The Nottingham Ischaemic Cardiovascular Magnetic Resonance resource (NotIs CMR): a prospective paired clinical and imaging scar database-protocol.

INTRODUCTION: Research utilising artificial intelligence (AI) and cardiovascular magnetic resonance (CMR) is rapidly evolving with various objectives, however AI model development, generalisation and performance may be hindered by availability of robust training datasets including contrast enhanced images. METHODS: NotIs CMR is a large UK, prospective, multicentre, observational cohort study to guide the development of a biventricular AI scar model. Patients with ischaemic heart disease undergoing clinically indicated contrast-enhanced cardiac magnetic resonance imaging will be recruited at Nottingham University Hospitals NHS Trust and Mid-Yorkshire Hospital NHS Trust. Baseline assessment will include cardiac magnetic resonance imaging, demographic data, medical history, electrocardiographic and serum biomarkers. Participants will undergo monitoring for a minimum of 5 years to document any major cardiovascular adverse events. The main objectives include (1) AI training, validation and testing to improve the performance, applicability and adaptability of an AI biventricular scar segmentation model being developed by the authors and (2) develop a curated, disease-specific imaging database to support future research and collaborations and, (3) to explore associations in clinical outcome for future risk prediction modelling studies. CONCLUSION: NotIs CMR will collect and curate disease-specific, paired imaging and clinical datasets to develop an AI biventricular scar model whilst providing a database to support future research and collaboration in Artificial Intelligence and ischaemic heart disease.

Avoiding inappropriate therapy of single-lead implantable cardioverter-defibrillator by using atrial-sensing electrodes.

INTRODUCTION: The single-chamber implantable cardioverter-defibrillator (ICD) can be associated with more frequent inappropriate therapies compared with dual-chamber ICDs, when they are accompanied by a simpler implantation procedure. The aim of this study was to investigate whether the use of a single-lead ICD system with atrial-sensing electrodes results in a reduction of inappropriate ICD therapy. METHODS AND RESULTS: The study population consisted of 212 consecutive patients, who underwent primary prophylactic single-lead ICD implantation at our institute. A ventricular lead with atrial-sensing electrodes was implanted in 77 patients (36%; Group-VDD) and a ventricular lead without atrial-sensing electrodes was implanted in 135 patients (64%; Group-VVI). Procedural and follow-up data were collected in a prospective registry. A higher prevalence of atrial fibrillation was present in Group-VDD. There were no other significant differences in patient baseline characteristics (age, sex, and other comorbidities) or follow-up period between the two groups. The operative parameters including fluoroscopic burden showed no significant differences between Group-VDD and Group-VVI. During a mean follow-up period of 697 ± 392 days, 26 patients (12%) experienced appropriate ICD therapies and 13 patients (6%) suffered inappropriate ICD therapies. The incidence of inappropriate ICD therapies in Group-VDD was significantly lower as compared to that of Group-VVI (1/77 [1%] vs 12/135 [9%]; log-rank, P = 0.028). The incidence of appropriate ICD therapies and the occurrence of device-related complications showed no significant difference between the two groups. CONCLUSION: Single-lead ICD with atrial-sensing electrodes shows a lower incidence of inappropriate ICD therapy compared with the absence of atrial-sensing electrodes, without additional operative burden or increased complications.

Hybrid surgical epicardial cryoablation for ventricular tachycardia in the electrophysiology laboratory: a case report.

Background: Scar-related ventricular tachycardia (VT) is a challenging medical condition, with catheter ablation providing a valuable treatment option. Whilst most VTs can be ablated endocardially, epicardial ablation is often required in patients with non-ischaemic cardiomyopathy. The percutaneous subxiphoid technique has become instrumental for epicardial access. However, it is not feasible in up to 28% of cases for multiple reasons. Case summary: A 47-year-old patient was managed at our centre for VT storm and recurrent implantable cardioverter defibrillator shocks for monomorphic VT despite maximum drug therapy. No scar was noted during endocardial mapping, with confirmation of the localized epicardial scar on cardiac magnetic resonance imaging (CMR). Following failed percutaneous epicardial access, a successful hybrid surgical epicardial VT cryoablation via median sternotomy was performed in the electrophysiology (EP) laboratory utilizing data from CMR, prior endocardial ablation, and conventional EP mapping. The patient has remained arrhythmia-free for 30 months post-ablation without antiarrhythmic therapy. Discussion: This case describes a practical multidisciplinary approach to managing a challenging clinical problem. Whilst the described technique is not entirely novel, this is the first case report that describes the practicalities and demonstrates the safety and feasibility of hybrid epicardial cryoablation via median sternotomy performed in the cardiac EP laboratory for the sole treatment of VT.

Diagnostic utility of artificial intelligence for left ventricular scar identification using cardiac magnetic resonance imaging-A systematic review.

Background: Accurate, rapid quantification of ventricular scar using cardiac magnetic resonance imaging (CMR) carries importance in arrhythmia management and patient prognosis. Artificial intelligence (AI) has been applied to other radiological challenges with success. Objective: We aimed to assess AI methodologies used for left ventricular scar identification in CMR, imaging sequences used for training, and its diagnostic evaluation. Methods: Following PRISMA recommendations, a systematic search of PubMed, Embase, Web of Science, CINAHL, OpenDissertations, arXiv, and IEEE Xplore was undertaken to June 2021 for full-text publications assessing left ventricular scar identification algorithms. No pre-registration was undertaken. Random-effect meta-analysis was performed to assess Dice Coefficient (DSC) overlap of learning vs predefined thresholding methods. Results: Thirty-five articles were included for final review. Supervised and unsupervised learning models had similar DSC compared to predefined threshold models (0.616 vs 0.633, P = .14) but had higher sensitivity, specificity, and accuracy. Meta-analysis of 4 studies revealed standardized mean difference of 1.11; 95% confidence interval -0.16 to 2.38, P = .09, I2 = 98% favoring learning methods. Conclusion: Feasibility of applying AI to the task of scar detection in CMR has been demonstrated, but model evaluation remains heterogenous. Progression toward clinical application requires detailed, transparent, standardized model comparison and increased model generalizability.

Clinical impact of "pure" empirical catheter ablation of slow-pathway in patients with non-ECG documented clinical on-off tachycardia.

BACKGROUND: Catheter ablation of slow-pathway (CaSP) has been reported to be effective in patients with dual atrioventricular nodal conduction properties (dcp-AVN) and clinical ECG documentation but without the induction of tachycardia during electrophysiological studies (EPS). However, it is unknown whether CaSP is beneficial in the absence of pre-procedural ECG documentation and without the induction of tachycardia during EPS. The aim of this study was to evaluate long-term results after a "pure" empirical CaSP (peCaSP). METHODS: 334 consecutive patients who underwent CaSP (91 male, 47.5 ± 17.6 years) were included in this study. Sixty-three patients (19%) who had no pre-procedural ECG documentation, and demonstrated dcp-AVN with a maximum of one echo-beat were assigned to the peCaSP group. The remaining 271 patients (81%) were assigned to the standard CaSP group (stCaSP). Clinical outcomes of the two groups were compared, based on ECG documented recurrence or absence of tachycardia and patients' recorded symptoms. RESULTS: CaSP was performed in all patients without any major complications including atrioventricular block. During follow-up (909 ± 435 days), 258 patients (77%) reported complete cessation of clinical symptoms. There was no statistically significant difference in the incidence of AVNRT recurrence between the peCaSP and stCaSP groups (1/63 [1.6%] vs 3/271 [1.1%], P = 0.75). Complete cessation of clinical symptoms was noted significantly less frequently in patients after peCaSP (39/63 [62%] vs 219/271 [81%], P = 0.0013). The incidence of non-AVNRT atrial tachyarrhythmias (AT) was significantly higher in patients after peCaSP (5/63 [7.9%] vs 1/271 [0.4%], P = 0.0011). CONCLUSION: A higher incidence of other AT and subjective symptom persistence are demonstrated after peCaSP, while peCaSP improves clinical symptoms in 60% of patients with non-documented on-off tachycardia.