Sorry, I only just saw this.
As someone else said, a fairly standard Catholic position would be that those Christians who are still alive at the time of the Second Coming will not die a normal death but will be “caught up” in the clouds with Jesus Christ, probably just after the General Resurrection (and maybe even after the General Judgment?), in accordance with the inspired words of St. Paul:
“For the Lord himself will descend from heaven with a cry of command, with the archangel’s call, and with the sound of the trumpet of God. And the dead in Christ will rise first; then we who are alive, who are left, shall be caught up together with them in the clouds to meet the Lord in the air, and so we shall always be with the Lord.” (1 Thessalonians 4:16-17)
The position that this “rapture” (being “caught up”) will happen before or during the Great Tribulation and over a thousand years before the definitive consummation of history is alien to mainstream Catholic thought and in my opinion is highly counterintuitive, though as far as I know it is not technically a heresy.