65 year old Buchan was rushed to hospital and is now resting up in a Colombian hotel.
The cult Scottish band were performing in Bogota on 10 December when the emergency happened.
Video shot at the concert showed Buchan clutching his chest momentarily before bending over and eventually dropping to his knees. Concert staff and bandmates quickly came to his aid.
On Facebook the band posted Buchan was “feeling better now and is resting in a hotel in Bogota”. The band also cancelled all remaining concerts for this year
This is not the first time Buchan has suffered a heart attack onstage – in February 2014, he ended up in hospital following a concert in Portugal where he eventually had a quadruple bypass.