Q. Re- question 1283; Did Rav Miller shlit’a explain why he agrees with the view of the Chayei Adam, which, as mentioned, is contrary to the opinion of most poskim? In that case (following the psak of the Chayei Adam and Rav Miller), should he daven again after, as a voluntary prayer, in order to be certain that he has fulfilled his obligation?

A. There is a substantial amount of Poskim that do follow the opinion of the Chaye Adam, such as Pischei Olam (O.H. 119: 8), Beer Yaakov (O.H. 107: 2), Eishel Avrohom (Butach), Pekudas Elozor (119) and others.
Horav Shlomo Miller Shlit’a does not consider continuing and reciting the rest of the amida to be in vain or a bracha lebatala, when in doubt if he missed others, because after all even if this tefilah does not posses the attribute of shemoneh esreh, the brochos are still brochos, and not in vain, the same applies to the brochos already said.
He also maintains, that having finished the amida, if he feels able now to concentrate properly, he should daven a tefilas nedovo.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a