An acyclic edge coloring of a graph is a proper edge coloring such that there are no bichromatic cycles. The acyclic chromatic index of a graph is the minimum number k such that there is an acyclic edge coloring using k colors and is denoted by a (G). It was conjectured by Alon, Sudakov, and Zaks that for any simple and finite graph G, a (G) ≤ +2, where = (G) denotes the maximum degree of G. We prove the conjecture for connected graphs with (G) ≤ 4, with the additional restriction that m ≤ 2n−1, where n is the number of vertices and m is the number of edges in G.