Stochastic integration with respect to additive functionals of zero quadratic variation

We consider a Markov process $X$ associated to a nonnecessarily symmetric Dirichlet form $\mathcal{E}$. We define a stochastic integral with respect to a class of additive functionals of zero quadratic variation and then we obtain an It\^{o} formula for the process $u(X)$, when $u$ is locally in the domain of $\mathcal{E}$.