Hello Ranjini,
You dont need to configuire eCATT with QTP unless you are using QTP to automate applications which are not feasible using eCATT. If you want to maintain all your test scripts automated at one central location (automated either using eCATT, QTP or any other third party tool) then you can configure your Central system to link to QTP, else you dont need this configuration.
Hope it helps.
Thanks,
Aj