  We study the final-state interactions in $B \to \pi K$ decays through $B \to
VV \to \pi K$ processes where the inelastic rescattering occurs via single pion
exchange. The next-to-leading order low energy effective Hamiltonian and BSW
model are used to evaluate the weak transition matrix elements and the
final-state interactions. We found that the final-state interaction effects in
$B \to \rho K^* \to \pi K$ processes are significant. The Fleischer-Mannel
relation about the CKM angle $\gamma$ may be significantly modified.
