QRS Morphology Research Articles

Potential Underestimation of Left Ventricular Mechanical Dyssynchrony in Dyssynchrony and Outcomes Assessment.

Left ventricular (LV) mechanical dyssynchrony (LVMD) is fundamental to the progression of heart failure and ventricular remodeling. The status of LVMD in different patterns of bundle branch blocks (BBB) is unclear. In this study, we analyzed the relationship between LVMD and left ventricular systolic dysfunction using real-time three-dimensional echocardiography (RT-3DE). RT-3DE and conventional two-dimensional echocardiography were performed on 68 patients with left bundle branch block (LBBB group), 106 patients with right bundle branch block (RBBB group), and 103 patients without BBB (Normal group). The RT-3DE data sets provided time-volume analysis for global and segmental LV volumes. The LV systolic dyssynchrony index (LVSDI) was calculated using the standard deviation (SD) and maximal difference (Dif) of time to minimum segmental volume (tmsv) for LV segments adjusted by the R-R interval. LVMD was considered if the LVSDI (Tmsv-16-SD) was greater than or equal to 5%. LVSDI is negatively and significantly correlated with left ventricular ejection fraction (LVEF), but not with BBB or QRS duration. The proportion of LVMD in the LBBB, RBBB, and Normal group was 30.88%, 28.30%, and 25.24%, respectively, and there was no significant difference. In dilated cardiomyopathy, LVMD is more closely related to LVEF reduction than QRS morphology and duration.

Unlocking the potential of sacubitril/valsartan therapy in improving ECG and echocardiographic parameters in heart failure patients with reduced ejection fraction (HErEF)

BackgroundSacubitril/valsartan therapy has been found to reduce hospitalizations, improve echocardiogram parameters, and improve mortality in HFrEF. The objective is to assess S/V therapy effect on electrocardiogram indices and how those parameters related to echocardiographic parameters.ResultsFrom June 2022 until June 2023, this prospective study enrolled 100 patients (mean age 56.1, 8.2, 78% male) with non-ischemic dilated cardiomyopathy (NIDCM) used PARADIGM-HF criteria: NYHA Class II, III, or IV HF; ejection fraction EF ≤ 40%; and hospitalization for HF within previous 12 months. Before starting S/V therapy, an echo and ECG were performed, as well as 6 months following the optimal dose and if LVEF was improved by more than 5%, they were termed notable S/V treatment responders. Aside from improving echo parameters, ECG parameters improved significantly. The QRS width was reduced from 123.7 ± 20.3 to 117.1 ± 18.8 ms (p 0.00), and QTc interval was reduced from 425.4 ± 32.8 to 421.4 ± 32.3 ms (p = 0.012). QRS width was significantly reduced in patients with LBBB, RBBB, and IVCD based on QRS morphology. QRS width (r = − 0.243, p = 0.016) and QTc (r = − 0.252, p = 0.012) had a negative connection with LVEF.ConclusionS/V therapy, in addition to improving echo parameters and NYHA class, improves QRS width and corrected QTc interval on ECG in HFrEF patients. This is an indication of reverse electrical LV remodeling and can be used as an auxiliary prediction for tracking therapy outcomes.

QRS Detector Performance Evaluation Aware of Temporal Accuracy and Presence of Noise.

Algorithms for QRS detection are fundamental in the ECG interpretive processing chain. They must meet several challenges, such as high reliability, high temporal accuracy, high immunity to noise, and low computational complexity. Unfortunately, the accuracy expressed by missed or redundant events statistics is often the only parameter used to evaluate the detector's performance. In this paper, we first notice that statistics of true positive detections rely on researchers' arbitrary selection of time tolerance between QRS detector output and the database reference. Next, we propose a multidimensional algorithm evaluation method and present its use on four example QRS detectors. The dimensions are (a) influence of detection temporal tolerance, tested for values between 8.33 and 164 ms; (b) noise immunity, tested with an ECG signal with an added muscular noise pattern and signal-to-noise ratio to the effect of "no added noise", 15, 7, 3 dB; and (c) influence of QRS morphology, tested on the six most frequently represented morphology types in the MIT-BIH Arrhythmia Database. The multidimensional evaluation, as proposed in this paper, allows an in-depth comparison of QRS detection algorithms removing the limitations of existing one-dimensional methods. The method enables the assessment of the QRS detection algorithms according to the medical device application area and corresponding requirements of temporal accuracy, immunity to noise, and QRS morphology types. The analysis shows also that, for some algorithms, adding muscular noise to the ECG signal improves algorithm accuracy results.

Paced QRS morphology mimicking complete left bundle branch block induced by right ventricular pacing is associated with pacing-induced cardiomyopathy.

Right ventricular (RV) pacing sometimes causes left ventricular (LV) systolic dysfunction, also known as pacing-induced cardiomyopathy (PICM). However, the association between specifically paced QRS morphology and PICM development has not been elucidated. This study aimed to investigate the association between paced QRS mimicking a complete left bundle branch block (CLBBB) and PICM development. We retrospectively screened 2009 patients who underwent pacemaker implantation from 2010 to 2020 in seven institutions. Patients who received pacemakers for an advanced atrioventricular block or bradycardia with atrial fibrillation, baseline LV ejection fraction (LVEF) ≥ 50%, and echocardiogram recorded at least 6 months postimplantation were included. The paced QRS recorded immediately after implantation was analyzed. A CLBBB-like paced QRS was defined as meeting the CLBBB criteria of the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society in 2009. PICM was defined as a ≥10% LVEF decrease, resulting in an LVEF of <50%. Among the 270 patients analyzed, PICM was observed in 38. Baseline LVEF was lower in patients with PICM, and CLBBB-like paced QRS was frequently observed in PICM. Multivariate analysis revealed that low baseline LVEF (odds ratio [OR]: 0.93 per 1% increase, 95% confidence interval [CI]: 0.89-0.98, p = 0.006) and CLBBB-like paced QRS (OR: 2.69, 95% CI: 1.25-5.76, p = 0.011) were significantly associated with PICM development. CLBBB-like paced QRS may be a novel risk factor for PICM. RV pacing, which causes CLBBB-like QRS morphology, may need to be avoided, and patients with CLBBB-like paced QRS should be followed-up carefully.

Digital twinning of the human ventricular activation sequence to Clinical 12-lead ECGs and magnetic resonance imaging using realistic Purkinje networks for in silico clinical trials

Cardiac in silico clinical trials can virtually assess the safety and efficacy of therapies using human-based modelling and simulation. These technologies can provide mechanistic explanations for clinically observed pathological behaviour. Designing virtual cohorts for in silico trials requires exploiting clinical data to capture the physiological variability in the human population. The clinical characterisation of ventricular activation and the Purkinje network is challenging, especially non-invasively. Our study aims to present a novel digital twinning pipeline that can efficiently generate and integrate Purkinje networks into human multiscale biventricular models based on subject-specific clinical 12-lead electrocardiogram and magnetic resonance recordings. Essential novel features of the pipeline are the human-based Purkinje network generation method, personalisation considering ECG R wave progression as well as QRS morphology, and translation from reduced-order Eikonal models to equivalent biophysically-detailed monodomain ones. We demonstrate ECG simulations in line with clinical data with clinical image-based multiscale models with Purkinje in four control subjects and two hypertrophic cardiomyopathy patients (simulated and clinical QRS complexes with Pearson's correlation coefficients > 0.7). Our methods also considered possible differences in the density of Purkinje myocardial junctions in the Eikonal-based inference as regional conduction velocities. These differences translated into regional coupling effects between Purkinje and myocardial models in the monodomain formulation. In summary, we demonstrate a digital twin pipeline enabling simulations yielding clinically consistent ECGs with clinical CMR image-based biventricular multiscale models, including personalised Purkinje in healthy and cardiac disease conditions.

Kiosk 2R-TB-06 - Association of QRS Morphology with CMR Features in Cardiac Amyloidosis

Kiosk 2R-TB-06 - Association of QRS Morphology with CMR Features in Cardiac Amyloidosis

Differentiating Origins of Outflow Tract Ventricular Arrhythmias: The Correction of Transitional Zone Index Is Not Superior to the Original One

Introduction: Our team once proposed a correction of transitional zone index (CTZI) based on the transitional zone index (TZI) in view of achieving a more precise prediction of outflow tract ventricular arrhythmia (OTVA). The predictive accuracy of these two electrocardiogram (ECG) algorithms has not been validated and compared. The purpose of this study was to compare the predictive accuracy of TZI and CTZI in a much larger population with idiopathic OTVA. Methods: The predictive accuracy of TZI and CTZI was compared in 695 individuals with idiopathic premature ventricular complex or ventricular tachycardia which exhibited a left bundle branch block pattern and inferior axis QRS morphology. Receiver operating characteristic curve analysis, decision curve analysis, and calibration curve were used to compare the predictive accuracy of TZI and CTZI. Results: TZI and CTZI manifested the similar area under the curve. While a TZI of <0 predicted a left ventricular outflow tract (LVOT) origin with a high specificity of 88.2% but a low sensitivity of 67.1%, a CTZI of <0 yielded a high sensitivity of 84.3% but a low specificity of 59.5% in the overall analysis. Similar results were yielded in the sub-analysis of participants with a precordial transition occurring at lead V3. In the sub-analysis of participants with a TZI = 0, CTZI demonstrated a bit higher but not satisfactory predictive accuracy than TZI. Conclusion: Based on the scientific spirit of self-criticism and seeking truth from facts, our team disproves the correction of TZI proposed previously.

Analysis of QRS complex morphology in children and adolescents with obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) leads to many cardiovascular, neurologic, metabolic, and neurocognitive consequences. Conduction deficits, deviations in electrical axis, and changes in QRS morphology reflect the impairments in cardiac muscle activity and underlie the cardiovascular complications of OSAS. Here we aimed to determine the relationship between OSAS and changes in the cardiac conduction system in children and adolescents. During the 6-month duration of the study, all children having the diagnosis of OSAS in Sleep and Disorders Unit following a full-night polysomnography (PSG) were consecutively evaluated. ECGs were performed and analyzed in the Division of Pediatric Cardiology, Department of Pediatrics. The maximum spatial vector size (QRSmax), QRS electrical axis (EA), left and right ventricular hypertrophy, and the presence of fragmented QRS (fQRS) or prolonged R or S wave were examined in detail. A total of 17 boys with OSAS and 13 healthy boys participated in the study. The mean QRSmax and the QRSmax on V5 derivative were significantly lower in the patient group compared to those in the control group (p = 0.011 and p = 0.017, respectively). EA was similar between the two groups. While none of the patients with OSAS nor the control group had left ventricular hypertrophy, only one boy with OSAS had right ventricular hypertrophy according to ECG-derived analysis. The percentage of fQRS or notched R or S waves was significantly higher in patients with OSAS compared to healthy controls (p = 0.035), especially in children below the age of 5years (p = 0.036). Conclusion: This study demonstrated that male children and adolescents with OSAS have a combination of QRS complex changes characterized by low QRS voltages, and increased frequency of fragmented QRS. These findings reflect that the electrical remodeling and structural remodeling of the myocardium are considerably affected by OSAS in children and adolescents, leading to ventricular changes and intraventricular conduction problems. What is Known: • Pediatric obstructive sleep apnea syndrome (OSAS) characterized by recurrent intermittent hypoxemia, hypercapnia, and sleep fragmentation results in sympathetic nervous system activation, increased inflammation, and hypoxic endothelial dysfunction. When left untreated, OSAS leads to many cardiovascular, neurologic, metabolic and neurocognitive consequences, and also to sudden infant death syndrome in young children, probably due to the involvement of the cardiac conduction system. What is New: • This study demonstrated that mean QRSmax was significantly lower in male children and adolescents with OSAS, reflecting the structural and electrical remodeling of the myocardium, and one boy with OSAS had RVH according to ECG-derived analysis. The percentage of fQRS or notched R or S waves was much higher in boys with OSAS, especially in children below the age of five years. These finding showed that myocardium was considerably affected to impair the intraventricular conduction in younger children with OSAS.

QRS Morphology and the Risk of Ventricular Tachyarrhythmia in Cardiac Resynchronization Therapy Recipients

BackgroundThere are conflicting data on the effect of cardiac resynchronization therapy with a defibrillator (CRT-D) on the risk of life-threatening ventricular tachyarrhythmia in heart failure patients. ObjectivesThe authors aimed to assess whether QRS morphology is associated with risk of ventricular arrhythmias in CRT recipients. MethodsThe study population comprised 2,862 patients implanted with implantable cardioverter defibrillator (ICD)/CRT-D for primary prevention who were enrolled in 5 landmark primary prevention ICD trials (MADIT-II [Multicenter Automated Defibrillator Implantation Trial], MADIT-CRT [Multicenter Automated Defibrillator Implantation Trial-Cardiac Resynchronization Therapy], MADIT-RIT [Multicenter Automated Defibrillator Implantation Trial-Reduction in Inappropriate Therapy], MADIT-RISK [Multicenter Automated Defibrillator Implantation Trial-RISK], and RAID [Ranolazine in High-Risk Patients With Implanted Cardioverter Defibrillators]). Patients with QRS duration ≥130 ms were divided into 2 groups: those implanted with an ICD only vs CRT-D. The primary endpoint was fast ventricular tachycardia (VT)/ventricular fibrillation (VF) (defined as VT ≥200 beats/min or VF), accounting for the competing risk of death. Secondary endpoints included appropriate shocks, any sustained VT or VF, and the burden of fast VT/VF, assessed in a recurrent event analysis. ResultsAmong patients with left bundle branch block (n = 1,792), those with CRT-D (n = 1,112) experienced a significant 44% (P < 0.001) reduction in the risk of fast VT/VF compared with ICD-only patients (n = 680), a significantly lower burden of fast VT/VF (HR: 0.55; P = 0.001), with a reduced burden of appropriate shocks (HR: 0.44; P < 0.001). In contrast, among patients with non-left bundle branch block (NLBBB) (N = 1,070), CRT-D was not associated with reduction in fast VT/VF (HR: 1.33; P = 0.195). Furthermore, NLBBB patients with CRT-D experienced a statistically significant increase in the burden of fast VT/VF events compared with ICD-only patients (HR: 1.90; P = 0.013). ConclusionsOur data suggest a potential proarrhythmic effect of CRT among patients with NLBBB. These data should be considered in patient selection for treatment with CRT.

QRS axis and polarity in the inferior leads during left bundle branch pacing: Novel criteria in the search for better results.

Left bundle branch pacing (LBBP) may be achieved in various anatomical sites within the interventricular septum (IVS), thus influencing paced QRS duration (QRSd).The purpose of this study was to determine whether paced QRS axis (QRSâ) and predominant polarity in inferior leads could be associated with a shorter paced QRSd. We analyzed paced QRSd, QRSâ, polarity in inferior leads, and IVS thickness in patients referred for LBBP. Three paced morphology patterns in the inferior leads were considered: All positive (P), all negative (N) and intermediate (combination of isoelectric, positive, and negative complexes, (I). Patients were divided into two groups according to a paced QRSd<120 or ≥ 120ms. A total of 125 patients were included (age 76±10 years, 46% female). Mean baseline QRSâ was 8±37°. Paced QRSd was significantly shorter as compared to baseline (120±10vs. 127±33ms; p=.017) and significantly different according to paced QRS morphology pattern in the inferior leads (P 49%, 119±9; N 30%, 126±12; I 21%; 113±10ms; p<.001) or paced QRSâ (Normal 59%, 116±1; Right 6%, 129±1; Left 35%, 124±11ms; p<.001). On multivariate analysis, a QRSâ>-30°(OR 5.79 [2.40-13.93; 95% CI] p=.001), an Intermediate pattern in inferior leads (OR 3.00 [1.67-8.43; 95% CI] p=.037), and an IVS thickness ≤ 10mm (OR 2.59 [1.10-6.10; 95% CI]; p=.029) were significantly associated with a paced QRSd<120ms. During LBBP, a QRSâ>-30° and intermediate final polarity in inferior leads are associated with a shorter paced QRSd.

Cardiac Magnetic Resonance Identifies Responders to Cardiac Resynchronization Therapy with an Assessment of Septal Scar and Left Ventricular Dyssynchrony.

Background: The response to cardiac resynchronization therapy (CRT) depends on septal viability and correction of abnormal septal motion. This study investigates if cardiac magnetic resonance (CMR) as a single modality can identify CRT responders with combined imaging of pathological septal motion (septal flash) and septal scar. Methods: In a prospective, multicenter, observational study of 136 CRT recipients, septal scar was assessed using late gadolinium enhancement (LGE) (n = 127) and septal flash visually from cine CMR sequences. The primary endpoint was CRT response, defined as ≥15% reduction in LV end-systolic volume with echocardiography after 6 months. The secondary endpoint was heart transplantation or death of any cause assessed after 39 ± 13 months. Results: Septal scar and septal flash were independent predictors of CRT response in multivariable analysis (both p < 0.001), while QRS duration and morphology were not. The combined approach of septal scar and septal flash predicted CRT response with an area under the curve of 0.86 (95% confidence interval (CI): 0.78-0.94) and was a strong predictor of long-term survival without heart transplantation (hazard ratio 0.27, 95% CI: 0.10-0.79). The accuracy of the approach was similar in the subgroup with intermediate (130-150 ms) QRS duration. The combined approach was superior to septal scar and septal flash alone (p < 0.01). Conclusions: The combined assessment of septal scar and septal flash using CMR as a single-image modality identifies CRT responders with high accuracy and predicts long-term survival.

Novel PVC detection algorithm in an implantable cardiac monitor for longitudinal risk monitoring

Abstract Background Guideline therapy is recommended in patients with frequent premature ventricular contractions (PVCs). Longitudinal monitoring of the PVC burden can effectively guide treatment options, stratify patient risk, and manage HF progression. Implantable cardiac monitors (ICMs) may provide a suitable long-term diagnostic tool to monitor PVC burden and guide clinical therapy. Objective Quantify the performance of a novel QRS morphology and timing-based PVC detection algorithm as implemented for an ICM. Methods The algorithm utilizes self-adapting timing-based ectopy detection and dynamic measures of QRS morphology to identify unifocal and multifocal PVCs. The training dataset consisted of 200 sECG episodes recorded in implanted BIOMONITOR (BM) devices, collected from 48 patients. The algorithm was then evaluated on 227 sixty-second duration sECG episodes from 79 BM patients in the CERTITUDE registry. Each beat was adjudicated as normal, PVC, or PAC by at least two clinical experts. In a total of 22,433 beats, 756 true PVCs were assessed (3.4% PVC prevalence). Overall, patient averaged, and generalized estimating equation (GEE) estimates for sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated, as well as patient-specific PVC burden (PVCs/Total Beats). Results Patient-averaged PVC detection sensitivity was 73.8%, with a PPV of 89.2%, specificity of 99.6%, and NPV of 99.1%. Using a GEE model to adjust for multiple episodes per patient, the algorithm achieved detection sensitivity of 66.6±9.8% (95% CI) and PPV of 86.6±6.5%, with specificity of 99.5±0.4% and NPV of 99.0±0.5%. The main reasons for missed PVC detections were morphological similarities to normal beats, insufficient prematurity, or lack of a compensatory pause. Additionally, the algorithm faithfully represented the PVC burden, with a median difference of -0.24% between the PVC burden calculated by the detection algorithm and the adjudicated burden. Algorithm burden was highly correlated with the true PVC burden for each patient, with a Pearson correlation coefficient of 0.80 (p &amp;lt; 0.0001). Conclusions The PVC detection algorithm was highly specific, achieving a specificity of 99.6% and a sensitivity of 73.8%, and accurately representing the overall PVC burden for each patient. This PVC detection algorithm would provide a valuable clinical diagnostic marker to monitor PVC burden trends to guide therapy as well as assess the longitudinal risk of HF. Measurement of PVC burden combined with the 5.5-year longevity of the BIOMONITOR ICM could provide an innovative approach to optimize clinical management of patients.Example PVCs detected by the algorithm

Left ventricular afterload reduction by transcatheter aortic valve implantation acutely alleviates right ventricular pacing-induced left ventricular dysfunction in patients with aortic stenosis

Abstract Introduction In patients with left bundle branch block (LBBB) cardiac function has been found to be particularly sensitive to alterations in left ventricular (LV) afterload. Nevertheless, whether the detrimental hemodynamic effect of right ventricular pacing (RVP)-induced electromechanical dyssynchrony on LV function is also associated with afterload dependency, has not been investigated yet. Purpose Hence, in the current study we sought to examine the acute effect of RVP on LV function in patients with aortic stenosis (AS) before (with elevated afterload) and after (without elevated afterload) transcatheter aortic valve implantation (TAVI). Methods Patients with a previously implanted permanent pacemaker (PM) and significant AS referred for TAVI at our heart and vascular center university were screened for this observational study. Only those patients who had an intrinsic, regular, narrow QRS or right bundle branch block (RBBB) morphology rhythm were included. From 2022 March to 2023 February, nine patients with a DDD PM (with sick sinus syndrome and maintained AV conduction) and four patients with a VVI PM (with atrial fibrillation and complete AV block but stable junctional escape rhythm) were enrolled. Following TAVI, four patients were excluded due to the development of new-onset persistent LBBB. Transthoracic conventional and advanced echocardiography and non-invasive blood pressure monitoring were performed immediately before TAVI and on the second postoperative day. The measurements were carried out during intrinsic QRS rhythm and during frequency-matched RVP as well. Global longitudinal strain was determined by speckle-tracking echocardiography, then using LV pressure curves estimated from systolic blood pressure and mean aortic gradient, global myocardial work index (GMWI) was calculated to assess LV contractility. Results Mean aortic gradient was decreased after TAVI (40.2±3.6 vs. 6.7±1.3mmHg before vs. after TAVI, P&amp;lt;0.001) indicating successful reduction of LV afterload. Compared to the intrinsic QRS rhythm, RVP decreased GMWI before TAVI (GMWI: 1967±206 vs. 1240±174mmHg% intrinsic QRS vs. RVP, P&amp;lt;0.001) and after TAVI (GMWI: 1399±149 vs. 1020±121mmHg% intrinsic QRS vs. RVP, P=0.019) as well. Nevertheless, the extent of RVP-induced LV contractility impairment (expressed as ΔGMWI) was significantly alleviated after pressure unloading therapy (ΔGMWI: -37.1±6.6 vs. -24.5±7.8% before TAVI vs. after TAVI, P=0.024). Conclusion Our preliminary results indicate that RVP-induced LV dysfunction is afterload dependent. Hence, in patients with AS and a high percentage of RVP, TAVI might entail substantial functional improvement.

Biventricular or conduction system pacing for cardiac resynchronization therapy: a proposed treatment algorithm based on interventricular conduction delays

Abstract Background Cardiac resynchronization therapy (CRT) is usually performed with biventricular pacing (BiVP), but recently conduction system pacing (CSP) has been proposed as an alternative in case of unsuccessful coronary sinus lead implantation. However , further evidence is needed to determine when CSP should be used in lieu of BiVP to improve clinical benefit. Purpose To assess the clinical benefit of a treatment algorithm based on interventricular conduction delays (IVCD) to choose between BiVP or CSP in candidates to CRT. Methods Consecutive patients presenting at our Institution from January 2018 to December 2020 with an indication to CRT were prospectively enrolled in the study group (delays-guided resynchronization group, DRG). IVCD were measured after left ventricle (LV) lead positioning in a lateral or posterior-lateral cardiac vein, when feasible, using endocavitary electrogram. Treatment algorithm based on IVCD was used to decide whether to leave LV lead to perform BiVP or pull it out and perform CSP. An historical cohort of patients who underwent CRT from January 2016 to December 2017 independently from IVCD was used as a control group (standard resynchronization group, SRG). The primary endpoint was a composite of cardiovascular mortality, heart failure (HF) hospitalization, or urgent unplanned clinic visits at 1 year after the date of intervention. Results Study population consisted in 292 patients, of which 160 (54.8%) in the DRG and 132 (45.2%) in the SRG. Age, sex, HF etiology, NYHA class, left ventricular ejection fraction and QRS duration and morphology did not differ between the two groups. In the DRG 41 of 160 patients underwent CSP based on treatment algorithm (25.6%). The primary endpoint was significantly reduced in the DRG (35/160, 21.8%) compared to SRG (48/132, 36.4%)(hazard ratio (HR): 1.72; 95% confidence interval (CI):1.12-2.65; p=0.013). Conclusion A treatment algorithm based on IVCD shifted 1 patient every 4 from BiVP to CSP, with consequent reduction in cardiovascular deaths, HF hospitalizations or urgent unplanned clinic visits after implantation. Therefore, its application could be useful to determine whether to perform BiVP or CSP in CRT candidates.Treatment Algorithm

The predictive role of left ventricular cathode topography relative to CMR-determined latest mechanical activation and scar segments on response to cardiac resynchronisation therapy

Abstract Background Cardiac resynchronisation therapy (CRT) is still burdened by considerable rates of non-response. Herein left ventricular cathode (LVC) positioning has the greatest room for optimisation. Nonetheless, a purely CMR-based approach exploring LVC topography relative to both mechanical delay and tissue viability is yet to be investigated. Purpose To retrospectively analyse the effect on reverse remodelling of CMR-determined LVC topography relative to latest mechanical activation (LMA) and scar segments in a CRT population. Methods This is a retrospective single-centre analysis of 104 CRT-D/P consecutive patients with CMR performed within 6 months before implantation. Electrical delay (Q-LV time) was mapped on all suitable veins with LV lead positioning and cathode programming set in the region of latest electrical activation. Through CART-Tech® software analysis of CMR images, 36-segment 3D anatomical models of radial strain and scar were superimposed on their corresponding fluoroscopy images (Figure 1). Patients were then stratified based on LVC concordance (within), semi-concordance (adjacent) or non-concordance (at least one segment away) with LMA and scar segments (defined as segments with &amp;gt;50% scar transmurality). Follow-up echocardiography was performed at least 6 months after implantation and the degree of reverse remodelling expressed as percentage reduction in end-systolic volume (ESV). Results Of the 104 patients, 36 were excluded due to suboptimal CMR quality (8), switch to conduction system pacing (5), loss to follow-up (18) or death within 6 months of implantation (5), leaving a total of 68 (63 CRT-D and 5 CRT-P). LVC concordance with LMA was associated with a statistically significant improvement in reverse remodelling (Figure 2, A), while the contrary occurred with regards to scar (Figure 2, B). A greater impact of distance from scar compared to LMA proximity was observed, thus a combined analysis of LVC topography relative to both was developed accordingly. Patients were stratified into 4 categories of LVC optimality: optimal (LVC-LMA concordance + LVC-scar non-concordance), semi-optimal (LVC-LMA semi-concordance + LVC-scar non-concordance), suboptimal (LVC-LMA non-concordance + LVC-scar non-concordance), and unfavourable (LVC-scar semi-concordance or concordance regardless of LVC-LMA). The unfavourable group had higher rates of atrial fibrillation, non-LBBB QRS morphology and higher scar burden, while no significant differences were observed in the other 3 groups. This classification appears to predict the degree of reverse remodelling, ESV reduction being more pronounced the more optimal the group (Figure 2, C). Conclusions CMR-determined LVC topography relative to LMA and scar segments predicts left ventricular reverse remodelling in Q-LV-guided CRT implants. Optimisation of CRT response may thus benefit from a CMR-based approach assessing mechanical delay and tissue viability to guide LVC positioning.Figure 1Figure 2

Performance comparisons between two artificial intelligence based premature ventricular complex detection models using insertable cardiac monitor

Abstract Background Premature ventricular complex (PVC) detection using computationally simple techniques has been recently introduced in insertable cardiac monitors (ICMs). An ICM device capable of monitoring PVC burden over a longer period can be a useful tool for evaluating temporal dynamics of PVC burden leading to appropriate and timely clinical interventions in patients with high PVC burden. Objective The study evaluated the performances of two artificial intelligence (AI) based PVC detection models to improve PVC detection accuracy in ICMs. Methods We developed and evaluated two deep learning convolution neural network (CNN) based PVC detection models which were trained and validated on ICM ECG data. The models were developed and validated using ECG strips stored by ICM implanted in real world patients and collected in the deidentified ICM device data warehouse. All ECG strips were manually annotated for PVCs beat-by-beat. For the first model, only the ICM ECG of three consecutive beats was provided as an input feature whereas for the second model, additional features including QRS morphology differences, RR interval differences, QRS amplitude and slope differences between adjacent beats were extracted and provided as input. The trained AI models were tested on a validation dataset and performance metrics including accuracy, sensitivity and specificity metrics were computed and compared between both models. Results The CNN ResNet-18 models with different input features were trained and validated on a dataset of over 90 patient activated ICM ECG episodes which provided a total of 14,354 beats with over 2,200 PVC beats. This dataset provided PVC beats with different morphologies including monomorphic, polymorphic, bigeminy and trigeminy PVCs. The validation dataset consisted of over 4,300 beats including 664 true PVC beats with various morphologies. On the validation dataset, the first model with only ECG as input obtained an accuracy, sensitivity and specificity of 98%, 92% and 99.1% respectively. Whereas for the second model with ECG plus additional features as input, an accuracy, sensitivity and specificity of 98.9%, 97.3% and 99.2% were obtained respectively (Figure 1). Error analysis of both the AI models revealed that the main reason for misidentifying PVC beats was due to the presence of noise around the QRS complex or the T-wave of the beat in the ECG. Conclusion Detection of PVCs utilizing a novel AI algorithm is both feasible and capable of exceeding sensitivity and specificity performance metrics of non-AI based algorithms and AI models with manually extracted ECG features provide better performance for targeted PVC detection in ICMs.

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.

Outcomes of Upgrading to LBBP in CRT Nonresponders: A Prospective, Multicenter, Nonrandomized, Case-Control Study

BackgroundCardiac resynchronization therapy (CRT) nonresponders account for nearly 30% of CRT candidates. Left-bundle branch pacing (LBBP) is an alternative to CRT. ObjectivesThis study aimed to evaluate the feasibility, clinical efficacy, and outcomes of upgrading to LBBP in CRT nonresponders, using propensity-score matching (PSM) analysis. MethodsCRT nonresponders were defined as those with an implantable CRT-pacemaker or CRT-defibrillator for more than 12 months who remained nonresponsive (a decrease in left ventricular end-systolic volume of <15% or a left ventricular ejection fraction [LVEF] absolute increase of <5%) after optimal medical therapy and device optimization compared with baseline. In total, 145 CRT nonresponders were prospectively enrolled and randomly divided into 2 groups: upgraded to LBBP (n = 48), and continuing biventricular pacing (BVP) (control; n = 97). PSM was performed at a 1:1 ratio, and clinical evaluation and echocardiographic assessments were compared at baseline and follow-up in paired cohorts. The primary composite endpoint for clinical outcomes (heart failure-related rehospitalization events, all-cause death, or heart transplantation) was analyzed. ResultsSuccessful upgrading to LBBP was achieved in 48/49 patients (97.96%), with a significant decrease in QRS duration (P < 0.001). In the paired LBBP group, LVEF significantly increased (baseline: 29.75% ± 7.79%; 6 months: 37.78% ± 9.25% [P < 0.001]; 12 months: 38.84% ± 12.13% [P < 0.001]) with 21/44 patients (47.73%) classified as echocardiographically responsive, whereas in the BVP control group, no significant improvement was observed (29.55% ± 6.74% vs 29.22% ± 8.10%; P = 0.840). In a multivariate logistic regression model, LV end-diastolic volume and baseline LBBB QRS morphology were independent predictors of echocardiographic response after upgrading to LBBP. At a median 24 months, the primary composite endpoint was significantly lower in the LBBP group (HR: 0.31; 95% CI: 0.14-0.72; log-rank P = 0.007). ConclusionsUpgrading to LBBP is feasible and effective in achieving significant heart function improvement and better clinical outcomes in CRT nonresponders, making it a reasonable and promising pacing strategy. (LBBP in CRT Non-Response patients; ChiCTR1900028131)

Abstract 14046: Cardiac Tamponade: A Handy Case of Early Detection

Case Presentation: A 63-year-old man with severe bicuspid aortic valve stenosis underwent surgical aortic valve replacement and the post operative echocardiogram was normal.In the month after discharge, the patient developed progressive episodes of lightheadedness, fatigue, and exertional weakness. He had no associated dyspnea on exertion, chest pain or fever. He was alerted of new sinus tachycardia on his Apple Watch, and the ECG morphology began changing with an overall decrease in QRS amplitude as well as alternating QRS amplitudes consistent with electrical alternans (Figure 1). These ECG strips were sent to the patient’s cardiologist who suspected a pericardial effusion due to these characteristic ECG findings.The patient underwent outpatient echocardiography which showed a normal functioning bioprosthetic valve with new large circumferential pericardial effusion and signs of cardiac tamponade physiology. The patient was admitted and underwent urgent pericardial drain placement with removal of 250cc of serosanguineous fluid. He recovered and was discharged with 3 months of colchicine. Discussion: Pericardial effusions are a known potential complication after cardiac surgery and often have an occult presentation making detection difficult. Smart watches with ECG capabilities provide valuable data because they can be used to detect the development of a new tachycardia and changes in QRS morphology. By observing the progressive changes in the QRS morphology from baseline, it is possible to monitor for the development of electrical alternans. This finding coupled with the patient’s clinical presentation prompted rapid evaluation and treatment. Conclusions: The Apple Watch can perform single-lead ECGs which are capable of diagnosing arrhythmias including atrial fibrillation. This case now opens the door to the early detection of postoperative pericardial effusions by monitoring the Apple watch for electrical alternans.

Abstract 11698: Torsades de Aortique Pustule: A Case of Aortic Abscess Leading to 2:1 AV Block and Torsades de Pointes

Introduction: Endocarditis of the aortic valve has a propensity to create A-V conduction disturbances in up to 10% of cases. Torsades de pointes (TdP) is polymorphic ventricular tachycardia in the setting of prolonged QT interval and bradycardia that is typically preceded by a short-long-short sequence of ventricular activation. We present a case of infective endocarditis with aortic root abscess leading to acute 2:1 A-V conduction and culminating in TdP. Case Summary: A 30-year-old male with history of IV drug use and bioprosthetic aortic valve repair presented with pleuritic chest pain, nausea and vomiting. He was febrile and tachycardic with a systolic murmur at the right upper sternal border. Initial electrocardiogram showed sinus rhythm with no conduction abnormalities. A Transthoracic echocardiography showed a large aortic valve vegetation with an abscess cavity. E Blood cultures grew Streptococcus oralis. Two days later, he developed VT/VF arrest requiring external defibrillation. Preceding ECGs and telemetry showed sinus tachycardia with new left bundle branch block and prolonged QTc. B This progressed to 2:1 AV block C with abrupt transition to relative bradycardia and ventricular ectopy leading to short-long-short ventricular intervals and subsequent TdP. D A temporary pacemaker was placed, and he underwent an aortic root reconstruction with valve replacement. Discussion: While both the etiology of TdP and aortic root abscesses leading to conduction system disease are well described, this case exhibits the real time progression of aortic abscess involvement. The patient presented with a normal QRS morphology. During hospitalization, he developed new LBBB, and the appropriate sinus tachycardia then deteriorated into 2:1 AV conduction leading to relative bradycardia. This abrupt transition with QTc prolongation sets up the nidus for ventricular ectopy (due to early after depolarizations) with salvos of short-long-short sequences causing TdP.