrade to BiVP. Secondary endpointsxa0were mortality and HFH.nnnRESULTSnHBP was successful in 304 of 332 consecutive patients (92%), whereas 433 patients underwent RVP. The primary endpoint of death, HFH, or upgrade to BiVP was significantly reduced in the HBP group (83 of 332 patients [25%]) compared to RVP (137 of 433 patients [32%]; hazard ratio [HR]: 0.71; 95% confidence interval [CI]: 0.534 to 0.944; pxa0=xa00.02). This difference was observed primarily in patients with ventricular pacing >20% (25% in HBP vs. 36% in RVP; HR: 0.65; 95% CI: 0.456 to 0.927; pxa0=xa00.02). The incidence of HFH was significantly reduced in HBP (12.4% vs. 17.6%; HR: 0.63; 95% CI: 0.430 to 0.931; pxa0=xa00.02). There was a trend toward reduced mortality in HBP (17.2% vs. 21.4%, respectively; pxa0=xa00.06).nnnCONCLUSIONSnPermanent HBP was feasible and safe in a large real-world population requiring permanent pacemakers. His bundle pacing was associated with reduction in the combined endpoint of death, HFH, or upgrade to BiVPxa0compared to RVP in patients requiring permanent pacemakers.

New Research PaperElectrophysiologic Insights Into Site of Atrioventricular Block: Lessons From Permanent His Bundle Pacing

OBJECTIVESnThis study sought to report the feasibility of permanent His bundle pacing (HBP) in patients with advanced atrioventricular block (AVB) and electrophysiological observations into site of block in patients with infranodal AVB.nnnBACKGROUNDnHBP is a physiological alternative to right ventricular pacing. Historic studies have reported a low incidence of intra-His AVB. Recent studies of permanent HBP reported limited success in patients with infranodal AVB.nnnMETHODSnConsecutive patients with advanced AVB underwent permanent HBP using Medtronic 3830 lead (Minneapolis, Minnesota) and a fixed-shaped catheter (C315 His). The HB was mapped using unipolar recording from thexa0lead tip or by pace mapping. Success of HBP, type of AVB, and pacing outcomes were documented. Patients were followed at 2 weeks, 2 months, and then yearly.nnnRESULTSnA total of 100 patients with advanced AVB (age 75 ± 12 years; male 62%; AV nodal 46%; infranodal 54%) underwent permanent HBP. HBP was successful in 84 patients (84%; AV nodal 93%, infranodal 76%). Mean procedure time was 71 ± 21 min, mean fluoroscopy time was 11 ± 6 min. Baseline QRS duration was 122 ± 27 ms; paced QRSdxa0was 124 ± 22 ms. The HB pacing threshold at implant, 2 weeks, 2 months, and last follow-up (19 ± 12 months; range: 6 toxa046 months) was 1.3 ± 0.9 V, 1.6 ± 1.0 V, 1.6 ± 1.1 V, and 1.7 ± 1.0 V at 0.5 ms, respectively. Five patients required lead revision.nnnCONCLUSIONSnPermanent HBP was successful in 84% of unselected patients with AVB. His-Purkinje conduction could be normalized in 76% of patients with infranodal block, suggesting intra-His block. Incidence of infra-His AVB was low (24%) in this series. Routine HBP in patients with AVB is feasible and safe for at least up to 18 months.

Permanent His Bundle Pacing: Long-Term Lead Performance and Clinical Outcomes

BACKGROUNDnRight ventricular pacing (RVP) is associated with heart failure and increased mortality. His-bundle pacing (HBP) is a physiological alternative to RVP.nnnOBJECTIVEnThe purpose of this study was to report long-term performance and compare the clinical outcomes of permanent HBP vs RVP.nnnMETHODSnAll patients requiring pacemaker implantation underwent an attempt at permanent HBP in 2011 at one hospital and RVP at the sister hospital. Patients were followed from implantation, 2 weeks, 2 months, and yearly for 5 years. Left ventricular ejection fraction (LVEF), pacing thresholds, lead revision, and generator change were tracked. Primary outcome was the combined endpoint of death or heart failure hospitalization (HFH) at 5 years.nnnRESULTSnHBP was attempted in 94 consecutive patients and was successful in 75 (80%); 98 patients underwent RVP. LVEF remained unchanged in the HBP group (55% ± 8% vs 57% ± 6%; P = .13), whereas significant decline was noted in the RVP group (57% ± 7% vs 52% ± 11%; P = .002). Incidence of pacing-induced cardiomyopathy was significantly lower in HBP compared to RVP patients (2% vs 22%; P = .04). At 5 years, death or HFH was significantly lower in HBP compared to RVP patients with >40% ventricular pacing (32% vs 53%; hazard ratio 1.9; P = .04). At 5 years, the need for lead revisions (6.7% vs 3%) and for generator change (9% vs 1%) were higher in the HBP group.nnnCONCLUSIONnIn patients undergoing pacemaker implantation, permanent HBP was associated with reduction in death or HFH during long-term follow-up compared to RVP. HBP was associated with higher rates of lead revisions and generator change.

Atrioventricular node ablation and His bundle pacing

AimsnAtrioventricular node ablation (AVNA) and right ventricular pacing (RVP) are effective therapies for patients with atrial fibrillation (AF) and rapid ventricular rates. His bundle pacing (HBP) is a physiologic alternative to RVP. The aim of our study is to assess the feasibility and safety of HBP in patients undergoing AVNA and its effect on left ventricular (LV) function.nnnMethods and resultsnPermanent HBP is the preferred form of ventricular pacing at our institute. Atrioventricular node ablation and HBP were performed in patients with AF and difficulty in rate control. His bundle pacing implant characteristics and thresholds were recorded. Fluoroscopic relationship of AVNA site to HBP lead electrodes was documented. Left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class at baseline and during follow-up were assessed. Forty-two patients underwent HBP and AVNA: age 74u2009±u200911u2009years; men 45%; HTN 64%; DM 19%; CAD 36%; permanent AF 40%; cardiomyopathy 55%. His bundle pacing was successful in 40 of 42 patients (95%). Successful AVNA site was at or below the ring electrode in 22 (no acute change in HBP threshold); above the ring electrode in 13 and left side in 2 pts (acute increase in HBP threshold in 7 of 15 pts). Final HBP threshold at implant was 1u2009±u20090.8u2009V@1u2009ms and increased to 1.6u2009±u20091.2u2009V@1u2009ms during a mean follow-up of 19u2009±u200914u2009months. Left ventricular ejection fraction increased from 43u2009±u200913% to 50u2009±u200911% (Pu2009=u20090.01). New York Heart Association functional status improved from 2.5u2009±u20090.5 to 1.9u2009±u20090.5 (Pu2009=u20090.04).nnnConclusionnAtrioventricular node ablation and HBP were successful in 95% of patients. His bundle pacing lead characteristics remained relatively stable. Left ventricular ejection fraction improved significantly during follow-up. His bundle pacing is feasible, safe and effective in pts undergoing AVNA.