Constantinople, intersting idea to start this thread. I have only one question for you: what do you mean with the word "aristocrats"? Intellectuals, poets, writers, artists, political functionaries or what exactly? Common people or genius and famous people? Needs more clarity.
In general this list is enormous. I can mention maybe the most famous names, like Mayakovsky, Erenburg, Voloshin, Gorky, Stanislavsky, Pavlov, Vernadsky, Brusilov and so on....
If about aristocracy in general, then all these people that I've mentioned and other big part of them unfortunately as an any reflective people with big intellect and brains succumbed to the bait of all these left-wing ideas and stayed in the USSR. The main part suffered in the Stalin times and finally were repressed. Some survived and nowadays their descendants live in Russia. Sadly, but the main amount of them are simply don't know anything about the ancestors.
If you don't mind, I can post sometimes information about some of these people (most interesting) on this thread.