We investigate the potential of an instrument combining timeresolved
spectrofluorometry and diffuse reflectance spectroscopy to
measure structural and metabolic changes in cardiac tissue in vivo in a 16
week post-myocardial infarction heart failure model in rats. In the scar
region, we observed changes in the fluorescence signal that can be
explained by increased collagen content, which is in good agreement with
histology. In areas remote from the scar tissue, we measured changes in the
fluorescence signal (p < 0.001) that cannot be explained by differences in
collagen content and we attribute this to altered metabolism within the
myocardium. A linear discriminant analysis algorithm was applied to the
measurements to predict the tissue disease state. When we combine all
measurements, our results reveal high diagnostic accuracy in the infarcted
area (100%) and border zone (94.44%) as well as in remote regions from
the scar (> 77%). Overall, our results demonstrate the potential of our
instrument to characterize structural and metabolic changes in a failing heart
in vivo without using exogenous labels.