Treatment Planning for Atrial Fibrillation Using Patient-Specific Models Showing the Importance of Fibrillatory-Areas.

Computational models have made it possible to study the effect of fibrosis and scar on atrial fibrillation (AF) and plan future personalized treatments. Here, we study the effect of area available for fibrillatory waves to sustain AF. Then we use it to plan for AF ablation to improve procedural outcomes. CARPentry was used to create patient-specific models to determine the association between the size of residual contiguous areas available for AF wavefronts to propagate and sustain AF [fibrillatory area (FA)] after ablation with procedural outcomes. The FA was quantified in a novel manner accounting for gaps in ablation lines. We selected 30 persistent AF patients with known ablation outcomes. We divided the atrial surface into five areas based on ablation scar pattern and anatomical landmarks and calculated the FAs. We validated the models based on clinical outcomes and suggested future ablation lines that minimize the FAs and terminate rotor activities in simulations. We also simulated the effects of three common antiarrhythmic drugs. In the patient-specific models, the predicted arrhythmias matched the clinical outcomes in 25 of 30 patients (accuracy 83.33%). The average largest FA (FAmax) in the recurrence group was 8517 ± 1444 vs. 6772 ± 1531 mm2 in the no recurrence group (p < 0.004). The final FAs after adding the suggested ablation lines in the AF recurrence group reduced the average FAmax from 8517 ± 1444 to 6168 ± 1358 mm2 (p < 0.001) and stopped the sustained rotor activity. Simulations also correctly anticipated the effect of antiarrhythmic drugs in 5 out of 6 patients who used drug therapy post unsuccessful ablation (accuracy 83.33%). Sizes of FAs available for AF wavefronts to propagate are important determinants for ablation outcomes. FA size in combination with computational simulations can be used to direct ablation in persistent AF to minimize the critical mass required to sustain recurrent AF.

Non-invasive simulated electrical and measured mechanical indices predict response to cardiac resynchronization therapy.

BACKGROUND: Cardiac Resynchronization Therapy (CRT) in dyssynchronous heart failure patients is ineffective in 20-30% of cases. Sub-optimal left ventricular (LV) pacing location can lead to non-response, thus there is interest in LV lead location optimization. Invasive acute haemodynamic response (AHR) measurements have been used to optimize the LV pacing location during CRT implantation. In this manuscript, we aim to predict the optimal lead location (AHR>10%) with non-invasive computed tomography (CT) based measures of cardiac anatomical and mechanical properties, and simulated electrical activation times. METHODS: Non-invasive measurements from CT images and ECG were acquired from 34 patients indicated for CRT upgrade. The LV lead was implanted and AHR was measured at different pacing sites. Computer models of the ventricles were used to simulate the electrical activation of the heart, track the mechanical motion throughout the cardiac cycle and measure the wall thickness of the LV on a patient specific basis. RESULTS: We tested the ability of electrical, mechanical and anatomical indices to predict the optimal LV location. Electrical (RV-LV delay) and mechanical (time to peak contraction) indices were correlated with an improved AHR, while wall thickness was not predictive. A logistic regression model combining RV-LV delay and time to peak contraction was able to predict positive response with 70 ± 11% accuracy and AUROC curve of 0.73. CONCLUSION: Non-invasive electrical and mechanical indices can predict optimal epicardial lead location. Prospective analysis of these indices could allow clinicians to test the AHR at fewer pacing sites and reduce time, costs and risks to patients.

Double-kissing culotte technique for coronary bifurcation stenting.

AIMS: The aim of this study was to assess whether the culotte technique could be improved by an additional kissing dilation prior to main branch (MB) stenting. METHODS AND RESULTS: Double-kissing (DK) culotte was compared to the culotte and DK-crush techniques in a bench model (n=24). Results were evaluated for stent apposition, luminal opening and flow dynamics. The total procedure duration of DK-culotte was 18.3±3.4 minutes, significantly lower than for DK-crush (24.3±5.7 min; p=0.015), but similar to culotte (21.6±5.9 min, p=0.104). In DK-culotte the overall rate of moderate (200-500 µm) and significant (>500 µm) malapposition was 2.1±1.9% and 0.4±0.2%, similar as compared to culotte (3.7±3.8%, p=0.459 and 1.0±1.0%, p=0.517, respectively), and lower as compared to DK-crush (8.1±2.5%, p<0.001 and 3.7±5.3%, p=0.002, respectively). The lower malapposition rate of DK-culotte as compared to DK-crush was due to less moderate and significant malapposition in the proximal MB (0.0±0.0% vs 14.0±7.6%, p<0.001 and 0.0±0.0% vs 4.2±9.1%, p=0.026, respectively). Micro-computed tomography did not show a difference in luminal opening at the proximal MB, distal MB or SB. There was no difference either in the maximum shear rate or in areas of high shear or recirculation. CONCLUSIONS: Bench test data suggest that the DK approach facilitates the culotte technique. The clinical validity and relevance remain to be confirmed in a larger in vivo population.