The Triffids were an Australian alternative rock and pop band, formed in Perth in Western Australia in May 1978 with David McComb as singer-songwriter, guitarist, bass guitarist and keyboardist. They achieved negligible success in Australia, but greater success in the UK and in Scandinavia in the 1980s before disbanding in 1989. Some of their best-known songs include "Wide Open Road" (February 1986) and "Bury Me Deep in Love" (October 1987). SBS television featured their 1986 album, Born Sandy Devotional, on the Great Australian Albums series in 2007, and in 2010 it ranked 5th in the book

Following the breakup of the band, Alsy MacDonald, Jill Birt and Robert McComb took "proper jobs" as a lawyer (currently with the Equal Opportunity Commission), architect and teacher respectively, with MacDonald and Birt marrying (Robert McComb currently teaches at Melbourne High School). David McComb and Lee continued to be involved with The Blackeyed Susans, a group David McComb formed as a side band during an earlier Triffids' summer tour of Australia. Martyn Casey briefly joined the Blackeyed Susans and then became a permanent member of Nick Cave and the Bad Seeds in April 1990.  In 1990, David McComb moved back to London with the aim of pursuing his solo career. Since sustaining crushed vertebrae in the UK in 1986 McComb had suffered chronic and severe back pain that plagued him till his death. In 1992, after no success, he returned to Australia to make some solo recordings for Mushroom Records (featuring both Casey and Lee), releasing just one solo album, Love of Will, in 1994. He also worked with many other musicians on various projects, including assembling a band, the Red Ponies, to tour Europe. In June 1993 three former members of The Triffids: David McComb, Robert McComb and Lee; as well as Charlie Owen and Chris Wilson guested on Acuff's Rose's debut studio album, Never Comin' Down. Another project, costar, was formed when David moved to Melbourne, but due to his ill health they only played sporadically around Melbourne, although recordings had begun and a single was ready for a limited release.  Following the Red Ponies tour David McComb suffered substance abuse-related health problems, which ultimately resulted in him undergoing a heart transplant in 1996. Despite the exacerbation of his back problem from the transplant procedure he embarked on a university course and his prolific output of songs continued.He recorded 7 demos at the studio of Julian Wu, a long time supporter with old friends Martin Casey, Mick Harvey, Warren Ellis, Kiernan Box and Stuart Solar on drums. Forming 'costar' with Graham Lee, Kiernan Box on piano, Stuart Soler on drums Will Akers on bass and Matt Habbin on Saxophone. Ill health limited live performances but writing, arranging and other literary projects continued at a furious pace. Following a car accident in Melbourne, he was admitted to St Vincent's hospital. Three days later he died at home, on 2 February 1999, a few days short of his 37th birthday.  In February 2000, after the State Coroner of Victoria published his findings, The West Australian newspaper wrote: "[Coroner] Johnstone said McComb's mental and physical condition had deteriorated after his (car) accident but his death was due to heroin toxicity and mild acute rejection of his 1996 heart transplant."

Using a quote from the above article, answer the following question: What caused the breakup?