Narrow QRS Research Articles

The Significance of rS Change in the V2 Lead for Diagnosing Ventricular Tachycardia Deserves Attention: A Case Report

Abstract Occasionally, incessant ventricular tachycardia (VT) exhibits a narrow QRS complex pattern that could be misdiagnosed as supraventricular tachycardia. In this case, a 66-year-old woman was referred to the emergency department due to the worsen hemodynamic and incessant VT manifesting as a narrow QRS complex pattern that was initially misdiagnosed as supraventricular tachycardia (SVT), which was unresponsive to antiarrhythmic drugs. The electrocardiogram manifestation of VT was characterized by an rS configuration in lead V2 with Rs pattern in leads V1 and V3, and the R-wave amplitude of lead V1 and V3 was greater than that of lead V2, which was different from the typical electrocardiogram features of right bundle branch block. The patient was subsequently found to have suspected acute myocarditis when the cause of the disease was investigated. A combination of high-dose methylprednisolone, immunoglobulin and intra-aortic balloon pump was given immediately. Hemodynamics gradually stabilized, and ventricular tachycardia did not recur. The rS change in the V2 lead may be helpful to distinguish VT from supraventricular tachycardia.

Abstract 4134305: Intraoperative indicators depending on QRS morphology are required to narrow QRS width during CRT implantation

Introduction: Various indicators to detect the most delayed electrical or mechanical activation site of left ventricular (LV) have been studied using intracardiac electrocardiogram or speckle tracking echocardiogram to narrow QRS width in patients with cardiac resynchronization therapy (CRT). Hypothesis: Unusual intraoperative indicators are required to narrow QRS width in patients with non-LBBB (left bundle branch block) during CRT implantation. Methods: Nineteen patients (14 men, 71±12yrs, 7 with left bundle branch block: LBBB / 10 non-LBBB / 2 pacing-depend, 6 ischemic cardiomyopathy, LVEF 29.6±8.9%, QRS 152±28ms) underwent CRT implantation. Q-LV (an interval from QRS onset to LV potential), RV-LV (from RV to LV), RVp-LV (from RV pacing to LV), and S-QRS (from LV pacing stimulation to QRS onset) were measured in multi-sites of coronary sinus (CS) veins using a 5 mm spacing 2Fr 8-polar catheters. Q-peak strain (an interval from QRS onset to peak radial strain) was evaluated by speckle tracking echocardiogram in each LV segment during sinus rhythm (SR) and RVp. QRS narrowing was defined as the difference between the QRS interval during SR (or RVp) and the QRS interval with biventricular pacing. Results: Parameters were evaluated in 17±7 (8-32) sites of 1.9±0.9 (1-4) CS branches in each patient. In LBBB patients, longer Q-LV during SR, extended RV-LV during SR, and lengthy Q-peak strain during SR were associated with QRS narrowing. Shorter S-QRS during LVP and longer RVP-LV during RVP were related to QRS narrowing in non-LBBB patients. (Table) Conclusion: Suitable indicators depending on QRS morphology are required for QRS narrowing in CRT implantation. The parameters using speckle tracking echocardiogram to detect mechanical LV delay sites might not be useful in patients with non-LBBB.

Abstract 4135061: Myocardial work in different patients with electrical dysynchrony due to left bundle branch block

Left bundle branch block (LBBB) in patients with dilated cardiomyopathy (DCM) is defined by huge wasted work and decreased myocardial constructive work. The aim of this study is to assess the myocardial work in patients in LBBB and other clinical situations. Materials and methods: The echocardiographic study was performed in 25 patients with LBBB and DCM (LBBB-DCM); 20 patients with DCM and narrow QRS complex (nonLBBB-DCM group); 15 patients with LBBB developed after transcatheter aortic valve implantation (TAVI group); 12 patients with idiopathic LBBB, normal systolic LV function and excluded cardiovascular pathology (LBBB group); 27 patients with right ventricular pacing due to atrioventricular block of high grade (RVP group) and 20 healthy volunteers (HV group). In all of them global longitudinal strain (GLS) and myocardial work parameters including global constructive work (GCW), global wasted work (GWW), global work index (GWI) and global work efficiency (GWE) were assessed. In all patients the segments with maximum and minimum GWI value were determined. Results: GLS, GWI and GCW values were comparable in LBBB and RVP groups, whereas in TAVI and in both DCM groups they was significantly lower than in HV (p = 0.049, 0.006, 0.025; p < 0,001 respectively, (Fig.1A,B,C)). Patients from LBBB, TAVI, RVP and LBBB-DCM groups were characterized by increased amount of GWW (261 [203.5; 291.5], 273 [184.8; 385,3] and 237 [149.5; 445.3] vs 108 [74.3; 137.3] mmHg%, p = 0.033, 0.006, < 0.001, < 0.001 respectively). GWW value in LBBB-DCM group was the highest (346.5 [255.5; 437.8] mmHg% (Fig.1D). There was moderate strength of relation between GWW and QRS duration (ρ=0.456, p<0.001). A huge amount of wasted work affected the GWE value and led to its considerable reduction in LBBB, TAVI, RVP and LBBB-DCM groups compared to HV (p = 0.033, 0.007, 0.023, < 0,001, respectively, Fig.1E). The zone of maximum GWI localized in posterolateral wall, the zone of minimum GWI was in interventricular septum in most LBBB patients (Fig.1F). At the same time, these zones turned out to be very variable in RVP group. Conclusion: Although all patients with LBBB pattern of electrical activation are characterized by significant amount of wasted work, its contribution to global myocardial work manifested only in DCM patients. Wasted work doesn’t lead to reduced constructive work in patients with idiopathic LBBB and RVP and normal systolic function probably due to compensatory mechanisms.

Atrial fibrillation – a comparative review of one of the most common arrhythmias in dogs and humans

Atrial fibrillation is the most prevalent arrythmia in dogs and humans and is characterised by chaotic depolarisation of the atria, resulting in damage to the atrial myocardium. It can lead to heart failure or worsen an existing condition and cause sudden death. Electrocardiographically, atrial fibrillation is characterised by the absence of P waves and an irregularly irregular rhythm, with narrow QRS complexes. Treatment of atrial fibrillation requires knowledge of pathophysiology and the pharmacology of antiarrhythmic drugs. In contrast to human medicine, the treatment of dogs revolves mainly around rate control strategies, although new studies propose the consideration of several rhythm strategies. Considering the complexity of atrial fibrillation, there is strong need for a consensus on classification, diagnosis and treatment in dogs.

Right bundle branch block in suspected acute coronary syndromes: Diagnostic challenges, treatment and prognosis

BackgroundThere is still conflicting evidence regarding the prognostic implications of right bundle branch block (RBBB) in the general population but also in patients with heart diseases like acute coronary syndromes (ACS). In accordance with current guidelines, RBBB in ACS patients is considered as STEMI equivalent. However, recent studies indicate that further differentiation is necessary in this group, as we will outline below. Methods and resultsA literature search was conducted in PubMed and Google Scholar.In previous studies, RBBB in the general population were mostly considered benign changes of the electrical conduction system. However, recent studies indicate that both complete and incomplete RBBB are associated with increased cardiovascular morbidity and mortality. In addition, among unselected patients with suspected ACS presenting to the emergency department, the prevalence of RBBB was 3 % and it was associated with elevated mortality. The subsequent angiographic identification of a culprit coronary artery stenosis leading to stent implantation was similar at approximately 2 % regardless of the initial ECG presentation with narrow QRS complexes, left bundle branch block (LBBB), or RBBB.Finally, in a group of high-risk patients for ST-elevation myocardial infarction (STEMI), the prevalence of RBBB was 12 %. While RBBB was associated with poor outcome compared to non-BBB and LBBB patients, diagnostic accuracy of STEMI criteria was not affected by the presence of RBBB. However, RBBB patients without distinct STEMI signs in ECG often showed acute STEMI on angiography indicating a potential benefit from immediate transfer to the cardiac catheterization laboratory. ConclusionIn the general population, patients with RBBB and risk factors may need further evaluation. Regarding ACS patients, recent studies support current guidelines that recommend acute invasive evaluation for high-risk ACS patients with RBBB, regardless of ST-T deviations. However, in an unselected group of ACS patients, differential diagnoses should also be investigated through additional diagnostic procedures.

Mitigation of pacing-induced cardiomyopathy with superficial right ventricular mid-septal pacing: A long-term retrospective comparison with apical pacing.

It remains unclear if pacing induced cardiomyopathy (PICM) may be minimized by standard pacing of the right ventricle (RV) at sites other than the RV apex. The purpose of this study is to compare the relative frequency of PICM in a population of patients paced at either the superficial RV mid septum (RVMS) or RV apex (RVA), and other outcomes that may differ between these sites. A retrospective evaluation was performed on all patients undergoing pacemaker implantation between 2011 and 2022. Potential study patients were those with Medtronic 3830 superficial RVMS leads placed with septal specific guidance catheters, and any with RVA leads. Patients were included if they had ≥20% RV pacing, available baseline and follow-up measurements of left ventricular ejection fraction (LVEF) at least 6 months postimplantation, and a baseline LVEF ≥50%. PICM was defined as a decline in the LVEF of at least 10%, resulting in LVEF <50%. Patients were excluded for Biventricular devices, and for alternative causes of cardiomyopathy. The study criteria were met in 324 patients, with 220 RVMS and 104 RVA paced patients. PICM occurred in 4.5% of RVMS patients, and 22.1% of RVA patients (p < .001). Additional differences were demonstrated in paced QRS duration (144 ± 15.5 ms in RVMS, 166 ± 19.4 ms in RVA; p < .001); QRS axis (2.3 ± 64.9 in RVMS, -65.2 ± 49.5 in RVA; p < .001), and various qualitative QRS morphologic characteristics. Patients with normal LVEF experienced significantly less PICM with superficial RVMS pacing performed via septal specific guidance catheters than similar counterparts with RVA pacing. Narrower paced QRS duration and less left axis deviation was also demonstrated.

Larger QRS but better hemodynamic function after high output His bundle pacing in patients with heart failure and narrow QRS. A paradox or a new concept?

Abstract Background QRS duration is an important factor in determining Cardiac Resynchronisation Therapy (CRT) response and a useful surrogate for electromechanical dyssynchrony. However, we don’t have studies confirming this concept in conduction system pacing. Purpose We performed His Bundle Pacing (HBP) with high output (3.5V/1msec) in HF patients with dilated or ischemic cardiomyopathy and narrow QRS to evaluate hemodynamic benefit independent of the QRS duration or AV delay shortening. Methods 14 patients with dilated (7 patients) or ischemic (7 patients) cardiomyopathy (EF&amp;lt;35%) and narrow QRS (&amp;lt;120ms) were referred for implantation of a defibrillator. We implanted an ICD- HBP system, and we collected clinical, echocardiographic, and electrocardiographic data. Results We obtained HBP in all 14 patients successfully. PQ after implantation was shorter from 172±48 to 143±16 (P=0.048) so as to pace the ventricle. Baseline QRS duration increased after pacing from 110±15 to 123±16ms (P=0.008) as measured by ECG analyzer. Despite this increase in QRS duration basal mean EF increased from 30±4% to 46±10% (P&amp;lt;0.001) after a median follow-up of 17 months. Left ventricular end-diastolic diameter and left ventricular end-diastolic volume decreased from 62±5 to 57±5mm (P=0.013) and from 195±69 to 126±27ml (P&amp;lt;0.001), respectively. Left ventricular end-systolic volume decreased from 139±58 to 69±27 (P&amp;lt;0.001). TAPSE increased from 19±4 to 27±4. NYHA class decreased by one class in every patient after only one month. HBP threshold was 1.05V±0.7/1msec and raised to 1.33±0.93/1msec (due mainly to 2 patients with very high threshold). The impedance was 588±109 and decreased to 484±69 Ohms. R-wave at implant was 3.2±1.8mV. In 2 out of 14 patients, threshold increased but was still less than 3.5V/1msec. Conclusions HBP in HF patients with dilated or ischemic cardiomyopathy and narrow QRS improves hemodynamic function in right and left ventricle and decreases NYHA class. This benefit appears to be produced by a higher stimulation output despite a larger QRS after pacing. We exclude that a very short AV delay could be favorable, by measuring acute EF changes only after increasing the pacing output without AV delay modifications. To our knowledge these are the first cases of beneficial HBP in HF patients with narrow QRS. Interestingly, larger QRS corresponds to higher EF in patients with high output HIs Bundle Pacing.

HV interval measure immediately before TAVI with SEV for predicting pacemaker implantation

Abstract Introduction Although improvements, new onset persistent disturbances in electrocardiogram (ECG) after transcatheter aortic valve implantation (TAVI) remains up to 34% at hospital discharge (1), needing permanent pacemaker implantation (PPM) in self-expanding valves (SEV) as high as 15-27% (2,3). In post TAVI scenario, European Society of Cardiology guidelines recommend an electrophyisiologic study centered in His-ventricular electrogram (HV) interval measure for assessing risk of progression to high auriculoventricular block (AVB), if abnormal a PPM is indicated (4,5). We aim to predict PPM through basal HV interval measurement prior TAVI with SEV. Furthermore, we aim to compare different current SEV with basal HV interval and the distinct rate of PPM before discharge. Methods and Results Single-center prospective cohort study, patients with severe aortic stenosis scheduled for TAVI, sinus rhythm at intervention day, without PPM or history of PPM indication were included. At time of TAVI, contralateral venous puncture to femoral arterial access was made, a tetrapolar catheter was advanced and placed at the septal aspect of tricuspid valve searching for His electrogram. A mobile polygraph was used to measure ECG parameters and HV interval before TAVI. Then, a tetrapolar catheter was advanced to ventricle to perform rapid stimulation as part of habitual valve implantation protocol. After procedure, we performed rhythm surveillance for at least &amp;gt;48-72 hours and based in electrical evolution one of three decisions was made: 1)PPM implant, 2)late post TAVI HV interval re-measure or 3)clinical daily ECG vigilance, if this last was normal, unchanged from basal or with new but stable conduction disturbances, discharge were indicated following ESC guidelines. A total of 41 patients were enrolled, median age 84±4 years, 24 females (54.5%), PR mean 198±42ms, QRS mean 112±30ms. 18 had a 1st degree AVB (40.9%) of whom 13 (72.5%) had a PR ˂240ms. EPS data showed prior HV interval mean of 55±9ms. A Mild abnormal HV interval (56-69ms) were seen in 21 patients (51.2%), of whom 12 had a narrow QRS. SEV implanted were 11 (25%) Medtronic CoreValve Evolut+, 5 (11.4%) Biosensors Allegra, 25 (56.8%) Abbott Navitor. Post TAVI procedure, 5 (12.2%) women and 8 (19.5%) men met criteria for PPM implantation before discharge. One woman was implanted 6 days after discharge due to high AVB (66ms HV interval prior TAVR). In a multivariate analysis including sex, age, PR, QRS and HV interval &amp;gt;55ms, valve type the RR (IC 95% 1.37-30.99) risk of PPM was 6.52 folds higher (p=0.019). Conclusions An HV interval &amp;gt;55ms before TAVI with SEV increases risk of PPM after TAVI and before hospital discharge. There was no difference in PPM implantation after TAVI between different SEV types in our center.

LBBAP versus conventional CRT reimplantation after transvenous lead extraction: report from a monocentric experience

Abstract Background Cardiac resynchronization therapy – defibrillator (CRT-D) reimplantation after transvenous lead extraction (TLE) can be challenging due to fibrotic remnants and absence of target veins. Left bundle branch area pacing (LBBAP) is emerging as an alternative to conventional CRT, but data is lacking about its feasibility after TLE. Purpose To explore the feasibility and safety of LBBAP as alternative to conventional CRT though epicardial pacing (EP) in patients undergoing CRT-D TLE. Methods We prospectively enrolled all patients admitted for complete CRT-D extraction and replacement from July 2022 to September 2023. At the moment of reimplantation, the choice between EP and LBBAP was made on the basis of posterolateral CS branches viability at post-extraction CS venography. Procedural success was defined as effective stimulation and absence of major complications while the primary endpoints were procedural time, QRS complex duration and electrical lead parameters. Patients undergoing LBBAP and EP reimplantation were compared. Results Twenty-six patients were enrolled (mean age 68.3 ± 7.2 years, p = 0.538; 12% females, p = 0.859). The most frequent cause of device extraction was pocket infection (58%, p = 0.773). Seventeen (65%, p = 0.783) patients had estimated high risk of procedural severe complications measured by EROS score. Overall, 80 leads were extracted. Mechanical extractors and snares were deemed necessary in 35 cases (43%, p = 0.917) and in 2 cases, respectively. Almost all patients (n=25, 96%) underwent right-sided reimplantation. Procedural success was achieved in 24 cases (92%). Compared to standard CRT through EP, LBBAP reimplantation accounted for a faster procedure (109.5 ± 34.2 vs. 126.5 ± 46.8 min; p = &amp;lt;0.001), less radiologic exposure (877.0 ± 234.6 vs. 1332.0 ± 515.1 sec, p &amp;lt;0.001) and better ventricular pacing thresholds (0.7± 0.1 vs. 1.8± 0.6 V, p &amp;lt;0.001). Despite a similar pre-extraction paced QRS duration (127.4 ± 13.8 vs. 133.0 ± 14.4 msec; p = 0.610), LBBAP reported significant improvement in final QRS duration (105.0 ± 13.1 vs. 127.1 ± 10.4 msec, p &amp;lt; 0.001) with major reduction in QRS duration (- 10.9 ± 7.5 vs - 6.8 ± 10.1, p &amp;lt; 0.001). Conclusion After a CRT TLE procedure, LBBAP reimplantation accounted for lower procedure duration, lower radiologic exposure, narrower QRS and lower ventricular pacing thresholds, demonstrating to be a valuable alternative to EP.

The effect of afterload on right ventricular pacing-induced left ventricular dysfunction: a translational study

Abstract Introduction Right ventricular (RV) pacing (RVP) impairs left ventricular (LV) function. Nevertheless, the interaction between arterial afterload and RVP-associated LV dysfunction has not been investigated yet. Purpose We sought to examine the effect of afterload on RVP-evoked LV hemodynamic changes in patients with aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) as well as in a small animal model of sustained LV pressure overload (PO). Methods Thirty-five patients with AS and a previously implanted pacemaker underwent detailed echocardiographic examination immediately before TAVI and also on the second postoperative day. The ultrasound measurements were carried out during intrinsic, narrow QRS rhythm and during frequency-matched RVP as well. Global myocardial work index (GMWI) was calculated to assess LV contractility. In parallel, LV pressure-volume analysis was performed in Wistar rats with transverse aortic constriction (TAC) or sham operation (Sham) during intrinsic narrow QRS rhythm (termed as TAC-Vsense and Sham-Vsense) as well as during RVP (termed as TAC-Vpace and Sham-Vpace). RVP was achieved in rats by an octopolar electrophysiology catheter placed in the RV. Results RVP decreased LV contractility in AS patients before and after TAVI as well. Nevertheless, the extent of RVP-evoked LV dysfunction was alleviated following pressure unloading (ΔGMWI: -37±7 vs. -25±8%, before TAVI vs. after TAVI, P&amp;lt;0.05). Similarly, although RVP was associated with reduced LV contractility in both the TAC (the slope of the maximum rate of LV pressure rise-end-diastolic volume relation [dPdtmax-EDV]: 92±8 vs. 53±6mmHg/s/µl, TAC-Vsense vs. TAC-Vpace; P&amp;lt;0.05) and Sham groups (dPdtmax-EDV: 74±5 vs. 60±9 mmHg/s/µl, Sham-Vsense vs. Sham-Vpace; P&amp;lt;0.05), the negative inotropic effect of RVP was found to be stronger in the TAC compared to the Sham group (ΔdPdtmax-EDV: -42±4 vs. -19±6%; TAC vs. Sham, P&amp;lt;0.01). Furthermore, reduction of the maximal rate of LV pressure decrease (ΔdPdtmin: -20±3 vs. -5±5%, TAC vs. Sham, P&amp;lt;0.01) and prolongation of the active relaxation time constant (Δτ: 22±3 vs. 6±3%, TAC vs. Sham, P&amp;lt;0.01) also occurred to a greater extent in case of sustained LV PO, indicating augmented diastolic dysfunction. Conclusion Our translational results indicate that RVP-induced LV dysfunction might be afterload dependent.

Dual-chamber CRT-D using ICD lead implantation in the LBBAP position

Abstract Background Interest in conduction system pacing (CSP) has increased in recent years. For left bundle branch area pacing (LBBAP), 4F and 6F pacing leads have been shown to be effective and safe. No information is available on the potential use of ICD leads for LBBAP. Aim The objective of the study was to demonstrate the feasibility of implanting an ICD lead in the LBBAP position to reduce the number of leads for CRT-D therapy. Patients and Methods We implanted the 7F ICD lead in the LBBAP position through a new 10F CSP delivery sheath in ten consecutive patients. Periprocedural data, QRS morphology and degree of QRS reduction were analyzed. Results Ten consecutive patients (one female) aged 69.5±9.2 years were treated with the above-mentioned method. Eight patients had ischemic cardiomyopathy and two patients had nonischemic cardiomyopathy. All patients had a CRT-D indication. Eight patients had a wide QRS complex with complete LBB and a QRS complex of 184.8±25.8 ms. Two patients had a narrow QRS complex but first-degree AV block with a PR interval greater than 240 ms. Left ventricular ejection fraction was 31.8±8.6%. Operative and fluoroscopy times were 103.6±30.3 minutes and 10.5±6.1 minutes, respectively. On average, 1.7 ± 0.6 screwing attempts were required per patient. The intraprocedural LBBAP threshold was 0.78±0.6V/1.0ms, the impedance was 530.8±86.5 ohm, and the R-wave amplitude was 9±3.3mV. The unipolar paced QRS complex was 123.6±15.9ms, the bipolar paced QRS complex was 129.5±12.8ms, and the bipolar paced QRS complex on the next day was 133.3±11.7. The mean duration from stimulus to R-wave peak in lead V6 was 82.9 ± 19.7 ms. The R-wave interpeak interval between leads V6 and V1 was 43.4 ± 9.7 ms. All but one patient received an effective defibrillation threshold test at 30J (n=8) and 36J (n=1). One patient was not tested during the procedure due to high risk. Conclusion This first-in-human study of ICD lead implantation in the LBBAP position demonstrated its feasibility and efficacy in achieving conduction system stimulation. This approach may lead to a reduction in the number of leads implanted for cardiac resynchronization therapy. Figure 1. A- RAO view, angiography of the RV for verification of the TVA-summit. B- LAO view, angiography from the CSP- sheath after reaching final position of the LBBAP lead (right sided interventricular septum - yellow dotted line). C – 12 lead ECG (speed 50mm/sec) demonstrating paced and native QRS complexes. D – Fluoroscopy in RAO view, final result. E – Fluoroscopy in LAO view, final result. F – Transthoracic echocardiography the next day (4Ch view) demonstrates optimal LBBAP lead position.. RAO – right anterior oblique; LAO – left anterior oblique; TVA – tricuspid valve anulus; CSP – conduction system pacing; LBBAP – left bundle branch area pacing.Figure 1.

Association of left ventricular ejection fraction improvement with prognosis in patients with cardiac sarcoidosis: insights from the ILLUMINATE-CS study

Abstract Introduction While the beneficial impact of enhancing left ventricular ejection fraction (LVEF) is well-documented in patients with heart failure with reduced LVEF, its relevance in cardiac sarcoidosis (CS) remains unclear. Purpose This study aimed to identify predictive factors for LVEF improvement and explore its association with prognosis in patients with CS. Methods A post-hoc analysis of the ILLUMINATE-CS registry, a retrospective observational study across multiple centers, was conducted. CS diagnosis adhered to either the 2016 Japanese Circulation Society guidelines or the 2014 Heart Rhythm Society expert consensus statement. Patients with baseline LVEF ≥50% were excluded in the current analysis. LVEF improvement was quantified as the variance between baseline and follow-up echocardiography. Patients were categorized into tertiles based on LVEF improvement: 1st tertile (≤0%, least improved), 2nd tertile (0–9%), and 3rd tertile (&amp;gt;9%, most improved) groups. The primary outcome was all-cause mortality after follow-up echocardiography. Results Among 188 enrolled patients (mean age 62.1±10.7 years; 42.6% male), 65, 60, and 63 were allocated to the 1st, 2nd, and 3rd tertile groups, respectively. Multivariate linear regression analysis revealed that narrower QRS duration, lower baseline LVEF, and absence of beta-blocker prescription at baseline were independently associated with greater LVEF improvement. Over a median follow-up of 407 days, 26 all-cause deaths occurred. Kaplan–Meier curves exhibited significant difference among the tertile groups (log-rank, P=0.002). Cox proportional hazard analysis, adjusted for possible prognostic factors including LVEF, demonstrated significantly higher mortality in the 1st and 2nd tertile groups compared to the 3rd tertile group (vs. 1st tertile: hazard ratio [HR] 22.14, 95% confidence interval [CI] 2.73–179.50, P=0.004; vs. 2nd tertile: HR 8.17, 95% CI 1.02–65.71, P=0.048). Additionally, treating LVEF improvement as a continuous variable revealed an independent association with increased mortality (LVEF improvement per 5%: HR 0.69, 95% CI 0.54–0.87, P=0.002). Conclusions Improvement LVEF in patients with CS is significantly associated with improved outcomes, highlighting its clinical importance in managing CS.Kaplan–Meier curves for all-cause death

Clinical case on the use of the Bimod Vet® on a Doberman Pinscher puppy with atrial fibrillation

Similarly as in people, the diagnosis of cardiac diseases in dogs typically relies on echocardiography and electrocardiography, examinations that are usually reserved to cardiologists. A new medical device (footnote: Bimod Vet®) acquiring the electrocardiogram and phonocardiogram of dogs simultaneously and processing them with built-in algorithms has been developed to assist general practitioners in the management of cases suggestive of suffering from a cardiac disorder. This article displays the use of this device in a 5-month-old Doberman Pinscher puppy referred to a cardiologist and eventually diagnosed with cardiomyopathy of dilated phenotype with atrial fibrillation of unknown origin.In this case, Bimod Vet® enabled to acquire some cardiorespiratory parameters highly suggestive of a cardiac disorder, in a fast and stress-free manner. The rhythm analysis performed by the software lead to a suspicion of atrial fibrillation, based on a rapid and irregular rhythm, narrow QRS complexes and absence of P wave on the electrocardiogram tracing. A systolic murmur was also detected and the respiratory rate was measured.The device Bimod Vet® can therefore assist veterinarians in the detection of several abnormalities suggestive of an underlying cardiac disorder.

Narrow QRS Regular Tachycardia With VA Dissociation: What Is the Mechanism?

Narrow QRS Regular Tachycardia With VA Dissociation: What Is the Mechanism?

A case of “regularly irregular” tachycardia with wide and narrow QRS complexes

A case of “regularly irregular” tachycardia with wide and narrow QRS complexes

What is the mechanism of this narrow QRS tachycardia in a patient with type-A Wolff-Parkinson-White (WPW) syndrome?

What is the mechanism of this narrow QRS tachycardia in a patient with type-A Wolff-Parkinson-White (WPW) syndrome?

Cardiac contractility modulation in heart failure with reduced ejection fraction patients with QRS duration 120–149 ms: Reduction in heart failure hospitalizations and improvement in functional outcome

BackgroundA subset of heart failure (HF) patients qualifies for cardiac resynchronization therapy (CRT). However, a 30% CRT nonresponder rate persists, with patients having narrower QRS durations (ie, QRSd 120–149 ms) receiving less or inconsistent benefit. Cardiac contractility modulation (CCM) may be an important alternative therapy option but has largely been evaluated only in HF patients with QRSd <120 ms. ObjectivesThe purpose of this study was to evaluate the impact of CCM on HF-related hospitalizations and on left ventricular ejection fraction (LVEF) as well as quality of life in HF patients with QRSd 120–149 ms compared to QRSd <120 ms. MethodsThe CCM-REG Registry enrolled 503 HF patients with follow-up up to 2 years. Hospitalization rates were available for 1 year preimplant. Safety was assessed by comparison of actual vs Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) score– or Seattle Heart Failure Model (SHFM)–predicted mortality. ResultsAmong 111 of 455 subjects with QRSd 120–149 ms (mean QRSd 130 ± 8 ms; age 68 ± 10 years; 20% female; LVEF 29% ± 9%; 82% New York Heart Association [NYHA] class III), CCM diminished HF-related hospitalization rate by 72% (pre- vs postimplant 0.90 vs 0.25 events per patient-year over 2 years; P <.001). LVEF improved by 7% ± 8% (P = .01 vs baseline), Minnesota Living with Heart Failure Questionnaire score by 10 ± 23 points (P = .01 vs baseline), and NYHA class by 0.5 ± 0.7 classes (<0.001 vs baseline). The effect size was similar to that in QRSd <120 ms patients. Mortality within the first year was 19% in QRSd 120–149 ms patients (ie, not significantly different from the MAGGIC score or SHFM prediction). ConclusionsCCM significantly improved HF control in NYHA class III HF with reduced ejection fraction patients with moderately prolonged QRSd 120–149 ms. The effect was similar to that in patients with QRSd <120 ms.

Comparison of clinical and echocardiographic outcomes between left bundle branch area pacing and right ventricular pacing in older patients.

Left bundle branch area pacing (LBBAP) is safe and effective, but studies in older patients are lacking. This study compared the clinical and echocardiographic outcomes of LBBAP and right ventricular pacing (RVP) in patients aged ≥75 years. This prospective observational study included older patients with symptomatic bradycardia who underwent LBBAP or RVP between 2019 and 2022. Clinical data, including pacing and electrophysiological characteristics, echocardiographic measurements, and device-related complications were collected. The primary endpoint was a composite of all-cause mortality, heart failure hospitalization, and upgrade to biventricular pacing. Secondary outcomes included changes in left ventricular ejection fraction (LVEF). Of 267 included patients, 110 underwent LBBAP and 157 underwent RVP. LBBAP was successful in 109 patients (success rate: 99.1%), with one patient eventually undergoing RVP. The pacing parameters of LBBAP were similar to those of RVP, except for a significantly narrower paced QRS duration (112.8±11.6vs. 138.3±23.9ms, p<.001). Ventricular lead implanting procedural duration was longer for LBBAP than RVP (14.0vs. 6.0min, p<.001), as was the fluoroscopy time (4.0vs. 2.0min, p<.001). During a mean follow-up period of 31.0±16.8 months, the primary outcome incidence was significantly lower following LBBAP than RVP (15.1%vs. 21.1%; hazard ratio, 0.471; 95% confidence interval, 0.215-1.032; p=.036) in 149 patients (55.8%) with ventricular pacing burden>20%. RVP reduced LVEF from 62.7±4.1% at baseline to 59.8±7.8% at the final follow-up (p=.001), whereas LBBAP preserved LVEF (61.4±6.3%vs. 60.1±7.4%, p=.429). LBBAP demonstrated improved clinical outcomes compared with RVP and maintained LVEF in older patients with high ventricular pacing burdens.

Diagnosis of Narrow QRS Tachycardia

Narrow QRS tachycardia is a common clinical condition characterized by a heart rate exceeding 100 beats per minute and a QRS complex duration of less than 120 ms. This article provides an overview of the diagnostic approach to narrow QRS tachycardia, focusing on the differentiation between various supraventricular tachycardias, such as atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), atrial tachycardia (AT), and sinus tachycardia. The discussion includes an analysis of the presenting symptoms, electrocardiographic (ECG) findings, and the use of vagal maneuvers and pharmacological agents in diagnosis.

Conflicting responses with simultaneous atrioventricular pacing. What is the mechanism?

A 60-year-old woman presented with recurrent episodes of palpitations, documented short RP, narrow QRS tachycardia and absence of preexcitation in the electrocardiogram during sinus rhythm. During an electrophysiology study, programmed stimulation induced a narrow QRS tachycardia with cycle length of 380 ms, VA interval of 164 ms and earliest atrial activation in the His region. Ventricular overdrive pacing failed to entrain the atrium even with isoprenaline infusion and atrial burst pacing repeatedly terminated the tachycardia. Difference in AH interval with pacing and SVT was 27 msec. Simultaneous atrial and ventricular pacing was done with atrial pacing from the high right atrium and showed a His signal as the first return electrogram suggestive of atrioventricular nodal reentrant tachycardia (AVNRT). The manoeuvre was repeated with atrial pacing from the proximal coronary sinus and showed an atrial signal as the first return electrogram suggestive of atrial tachycardia (AT). What is the explanation for the conflicting results of the two pacing maneuvers?