Westpac New Zealand chief executive Peter Clare has resigned from the bank after an operation to correct a pre-existing heart condition. The surprise departure has opened up a plum role in Australasian banking that is seen as a perfect training ground for group chief executives.Clare stood aside in May for the operation and had intended to return after his recovery, but Westpac Group chief executive Gail Kelly announced Clare had decided to take an extended break and would be leaving the group."I would like to thank Peter for his contribution to the Group and wish him and his family well in his recuperation and into the future," Kelly said.Clare, an Australian, had previously led Westpac's products and operations division in Australia and was a key player in the integration with St George Bank.  His departure after just two years in the job has surprised many in New Zealand given he had pledged to be a long-term chief executive in New Zealand. Clare's wife is a New Zealander and Westpac had been through four chief executives in New Zealand since 2007.Clare's predecessor, George Frazis, went on to become the chief executive of St George Bank after a four-year stint in New Zealand. The last two chief executives of National Australia Bank's BNZ, Cameron Clyne and Andrew Thorburn, have gone on to head up the entire group.Kelly said Clare "had delivered all-round solid results" in his time in charge in New Zealand. He had focused on improving Westpac NZ's digital offerings and spoken out against taking on too much risk in the low deposit mortgage market at a time when ANZ and Commonwealth Bank's ASB had aggressively chased market share in the Auckland housing market. Clare said the New Zealand business was in good shape and it had been a privilege to lead its 4,600 staff."I look forward to watching its continued success. However, following my recent, successful surgery to correct a heart condition I have decided that now is the right time to have an extended break to ensure a complete recovery," Clare said.Westpac Institutional Bank's Head of America's division, David McLean, was made acting chief executive in May and will remain in that role while Westpac conducts an internal and external search for a replacement.McLean, a New Zealander, has previously been the head of Westpac New Zealand's institutional and private wealth management operation. McLean's background in investment banking could prove a hurdle in stepping up into the top job permanently, given retail bankers are more often selected for these top roles.Other local candidates include Westpac NZ's Head of Business Bank, Private Bank, Wealth & Insurance, Simon Power, who came to Westpac from a career as a cabinet minister in the current National Government. Previously touted as a future Prime Minister, Power left politics in 2011 after stints as Justice and Commerce Minister.