According to Shia belief, the beginning part of verse 27:62: “He, Who answers the one in distress when he calls upon Him and removes the evil [harm]…” has a great role in the acceptance of Dua.
According to Shia traditions, the first part of verse 27:62  has a significant role in the acceptance of Dua which says: “He, Who answers the one in distress when he calls upon Him and removes the evil [harm]…”.
Based on the verse, the one who calls Dua must be desperate. It refers to the one who is helpless and powerless, in the sense of being in a bad situation through no choice of one’s own, and perhaps afflicted by poverty or sickness. It is known that one of the significant conditions of Dua to be accepted is that one should be in distress and have no other choice except Allah (swt). In other words, Dua will not be left unanswered if the one who makes it is true in his inquiry, loses hope from others and believes that only God can fulfill his request.
Imam Sadiq (A) is quoted to have said: “This verse refers to Imam Mahdi (He Who Arises). I swear that he is the desperate one when he prays behind the Station of Abraham (Maqam-e Ibrahim), raises his hand while praying, and Allah (swt) fulfills his request and makes him His successor. 
1. Chapter 27, verse 62. أَمَّنْ يجِيبُ الْمُضْطَرَّ إِذَا دَعَاهُ وَيكْشِفُ السُّوءَ
2. Tafsir-e Qomi, vol 2, p 129