JACC. Clinical electrophysiology最新文献

Background: Atrial conduction velocity (CV) is influenced by autonomic tone and contributes to the pathophysiology of re-entrant arrhythmias and atrial fibrillation. Cardiac sympathetic nerve activation has been reported via electrical stimulation within the vertebral vein (VV).

Objectives: This study sought to characterize changes in right atrial (RA) CV associated with sympathetic stimulation from pharmacologic (isoproterenol) or direct electrical (VV stimulation) approaches.

Methods: Subjects undergoing catheter ablation for atrial fibrillation had baseline RA electroanatomic maps performed in sinus rhythm (SR). RA mapping was repeated during right VV stimulation (20 Hz; up to 20 mA) and again with both RA pacing and during isoproterenol infusion, each titrated to the heart rate achieved with VV stimulation.

Results: A total of 100 RA maps were analyzed from 25 subjects (mean age: 58 ± 14 years; 56% male), and CV was calculated from 51,534 electroanatomic map points. VV stimulation increased heart rate from baseline in all subjects (22.5 ± 5.5 beats/min). The average CV increased with VV stimulation (82.0 ± 34.5 cm/s) or isoproterenol (83.7 ± 35.0 cm/s) when compared to SR (70.8 ± 32.5 cm/s; P < 0.001). Heterogeneity of CV decreased with VV stimulation or isoproterenol when compared to SR (coefficient of variation: 0.33 ± 0.21 vs 0.35 ± 0.23 vs 0.57 ± 0.29; P < 0.001). There was no difference in CV or CV heterogeneity between SR and RA pacing, suggesting that these changes were independent of heart rate.

Conclusions: Global RA CV is enhanced, and heterogeneity of CV is reduced, with either pharmacologic or direct electrical sympathetic stimulation via the right VV.

Background: Artificial intelligence-enhanced electrocardiogram (AI-ECG) analysis shows promise to predict mortality in adults with acquired cardiovascular diseases. However, its application to the growing repaired tetralogy of Fallot (rTOF) population remains unexplored.

Objectives: This study aimed to develop and externally validate an AI-ECG model to predict 5-year mortality in rTOF.

Methods: A convolutional neural network was trained on electrocardiograms (ECGs) obtained at Boston Children's Hospital and tested on Boston (internal testing) and Toronto (external validation) INDICATOR (International Multicenter TOF Registry) cohorts to predict 5-year mortality. Model performance was evaluated on single ECGs per patient using area under the receiver operating (AUROC) and precision recall (AUPRC) curves.

Results: The internal testing and external validation cohorts comprised of 1,054 patients (13,077 ECGs at median age 17.8 [Q1-Q3: 7.9-30.5] years; 54% male; 6.1% mortality) and 335 patients (5,014 ECGs at median age 38.3 [Q1-Q3: 29.1-48.7] years; 57% male; 8.4% mortality), respectively. Model performance was similar during internal testing (AUROC 0.83, AUPRC 0.18) and external validation (AUROC 0.81, AUPRC 0.21). AI-ECG performed similarly to the biventricular global function index (an imaging biomarker) and outperformed QRS duration. AI-ECG 5-year mortality prediction, but not QRS duration, was a significant independent predictor when added into a Cox regression model with biventricular global function index to predict shorter time-to-death on internal and external cohorts. Saliency mapping identified QRS fragmentation, wide and low amplitude QRS complexes, and flattened T waves as high-risk features.

Conclusions: This externally validated AI-ECG model may complement imaging biomarkers to improve risk stratification in patients with rTOF.

Idiopathic ventricular fibrillation (IVF) is an unrefined diagnosis representing a heterogeneous patient group without a structural or genetic definition. IVF treatment is not mechanistic-based due to the lack of experimental patient-models. We sought to create a methodology to assess cellular arrhythmia mechanisms for IVF as a proof-of-concept study. Using IVF patient-specific induced pluripotent stem cell-derived cardiomyocytes, we integrate electrophysiological optical mapping with computational modeling to characterize the cellular phenotype. This approach flips the traditional paradigm using a biophysically detailed computational model to solve the problem inversely. Insight into the cellular mechanisms of this patient's IVF phenotype could also serve as a therapeutic testbed.

Background: Patients with repaired tetralogy of Fallot (rTOF) have a time-dependent increased risk of ventricular tachycardia (VT). Slow conducting anatomical isthmuses (SCAIs) are the dominant VT substrates in adults with rTOF. It is unknown if they are present at younger age.

Objectives: This study aimed to characterize VT substrates in patients with rTOF <30 years of age.

Methods: Data of consecutive patients with rTOF aged <30 years who underwent electroanatomical mapping and programmed electrical stimulation between 2005 and 2022 were analyzed.

Results: Fifty-five patients were included (median age: 15.8 years, IQR: 13.8-21.8 years; 15 repaired via ventriculotomy; 13 complex TOF variants). Twelve patients had right ventricle-to-pulmonary artery conduits inserted during initial repair or had early pulmonary valve replacement (PVR) (<1 year after repair). Indications for electroanatomical mapping and programmed electrical stimulation were spontaneous VT, before PVR, and risk stratification in 5, 40, and 10 patients, respectively. In 16 patients (29%), SCAI 3 was identified; no other SCAI was present. Monomorphic VT was inducible in 8 and related to SCAI 3 in 7 patients. Identified VT substrates were targeted by ablation. Right ventricle-to-pulmonary artery conduit/early PVR, ventriculotomy, and complex TOF were associated with SCAI 3 in univariable analysis. During a median follow-up of 5.3 years, VT recurred in 2 patients. No patients died.

Conclusions: In young patients with rTOF, SCAI 3 is the dominant substrate for VT. Complex TOF and interrelated type and timing of (re-)operation may contribute to the development of SCAI 3 already at a young age.