Epicardial fat and accessory pathway ablation

Epicardial fat and accessory pathway ablation

Epicardial fat makes it difficult to ablate epicardial accessory pathways by the epicardial route as the fat in the AV groove prevents ablation energy from reaching the pathways at the annulus. With epicardial fat thickness above five millimeters, even cooled tip catheters may not achieve an adequate radiofrequency lesion at the intended epicardial ablation site [1]. Standard radiofrequency catheters may fail to produce a lesion even with epicardial fat thickness above three millimeters. It is easier to ablate them through the coronary veins. High impedance during epicardial ablation may be noted in the presence of epicardial fat.
Another potential option when epicardial fat interferes with ablation of ventricular insertion site of an accessory pathway is to ablate at the atrial insertion site [2].

Interference with epicardial mapping

Both epicardial fat and scar tissue show low voltage with epicardial voltage mapping. Cardiac computerized tomographic (CT) scan is useful in differentiating fat from scar tissue as the attenuation on CT is different for scar tissue and fat [3]. High density electroanatomic mapping techniques have been applied to differentiate epicardial fat from scar tissue by electrogram characteristics [4]. Longer duration of electrogram and more fractionation of electrogram were noted in scars of healed myocardial infarction, compared to epicardial fat. Late potentials were specific for locating infarcts [4].

References

1. Boyle NG, Shivkumar K. Epicardial interventions in electrophysiology. Circulation. 2012 Oct 2;126(14):1752-69.
2. Cipoletta L, Acosta J, Mont L, Berruezo A. Posterior coronary vein as the substrate for an epicardial accessory pathway. Indian Pacing Electrophysiol J. 2013 Aug 1;13(4):142-7.
3. Desjardins B, Morady F, Bogun F. Effect of epicardial fat on electroanatomical mapping and epicardial catheter ablation. J Am Coll Cardiol. 2010 Oct 12;56(16):1320-7.
4. Tung R, Nakahara S, Ramirez R, Lai C, Fishbein MC, Shivkumar K. Distinguishing epicardial fat from scar: analysis of electrograms using high-density electroanatomic mapping in a novel porcine infarct model. Heart Rhythm. 2010; 7: 389-395.