As an expat in KL finding a good doctor or emergency services can be a minefield, especially when there are so many centres and hospitals to choose from. The 2 medical centres that I have had verbal recommendations for and that keep popping up in conversations are: Prince Court Medical Centre and Pantai Hospitals.
Prince Court Medical Centre is affiliated with the medical university of Vienna, Austria. For more details
please visit their website: http://www.princecourt.com/
Pantai Hospitals have various Hospitals around Malaysia. Details can be found at: http://www.pantai.com.my/
Most international companies and schools also have memberships with International SOS, who provide medical assistance, security and evacuation services all over the world. They also provide medical advice and information over the phone via a large pool of registered and recommended doctors. For more details have a look at: http://www.internationalsos.com/