High initial heart rate score is an independent predictor of new atrial high-rate episodes in pacemaker patients with sinus node dysfunction.

BACKGROUND: Heart rate score (HRSc), the percentage of atrial depolarizations in the largest paced and sensed 10-beats/min histogram bin recorded in cardiac devices, is associated with several adverse outcomes, but it remains uncertain whether HRSc independently predicts atrial high-rate episodes (AHREs) in patients with sinus node dysfunction (SND) undergoing pacemaker (PM) implantation. OBJECTIVE: This study aimed to determine whether initial HRSc after PM implantation predicts new-onset AHREs in patients with SND. METHODS: Patients had Boston Scientific PMs implanted for SND from 2012 to 2021 at Cleveland Clinic, University of Occupational and Environmental Health, Japan, Kyushu Rosai Hospital, and JCHO Kyushu Hospital. Patients were excluded if they had atrial fibrillation before PM implantation or AHREs within 3 months after implantation. Subsequent AHREs after implantation were evaluated and correlated with HRSc. RESULTS: During 48.9 (interquartile range, 25.7-50.4) months, 130 consecutive PM patients (76 ± 10 years; 40% male) had a median initial HRSc of 74% (57%-86%). AHREs defined by >1%, >6 h/d burden, and atrial tachycardia response events >24 hours developed in 27 of 130 (21%), 15 of 130 (12%), and 9 of 130 (7%), respectively. For each definition, patients with HRSc ≥80% had higher occurrence of AHREs than those with HRSc <80% (both P = .008, log-rank test). After adjustment for age, race, comorbidities, left ventricular ejection fraction, left atrial diameter, and cumulative percentage of right atrial and right ventricular pacing, initial HRSc ≥80% (hazard ratio, 3.33; 95% CI, 1.35-8.18; P = .009) and male sex (hazard ratio, 2.59; 95% CI, 1.06-6.33; P = .04) independently predicted AHREs. CONCLUSION: HRSc ≥80% is associated with new-onset, device-determined AHREs for patients undergoing PM implantation for SND. HRSc may have prognostic and therapeutic implications.

Unusual atrial pacing induced by type II far-field p-wave sensing in a patient with complete atrioventricular block.

An 88-year-old Japanese woman underwent DDD pacemaker (MicroPort KORA 250 DR, V lead: VEGA R52) implantation for complete atrioventricular block. A 12-lead electrocardiogram for a routine examination showed atrial pacing within the intrinsic P wave, followed by inhibition of ventricular pacing. Pacemaker interrogation revealed no abnormalities in the basic parameters; however, ventricular pacing was inhibited by far-field sensing of intrinsic atrial waves before atrial events; type II far-field P-wave sensing. As a result, unusual atrial pacing occurred due to the pause suppression algorithm, which is the one of the functions that prevent atrial fibrillation development.

Initial heart rate score predicts new-onset atrial tachyarrhythmias in pacemaker patients.

AIMS: Heart rate score (HRSc), the per cent of atrial paced and sensed event in the largest 10 b.p.m. rate histogram bin of a pacemaker, predicts survival in patients with cardiac devices. No correlation between HRSc and development of atrial fibrillation (AF) has been reported. In this study, we evaluated the relationship between pacemaker post-implantation HRSc and the incidence of newly developed atrial tachyarrhythmias (ATAs). METHODS AND RESULTS: Patients with dual-chamber pacemakers, implanted 2013-17, with the LATITUDE remote monitoring data with ≥600 000 beats of histogram data collected at baseline were included (N = 34 543). Heart rate score was determined from the initial 3-month post-implantation histogram data. Patients were excluded if they had ATAs, defined as atrial high-rate episodes >5 min or >1% of right atrial beats >170 b.p.m. during the initial 3 months post-implantation. New ATAs, after the baseline period, were defined by each of the following: >1, >10, or >25% of atrial beats >170 b.p.m. or atrial tachycardia response (ATR) events >24 h. Patients were followed a median of 2.8 (1.0-4.0) years. The incidence of ATAs increased in proportion to HRSc (log-rank P-value <0.001), and the initial HRSc ≥70% was associated with increased ATAs by all definitions. Patients with initial HRSc ≥70% were older, had a higher percentage of right atrium pacing (%RA pacing), had a lower percentage of right ventricular pacing (%RV pacing), and were more likely programmed with rate-response vs. subjects with HRSc <70%. Initial HRSc (hazard ratio: 1.07, 95% confidence interval: 1.05-1.09; P < 0.0001) independently predicted ATAs after adjusting for age, gender, %RV pacing, and rate-response programming. The %RA pacing and initial HRSc were correlated. CONCLUSION: Heart rate score independently predicts any subsequent duration of ATAs in pacemaker patients.

Belt-type electrocardiograph for diagnosing palpitation occurring only during high-intensity exercise in athletes.

Belt-type ambulatory electrocardiograph (EV-201) is an arrhythmia diagnostic device that can record an electrocardiogram (ECG) for a maximum of 2 weeks. Here, we report the novel utility of EV-201 in detecting arrhythmias in two professional athletes. Treadmill exercise test and Holter ECG failed to detect arrhythmia because of insufficient exercise, electrocardiogram noise. However, by wearing EV-201 only during a marathon run, supraventricular tachycardia onset and termination were successfully detected. Throughout, both athletes were diagnosed with fast-slow atrioventricular nodal re-entrant tachycardia. Therefore, EV-201 enables long-term belt-type recording, thereby being useful in detecting tachyarrhythmias that occur infrequently and during strenuous exercises. Learning objective: Diagnosis of arrhythmias during high-intensity exercise in athletes by conventional electrocardiography is sometimes difficult due to inducibility and frequency of arrythmias or motion artifacts. The primary finding of this report is that EV-201 is useful in diagnosing such arrhythmias. The secondary finding is that fast-slow atrioventricular nodal re-entrant tachycardia is a common occurrence in arrhythmias among athletes.

Prediction of PR interval prolongation after catheter ablation of incisional atrial tachycardia.

A three-dimensional (3D) mapping system is safe and effective for catheter ablation of incisional atrial tachycardia (IAT). Prolongation of the PR interval is occasionally observed after this procedure. Although a first-degree atrioventricular block is typically benign, an excessively prolonged PR interval can indicate a worse prognosis. Currently, a method to predict the PR interval after ablation therapy for IAT is lacking. We report the case of a 70-year-old woman with paroxysmal atrial tachycardia, in which our maneuver using a 3D mapping system and the electrophysiological findings enabled us to preoperatively predict the post-ablation PR interval. We believe that this method is useful for determining treatment strategies for IAT. Learning objective: Three-dimensional (3D) mapping systems can clearly visualize macro-reentrant circuits and enable the creation of precise ablation lines. When creating ablation lines for incisional atrial tachycardia, attention should be paid to the prolongation of the PR interval, because an excessively prolonged PR interval may indicate a worse prognosis. Herein, we have presented a method for predicting the post-ablation PR interval using a 3D mapping system and electrophysiological findings.

Relationship between Effective Refractory Period and Inducibility of Atrial Fibrillation from the Superior Vena Cava after Pulmonary Vein Isolation.

In terms of the pulmonary vein (PV), atrial fibrillation (AF) patients have a shorter effective refractory period (ERP) than those without AF and a large dispersion of the ERP. Although the frequency of AF from the superior vena cava (SVC) was the highest among non-PV foci, the characteristics of the ERP in the SVC (SVC-ERP) were unclear. The purpose of this study was to elucidate the relationship between SVC-ERP and the inducibility of AF after PV isolation (PVI).Consecutive 28 patients who underwent PVI were included. After successful PVI, the SVC-ERP was measured at three positions in SVC. Rapid electrical stimuli were delivered at the shortest SVC-ERP to induce AF. Patients in whom AF was induced were assigned to the SVC-induced group (SIG), and the remaining patients were the non-SVC-induced group (non-SIG). The size of the SVC sleeve was evaluated via three-dimensional electroanatomic mapping.The SIG had a significantly shorter average SVC-ERP (236.0 ± 25.2 versus 294.8 ± 36.8 ms, P < 0.001), whereas SVC-ERP dispersion was not significantly different (30.0 ± 25.4 versus 33.3 ± 20.1 ms, P = 0.56). Although the longer SVC diameter was significantly longer in the SIG (27.4 ± 4.3 versus 22.9 ± 4.6 mm, P = 0.03), the SVC-ERP was significantly associated with pacing inducibility of AF after adjustment for the longer SVC diameter (odds ratio: 0.96 [1 ms increments], P = 0.01).The SIG had a shorter SVC-ERP, whereas the dispersion was not significantly different between the two groups. The SVC-ERP can be one of the mechanisms of arrhythmogenicity for AF originating from the SVC.

Influence of the right ventricular septum/free-wall boundary (hinge) on differentiation of the ventricular lead implantation site.

BACKGROUND: The prognosis associated with right ventricular (RV) free-wall pacing is worse than that of septal pacing. Identification of the pacing site using a 12­lead electrocardiogram (ECG) is controversial and may be influenced by ECG changes within the same septal or free-wall area. The relationship between the diagnostic capabilities of ECG and pacing sites has previously been qualitatively evaluated. However, in this study, this relationship was analyzed quantitatively, and accurate evaluation of the pacing site was determined using computed tomography (CT). METHODS: Of 779 consecutive outpatients, 65 who underwent pacemaker implantation and thoracic CT were prospectively included and classified into the following groups according to the lead tip position: free-wall, septal, or septum/free-wall boundary (hinge) group. The hinge was used as an anatomical marker, and the distance from the hinge to the lead tip was measured. Under RV pacing, a 12­lead ECG was obtained. ECG findings were evaluated using three criteria (including lead I, II, and aVL and precordial leads V5 and V6) previously reported to be useful in differentiating pacing sites. RESULTS: The lead tips were anchored at the free-wall in 10 patients, the septal wall in 19 patients, and the hinge in 32 patients. Paced QRS duration correlated with the distance from the hinge to the lead tip for the free-wall and septum (r = 0.47 and - 0.68, respectively). Estimation of the lead tip implantation site using the ECG algorithm was useful; however, the algorithm's accuracy decreased around the hinge. CONCLUSIONS: ECG is useful in differentiating pacing sites but is less accurate around the hinge, which may be the reason that the identification of the RV pacing site using ECG remains controversial.

Relationship between device displacement distance toward the caudal side during standing and pocket position laterality.

BACKGROUND: The displacement of cardiac implantable electronic devices (CIEDs) toward the caudal side during standing after CIED implantation could cause lead dislodgement. This study investigated the relationship between supine pocket position and standing CIEDs' displacement distance after the implantation. METHODS: After CIED surgeries performed at 2 hospitals between 2012 and 2020, 134 patients underwent postoperative chest x-rays in the supine and standing positions during hospitalization. To measure the displacement distance of CIEDs from the supine to the standing position, we identified the first thoracic vertebrae (Th1) in the supine position using the first rib as an index, drew a horizontal line at the lower edge of the Th1, and calculated the distance from that point to the upper edge of the CIED. The difference between measures for the two positions was compared. At the position of the pocket in the thorax in the supine position, the ratio of the distance between the thorax and the device is defined as the device thorax ratio (DTR). We examined the relationship between DTR and CIED displacement distance. RESULTS: In this study, we included 134 patients (53% men; median age, 79 years, body mass index, 22.3 ± 3.4; pacemaker 93%, left implantation 96%). We found that the more lateral the position of the CIED pocket, the more the CIED fell when standing (confidence interval = 0.34-0.60, P < .001). CONCLUSIONS: The farther the CIED was implanted outside the thorax in the supine position, the more significantly the CIED was displaced in the standing position.

Accessory pathway ablation during atrial fibrillation in Ebstein anomaly.

An 84-year-old woman with type B Wolff-Parkinson-White (WPW) with Ebstein anomaly was admitted with heart failure. She had rapid wide QRS tachycardia due to accessory pathway (AP) conduction associated with atrial fibrillation (AF). Since transesophageal echocardiography before catheter ablation showed a left atrial thrombus, ablation was performed using a 3D mapping system under AF. After marking the functional tricuspid anulus with intra-cardiac echocardiography, 3D intra-cardiac electrogram visualization (ripple map) during AF enabled clear identification of location of the AP. After ablation, there was no complication of cerebral infarction, and the heart failure improved.

Large discrepancy in optimal atrioventricular delay between sensed and paced atrial events in a pacemaker patient.

A 74-year-old man experienced complete atrioventricular (AV) block 2 days after catheter ablation for right atrial (RA) macroreentrant tachycardia. We performed DDD pacemaker implantation with atrial septal pacing because other sites of pacing threshold were not acceptable. The maximum left ventricular outflow tract velocity time integral was 15.8 cm with sensed AV delay (40 ms) and 15.0 cm with paced AV delay (220 ms); however, this exceeded the pacemaker's maximum difference of 100 ms. We herein report the case of a large discrepancy in optimal AV delay intervals between sensed and paced atrial events, requiring consideration of proper pacemaker settings.

Heart failure caused by iatrogenic atrial septal defect after cryoballoon ablation for atrial fibrillation.

An 83-year-old man with no structural heart disease underwent pulmonary vein isolation (PVI) for symptomatic paroxysmal atrial fibrillation (AF). The PVI was successfully performed by cryoballoon ablation with a single transseptal puncture. A 12Fr deflectable sheath and an 8.5Fr long sheath crossed the interatrial septum via the same puncture site. Five months after PVI, the patient was readmitted because of heart failure and recurrence of AF. The echocardiogram showed a large (10.7 × 5.8 mm) iatrogenic atrial septal defect (IASD) at the previous puncture site. Both right-to-left and left-to-right shunts were observed during systole and diastole, respectively. Despite the initiation of optimal medical therapy for heart failure, symptoms were not completely controlled and IASD remained 11 months after PVI. Eventually, he received multiple additional PVI for recurrence of AF and percutaneous transcatheter closure (13 mm disc for 10.9 × 8.9 mm- IASD), then heart failure was controlled with the improvement of the right atrial and ventricular size. Although the induction of heart failure by IASD after PVI is rare, it should be noted as one of the causes, especially after cryoballoon ablation with simultaneous mapping catheter insertion via a single transseptal puncture. .

Incidence of out-of-hospital cardiac arrests and survival rates after 1 month among the Japanese working population: a cohort study.

OBJECTIVES: The prevention and improvement of the prognosis of out-of-hospital cardiac arrests (OHCAs) are important issues especially with respect to their social and economic significance in working populations. The age distribution of the working population in Japan is expected to change continually due to its ageing society and extension of retirement; however, few reports have examined the long-term condition of OHCA in the working population, defined by age. The aim of this study was to determine the incidence of OHCAs and the survival rates after 1 month, among the Japanese working population, defined by age, considering the changing age distribution. DESIGN AND SETTING: We analysed the All-Japan Utstein registry, a prospective, nationwide, population-based, observational registry (2005-2016). PARTICIPANTS: From the registry, 212 961 patients with OHCA from the Japanese working population (defined aged 20-69 years), with only cardiogenic aetiology participated in this study. These patients were further divided into four groups according to the type of citizen bystander (family, friends, work-colleagues and passers-by). PRIMARY AND SECONDARY OUTCOME MEASURES: The main outcomes were 1-month survival with favourable neurological outcomes. RESULTS: The incidence of OHCAs, in any age group, was almost constant during the 12-year period. The work-colleagues had the best prognosis despite having significantly longer times to initial defibrillations compared with the passers-by (13 vs 12 min, respectively, p<0.001) that was associated independently with 1-month survival with favourable neurological outcomes (adjusted OR: 0.94 (1 min increments), p<0.001). CONCLUSIONS: In the 12-year period, the incidence of OHCAs in any age group remained almost constant, whereas the prognosis improved each year. Reducing the time to initial defibrillation may further improve the prognosis of OHCAs with a work-colleague bystander.

Ambulatory ECG monitoring for syncope and collapse in United States, Europe, and Japan: The patients' viewpoint.

BACKGROUND: Practice guidelines provide clinicians direction for the selection of ambulatory ECG (AECG) monitors in the evaluation of syncope/collapse. However, whether patients' understand differences among AECG systems is unknown. METHODS AND RESULTS: A survey was conducted of USA (n = 99), United Kingdom (UK)/Germany (D) (n = 75) and Japan (n = 40) syncope/collapse patients who underwent diagnostic AECG monitoring. Responses were quantitated using a Likert-like 7-point scale (mean ± SD) or percent of patients indicating a Top 2 box (T2B) for a particular AECG attribute. Patient ages and diagnosed etiologies of syncope/collapse were similar across geographies. Patients were queried on AECG attributes including the ability to detect arrhythmic/cardiac causes of collapse, instructions received, ease of use, and cost. Patient perception of the diagnostic capabilities and ease of use did not differ significantly among the AECG technologies; however, USA patients had a more favorable overall view of ICM/ILRs (T2B: 42.4%) than did UK/D (T2B: 28%) or Japan (T2B: 17.5%) patients. Similarly, US patient rankings for education received regarding device choice and operation tended to be higher than UK/D or Japan patients; nevertheless, at their best, the Likert scores were low (approximately 4.7-6.0) suggesting need for education improvement. Finally, both US and UK/D patients were similarly concerned with ICM costs (T2B, 31% vs 20% for Japan). CONCLUSIONS: Patients across several geographies have a similar but imperfect understanding of AECG technologies. Given more detailed education the patient is likely to be a more effective partner with the clinician in establishing a potential symptom-arrhythmia correlation.

RR interval variability in the evaluation of ventricular tachycardia and effects of implantable cardioverter defibrillator therapy.

BACKGROUND: An implantable cardioverter defibrillator (ICD) is the most reliable therapeutic device for preventing sudden cardiac death in patients with sustained ventricular tachycardia (VT). Regarding its effectiveness, targeted VT is defined based on the tachyarrhythmia cycle length. However, variations in RR interval variability of VTs may occur. Few studies have reported on VT characteristics and effects of ICD therapy according to the RR interval variability. We aimed to identify the clinical characteristics of VTs and ICD therapy effects according to the RR interval variability. METHODS: We analyzed 821 VT episodes in 69 patients with ICDs or cardiac resynchronization therapy defibrillators. VTs were classified as irregular when the difference between two successive beats was >20 ms in at least one of 10 RR intervals; otherwise, they were classified as regular. We evaluated successful termination using anti-tachycardia pacing (ATP)/shock therapy, spontaneous termination, and acceleration between regular and irregular VTs. The RR interval variability reproducibility rates were evaluated. RESULTS: Regular VT was significantly more successfully terminated than irregular VT by ATP. No significant difference was found in shock therapy or VT acceleration between the regular and irregular VTs. Spontaneous termination occurred significantly more often in irregular than in regular VT cases. The reproducibility rates of RR interval variability in each episode and in all episodes were 89% and 73%, respectively. CONCLUSIONS: ATP therapy showed greater effectiveness for regular than for irregular VT. Spontaneous termination was more common in irregular than in regular VT. RR interval variability of VTs seems to be reproducible.

Mast Cell Activation Disorder and Postural Orthostatic Tachycardia Syndrome: A Clinical Association.

Background Recently there has been increased interest in a possible association between mast cell activation (MCA) disorder and postural orthostatic tachycardia syndrome (POTS). This study examined the frequency with which symptoms and laboratory findings suggesting MCA disorder occurred in patients diagnosed with POTS. Methods and Results Data were obtained from patients in whom symptoms and orthostatic testing were consistent with a POTS diagnosis. Individuals with <4 months symptom duration, evident ongoing inflammatory disease, suspected volume depletion, or declined consent were excluded. All patients had typical POTS symptoms; some, however, had additional nonorthostatic complaints not usually associated with POTS. The latter patients underwent additional testing for known MCA biochemical mediators including prostaglandins, histamine, methylhistamine, and plasma tryptase. The study comprised 69 patients who met POTS diagnostic criteria. In 44 patients (44/69, 64%) additional nonorthostatic symptoms included migraine, allergic complaints, skin rash, or gastrointestinal symptoms. Of these 44 patients, 29 (66%) exhibited at least 1 laboratory abnormality suggesting MCA disorder, and 11/29 patients had 2 or more such abnormalities. Elevated prostaglandins (n=16) or plasma histamine markers (n=23) were the most frequent findings. Thus, 42% (29/69) of patients initially diagnosed with POTS exhibited both additional symptoms and at least 1 elevated biochemical marker suggesting MCA disorder. Conclusions Laboratory findings suggesting MCA disorder were relatively common in patients diagnosed with POTS and who present with additional nonorthostatic gastrointestinal, cutaneous, and allergic symptoms. While solitary abnormal laboratory findings are not definitive, they favor MCA disorder being considered in such cases.

Adenosine revives catheter-induced mechanical blocks in radiofrequency ablation.

Adenosine can hyperpolarize the atrial action potential, which helps rapidly re-establish the membrane potential in ablated sites and unmask "dormant conduction." It has been reported that pharmacological agents, including adenosine, were unable to revive traumatized tissues. We present the first case of the catheter-induced mechanical block ("bump" phenomenon) that was unmasked with adenosine administration in the working myocardium of the superior vena cava. This result may be because, unlike before, we could determine the force of contact between the tip of the ablation catheter and the myocardial tissue. This case suggests the clinical usefulness of adenosine for unmasking bumped sites.

Current status and role of programmed ventricular stimulation in patients without sustained ventricular arrhythmias and reduced ejection fraction: Analysis of the Japan cardiac device treatment registry database.

BACKGROUND: The aim of this study was to clarify the current status and role of programmed ventricular stimulation in patients without sustained ventricular arrhythmias and reduced left ventricular ejection fraction (LVEF). METHODS: The follow-up data of the Japan cardiac device treatment registry (JCDTR) was analyzed in 746 patients with LVEF ≦35% and no prior history of sustained ventricular arrhythmias who underwent de novo implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy with a defibrillator (CRT-D) implantation between January 2011 and August 2015. RESULTS: Electrophysiological study (EPS) with programmed ventricular stimulation had been performed before the device implant in 118 patients (15.8%, EPS group). During the mean follow-up of 21 ± 12 months, the rate of freedom from any death and appropriate defibrillator therapy was not significantly different between EPS group (n = 118) and No EPS group (n = 628). NYHA class II-IV, and QRS duration were negatively associated with performing EPS. Among patients in the EPS group, the rate of ventricular tachycardia (VT)/ventricular fibrillation (VF) induction was 48%. The inducibility was not a predictor of appropriate defibrillator therapy, whereas BNP ≧535 pg/mL and no use of amiodarone were significantly associated with a risk of the appropriate therapy. CONCLUSION: EPS for induction of VT/VF had been performed in about 16% of patients with reduced LVEF before primary prevention ICD/CRT-D implantation. Elevated BNP levels and no use of amiodarone, but not inducibility of VT/VF, appeared to be associated with appropriate defibrillator therapy in these populations.