Epicardial catheter ablation has been increasingly recognized as an important adjunct in treating ventricular arrhythmias unamenable by endocardial ablation alone. The presence of epicardial adipose tissue (EAT) is a primary cause for ineffective ablation energy delivery and electrogram misinterpretation. To address this need, we propose a catheter-based near-infrared spectroscopic technique for mapping EAT and lesion deposition, and validate it within excised human donor hearts. We introduce a new parameter, the adipose contrast index (ACI), for rapid lipid assessment. Strong correspondence was observed between values derived from interpolated 3-dimensional ACI maps and histologically-determined EAT layer thickness (Pearson’s, R = 0.903).