Auckland Mayor Phil Goff is in hospital after an unscheduled surgery.
The 64-year-old politician had an angioplasty in a public hospital this weekend.
An angioplasty is a procedure in which a narrowed section of the coronary artery is widened to increase blood flow to the heart. It is less invasive than a bypass.
A mayoral spokesman said he had recovered well, but was expected to stay in hospital for another day or two before returning to work on April 23.
Deputy Mayor Bill Cashmore will be stepping in for some of the mayor's duties during his absence.
Goff was elected Mayor of Auckland in 2016. Before that he had a long and distinguished career in Parliament as the Labour MP for Mt Roskill, served as Leader of the Opposition between 2008 and 2011 and held a number of senior Cabinet positions.