Garden-Bachop, who played two tests for the Maori All Blacks, died overnight on June 16, 2024, while staying at the Christchurch home of his aunt and uncle.
The father of twin girls was 25.
His death was referred to coroner Mary-Anne Borrowdale who said Garden-Bachop had an abnormal heart and found no suspicious circumstances.
"The cause of Mr Garden-Bachop's death was therefore given as sudden death in the context of a mildly dilated heart," she said in findings released on Tuesday.
Garden-Bachop was born into a family of rugby internationals.
His father Stephen Bachop played for Samoa and New Zealand and his mother Sue Garden-Bachop played for the national women's team.
His uncle, Graeme Bachop, played at two World Cups (1991, 1995) for the All Blacks and represented Japan at the global showpiece in 1999.
His brother Jackson, who plays for Super Rugby side Moana Pasifika, said the family was glad the coroner's report was complete.
"On behalf of the family we'd like to thank everyone for the continued love and support in relation to Connor," he said in a statement published by New Zealand media.
"We miss Connor every day, and will continue to try and honour and emulate all that he was in the way we live our lives."