Systems and methods for determining lesion depth using fluorescence imaging

Systems, catheter and methods for treating Atrial Fibrillation (AF) are provided, which are configure to illuminate a heart tissue having a lesion site; obtain a mitochondrial nicotinamide adenine dinucleotide hydrogen (NADH) fluorescence intensity from the illuminated heart tissue along a first line across the lesion site; create a 2-dimensional (2D) map of the depth of the lesion site along the first line based on the NADH fluorescence intensity; and determine a depth of the lesion site at a selected point along the first line from the 2D map, wherein a lower NADH fluorescence intensity corresponds to a greater depth in the lesion site and a higher NADH fluorescence intensity corresponds to an unablated tissue. The process may be repeated to create a 3 dimensional map of the depth of the lesion.