Preliminary Studies to Evaluate the Impact of Peri-Atrial Inflammatory Fat Tissue on Atrial Fibrillation Using Ultra-High Resolution CT

Investigators will prospectively enroll 200 adult participants referred to the Johns Hopkins Hospital for catheter ablation of atrial fibrillation (AF). Investigators will first enroll participants with paroxysmal AF (n=100) to complete sensitivity analysis of inflammatory fat and potential target identification before enrolling participants with persistent AF (n=100). All participants (n=200) will undergo pre-procedural CT using the ultra-high resolution CT scanner 3-4 days prior the ablation procedure to allow a sufficient amount of time for image processing. In all participants (n=200), blood specimens will be collected immediately prior to the ablation procedure. The participants with paroxysmal AF (n=100) will receive the standard of care, which is PVI, and the clinical outcome will be followed up to 12 months post-procedure. In this group, investigators will conduct a sensitivity analysis to define the range of peri-left atrial (LA) fat tissue (in HU) that is associated with AF recurrence. Investigators will also conduct computation of source-sink mismatch arising from wall thinning due to fat infiltration into the myocardium that favors functional block and local reentry. For participants with persistent AF (n=100), investigators will conduct an exploratory clinical trial where the participants will be randomly assigned to 1) PVI group (n=50), or 2) PVI + inflammatory fat-targeted ablation group (n=50). In the latter group, additional focal ablation will be performed beyond PVI to target the inflammatory fat tissue based on the result of the sensitivity analysis. Randomization will be performed with the use of an automated computer-generated randomization algorithm. The participants will be unaware of the group assignment, but the operators will not be blinded (single-blinded design). In all patients, no ablation strategies beyond PVI except cavotricuspid isthmus (CTI) ablation for typical atrial flutter (AFL) will be allowed, such as linear lesions (e.g. roof lines, mitral isthmus lines), and focal ablation to eliminate complex fractionated atrial electrograms (CFAE) and rotating drivers.