infra-Hisian Block Research Articles

Clinically suspected acute right ventricular fulminant dengue myocarditis masquerading with dual lethal arrhythmias: a case report

BackgroundAcute right ventricular myocarditis is rare, comprising only 18% of myocarditis cases. Despite being relatively infrequent at 12.4%, dengue-induced myocarditis has a high mortality risk of 26.4%. This report presents a novel case of acute fulminant right ventricular myocarditis due to severe dengue infection, complicated by dual electrical disturbances: complete heart block and ventricular tachycardia.Case reportA 49-year-old Asian male patient was referred to our hospital with a temporary pacemaker due to a complete heart block. He had a history of recurrent syncope over three days and a fever five days before admission. Initial electrocardiography showed a total atrioventricular nodal block progressing to a high-degree atrioventricular block with a left bundle branch block, indicating an infra-Hisian block. Laboratory findings included thrombocytopenia, elevated troponin, high creatinine, increased liver transaminases, and a positive dengue nonstructural protein 1 test, confirming a diagnosis of dengue infection. Echocardiography showed reduced right ventricular systolic function, normal left ventricular systolic function (ejection fraction: 50%), and dyskinetic intraventricular septum. Coronary angiography revealed normal coronary anatomy. An endomyocardial biopsy was deferred due to severe thrombocytopenia. On the third day, the patient's condition worsened, developing cardiogenic shock and left ventricular systolic dysfunction (ejection fraction: 35%). He subsequently experienced a seizure and slow ventricular tachycardia originating from the right coronary cusp, followed by cardiac arrest. The patient’s family claimed not to resuscitate the patient. Furthermore, the patient died shortly after.ConclusionThis case underscores the critical need for prompt diagnosis and aggressive management of clinically suspected acute fulminant right ventricular myocarditis because complications can rapidly progress to left ventricular systolic dysfunction, leading to cardiogenic shock and sudden cardiac death.

Pause dependent left bundle branch block and infra-his block: A case report

Pause dependent left bundle branch block and infra-his block: A case report

PO-03-110 NEW INSIGHTS FROM HIS VENTRICULAR INTERVALS IN PATIENTS UNDERGOING TAVR AND IMPLICATIONS FOR PERMANENT PACING

Trans catheter aortic valve replacement (TAVR) represents a revolutionary treatment for patients with severe symptomatic aortic stenosis who are at high surgical risk. The rate of periprocedural complications has decreased over time. However, the incidence of conduction disease requiring permanent pacemaker (PPM) implantation has failed to decrease. The decision for PPM for conduction disease post TAVR is usually made based on ECG. It’s not uncommon for patients with conduction disease without evidence for infra-nodal block to receive a PPM, and pacing has been shown to have deleterious effects. To assess the utility of His Ventricular Interval (HVI) studies in predicting the need for PPM implantation. We included patients who underwent assessment of the AV nodal (AH interval) and the HVI pre and/or post TAVR and were continuously monitored until discharge and after discharge for 2 weeks. Repeat EP study was performed in the presence of new conduction disease during in-hospital or as an outpatient. PPM was recommended in the presence of complete heart block (CHB), infra-Hisian block or with an HV > 70 ms (discretion of the physician). Patients receiving PPM before 30 days were documented. Total of 71 patients who had pre and post TAVR EP study had follow up for at least 30 days. The Cohort predominantly male with an average age of 77 years. Forty-six patients received Edwards and 25 Medtronic valve. A total of 6 patients received PPM, 5 out of 6 within the index hospitalization, and 1 patient 5 days post discharge. Four out of 6 patients with PPM had Edwards and 2 out of 6 had Medtronic valve. Four out of 6 patient who received PPM, developed CHB during TAVR and HVI post TAVR was not measured; in 1 patient HVI could not be measured reliably because of atrial fibrillation and the other had normal pre and post HVI. Ten of 71 patients had pre-existing Bundle Branch Block (BBB). Four had right bundle branch block (RBBB) of which 1 required PPM, and 6 had left bundle branch block (LBBB) of which 1 required PPM. Six of 71 patients had new BBB post TAVR. 5 developed LBBB of which 2 required PPM, and 1 developed RBBB of which none required PPM In patients undergoing TAVR, pre and post TAVR EP study is very useful in determining the need for PPM. In the absence of significant infra-Hisian disease, Pre-TAVR RBBB or LBBB and new RBBB or LBBB are not an indication for PPM.Tabled 1HVI in pre-existing (Old)and post TAVR (new) Bundle Branch block (PO-03-110)Pre-existing LBBBPre-existing RBBBPost-TAVR (new) LBBBPost-TAVR (new) RBBBPatientPre-HVI (ms)Post-HVI (ms)PPM (yes/no)PatientPre-HVI (ms)Post-HVI (ms)PPM (yes/no)PatientPre-HVI (ms)Post-HVI (ms)PPM (yes/no)PatientPre-HVI (ms)Post-HVI (ms)PPM (yes/no)16063no155CHByes15255no14043no25060no25053no24871no35558yes35055no35058yes44548no44045no46063no55560no54859yes66373no Open table in a new tab

Syncope After Transcatheter Aortic Valve Implantation: Pace or Not?

Syncope After Transcatheter Aortic Valve Implantation: Pace or Not?

Permanent his bundle pacing in suprahisian versus infrahisian atrioventricular block . A single center experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Permanent His bundle pacing is currently considered the most physiological form of cardiac pacing. The main benefit of the procedure, compared to right ventricular pacing, is encountered in atrioventricular block, where a high burden of ventricular pacing is expected. One of the limits of His bundle pacing is a distal conduction abnormality in the His-Purkinje system. Nevertheless, there is published data that shows the possibility of conduction system capture even in these patients. This retrospective study evaluated the feasibility of permanent His bundle pacing in patients with second or third degree AV block, taking into account the level of block : suprahisian vs. infrahisian. Material and methods 45 patients with second or third degree AV block with an attempt at permanent His bundle pacing and an available intraprocedural hisian electrogram for review were included. The procedure went as follows: a lead delivery system including a preformed 3D shaped sheath and a lumenless lead with a fixed exposed helix was placed at the septal atrioventricular junction. Careful mapping was performed until a His bundle signal was recorded. At that site, the pacing response was evaluated at variable pacing outputs. The procedural criteria for success was conduction system capture (selective or non-selective) with an amplitude of less than 2,5V/1ms. If the criteria was met, the lead was fixed, an atrial lead was placed and both connected to a dual-chamber pacemaker. The periprocedural characteristics and those at the three-months follow-up were noted. Results 28 patients (62,2%) were diagnosed with suprahisian block, with a procedural success rate of 89 % and 17 (37,8%) with infrahisian block, with a procedural success rate of 59%. QRS duration was 96,4±21,6 ms in those with suprahisian block vs. 119,4±23,8 ms in those with infrahisian block (p=0,0027). There was no significant statistical difference regarding acute His bundle pacing thresholds (1,13±0,63 V/1ms vs. 1,25±0,76 V/1ms, p= 0,66), ventricular sensing (3,46±1,5 mV vs. 3,21±1,6 mV, p= 0,68) and fluoroscopy time (12,75±8,3 min vs. 10,78±9,5 min, p= 0,57) between suprahisian and infrahisian block. Also, the paced QRS duration was similar between the two groups (86,9±13,4 ms vs. 82±14,7 ms, p= 0,38) and narrower than the baseline complex. The three-months follow-up showed stable pacing and sensing parameters, without other procedural or lead related complications. Conclusions In atrioventricular block, permanent His bundle pacing achieves atrioventricular resynchronization, while maintaining rapid and synchronous biventricular depolarization. As expected, in suprahisian blocks the success rate is superior to infrahisian blocks. Nevertheless, in a significant proportion of the latter cases, His bundle pacing can recrute the intrinsic conduction system.

Electrocardiographic Evolution of Heart Block in Lyme Carditis

A 23-year-old male presented with dizziness and weakness and reported travel to a tick-prevalent region 1 month prior. Initial electrocardiogram showed a high-grade atrioventricular block with narrow-complex escape rhythm, which progressed to a complete heart block with a wide-complex escape the next day. Resolution of the heart block was documented at follow-up after treatment with appropriate antibiotic therapy. Heart block in Lyme carditis is more commonly reported to be supra-Hisian, manifesting as a narrow-complex escape rhythm. Infra-Hisian block is rare, which manifests as a wide-complex escape rhythm, and may occasionally require permanent pacemaker implantation.

His-Purkinje Conduction System Pacing inAtrioventricular Block: New Insights Into Site of Conduction Block.

This study aims to assess the safety and feasibility of achieving His-Purkinje conduction system pacing (HPCSP) in consecutive patients with atrioventricular block (AVB) and to describe the site of conduction block in patients with infranodal AVB. HPCSP has evolved as the preferred form of physiologic pacing. Left bundle branch area pacing (LBBAP) has emerged as an effective alternative to His bundle pacing (HBP). Consecutive patients with AVB referred for pacemaker implantation were included in the study. HBP or LBBAP was attempted in all patients. Site of conduction block was identified as nodal or infranodal (intra-Hisian or infra-Hisian) AVB. HPCSP was attempted in 333 consecutive patients with AVB and was successful in 322 (97%) patients. HBP was achieved in 140 patients, LBBAP in 179 patients, and both in 3 patients. Site of conduction block was nodal in 55% and infranodal in 45% (intra-Hisian 89%; infra-Hisian 4%; indeterminate 7%). QRS duration at baseline was 111 ± 27 versus 129 ± 31 (P< 0.001) compared to 126 ± 24 vs 125 ± 21 milliseconds (P=0.75) during HBP and LBBAP, respectively. HBP thresholds at implant were higher compared to LBBAP (1.2 ± 0.7V at 0.9 milliseconds vs 0.6 ± 0.3V at 0.5 milliseconds; P< 0.001) but remained stable during follow-up. Lead revision was required in 3% and 2% of patients with HBP and LBBAP, respectively. HPCSP pacing was successfully performed in 97% of unselected patients with AVB irrespective of the site of conduction block. True infra-Hisian block (distal His-Purkinje conduction disease) is rare. HBP and LBBAP were complementary in achieving stable and low capture thresholds.

283 His bundle pacing: safety, performance, and clinical outcomes in a single-centre experience

Abstract Aims Permanent His bundle pacing (HBP) is a more physiological technique for cardiac stimulation and has recently emerged as an alternative for anti-bradycardia pacing and cardiac resynchronization therapy (CRT). Its main advantages over ‘classical’ pacing are both its protective role over pacing-induced cardiomyopathy and the possibility of resynchronization by normalization of His-Purkinje activation. To evaluate the intermediate-term outcomes of HBP in terms of safety, performance, and clinical outcomes. Methods and results Between December 2018 and July 2020, we enrolled a series of consecutive patients with indication for pacing in whom HBP was attempted. A specific lead (3830 Select Secure MRI SureScan) and sheath (C315His) was used. At follow-up clinical, safety and performance outcomes were evaluated. A significant rise in HBP pacing threshold was defined as an increase of at least 1 V@1ms in the minimum voltage that could produce an effective myocardial depolarization. Remote or in-hospital device interrogation was performed by an experienced electrophysiologist. HBP was attempted in 99 patients and all implantations were performed by the same two operators. Eighty-two procedures were successful (83%). The main reasons for HBP failure were high pacing-thresholds (n = 8, 47%), infra-Hisian block (n = 5, 29,4%), difficult HB location (n = 3, 17,6%), unsatisfactory sensing (n = 1, 5,9%), or lead instability (n = 1, 5,9%). During a mean follow-up of 9.5 ± 5.9 months, the overall technical and clinical complication rates were 39% and 13.3%, respectively. Three (3.6%) patients underwent His lead extraction and subsequent conventional right ventricular septum (RV) lead implantation because of lead dislodgement (n = 2) or rise in pacing threshold (n = 1), while two (2.4%) patients required His lead repositioning because of lead dislodgement (n = 1) and phrenic nerve stimulation (n = 1). Nineteen patients (23.2%) experienced a significant rise in Hisian pacing threshold and 1 of these patients also had poor sensing parameters. Oversensing was noted in 8 (9.7%) patients and in 7 of them (87.5%) it was due to both atrioventricular and ventriculoatrial crosstalk events. As regards clinical outcomes, seven patients (8.5%) were diagnosed with new onset atrial fibrillation (AF), one of them complicated by stroke. Three patients (3.6%) were hospitalized for acute heart failure, one of them after His lead dislodgement. Finally, five patients (6.1%) died during follow-up, but no death was related to cardiovascular events. Conclusions HBP is an effective technique to obtain a more physiological cardiac pacing, but it is limited by a moderate rate of procedural failure and follow-up complications, mainly rising in pacing threshold and oversensing events. This is probably due to suboptimal implantation tools and lack of specific programming algorithms. New dedicated tools, increased experience, knowledge of device limitations, and optimal programming are needed to improve future outcomes.

557 His bundle pacing: how to troubleshoot the implantation of a ventricular back-up lead

Abstract Aims Interest in permanent His bundle pacing (HBP) as a means of both preventing pacing-induced cardiomyopathy and providing physiological resynchronization by normalization of His-Purkinje activation is constantly growing. Current devices are not specifically designed for HBP, which gives rise to programming challenges. To evaluate the critical troubleshooting HBP options in patients with permanent atrial fibrillation (AF) and variable degree of atrio-ventricular block (AVB) who receive HBP through a lead connected to the atrial port, and an additional ventricular ‘backup’. Methods and results Between December 2018 and July 2021, 156 consecutive patients with indication for pacing underwent HBP. Among these, 37 had permanent AF with documented symptomatic pauses. Fourteen of them received a dual-chamber device which was used to place a backup right ventricle (RV) lead; in this scenario, the His lead is implanted in the right atrial (RA) port, the RV lead in the RV port. Depending on the presence of an additional left ventricle (LV) lead, either a dual-chamber and a CRT device can be used. In this context, the events marked as atrial sensed (As) or paced (Ap) are indeed ventricular, so that sensing is more complex. A clinical scenario is atrial activity oversensed on the His channel (As) leading to RV dyssynchronous pacing in the ventricular safety pacing (VSP) window. A second one is intrinsic QRS undersensing causing inappropriate His pacing. The interplay of intrinsic ventricular activity (rate, signal amplitude, and slew rate on both the His and the ventricular channel) and of the HV interval may be of key importance to troubleshoot As–Vp (atrial sensed–ventricular paced) (Figure 1A) as well as Vs–Ab (ventricular sensed–atrial blanking period) sequences (Figure 1B). Changing sensitivity and sensing configuration may help to fix these issues. DVI(R) mode programming may indeed prove safer than DDD(R) in the setting of preserved intrinsic activity or in the event of intermittent His capture loss. Paced AV delay should be programmed slightly longer than H-V+QRS duration to avoid unnecessary RV pacing with pseudo-fusion (too short) (Figure 2A) and possibly R/T events (too long). Stability of H-V interval and of QRS duration must be verified at each device follow-up by decremental His pacing to ensure consistent sensitivity of the ventricular signal beyond stable His capture, that may be challenged by infra-Hisian block (Figure 2B). Conclusions Owing to the absence of HBP-specific devices, HBP shall be made safe and effective by careful troubleshooting, consisting of sensitivity setting, paced AV interval and mode programming. 557 Figure

Optimal his bundle pacing programming in patients with permanent atrial fibrillation

Abstract Background Interest in permanent His bundle pacing (HBP) as a means of both preventing pacing-induced cardiomyopathy and providing physiological resynchronization by normalization of His-Purkinje activation is constantly growing. Current devices are not specifically designed for HBP, which gives rise to programming challenges. Purpose To evaluate the critical troubleshooting HBP options in patients with permanent atrial fibrillation (AF) and variable degree of atrio-ventricular block (AVB) who receive HBP through a lead connected to the atrial port, and an additional ventricular “backup”. Methods Between December 2018 and March 2021, 136 consecutive patients with indication for pacing underwent HBP. Among these, 24 had permanent AF with documented symptomatic pauses. Seven of them received a dual-chamber device which was used to place a backup right ventricle (RV) lead; in this scenario, the His lead is implanted in the right atrial (RA) port, the RV lead in the RV port. Depending on the presence of an additional left ventricle (LV) lead, either a dual-chamber and a CRT device can be used. Results In this context, the events marked as atrial sensed (As) or paced (Ap) are indeed ventricular, so that sensing is more complex. A clinical scenario is atrial activity oversensed on the His channel (As) leading to RV dyssynchronous pacing in the ventricular safety pacing (VSP) window. A second one is intrinsic QRS undersensing causing inappropriate His pacing with possible delivery of the RV pulse depending on capture of the His pulse. The interplay of intrinsic ventricular activity (rate, signal amplitude and slew rate on both the His and the ventricular channel) and of the HV interval may be of key importance to troubleshoot As-Vp (atrial sensed – ventricular paced) [Fig. 1A] as well as Vs-Ab (ventricular sensed – atrial blanking period) sequences [Fig. 1B]. Changing sensitivity and sensing configuration may help or fail to fix these issues depending on the abovementioned aspects, making it mandatory to check that the paced AV delay is appropriately set as to avoid inappropriate RV pacing on the T wave of an undersensed intrinsic event at the His channel. DVI(R) mode programming may indeed prove safer than DDD(R) in the setting of preserved intrinsic activity or in the event of intermittent His capture loss. Paced AV delay should be programmed slightly longer than H-V+QRS duration to avoid unnecessary RV pacing with pseudo-fusion (too short) and possibly R/T events (too long). Stability of H-V interval and of QRS duration must be verified at each device follow-up by decremental His pacing to ensure consistent sensitivity of the ventricular signal beyond stable His capture, that may be challenged by infra-hisian block. Conclusions Owing to the absence of HBP-specific devices, HBP shall be made safe and effective by careful troubleshooting, consisting of sensitivity setting, paced AV interval and mode programming. Funding Acknowledgement Type of funding sources: None. Different sensitivity settings for HBP

His bundle pacing: safety, performance, and clinical outcomes in a single centre experience

Abstract Background Permanent His bundle pacing (HBP) is a more physiological technique for cardiac stimulation and has recently emerged as an alternative for anti-bradycardia pacing and cardiac resynchronization therapy (CRT). Its main advantages over “classical” pacing are both its protective role over pacing-induced cardiomyopathy and the possibility of resynchronization by normalization of His-Purkinje activation. Objective To evaluate the intermediate-term outcomes of HBP in terms of safety, performance, and clinical outcomes. Methods Between December 2018 and July 2020, we enrolled a series of consecutive patients with indication for pacing in whom HBP was attempted. A specific lead (3830 Select Secure MRI SureScan) and sheath (C315His) were used. At follow-up clinical, safety and performance outcomes were evaluated. A significant rise in HBP pacing threshold was defined as an increase of at least 1V@1msec in the minimum voltage that could produce an effective myocardial depolarization. Remote or in-hospital device interrogation was performed by an experienced electrophysiologist. Results HBP was attempted in 99 patients and all implantations were performed by the same two operators. 82 procedures were successful (83%). The main reasons for HBP failure were high pacing-thresholds (n=8, 47%), infra-hisian block (n=5, 29,4%), difficult HB location (n=3, 17,6%), unsatisfactory sensing (n=1, 5,9%) or lead instability (n=1, 5,9%). During a mean follow up of 9,5±5.9 months, the overall technical and clinical complication rates were 39% and 13,3% respectively. 3 (3.6%) patients underwent His lead extraction and subsequent conventional right ventricular septum (RV) lead implantation because of lead dislodgement (n=2) or rise in pacing threshold (n=1), while 2 (2.4%) patients required His lead repositioning because of lead dislodgement (n=1) and phrenic nerve stimulation (n=1). 19 patients (23,2%) experienced a significant rise in Hisian pacing threshold and 1 of these patients also had poor sensing parameters. Oversensing was noted in 8 (9.7%) patients and in 7 of them (87.5%) it was due to both atrioventricular and ventriculoatrial crosstalk events. As regards clinical outcomes, 7 patients (8.5%) were diagnosed with new onset atrial fibrillation (AF), one of them complicated by stroke. 3 patients (3.6%) were hospitalized for acute heart failure, 1 of them after His lead dislodgement. Finally, 5 patients (6.1%) died during follow-up, but no death was related to cardiovascular events. Conclusions HBP is an effective technique to obtain a more physiological cardiac pacing but it is limited by a moderate rate of procedural failure and follow-up complications, mainly rising in pacing threshold and oversensing events. This is probably due to suboptimal implantation tools and lack of specific programming algorithms. New dedicated tools, increased experience and knowledge of device limitations and optimal programming are needed to improve future outcomes. Funding Acknowledgement Type of funding sources: None.

B-AB04-04 SITE OF CONDUCTION BLOCK IN AV BLOCK: NEW INSIGHTS FROM HIS-PURKINJE CONDUCTION SYSTEM PACING

His-Purkinje Conduction System Pacing (HPCSP) has evolved as the preferred form of physiologic pacing. The level of conduction block in patients with atrioventricular block (AVB) has not been well elucidated. HPCSP (His bundle pacing and left bundle branch pacing) provides new insight into site of conduction block. The aim of the study is to describe the site of block in patients with AV block. Consecutive patients requiring ventricular pacing for AVB were included in the study. Electrograms were recorded from the His bundle and/or left bundle branch regions. AV nodal block was diagnosed if Atrium-His block was observed on His electrograms. IntraHisian block was diagnosed if HV block with narrow QRS, split His potentials, correction with HBP or Left bundle potential-V(LB-V)<35 ms was observed. InfraHisian block was diagnosed if LB-V>35 ms or LB-V block was observed. Between April-2018 to Oct-2020, 365 consecutive patients with AV block underwent HPCSP. AV nodal block 213 (58%), Infranodal block 152 (42%). IntraHisian AVB was diagnosed in 135 (89%) patients (HV block with narrow QRS 18, split His 3 patients, correction with HBP 112, LB-V <35 ms in 75 pts) and InfraHisian AVB was observed in 6 (4%) patients (LB-V >35 in 4 and LB-V block in 2). Site of infranodal block was indeterminate in 11 (7%) pts. The site of AV block was intraHisian in the majority (89%) of patients with HV block. True infraHisian block was rare and confirmed in only 4% of patients. HPCSP is a feasible strategy in most patients with AV block.

NOT ALL INFRA-HISIAN BLOCK REQUIRES PERMANENT PACING

Syncope in the setting of infra-hisian block (HVB) is an indication for permanent pacemaker (PPM). However, not all HVB uncovered during electrophysiologic study (EPS) requires a PPM. A 39 year old woman presented with non-prodromal loss of consciousness while driving resulting in an accident.

Atrial and ventricular activation sequence after ventricular induction/entrainment pacing during fast–slow atrioventricular nodal reentrant tachycardia: New insight into the use of V-A-A-V for the differential diagnosis of supraventricular tachycardia

The atrial and ventricular response observed immediately after cessation of ventricular induction/entrainment pacing is commonly analyzed to discriminate atrial tachycardia from other supraventricular tachycardias during electrophysiologic studies. However, the response in fast-slow atrioventricular nodal reentrant tachycardia (F/S-AVNRT) remains poorly investigated. The purpose of this study was to analyze the atrial andventricular activation patterns after ventricular pacing in F/S-AVNRT. We enrolled 28 patients with F/S-AVNRT incorporating a typical slow pathway (typ-F/S-AVNRT) and 9 patients with F/S-AVNRT incorporating a superior slow pathway (sup-F/S-AVNRT). The V-A-A-V response was observed in 14 patients (38%) with F/S-AVNRT, more commonly in patients with sup-F/S-AVNRT than in those with typ-F/S-AVNRT (89% vs 21%, P = .0003). The underlying mechanisms included (1) a double atrial response (DAR) in 13 patients; (2) an anterograde block at the lower common pathway once after ventricular pacing in 2 patients; and (3) a pseudo-A-A-V response in 2 patients. The DAR was characterized by a V-A-A-V interatrial interval that was 55 ± 60 ms shorter than the tachycardia cycle length, whereas the block at the lower common pathway or infrahisian block had a V-A-A-V interatrial interval that was almost equal to or longer than the tachycardia cycle length. The V-A-A-V activation sequence immediately after ventricular induction/entrainment pacing is observed in patients with F/S-AVNRT, particularly in patients with sup-F/S-AVNRT, and is caused by multiple mechanisms, including a DAR, which is the major etiology.

Permanent pacemaker implantation in octogenarians with unexplained syncope and positive electrophysiologic testing

Syncope is a common problem in the elderly, and a permanent pacemaker is a therapeutic option when a bradycardic etiology is revealed. However, the benefit of pacing when no association of symptoms to bradycardia has been shown is not clear, especially in the elderly. The aim of this study was to evaluate the effect of pacing on syncope-free mortality in patients aged 80 years or older with unexplained syncope and "positive" invasive electrophysiologic testing (EPT). This was an observational study. A positive EPT for the purposes of this study was defined by at least 1 of the following: a corrected sinus node recovery time of >525 ms, a basic HV interval of >55 ms, detection of infra-Hisian block, or appearance of second-degree atrioventricular block on atrial decremental pacing at a paced cycle length of >400 ms. Among the 2435 screened patients, 228 eligible patients were identified, 145 of whom were implanted with a pacemaker. Kaplan-Meier analysis determined that time to event (syncope or death) was 50.1 months (95% confidence interval 45.4-54.8 months) with a pacemaker vs 37.8 months (95% confidence interval 31.3-44.4 months) without a pacemaker (log-rank test, P = .001). The 4-year time-dependent estimate of the rate of syncope was 12% vs 44% (P < .001) and that of any-cause death was 41% vs 56% (P = .023), respectively. The multivariable odds ratio was 0.25 (95% confidence interval 0.15-0.40) after adjustment for potential confounders. In patients with unexplained syncope and signs of sinus node dysfunction or impaired atrioventricular conduction on invasive EPT, pacemaker implantation was independently associated with longer syncope-free survival. Significant differences were also shown in the individual components of the primary outcome measure (syncope and death from any cause).

Prognosis assessment of persistent left bundle branch block after TAVI by an electrophysiological and remote monitoring risk-adapted algorithm: rationale and design of the multicentre LBBB–TAVI Study

IntroductionPercutaneous aortic valve replacement (transcatheter aortic valve implantation (TAVI)) notably increases the likelihood of the appearance of a complete left bundle branch block (LBBB) by direct lesion of the LBB...

All-trans retinoic acid-induced, life-threatening complete atrioventricular block

We report a case of complete atrioventricular block (CAVB) with ventricular asystole and recurrent AVBs due to all-trans retinoic acid (ATRA). A 57-year-old man with acute promyelocytic leukemia was undergoing induction therapy with ATRA and developed episodic seizures with altered consciousness on the 14th day and then CAVB followed by cardiac arrest on the 15th day. Although he initially recovered after resuscitation, he suffered from recurrent CAVB, which persisted for 3 days despite immediate ATRA discontinuation. He then received ATRA retreatment with reduction of dosage, but a high-degree AVB recurred on the 5th day. After discontinuation of ATRA therapy, the patient recovered 3 days later without any cardiovascular event during follow-up. The serial electrocardiogram changes suggested an infra-Hisian block with possible ATRA dose-response relationship. To our knowledge, this is the first established case of ATRA-induced CAVB in the literature. We suggest clinical alertness for this life-threatening complication.

Nodal and infranodal atrioventricular conduction block: Electrophysiological basis to correlate the ECG findings

A 68-year-old woman with a history of dilated non-ischemic cardiomyopathy presented with syncope. The index ECG showed sinus rhythm with left bundle branch block. On telemetry episodes of sinus rhythm with narrower QRS complexes conduced in 2:1 pattern were noted. Invasive electrophysiological study was performed to determine cause of syncope. Normal conduction up to the AV node with an AH interval of 79 ms (normal = 55-125 ms) was observed. However, every alternate sinus beat was blocked after the inscription of His deflection (infra-Hisian block). The narrow beats conducted through the His bundle with HV intervals of 54 ms (normal = 35-55 ms). When 1:1 conduction resumed further abnormality of the His-Purkinje conduction system became evident with a QRS morphology that of an LBBB and prolongation of HV interval (HV = 96 ms). Criteria to differentiate nodal versus infranodal block based on electrophysiological properties of the nodal and infranodal system are discussed.

Mitral valve m-mode echo in complete heart block with atrial tachycardia

We report a 48-year-old man who presented with history of syncope. Electrocardiogram on admission showed infrahisian complete heart block with a ventricular rate of 36 beats per min with wide QRS junctional escape and atrial rate was 188 beats per min. Transthoracic echocardiogram showed fine vibratory movement of both mitral leaflet tips. M-mode evaluation of mitral leaflets showed multiple 'a' waves corresponding to atrial tachycardia rate.

Late recurrence of infra-Hisian complete atrioventricular block

Acquired complete atrioventricular block that is caused by infectious myocarditis is usually transient and has a favourable outcome. We report the case of a 15-year-old girl who had complete infra-Hisian atrioventricular block due to adeno viral myocarditis and received a permanent pacemaker at the age of 10 months. The pacemaker lost its function at the age of 7 years. However, she experienced a late recurrence of complete atrioventricular block 10 years later. Complete atrioventricular block is rarely recovered if it persisted for 2 weeks. Even in the patients with late recovery, long-term follow-up and pacemaker therapy are still needed.