R-wave Amplitude Research Articles

Electrocardiographic markers in patients with type 2 diabetes and the role of diabetes duration

BackgroundThe association between type 2 diabetes and electrocardiographic (ECG) markers are incompletely explored and the dependence on diabetes duration is largely unknown. We aimed to investigate the electrocardiographic (ECG) changes associated with type 2 diabetes over time. MethodsIn this cross-sectional study, we matched people with type 2 diabetes 1:1 on sex, age, and body mass index with people without diabetes from the general population. We regressed ECG markers with the presence of diabetes and the duration of clinical diabetes, respectively, adjusted for sex, age, body mass index, smoking, heart rate, diabetes medication, renal function, hypertension, and myocardial infarction. ResultsWe matched 988 people with type 2 diabetes (332, 34% females) with as many controls. Heart rate was 8 bpm higher (p < 0.001) in people with vs. without type 2 diabetes, but the difference declined with increasing diabetes duration. For most depolarization markers, the difference between people with and without type 2 diabetes increased progressively with diabetes duration. On average, R-wave amplitude was 6 mm lower in lead V5 (p < 0.001), P-wave duration was 5 ms shorter (p < 0.001) and QRS duration was 3 ms (p = 0.03). Among repolarization markers, T-wave amplitude (measured in V5) was lower in patients with type 2 diabetes (1 mm lower, p < 0.001) and the QRS-T angle was 10 degrees wider (p = 0.002). We observed no association between diabetes duration and repolarization markers. ConclusionsType 2 diabetes was independently associated with electrocardiographic depolarization and repolarization changes. Differences in depolarization markers, but not repolarization markers, increased with increasing diabetes duration.

Clinical significance of R-wave amplitude in lead V1 and inferobasal myocardial infarction in patients with inferior wall myocardial infarction.

To assess electrocardiogram (ECG) for risk stratification in inferior ST-elevation myocardial infarction (STEMI) patients within 24 h. Three hundred thirty-four patients were divided into four ECG-based groups: Group A: R V1 <0.3 mV with ST-segment elevation (ST↑) V7-V9, Group B: R V1 <0.3 mV without ST↑ V7-V9, Group C: R V1 ≥0.3 mV with ST↑ V7-V9, and Group D: R V1 ≥0.3 mV without ST↑ V7-V9. Group A demonstrated the longest QRS duration, followed by Groups B, C, and D. ECG signs for right ventricle (RV) infarction were more common in Groups A and B (p < .01). ST elevation in V6, indicative of left ventricle (LV) lateral injury, was more higher in Group C than in Group A, while the ∑ST↑ V3R + V4R + V5R, representing RV infarction, showed the opposite trend (p < .05). The estimated LV infarct size from ECG was similar between Groups A and C, yet Group A had higher creatine kinase MB isoform (CK-MB; p < .05). Cardiac troponin I (cTNI) was higher in Groups A and C than in B and D (p < .05 and p = .16, respectively). NT-proBNP decreased across groups (p = .20), with the highest left ventricular ejection fraction (LVEF) observed in Group D (p < .05). Group A notably demonstrated more cardiac dysfunction within 4 h post-onset. For inferior STEMI patients, concurrent R V1 <0.3 mV with ST↑ V7-V9 suggests prolonged ventricular activation and notable myocardial damage. RV infarction's dominance over LV lateral injury might explain these observations.

T-wave inversion through inhomogeneous voltage diffusion within the FK3V cardiac model.

The heart beats are due to the synchronized contraction of cardiomyocytes triggered by a periodic sequence of electrical signals called action potentials, which originate in the sinoatrial node and spread through the heart's electrical system. A large body of work is devoted to modeling the propagation of the action potential and to reproducing reliably its shape and duration. Connection of computational modeling of cells to macroscopic phenomenological curves such as the electrocardiogram has been also intense, due to its clinical importance in analyzing cardiovascular diseases. In this work, we simulate the dynamics of action potential propagation using the three-variable Fenton-Karma model that can account for both normal and damaged cells through a the spatially inhomogeneous voltage diffusion coefficient. We monitor the action potential propagation in the cardiac tissue and calculate the pseudo-electrocardiogram that reproduces the R and T waves. The R-wave amplitude varies according to a double exponential law as a function of the (spatially homogeneous, for an isotropic tissue) diffusion coefficient. The addition of spatial inhomogeneity in the diffusion coefficient by means of a defected region representing damaged cardiac cells may result in T-wave inversion in the calculated pseudo-electrocardiogram. The transition from positive to negative polarity of the T-wave is analyzed as a function of the length and the depth of the defected region.

(845) - The R-Wave Amplitude Negatively Correlates with Preload in Stable Ventricular Assist Device Patients During Acute Postural Changes

(845) - The R-Wave Amplitude Negatively Correlates with Preload in Stable Ventricular Assist Device Patients During Acute Postural Changes

Early real-world implant experience with a helix-fixation ventricular leadless pacemaker.

Roughly one in six patients receiving conventional transvenous pacemaker systems experience significant complications within 1year of implant, mainly due to the transvenous lead and subcutaneous pocket. A new helix-fixation single-chamber ventricular leadless pacemaker (LP) system capable of pre-deployment exploratory electrical mapping is commercially available. Such an LP may mitigate complications while streamlining the implantation. In this study, the initial real-world implant experience of the helix-fixation LP was evaluated following its commercial release. In patients indicated for single-chamber right ventricular pacing, helix-fixation Aveir VR LPs (Abbott, Abbott Park, IL) were implanted using the dedicated loading tool, introducer, and delivery catheter. Implant procedural characteristics, electrical parameters, and any 30-day procedure-related adverse events of consecutive implant attempts were retrospectively evaluated. A total of 167 patients with Class I indication for permanent pacing received implants in four North American centers (57% male, 70years old). Pre-fixation electrical mapping of potential sites allowed repositioning to be avoided in 95.7% of patients. Median [interquartile range] LP procedure and fluoroscopy durations were 25.5min [20.0, 35.0] and 5.7min [4.0, 9.2], respectively. Pacing capture threshold, sensed R-wave amplitude, and impedance were 0.8V [0.5, 1.3], 9.0mV [6.0, 12.0], and 705 Ω [550, 910], respectively. Implantation was successful in 98.8% of patients, with 98.2% free from acute adverse events. The initial, real-world experience of the helix-fixation ventricular leadless pacemaker demonstrated safe and efficient implantation with minimal repositioning, viable electrical metrics, and limited acute complications.

Single operator experience, learning curve, outcomes, and insights gained with conduction system pacing.

Conduction system pacing (CSP) is increasingly utilized to prevent and correct dyssynchrony. Barriers to CSP adoption include limited training, methodologic variability, laboratory slot allocation, and few data on learning curves. We report learning curves/clinical outcomes from a single experienced electrophysiologist who was new to CSP, and share gained insights. Retrospective analysis of all patients who underwent attempted CSP implantation (2016-2023). Patient characteristics, ECGs, echocardiograms, fluoroscopy/procedure times, lead data were recorded at implant and follow-up. CSP leads were implanted successfully in 167/191(87.4%) patients with a follow-up of 278±378 days. His-bundle pacing (HBP=59) and left-bundle-area pacing (LBAP=108) had similar procedure/fluoroscopy times, QRS duration decreases, and ejection fraction improvements (all p>NS). Eight HBP lead revisions were required for high capture thresholds LBAP demonstrated lower pacing thresholds, higher lead impedances, and greater R-wave amplitudes at implant and follow-up. After 25 HBP cases, implant pacing thresholds, fluoroscopy, procedural times did not decrease. After 25 LBAP cases, there were significant decreases in all these parameters (p<0.05). A separate analysis in LBAP patients with recorded Purkinje signals showed no differences in paced ECG characteristics between patients with pre- QRS Purkinje signals versus patients with Purkinje signals post-QRS onset. Experienced implanters who are new to CSP can achieve steady-state procedural/fluoroscopy times after a learning curve of 25 implants. LBAP showed lower capture thresholds and higher success rates. Adequate depth of lead deployment (as determined by published parameters) does not require Purkinje potential to be pre-QRS. Operators new to CSP.can forego HBP and directly implement LBAP.

Effects of coronary artery disease in patients with permanent left bundle branch area pacing: A retrospective study

AimsMyocardial ischemia can affect traditional right ventricular (RV) pacing parameters, but it is unclear whether coronary artery disease (CAD) impact the pacing parameters and electrophysiological characteristics of left bundle branch area pacing (LBBaP) as a physiological pacing representative. MethodsPatients who underwent coronary angiography (CAG) after/before the LBBaP procedure and underwent percutaneous coronary intervention after LBBaP procedure were divided into CAD group and Non-CAD group according to visual CAG. Pacing parameters and electrophysiological characteristics were recorded at LBBaP implantation. Multivariate logistic regression analysis was implemented to evaluate the association between CAD and higher capture threshold. Sensitivity analyses were conducted to verify result stability. ResultsA total of 176 patients met inclusion criteria (115 Non-CAD patients and 61 CAD patients) with a mean age of 71.1 ± 9.0 years. Compared with the Non-CAD patients, CAD patients had the higher capture threshold (0.67 ± 0.22 V vs. 0.82 ± 0.28 V, P < 0.001) and lower R-wave amplitude (12.5 ± 4.8 mV vs. 10.1 ± 2.7 mV, P = 0.001). Moreover, CAD was independently associated with higher capture threshold (adjusted Odds ratio (OR) 3.418, 95% confidence interval (CI): 1.621–7.206, P = 0.001), which was further validated through sensitivity analyses. ConclusionPatients without CAD might have safer pacing parameters in the LBBaP procedure. Besides, CAD might be the risk factor of capture threshold increase during permanent LBBaP implantation.

Correlation between the electrocardiogram amplitude detected by an implantable cardiac monitor and the implantation depth.

Implantable cardiac monitors (ICMs) primarily use R-R intervals in subcutaneous electrocardiograms (ECGs) to detect arrhythmias. Therefore, reliable detection of R-wave amplitude by an ICM is vital. Since ICMs detect subcutaneous ECGs, the impact of the implantation depth should be assessed. This study investigated the influence of ICM depth on R-wave (ICM-R) amplitude on an ECG generated by an ICM (JOT Dx; Abbott). Overall, 58 patients who underwent ICM implantation at Kamagaya General Hospital from May 2022 to April 2023 were retrospectively reviewed. The depth-position was measured using ultrasound imaging after implantation. The depth of the ICM did not show any correlation with ICM-R amplitude (r = -.0141, p = .294). However, the distance between the ICM and the heart surface showed a significant correlation with ICM-R amplitude (r = -.581, p < .001). Body weight (r = -.0283, p = .033) and body mass index (r = -.0342, p = .009) were associated with ICM-R amplitude. S wave in the V1 -lead was also associated with ICM-R amplitude (r = .481, p < .001). After multivariate analysis, the distance between the ICM and heart surface and the S wave in V1 were independent determinants for the ICM-R amplitude. The ICM-R amplitude may be higher with the ICM implanted deeper.

The Utility of a Resting Electrocardiogram (ECG-PH Index) in Evaluating the Efficacy of Pulmonary Endarterectomy in Chronic Thromboembolic Pulmonary Hypertension.

The ECG-PH index (PH-ECG score) has been proposed as a valuable ECG-derived method of evaluating the effectiveness of balloon pulmonary angioplasty (BPA) in chronic thromboembolic pulmonary hypertension (CTEPH). Pulmonary endarterectomy (PEA) is the main form of therapy for CTEPH with a proximal clot location. The objective of this study was to assess the clinical utility of a resting electrocardiogram (ECG-PH index) in assessing the effectiveness of PEA in CTEPH patients. The retrospective analysis included 73 patients who underwent PEA. Their ECG-PH index values were calculated using four ECG parameters: R-wave amplitude V1 + S-wave amplitude V5/V6 > 10.5 mm, QRS-wave axis > 110 degrees, R-wave amplitude V1 > S-wave amplitude V1, and SIQIII pattern. PH-ECG scores were assessed after a median time of 13 months (IQR: 8-31 months) had passed since the PEA procedures. The current analysis documented that ECG-PH index = 0 is a good reflection of mPAP < 25mmHg (sensitivity 76.1%; specificity 66.7%; positive predictive value 79.5%; negative predictive value 62.1%) or mPAP ≤ 20 mmHg (sensitivity 69.6%; specificity 70.6%; positive predictive value 88.6%; negative predictive value 41.4%) after PEA. The values of the area under the ROC curve for ECG-PH index were 0.772 (95% CI: 0.676-0.867) and 0.743 (95% CI: 0.637-0.849) for the mPAP < 25 mmHg and mPAP ≤ 20 mmHg patient groups, respectively. The ECG-PH index may be useful for monitoring the haemodynamic effect of PEA in CTEPH patients.

Dysfunction of CRT-D in acute myocardial infarction: is there a place for programing?

The article describes a clinical case of a patient with a previously implanted cardiac resynchronization therapy with defibrillator function (CRT-D). For a long time, the patient was observed in the implanting clinic and the data was also transmitted via remote monitoring. The developing acute myocardial infarction in the right coronary artery caused a change in the parameter of the amplitude of the spontaneous R-wave in the patient. Subsequent ventricular fibrillation (VF) due to stent thrombosis was undetected by the defibrillator and resulted in no detection and cessation of VF, despite the implanted CRT-D. Changing the programming parameters did not affect the possibility of detecting a recurrent VF. The VF that occurred twice was stopped by the first discharge of the external device. In view of the remaining low hyposensing, a decision was made to reimplant the detecting part of the right ventricular electrode, after which defibrillation test proved to be effective for termination induced VF. We believe that at critically low parameters of spontaneous R-wave hyposensing, for the device to detect low-amplitude ventricular arrhythmias, programming the parameters does not solve the problem of hyposensing. Current myocardial infarction as the cause of hyposensing may require active surgical tactics replacement of the pacing and sensing electrode, in cases where the device connector allows this.

The R-Wave amplitude in V1 on baseline ECG correlates with the occurrence of high-degree atrioventricular block following left bundle branch block after transcatheter aortic valve replacement

Abstract Aims Several procedural and ECG parameters have been associated with the occurrence of high-degree atrioventricular block (AVB) requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement (TAVR). We hereunder sought to assess if the baseline R-wave amplitude in V1 ECG-lead of patients with normal QRS duration undergoing TAVR is associated with a higher patient’s risk for developing high-degree AVB following left bundle branch block (LBBB). Methods and Results In this retrospective single-center study in 720 consecutive patients who underwent TAVR, 141 (19.6%) patients with normal QRS duration developed a new LBBB after TAVR. The 24 (17%) patients who underwent PPI for reasons other than high-degree AVB were excluded from further analysis. In the remaining 117 study patients, 14 (12%) developed high-degree AVB requiring PPI (Group 1) while the remaining 103 (88%) patients did not (Group 2). There were no significant differences in baseline demographic or procedural characteristics nor in PR interval, QRS duration and QRS axis between these 2 groups. The incidence of left anterior hemiblock was higher in Group 1 (3 of 14, 21.4%) than in Group 2 (9 of 103, 8.7%) but the difference was not statistically significant (p=0.156). The R-wave amplitude in V1 was smaller in Group 1 than in Group 2 (0.029±0.04mV vs. 0.11±0.14mV, p=0.0316). In the receiver operating characteristics analysis, the cutoff for R-wave amplitude pre-TAVR was 0.03mV, area under the curve=0.7219, (p=0.0002). Conclusion The R-wave amplitude in lead V1 during baseline ECG in patients with normal QRS duration may predict the occurrence of high-degree AVB following new LBBB after TAVR.Figure 1.ROC AnalysisFigure 2.Representative case

Left bundle branch area pacing in patients with CRT indication: short-term results &amp; 1-year follow-up

Abstract Background Cardiac resynchronization therapy (CRT) using bi-ventricular pacing is class I recommendation for symptomatic patients with heart failure (LVEF ≤35%), QRS duration ≥150 msec and LBBB QRS morphology. Left bundle branch area pacing (LBBAP) has been reported as an alternative option for CRT. The aim of this study was to assess the feasibility and outcomes of LBBAP in patients eligible for CRT. Methods Patients with CRT indications were subjected to LBBAP. Peri-procedural outcomes &amp; QRS duration were recorded. Changes in New York Heart Association (NYHA) class, need for HF hospitalization, echocardiographic data, lead-device parameters were evaluated at follow-up. HF status was assessed by clinical (no HF hospitalization and improvement in NYHA class) and echocardiographic response (≥5% improvement in LVEF). Results LBBAP was attempted in 16 patients (mean age 59.3 ±7.04 years, 37.5% women, ischemic cardiomyopathy in 33.3%). All patients had baseline LBBB. Pacing threshold and R-wave amplitudes were 0.8 ± 0.3 V at 0.5 ms and 12.1 ± 3.5 mV at implantation and remained stable during mean follow-up of 11.25 ± 3.7 (Range 6-18) months. LBBAP resulted in significant QRS narrowing from 147.5 ± 9.7 to 116 ± 10.2 ms (p &amp;lt; 0.01). LVEF improved from 28.2 ± 2.8% to 38.9 ± 5.1% (p &amp;lt; 0.01). Clinical and echocardiographic improvement was observed in 77% and 74% of patients, respectively. Conclusions LBBAP is feasible, safe and effective. It provides an alternative option for CRT. LBBAP provides low and stable pacing thresholds and is associated with improved clinical and echocardiographic outcomes.

Risk prediction of inappropriate implantable cardioverter-defibrillator therapy using machine learning

Abstract Background Inappropriate shock from implantable cardioverter-defibrillators (ICDs) undermines quality of life and increases all-cause mortality risk. Various predictors of inappropriate ICD shock have also been indicated in previous studies. Nevertheless, no prediction model by machine learning has been reported. Purpose We developed ML models for evaluating the risk of inappropriate ICD therapy, and proposed easily calculable risk scoring. Methods In total, 182 consecutive cases implanted with ICD were enrolled. The predictive models were based on 16 statistically significant factors out of 189 items including electrocardiogram parameters and clinical features after ICD implantation. Statistical analysis and 14 ensemble learning methods were performed. Shapley additive explanation (SHAP) method was performed to extract important features in the best ML model, and easily calculable score was established from the features. Results Twenty-five patients (13.7%) underwent inappropriate therapy. The extra-trees classifier demonstrated the highest area under the receiver operating characteristic curve (AUROC; 0.839). The top six features were history of atrial arrhythmia, ischemic cardiomyopathy (ICM), no diabetes mellitus (DM), cardiac resynchronization therapy (CRT), and V4- and V5 R-wave amplitudes. From the six features, the Cardi45 score was developed (+6.5 points for history of atrial arrhythmia, -2.0 points for ICM, -1.0 points for DM, -0.5 points for CRT, and +0.5 points for V4 T-wave amplitude ≥1200 μV and V5 R-wave amplitude ≥1400 μV). The AUROC for the Cardi45 score was 0.886, which was higher than that of extra-trees classifier. Conclusion Our study demonstrates that the ML approach can provide a good prediction model and Cardi45 score was powerful predictors for inappropriate ICD therapy. Cardi45 score, derived from this model, may be used to judge whether an aggressive rhythm control strategy should be implemented or ICD implantation should be avoided in some patients.Picture 1Picture 2

Risk prediction of inappropriate implantable cardioverter-defibrillator therapy using machine learning

We aimed to develop machine learning-based predictive models for identifying inappropriate implantable cardioverter-defibrillator (ICD) therapy. Our study included 182 consecutive cases (average age 62.2 ± 4.5 years, 169 men) and employed 14 non-deep learning models for prediction (hold-out method). These models utilized selected electrocardiogram parameters and clinical features collected after ICD implantation. From the feature importance analysis of the best ML model, we established easily calculable scores. Among the patients, 25 (13.7%) experienced inappropriate therapy, and we identified 16 significant predictors. Using recursive feature elimination with cross-validation, we reduced the features to six with high feature importance: history of atrial arrhythmia (Atr-arrhythm), ischemic cardiomyopathy (ICM), absence of diabetes mellitus (DM), lack of cardiac resynchronization therapy (CRT), V3 ST level at J point (V3 STJ), and V5 R-wave amplitudes (V5R amp). The extra-trees classifier yielded the highest area under receiver operating characteristics curve (AUROC; 0.869 on test data). Thus, the Cardi35 score was defined as [+ 5.5*Atr-arrhythm − 1.5*CRT + 1.0*V3STJ + 1.0*V5R − 1.0*ICM − 0.5*DM], which demonstrated a hazard ratio of 1.62 (P < 0.001). A cut-off value of the score + 5.5 showed high AUROC (0.826). The ML approach can yield a robust prediction model, and the Cardi35 score was a convenient predictor for inappropriate therapy.

Remote monitoring of implantable cardiac monitors in patients with unexplained syncope: Predictors of false-positive alert episodes.

Remote monitoring is recommended for patients with implantable cardiac monitors (ICMs), but compared to other cardiac implantable devices, ICMs are less accurate and transmit a higher number of alerts. The aim of this study was to investigate the predictors of false-positive (FP) arrhythmic alerts in patients with unexplained syncope who were implanted with ICM and followed by an automatic remote monitoring system. We retrospectively evaluated all consecutive patients who received a long-sensing vector ICM for unexplained syncope between January 2019 to September 2021 at our Syncope Unit. The primary endpoint was the incidence of the first FP episode. The secondary endpoints included assessing the incidence of FP episodes for all types of algorhythms and indentifying the reasons for the misdetection of these episodes. Among 105 patients (44.8% males, median age 51 years), 51 (48.6%) transmitted at least one FP alert during a median follow-up of 301 days. The presence of pre-ventricular complexes (PVCs) on the resting electrocardiogram was the only clinical characteristic associated with an increased risk of FP alerts (adjusted Hazard ratio [HR] 5.76 [2.66-12.4], p=0.010). The other significant device-related variables were a low-frequency filter at 0.05Hz versus the default 0.5Hz (adjusted HR 3.82 [1.38-10.5], p=0.010) and the R-wave amplitude (adjusted HR 0.35 [0.13-0.99], p=0.049). Patients who have PVCs are at higher risk of inappropriate ICM activations. To reduce the occurrence of FP alerts, it may be beneficial to target a large R-wave amplitude during device insertion and avoid programming a low-frequency filter at 0.05Hz.

Beneficial effects of upgrading to His-Purkinje system pacing in patients with pacing-induced cardiomyopathy: a systematic review and meta-analysis.

The purpose of this study was to evaluate the effectiveness of His-Purkinje system pacing (HPSP) in the management of patients with pace-induced cardiomyopathy (PICM). PubMed, Embase, Web of Science, and the Cochrane Library were searched comprehensively to collect related studies published from the inception of databases to June 1, 2022. R 4.04 software, including the Metafor package, matrix package, and the Meta package, was utilized to conduct the singe-arm meta-analysis. The methodology index for non-randomized studies (MINORS) was used to assess the methodological quality of the included studies. A total of seven studies were included, involving 164 PICM patients. The meta-analysis showed that HPSP ameliorated the left ventricular ejection fraction (LVEF) by 13.41% (95% CI [11.21-15.61]), improved the New York Heart Association (NYHA) classification by 1.02 (95% CI [-1.41 to -0.63]), and shortened the QRS duration (QRSd) by 60.85 ms (95% CI [-63.94 to -57.75]), resulting in improved cardiac functions in PICM patients. Besides, HPSP reversed the ventricular remodeling, with a 32.46 ml (95% CI [-53.18 to -11.75]) decrease in left ventricular end systolic volume (LVESV) and a 5.93 mm (95% CI [-7.68 to -4.19]) decrease in left ventricular end-diastolic dimension (LVEDD). HPSP also showed stable electrical parameters of pacemakers, with a 0.07 V (95% CI [0.01-0.13]) increase in pacing threshold, a 0.02 mV (95% CI [-0.85 to 0.90]) increase in sensed R-wave amplitude, and a 31.12 Ω reduction in impedance (95% CI [-69.62 to 7.39]). Compared with LBBP, HBP improved LVEF by 13.28% (95% CI [-11.64 to 14.92]) vs 14.43% (95% CI [-13.01 to 15.85]), ameliorated NHYA classification by 1.18 (95% CI [-1.97 to -0.39]) vs 0.95 (95% CI [-1.33 to -0.58]), shortened QRSd by 63.16 ms (95% CI [-67.00 to -59.32]) vs 57.98 ms (95% CI [-62.52 to -53.25]), and decreased LVEDD by 4.12 mm (95% CI [-5.79 to -2.45]) vs 6.26 mm (95% CI [-62.52 to -53.25]). The electrical parameters of the pacemaker were stable in both groups. This meta-analysis showed that HPSP could significantly improve cardiac function, promote reverse remodeling, and provide stable electrical parameters of pacemakers for PICM patients.

Effect of Propofol on Heart Rate and Its Coupling to Cortical Slow Waves in Humans.

Propofol causes significant cardiovascular depression and a slowing of neurophysiological activity. However, literature on its effect on the heart rate remains mixed, and it is not known whether cortical slow waves are related to cardiac activity in propofol anesthesia. The authors performed a secondary analysis of electrocardiographic and electroencephalographic data collected as part of a previously published study where n = 16 healthy volunteers underwent a slow infusion of propofol up to an estimated effect-site concentration of 4 µg/ml. Heart rate, heart rate variability, and individual slow electroencephalographic waves were extracted for each subject. Timing between slow-wave start and the preceding R-wave was tested against a uniform random surrogate. Heart rate data were further examined as a post hoc analysis in n = 96 members of an American Society of Anesthesiologists Physical Status II/III older clinical population collected as part of the AlphaMax trial. The slow propofol infusion increased the heart rate in a dose-dependent manner (mean ± SD, increase of +4.2 ± 1.5 beats/min/[μg ml-1]; P < 0.001). The effect was smaller but still significant in the older clinical population. In healthy volunteers, propofol decreased the electrocardiogram R-wave amplitude (median [25th to 75th percentile], decrease of -83 [-245 to -28] μV; P < 0.001). Heart rate variability showed a loss of high-frequency parasympathetic activity. Individual cortical slow waves were coupled to the heartbeat. Heartbeat incidence peaked about 450 ms before slow-wave onset, and mean slow-wave frequency correlated with mean heart rate. The authors observed a robust increase in heart rate with increasing propofol concentrations in healthy volunteers and patients. This was likely due to decreased parasympathetic cardioinhibition. Similar to non-rapid eye movement sleep, cortical slow waves are coupled to the cardiac rhythm, perhaps due to a common brainstem generator.

Feasibility and safety of left bundle branch area pacing in patients with septal hypertrophy.

Left bundle branch area pacing (LBBAP) aims to provide physiological ventricular activation during pacing. Left ventricular septal hypertrophy (LVSH) might be challenging for LBBAP due to the thickness of the interventricular septum and potential presence of septal scar. This study assesses the feasibility, safety, and outcome of LBBAP in patients with LVSH using primarily stylet-driven leads (SDL). Adult patients with LVSH who underwent LBBAP between March 2019 and November 2022 were enrolled. Baseline patient characteristics, procedural data and postprocedural results were collected. The feasibility of LBBAP in LVSH patients was compared to a cohort of LBBAP patients with normal septal wall thickness (NST). SeventeenLVSH and 133 NST patients underwent LBBAP with successful implantation achieved in 15 LVSH patients (88%). Mean implant depth was 17.2 ± 1.9 mm, with 53% proven left bundle branch (LBB) capture. Paced QRS duration (146 ± 14 ms) and V6 R-wave peak time (V6 RWPT; 79 ± 20 ms) were comparable between patients with and without septal hypertrophy, although patients with NST had higher rates of proven LBB capture (71% vs. 53%). In LVSH pacing thresholds (0.6 ± 0.3 V at 0.4 ms) and R-wave amplitude (13.9 ± 5.6 mV) were favorable and remained stable at follow-up. At 12 months, 87% of patients had stable or improved left ventricular ejection fraction. The results of the study indicate that LBBAP in patients with LVSH is safe and feasible and no lead-related complications were observed despite a mean implant depth exceeding 15 mm. LBBAP using SDL results in favorable pacing and electrocardiographic characteristics in LVSH patients, comparable to patients with NST.

Evolution of surface and endocavitary signals in patients with arrhythmogenic cardiomyopathy at 1 and 5 years

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Small fee from Boston Scientific. Background The use of subcutaneous defibrillator (S-ICD) is a viable alternative to transvenous ICD in patients with Arrhythmogenic Cardiomyopathy (ACM). In transvenous ICD recipients low sensing values may exist at the time of implantation and a progressive decline of signal amplitude may occur later on due to the progressive myocardial fibrofatty replacement. Similarly to what happens at the intracavitary level, in patients with ACM there is a progressive modification of the surface ECG over time. Data on the impact of ECG evolution on S-ICD sensing are still lacking, particularly for different ACM phenotypes. Purpose This study aims to analyze the evolution of surface electrocardiogram (ECG), focusing on R-wave amplitude variation, and intracavitary electrograms (EGMs) in ACM different phenotypes during a 1-year and a 5 five-year follow-up. Methods This study is a retrospective analysis of the data of consecutive patients with ACM who were referred to our centre from January 1992 to October 2021. Using a dedicated software, the ECG analysis was performed in 7 leads: DI, DII, aVF (in view of the similar orientation with the three S-ICD vectors) and V1, V2, V3 and V5. Results We included 69 ACM patients: 28 patients (41%) had a right ventricular involvement (ARVC), 19 (27%) had a dominant LV involvement (ALVC) and 22 (32%) had biventricular involvement. 58 patients (84%) were ICD recipients; 45/58 patients (78%) had a transvenous ICD, and 13/58 (22%) had an S-ICD. During 5-year follow-up, in the whole ACM population, there were no significant changes in the amplitude of the R-wave, S-wave and T-wave. Phenotypic subgroups showed a different R-wave amplitude at baseline: biventricular ACM and ALVC patients had a lower R-wave amplitude in DII (p=0.04; p=0.05) and aVF (p=0.01; p=0.01) compared to ARVC patients. However, within each group, no difference was observed in R-wave amplitude at 1 and 5 years compared to baseline ECG (Figure 1). In the transvenous ICD recipients (45/69 patients) mean sensing decreased progressively over time (9,38 ± 4,24 mV at baseline, 7,70 ± 2,91 mV at 1 year, 1,85 ± 6,86 mV at 5 years). The reduction was not statistically significant at the first year of follow-up (p=0.239) but it reached significance at 5 years (p&amp;lt;0.001). Patients with biventricular ACM had lower sensing values at baseline than ARVC and ALVC (p&amp;lt;0,001). Sensing values in the biventricular patients did not decrease significantly during the 5-year follow-up (p=0.21), whereas in the ARVC and ALVC groups a reduction in sensing values was observed albeit not statistically significant in ALVC (p=0.01 in ARVC and p =0.06 in ALVC) (Figure2). Conclusions These data suggest that surface ECG may be more stable over time compared to EGM, therefore if a patient is suitable for S-ICD implantation S-ICD sensing may remain stable over time. Despite these findings, further studies are needed to support these hypotheses.

Long-term safety and efficacy of leadless pacemakers in the Dutch cohort

Abstract Funding Acknowledgements Type of funding sources: None. Background Leadless pacemakers (LPs) were designed to circumvent pocket- and lead-related pacemaker complications. Up to two years after implantation, adequate real-world safety and efficacy have been demonstrated. Because the duration of pacemaker therapy is well over two years, longer-term data is warranted for the net clinical benefit of leadless pacing. Objective Our aim was to evaluate the safety and efficacy of LP therapy on the long-term in a real-world cohort. Methods In this retrospective cohort study, all consecutive patients were included with a first LP implantation (Nanostim LP or Micra VR LP) from December 21, 2012 to December 13, 2016 in 6 Dutch high-volume centers. The primary safety endpoint was the rate of procedure- or device-related major complications at 5-year follow-up. Analyses were performed with and without the Nanostim battery advisory-related complications. The efficacy is described as pacing threshold, impedance and R-wave amplitude over time; changes in these parameters were assessed using mixed models. Results 179 patients were included (117 [65%] male, mean age 79±9 years), of whom 93 (52%) with a Nanostim and 86 (48%) with a Micra LP. Mean follow-up duration was 45±25 months. A total of 46 major complications occurred, of which 8 not advisory-related. The 5-year major complication rate without advisory-related complications was 4.5% (Figure, A). Including advisory-related complications, the 5-year major complication rate was 30.5%. Not advisory-related complications included dislocations (n=3, of which 2 periprocedurally), pericardial effusion (n=1), groin bleeding (n=1), loss-of-capture (n=2) and pacemaker syndrome (n=1). Reinterventions were required in 7/8 (88%), only prolonged hospitalization in 1 (12%; the groin bleeding), and surgery in none. All 8 occurred within 90 days after implantation. Pacing threshold was stable over time (p=0.53), R-wave amplitude increased (p=0.002), and impedance decreased (p&amp;lt;0.001) (Figure, B). Conclusion The long-term major complication rate excluding advisory-related complications was low. Especially few complications occurred after the acute phase, which may be a specific benefit of LP therapy. The performance was adequate with a stable pacing threshold over time, whereas in transvenous pacemakers usually a gradually increasing threshold is seen. These findings confirm previous safety and efficacy results and are promising for longer-term data on leadless pacing.