Artificial Intelligence in the Diagnosis and Management of Arrhythmias

Venkat D. Nagarajan; Su-Lin Lee; Jan-Lukas Robertus; Christoph A. Nienaber; Natalia A. Trayanova; Sabine Ernst

Disclosures

Eur Heart J. 2021;42(38):3904-3916. 

In This Article

Multimodal Integrative Approach to Predict Sites of Arrhythmia Origins and Role of Machine Learning

Non-invasive characterization of arrhythmia prior to attempting ablative therapy is gaining favour amongst electrophysiologists. This approach aids in focused targeting of the cardiac region of interest. One of the important contributors to this being ML aided advances in cardiac 3D imaging.

Application of DL methods including convolutional neural network has improved the speed of acquisition,[45] time efficiency, reconstruction quality of images,[46,47] and accuracy of cardiac magnetic resonance (CMR) segmentation.[48,49] Machine learning techniques have been applied to improve myocardial tissue characterization and texture analysis[50,51] and define the heterogeneous nature of the scarred myocardium in late gadolinium enhancement (LGE) CMR images in patients post-myocardial infarction.[52]

Automated CMR analysis using a convolutional neural network algorithm was shown to be similar in precision to human analysis for measuring left ventricular ejection fraction and left ventricular mass but was 186 times faster.[53]

In a proof of concept study, Fahmy et al. used U-Net deep convoluted networks with 150 operational layers to quantify scar volumes in patients with HCM. A strong correlation was observed between the manually and automatically segmented scar volumes.[54]

Cardiac magnetic resonance-defined scar regions have gained considerable importance and form the basis of some of the ablation strategies including scar homogenization and scar de-channelling in ventricular tachycardia (VT) ablation. These advancements have also paved the way for the concept of targeting fibrotic substrate that can perpetuate rotors, in addition to pulmonary vein isolation in patients with persistent AF.

Advances of ML-aided imaging[55] have set the stage for the development of several novel concepts in EP including non-invasive localization of arrhythmia foci with high precision, personalized virtual heart modelling including simulation of cardiac arrhythmias and concept of non-invasive ablation.

In parallel with developments in cardiac imaging, further advancements have been made in ECG acquisition with the development of body surface mapping (using up to 252 electrodes instead of standard 12 leads). Electrocardiography imaging systems that integrate body surface mapping with non-contrast computed tomography (CT) that simultaneously records electrode location and geometry of cardiac surface can localize focal activation of atrial or ventricular ectopy on the 3D reconstruction of the patient's heart using an inverse solution approach.

The Amycard 01C (EP Solutions SA, Yverdon-les-Bains, Switzerland)[56] and ECVUE (CardioInsight Technologies Inc., Cleveland, OH, USA)[57] systems are now commercially available and are able to locate atrial and ventricular arrhythmias. As they provide a simultaneous, quasi global view of the entire atrial or ventricular activation, these systems allow to visualize even AF. Using this technique, focal trigger and rotor sites are identified, which is impossible using the conventional sequential mapping techniques (Figure 4, left).

Figure 4.

Left panel: Example of non-invasive simultaneous mapping of atrial fibrillation of both the right and left atrium using the electrocardiogram imaging technology. Several mechanisms occur in various areas of the atria simultaneously and thereby maintain atrial fibrillation. Right panel: Example of non-invasive simultaneous mapping of ventricular ectopy using the view into ventricular onset technology.

View into ventricular onset (VIVO, Catheter Precision) is a next-generation non-invasive mapping system that combines knowledge of the exact location of the surface 12-lead ECG stickers with carefully reconstructed cardiac anatomy from either CMR or CT imaging (Figure 4, right). With the VIVO platform, prediction of the focus of premature ventricular electrical activity and VT focus is correct in 85% and 88% of patients, respectively.[58]

Using a multimodal integrative approach, feasibility of combining body surface mapping, cardiac gated multidetector CT, and/or delayed contrast-enhanced magnetic resonance (MR) imaging on a common platform is shown in Figure 5 (right); this approach was useful in understanding complex accessory pathway previously resistant to ablation and to identify rotor trajectories in patients with AF.[59]

Figure 5.

Left panel: 3D image information from computed tomography and myocardial thickness in a patient with coronary artery disease and apical scar after myocardial infarction. Middle panel: Image information of late gadolinium enhancement from cardiac magnetic resonance imaging of the left ventricle with identification of the potentially arrhythmogenic channels within the scar responsible for ventricular re-entrant tachycardia. Right panel: Example of perfusion information from functional nuclear imaging superimposed on a contrast computed tomography scan in a patient with arrhythmogenic right ventricular disease. Ao, aorta; CMR, cardiac magnetic resonance; LA, left atrium; LGE, late gadolinium enhancement; LV, left ventricle; RV, right ventricle.

Software (Automatic Detection of Arrhythmic Substrate, ADAS-VT, Galgo Medical SL, Barcelona, Spain), which processes LGE CMR images offline to characterize 3D scar architecture to be merged with electro anatomical mapping (EAM) during the ablation procedure, has been shown to facilitate the ablation procedure[60] (Figure 5, left).

With the development of methods for non-invasive localization of arrhythmia focus, several groups have reported on their experience of using radiation therapy in patients with mostly ischaemic ventricular arrhythmia.[61–65] Robinson et al.[66] reported successful utilization of radiotherapy in a cohort of patients with treatment-refractory episodes of VT or cardiomyopathy related to premature ventricular contractions. They identified scar regions using ECG imaging, cardiac anatomical imaging and delivered Focused stereotactic body radiation therapy (SBRT) with marked reduction in arrhythmia burden, reduced use of anti-arrhythmic medication and improved quality of life following therapy. Overall survival was 89% and 72% at the end of 6 and 12 months, respectively.

In addition, first-in-man treatment of paroxysmal AF using SBRT in two patients has been reported[67] with the demonstration of safety and efficacy of delivering SBRT lesion set in the left atrium confirmed by presence of fibrosis. Results from these initial pilot studies and case reports are encouraging. However, more robust data are required from larger clinical trials with longer follow-up to show long-term safety of these techniques, which are of great interest but still under evaluation.

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