IL6 and mitral valve insufficiency: On the other hand, our results contrast with those of Zois et al. [41], in which TNF-α and IL-6 levels were analyzed in 68 dogs, classified into 5 groups according to the degree of mitral regurgitation and the presence of decompensated CHF, but the TNF-α level could not be quantified, and the IL-6 level was quantifiable only in <25% of the recruited dogs.