Improvement in electrocardiographic parameters of repolarization related to sudden death in patients with ventricular dysfunction and left bundle branch block after cardiac resynchronization through His bundle pacing.

BACKGROUND: Cardiac resynchronization therapy (CRT) through permanent His bundle pacing (p-HBP) normalizes interventricular conduction disorders and QRS. Similarly, there are immediate and long-term changes in repolarization, which could be prognostic of a lower risk of sudden death (SD) at follow-up. We aimed to compare the changes in different electrocardiographic (ECG) repolarization parameters related to the risk of SD before and after CRT through p-HBP. METHODS: In this prospective, descriptive single-center study (May 2019 to December 2021), we compared the ECG parameters of repolarization related to SD in patients with non-ischemic dilated cardiomyopathy, left bundle branch block (LBBB), and CRT indications, at baseline and after CRT through p-HBP. RESULTS: Forty-three patients were included. Compared to baseline, after CRT through p-HBP, there were immediate significant changes in the QT interval (ms): 445 [407.5-480] vs 410 [385-440] (p = 0.006), QT dispersion (ms): 80 [60-100] vs 40 [40-65] (p < 0.001), Tp-Te (ms): 90 [80-110] vs 80 [60-95] (p < 0.001), Tp-Te/QT ratio: 0.22 [0.19-0.23] vs 0.19 [0.16-0.21] (p < 0.001), T wave amplitude (mm): 6.25 [4.88-10] vs - 2.5 [- 7-2.25] (p < 0.001), and T wave duration (ms): 190 [157.5-200] vs 140 [120-160] (p = 0.001). In the cases of the corrected QT (Bazzett and Friederichia) and the Tp-Te dispersion, changes only became significant at 1 month post-implant (468.5 [428.8-501.5] vs 440 [410-475.25] (p = 0.015); 462.5 [420.8-488.8] vs 440 [400-452.5] (p = 0.004), and 40 [30-52.5] vs 30 [20-40] (p < 0.001), respectively) (Table 1). Finally, two parameters did not improve until 6 months post-implant: the rdT/JT index, 0.25 [0.21-0.28] baseline vs 0.20 [0.19-0.23] 6 months post-implant (p = 0.011), and the JT interval, 300 [240-340] baseline vs 280 [257-302] 6 months post-implant (p = 0.027). Additionally, most of the parameters continued improving as compared with immediate post-implantation. CONCLUSIONS: After CRT through His bundle pacing and LBBB correction, there was an improvement in all parameters of repolarization related to increased SD reported in the literature.

His bundle pacing success and electrical parameter stability regardless of three-dimensional transthoracic echocardiography lead localization.

BACKGROUND OR PURPOSE: His bundle pacing (HBP) is the most physiological form of ventricular pacing. Few prospective studies have analyzed lead localization using imaging techniques and its relationship with electrical parameters and capture patterns. The objective of this study is to examine the correlation between electrical parameters and lead localization using three-dimensional transthoracic echocardiography (3D TTE). METHODS: This single-center, prospective, nonrandomized clinical research study (January 2018 to June 2020) included patients with an indication of permanent pacing, in whom 3D TTE was performed to define lead localization as supravalvular or subvalvular. RESULTS: A total of 92 patients were included: 56.5% of leads were supravalvular, and 43.5% were subvalvular, which resembles previous anatomic descriptions of autopsied hearts of His bundle localization within the triangle of Koch (ToK). R-wave sensing was higher when the His lead was localized subvalvular instead of supravalvular. His lead localization was not associated with HBP threshold or impedance differences, nor with the two different HBP patterns of capture, or with the ability of HBP to correct baseline BBB. The thresholds remained stable during follow-up visits, regardless of His lead localization. Higher R-wave sensing was observed during follow-up than at baseline, mainly in the subvalvular His leads. However, lead impedances in both positions decreased during follow-up. CONCLUSIONS: Lead localization in relation to the tricuspid valve did not influence the electrical performance of HBPs. Wide anatomical variations of the His bundle within the ToK explain our findings, reinforcing the idea that the technique for HBP should be fundamentally guided by electrophysiological and not anatomical parameters.

Cardiac resynchronization therapy in non-ischemic cardiomyopathy: a comparative non-randomized study of His Bundle pacing versus biventricular pacing.

BACKGROUND: Cardiac resynchronization therapy (CRT) via permanent His bundle pacing (pHBP) has gained acceptance globally, but robust studies comparing pHBP-CRT with classic CRT are lacking. In this study, we aimed to compare the improvement in left ventricular ejection fraction (LVEF) after pHBP-CRT versus classic CRT. METHODS: This was a single-center study comparing a prospective series of pHBP-CRT with a historical series of CRT via classic biventricular pacing (BVP). Patients with non-ischemic cardiomyopathy, baseline LVEF < 35%, left bundle branch block (LBBB), and CRT indications were selected. RESULTS: Fifty-one patients underwent classic CRT and 52 patients underwent pHBP-CRT. In the classic CRT group, the median (interquartile range) basal LVEF was 30% (IQR, 29-35%) before implantation and 40% (35-48%) at follow-up. In the pHBP-CRT group, the median basal LVEF was 30% (28-34%) before implantation and 55% (45-60%) at follow-up, with significant differences between both modalities at follow-up (p = 0.001). The median long term His recruitment threshold with LBBB correction was 1.25 (1-2.5) V at 0.4 ms in cases of pHBP-CRT, compared to a left ventricular coronary sinus threshold of 1.25 (1-1.75) V in cases of classic CRT (p = 0.48). After CRT, the median paced QRS was 135 (120-145) ms for pHBP-CRT versus 140 (130-150) ms for BVP-CRT (p = 0.586). CONCLUSIONS: The improvement in LVEF was superior with pHBP-CRT than with classic CRT. The thresholds at follow-up were similar in both groups.

Magnetic resonance imaging in patients with cardiac implantable electronic devices: A prospective study.

BACKGROUND: The number of patients with cardiac implantable electronic devices in whom magnetic resonance imaging (MRI) is indicated is constantly increasing. The potential risk of electromagnetic interference has limited its use and it is still contraindicated by the Food and Drug Administration in some cases. The aim of this study is to evaluate the safety and efficacy of MRI in these patients. METHODS: A prospective registry comprising patients with a pacemaker (PM) or implantable cardioverter-defibrillator (ICD), MRI-conditional or not, who were candidates for MRI (at 1.5 T) with no suitable alternative diagnostic technique. All devices were programmed before the procedure and patients were monitored throughout the test. Clinical, electrical, and technical parameters were evaluated before and after MRI. RESULTS: 147 MRI examinations (132 PM and 15 ICD) were performed. There were no clinical events or significant differences in the electrical parameters of the leads after MRI. A variation in the impedance of the ventricular leads was detected, although the difference was not clinically relevant. In one patient with a PM, a failure in release of the safety impulse was detected in the auto-threshold test, although the threshold was correctly determined. In 11 of the 17 thoracic MRIs, image artifacts were detected, preventing the diagnosis in two of them. CONCLUSIONS: In patients with cardiac implantable electronic devices, MRIs performed under a specific protocol has been shown to be safe in the short term even in the thoracic region, as well as interpretable in most cases.

Predictores de fibrilación auricular en pacientes con ictus embólico de origen indeterminado / Atrial fibrillation predictors in patients with embolic stroke of undetermined source

Antecedentes y objetivos: En el accidente cerebrovascular embólico de origen indeterminado (ESUS) la detección de fibrilación auricular (FA) conlleva un cambio de tratamiento y una reducción drástica en la incidencia de nuevos ictus. Es necesario determinar qué pacientes se benefician en mayor medida de una monitorización electrocardiográfica prolongada. Nuestro objetivo fue la búsqueda de predictores electrocardiográficos y ecocardiográficos de FA en pacientes con ESUS.Materiales y métodosSe diseñó un estudio observacional de cohortes en el que se incluyeron 95 pacientes consecutivos que ingresaron por ESUS en un hospital terciario. A todos se les realizó un electrocardiograma (ECG), un Holter electrocardiograma (Holter-ECG) de 24h y un ecocardiograma durante el ingreso. Se realizó un seguimiento presencial durante 2años mediante Holter-ECG de 24h, trimestral durante el primer año y semestral durante el segundo.ResultadosDurante el seguimiento se detectó FA en 11 pacientes (11,6%), siendo la tasa detección del 3,2% a los 6meses, del 7,4% a los 12meses y del 11,6% a los 18 y a los 24meses. Las variables que se relacionaron de forma independiente con el desarrollo de FA fueron la dilatación en grado moderado o severo de la aurícula izquierda (AI) (p=0,02), el bloqueo interauricular avanzado (BIA-A) (p=0,04) y la presencia de más de 1.000 extrasístoles auriculares (EA) en Holter-ECG de 24h (p=0,01).ConclusionesLa dilatación en un grado moderado o severo de AI, el BIA-A y la presencia de más de 1.000 EA en Holter-ECG de 24h se comportan como predictores independientes de FA en pacientes con ESUS. (AU)

Background and objectives: Atrial fibrillation (AF) detection in patients with embolic stroke of underdetermined source (ESUS) entails a change of medical treatment and a significant decrease in the incidence of new strokes. It is necessary to determine which patients would benefit more from prolonged electrocardiographic monitoring. Our aim was to find electrocardiographic and echocardiographic AF predictors in patients with ESUS.MethodsWe performed a cohort study that included 95 consecutive patients admitted to the hospital because of an ESUS. An electrocardiogram, each subject in the study underwent a 24-hour Holter-electrocardiogram (Holter-ECG) and an echocardiogram. A 2-year follow up was also conducted, with a 24-hour Holter-ECG every 3months for the first year, and every 6months during the second one.ResultsDuring the follow-up, AF was detected in 11 patients (11.6%), with a detection rate of 3.2% at 6months, 7.4% at 12months, and 11.6% at 18months as well as at 24months. The variables that were independently related to AF detection included moderate or severe left atrium dilation (P=.02), interatrial advanced block (P=.04) and more than 1000 premature atrial beats on 24-hour Holter-ECG (P=.01).ConclusionsModerate or severe atrial dilation, interatrial advanced block, and the presence of more than 1000 premature atrial beats on 24-hour Holter-ECG behave as AF predictors in patients with ESUS. (AU)

[Atrial fibrillation predictors in patients with embolic stroke of undetermined source]. / Predictores de fibrilación auricular en pacientes con ictus embólico de origen indeterminado.

BACKGROUND AND OBJECTIVES: Atrial fibrillation (AF) detection in patients with embolic stroke of underdetermined source (ESUS) entails a change of medical treatment and a significant decrease in the incidence of new strokes. It is necessary to determine which patients would benefit more from prolonged electrocardiographic monitoring. Our aim was to find electrocardiographic and echocardiographic AF predictors in patients with ESUS. METHODS: We performed a cohort study that included 95 consecutive patients admitted to the hospital because of an ESUS. An electrocardiogram, each subject in the study underwent a 24-hour Holter-electrocardiogram (Holter-ECG) and an echocardiogram. A 2-year follow up was also conducted, with a 24-hour Holter-ECG every 3months for the first year, and every 6months during the second one. RESULTS: During the follow-up, AF was detected in 11 patients (11.6%), with a detection rate of 3.2% at 6months, 7.4% at 12months, and 11.6% at 18months as well as at 24months. The variables that were independently related to AF detection included moderate or severe left atrium dilation (P=.02), interatrial advanced block (P=.04) and more than 1000 premature atrial beats on 24-hour Holter-ECG (P=.01). CONCLUSIONS: Moderate or severe atrial dilation, interatrial advanced block, and the presence of more than 1000 premature atrial beats on 24-hour Holter-ECG behave as AF predictors in patients with ESUS.