A lot has happened while I was in Central City! The thing that bothers me most is that Kryptonite seems to be landing on Earth again... And that's supposed to be highly unlikely! More "K"... Secrets being stolen from S.T.A.R.... Michaels disappearing... SKULL-ers dying--! There has to be a connection! But what in Krypton's name is it?! 
- — Superman
Superman #316 is an issue of the series Superman (Volume 1) with a cover date of October, 1977.
Synopsis for The "Heart Attack" That Crippled Superman!
Metallo resumes his murder campaign against SKULL, and traps Superman with Kryptonite, vowing he will take the Kryptonian's heart for his own once the Man of Steel dies.
Appearing in The "Heart Attack" That Crippled Superman!
Featured Characters:
- Superman (Flashback and main story)
Supporting Characters:
- Dr. Jenet Klyburn (Flashback only)
- Morgan Edge
- Lois Lane
- Albert Michaels (In a photograph only) and (Mentioned only)
Antagonists:
Other Characters:
- Joker (Mentioned only)
- Morgue Worker (Unnamed) (Single appearance)
- Muriel (Single appearance)
- Tractor Trailer Driver (Unnamed) (Single appearance)
- Transit Officer (Unnamed) (Single appearance)
- Martin Korda
- Clark Kent's future co-anchor (Mentioned only)
Locations:
- Metropolis
- Metropolis Museum of Natural History
- Geology Exhibit
- S.T.A.R. Labs (Flashback only)
- City Morgue
- Metropolis Bay Tunnel
- Galaxy Communications Building
- Morgan Edge's Office
- Metropolis Museum of Natural History
- Central City (Mentioned only)
- State Caverns
- Underground Stream
- Fortress of Solitude (Mentioned only)
Items:
- Green Kryptonite
- Synthetic Kryptonite
- Joker's Playing Card (Mentioned only)
- Daily Planet Newspaper
- Boeuf Bourguignon (Mentioned only)
- Vial of Uranium
Vehicles:
- Jet-Scooter
Notes
- The first issue that began crediting the Letterer.
- Metallo now wears a lead mask to hide his new face from Superman.
- Metallo now has the ability to aim a Kryptonite beam from his Energy Cell.
- Morgan Edge removed the Associate Producer title from Clark Kent and gave the job to the newly hired Martin Korda.