In this case I can only speak for Belgium, but large scale Russian involvement in heroin was only reported in the early to mid 90's in Antwerp. You had the group around Boris Nayfeld and Rachmiel Brandwain that supposedly imported and distributed millions worth of heroin in the Antwerp area. Later on there was also the involvement of the Abraham Melikhov and his clan; they distributed the stuff as well as used it to get the prostitutes addicted who worked for them.
Heroin was just part of the activity for the Russians. In reality most of them in Antwerp were Jews from Ukraine, Belarus and Georgia who had Israeli passports. Antwerp has a large Jewish community so they just tried to blend in and even "bought" themselves in. Lots of honest Jewish shopkeepers were offered insane amounts of money to hand over their establishments that the mafiosi could use to launder their illicit proceeds. If they couldn't be bought out, they were kicked out. The Russian criminals got busy with heroin trafficking, prostitution, forgery, theft...

The Netherlands has always been a major wholesale distribution point in that regard. A lot of crime firms from the Southeast, Merseyside, Glasgow or Dublin for instance travel to the Netherlands to make huge heroin deals. All the while in the UK there are definitely a lot of Indian and Pakistani groups in places like Luton, Middlesbrough, Bradford...as well as Kurdish groups in North London that are able to get in a lot of smack. Yet it seems that Scouse and Irish criminals in particular still prefer to do business with the groups that are active in the Netherlands.

The heroin business in the Netherlands knows many actors who come and go only to show up again when another type of group gets caught. When the power of Ah Kong was severely diminished, you had the Serbian clans that supplied a lot of the heroin market in the late 80's to early 90's. Sreten Jocic, connected to the Surcin clan, was of course the most famous of them, but others like the Zemun clan definitely showed up in Amsterdam as well.
Then when the spotlights were on the Serbs, the Turks cornered most of the market. At first the Black Sea-based groups, like the Oflu clan, carried on their heroin business (they had already been active since the late 90's in the Netherlands, at the same time the Serbs were), but when things got a bit too heated for the Turks you had a lot of Southeast Anatolia-based Kurdish groups that were moving tons of smack up until the early 2000's. Many of them were also connected to the Baybasin clan.
When the Kurds got nicked, I think it were the Albanians that came to prominence since the early 2000's in the heroin business. These days it seems a lot of Albanian groups are getting caught as well so who knows who's next to step in. None of those groups ever completely quit the smack business. They stay active in some way and slow down whenever law enforcement turns their interest on them.

The heroin business in Western Europe isn't as huge as the cocaine business. Come to think of it, it's crazy when I realize how many cocaine users I know personally while I don't know anyone who's addicted to heroin. In the bigger cities the demand is still there though. And that demand is still big enough to make sure there's more than a few groups that can get wealthy enough off heroin alone.