trim path, reverse direction

I'm creating a line animation using trim path feature. the image was created in illustrator. for example. in the animation the line is growing/extendiing from left to right. is it possible to reverse the direction to have the animation go from right to left?? w/o going into illustrator and redraw the line in different way??

no matter what i do with the starting/ending point setting it ALWAYS goes from left to right...

any thoughts??

my illustration is actually a lot more complicated than just one line. so to redraw the whole thing would not be efficient...