Why? Most PDF viewers allow printing to any size paper, scaling up or down.
Anyway you can print the file and select A-size at that time to create a Postscript file, then process it through Ghostview or Adobe Distiller or other distiller - NitroPDF comes to mind as a popular choice.
The problem you will run into is that PTC doesn't scale line widths along with paper size, so if on the E-size drawing you had a line 0.5 inches wide, it will still be a real 0.5 inches wide on the A-size, obliterating any neighboring details. Most lines aren't that wide, but even thin lines at E-size in lettering will result in unreadable text on an A-size.