But the medical examiner says it wasn't his heart that killed him:

The preliminary findings in the autopsy of 18-year-old Lance Lundsten showed the teen did not die from an enlarged heart, according to Douglas County Medical Examiner Dr. Mark Spanbauer. The teen's heart was slightly enlarged, but that finding was a secondary finding to an undetermined cause, according to Spanbauer... "He was a small young man. His heart showed slight swelling," Spanbauer said. "It was slightly enlarged. This was a secondary finding."

Lundsten's death was originally reported to be a suicide, then Lundsten's father claimed his son died of an undiagnosed heart condition. It could be weeks before we know for sure what caused Lundsten's death.