Ventricular tachycardia (VT), which can lead to sudden cardiac death, occurs frequently in patients with myocardial infarction. Catheter-based radiofrequency ablation of cardiac tissue has achieved only modest efficacy, owing to the inaccurate identification of ablation targets by current electrical mapping techniques, which can lead to extensive lesions and to a prolonged, poorly tolerated procedure. Here we show that personalized virtual-heart technology based on cardiac imaging and computational modelling can identify optimal infarct-related VT ablation targets in retrospective animal (5 swine) and human studies (21 patients) and in a prospective feasibility study (5 patients). We first assessed in retrospective studies (one of which included a proportion of clinical images with artifacts) the capability of the technology to determine the minimum-size ablation targets for eradicating all VTs. In the prospective study, VT sites predicted by the technology were targeted directly, without relying on prior electrical mapping. The approach could improve infarct-related VT ablation guidance, where accurate identification of patient-specific optimal targets could be achieved on a personalized virtual heart prior to the clinical procedure.

BACKGROUND Left atrial flutter (LAFL) occurs in patients after atrial fibrillation ablation. Identification of optimal ablation targets to terminate LAFL remains challenging. OBJECTIVE The purpose of this study was to use patient-specific models to simulate LAFL and predict optimal ablation targets using a novel approach based on flow network theory. METHODS Late gadolinium-enhanced cardiac magnetic resonance scans from 10 patients with LAFL were used to construct atrial models incorporating fibrosis by investigators blinded to procedural findings. Rapid pacing was applied in silico to induce LAFL. In each LAFL, we represented reentrant wave propagation as an electric flow network and identified the “minimum cut” (MC), which was the smallest amount of tissue that separated the flow into 2 discontinuous components. In silico ablation was applied at MCs, and targets were compared to those that terminated LAFL during catheter ablation. RESULTS Patient-specific atrial models were successfully generated from patient scans. LAFL was induced in 7 of 10 models. Ablation of MCs terminated LAFL in 4 models and produced new, slower LAFL morphologies in the other 3. For the latter cases, flow analysis was repeated to identify MCs of emergent LAFLs. Ablation of these MCs terminated emergent LAFLs. The MC-based ablation lesions in simulations were similar in length and location to ablation targets that terminated LAFL during catheter ablation for these 7 patients. CONCLUSION Personalized atrial simulations can predict ablation targets for LAFL. These simulations provide a powerful tool for planning ablation procedures and may reduce procedural times and complications.

Classically, the 3 pillars of atrial fibrillation (AF) management have included anticoagulation for prevention of thromboembolism, rhythm control, and rate control. In both prevention and management of AF, a growing body of evidence supports an increased role for comprehensive cardiac risk factor modification (RFM), herein defined as management of traditional modifiable cardiac risk factors, weight loss, and exercise. In this narrative review, we summarize the evidence demonstrating the importance of each facet of RFM in AF prevention and therapy. Additionally, we review emerging data on the importance of weight loss and cardiovascular exercise in prevention and management of AF.

Objectives We sought to a) use a novel method of late gadolinium enhancement (LGE) quantification that utilizes normalized intensity measures to confirm the association between LGE extent and atrial fibrillation (AF) recurrence following ablation, and b) examine the presence of interaction and effect modification between LGE and AF persistence. Background Recurrent AF after catheter ablation has been reported to associate with the baseline extent of left atrial (LA) LGE on cardiac magnetic resonance (CMR). Traditional methods for measurement of intensity lack an objective threshold for quantification and interpatient comparisons of LGE. Methods The cohort included 165 participants (60.0±10.2 years, 77% men, 57% persistent AF) that underwent initial AF ablation. The association of baseline LGE extent with AF recurrence was examined using multivariable Cox proportional hazard models. Multiplicative and additive interaction between AF type and LGE extent were examined. Results During 10.2±5.7 months of follow-up, 63 (38.2%) patients experienced AF recurrence. Baseline LGE extent was independently associated with AF recurrence after adjusting for confounders [hazard ratio (HR) 1.5 per 10% increased LGE, P<0.001]. The HR for AF recurrence progressively increased as a function of LGE. The magnitude of association between LGE >35% and AF recurrence was greater among patients with persistent AF (HR 6.5, P=0.001 versus HR 3.6, P=0.001); however, there was no evidence for statistical interaction. Conclusions Regardless of AF persistence at baseline, participants with LGE ≤ 35% have a favorable outcome, whereas those with LGE > 35% have a higher rate of AF recurrence in the first year after ablation. These findings suggest a role for a) patient selection for AF ablation using LGE extent, and b) substrate modification in addition to pulmonary vein isolation in patients with LGE extent exceeding 35% of LA myocardium.

Objectives To examine the association between LVH, defined by cardiovascular magnetic resonance (CMR) and electrocardiography (ECG), with incident AF. Background Previous studies of the association between atrial fibrillation (AF) and left ventricular hypertrophy (LVH) were based primarily on echocardiographic measures of LVH. Methods The Multi-Ethnic Study of Atherosclerosis (MESA) study enrolled 4942 participants free of clinically recognized cardiovascular disease. Incident AF was based on MESA ascertained hospital discharge ICD codes and Centers for Medicare and Medicaid Services (CMS) inpatient hospital claims. CMR-LVH was defined as left ventricular mass ≥ 95th percentile of the MESA population distribution. Eleven ECG-LVH criteria were assessed. The association of LVH with incident AF was evaluated using multivariable Cox proportional hazards models adjusted for CVD risk factors. Results During a median follow-up of 6.9 years, 214 incident AF events were documented. Participants with AF were more likely to be older, hypertensive, and overweight. The risk of AF was greater in participants with CMR-derived LVH [Hazard ratio (HR) 2.04, 95% CI 1.15-3.62]. AF was associated with ECG-derived LVH measure of Sokolow-Lyon voltage product after adjusting for CMR-LVH [HR=1.83 (1.06, 3.14), p= 0.02]. The associations with AF for CMR LVH and Sokolow-Lyon voltage product were attenuated when adjusted for CMR LA volumes. Conclusion In a multi-ethnic cohort of participants without clinically detected CVD, both CMR and ECG-derived LVH were associated with incident AF. ECG-LVH showed prognostic significance independent of CMR-LVH. The association was attenuated when adjusted for CMR LA volumes.

AF recurrence after catheter ablation is higher in overweight, obese, and morbidly obese patients comparing to normal-weight controls, driven primarily by outcomes differences in paroxysmal AF patients. Complications were not associated with increased BMI.

The diagnosis of cardiac sarcoidosis (CS), especially in cases where there is limited or no extracardiac involvement, is challenging. Patients with CS are at increased risk of ventricular arrhythmias and sudden cardiac death. Several techniques for risk stratification for sudden cardiac death have been proposed in this population, including advanced cardiac imaging and electrophysiology study. Clinical ventricular arrhythmias in patients with CS may be treated with immunosuppressant therapy, antiarrhythmic drugs, catheter ablation, or implantable cardioverter-defibrillator placement. This article will provide an update on techniques for diagnosing CS, risk stratifying patients with CS for sudden cardiac death, and treating patients with CS with ventricular arrhythmias, focusing on evidence that has become available since publication of the 2014 Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Management of Arrhythmias Associated With Cardiac Sarcoidosis.

Cardiac interventional procedures are often performed under fluoroscopic guidance, exposing both the patient and operators to ionizing radiation. To reduce this risk of radiation exposure, we are exploring the use of photoacoustic imaging paired with robotic visual servoing for cardiac catheter visualization and surgical guidance. A cardiac catheterization procedure was performed on two in vivo swine after inserting an optical fiber into the cardiac catheter to produce photoacoustic signals from the tip of the fiber-catheter pair. A combination of photoacoustic imaging and robotic visual servoing was employed to visualize and maintain constant sight of the catheter tip in order to guide the catheter through the femoral or jugular vein, toward the heart. Fluoroscopy provided initial ground truth estimates for 1D validation of the catheter tip positions, and these estimates were refined using a 3D electromagnetic-based cardiac mapping system as the ground truth. The 1D and 3D root mean square errors ranged 0.25-2.28 mm and 1.24-1.54 mm, respectively. The catheter tip was additionally visualized at three locations within the heart: (1) inside the right atrium, (2) in contact with the right ventricular outflow tract, and (3) inside the right ventricle. Lasered regions of cardiac tissue were resected for histopathological analysis, which revealed no laser-related tissue damage, despite the use of 2.98 mJ per pulse at the fiber tip (379.2 mJ/cm 2 fluence). In addition, there was a 19 dB difference in photoacoustic signal contrast when visualizing the catheter tip