ED BATEMAN'S Primary Health Care has not irrevocably committed to vote its 20 per cent stake in Symbion Health against the break-up and sale of Symbion to Healthscope and the Ironbridge and Archer private equity consortiums. It only says it will do so if there is no "material change in circumstances" or change in the proposal's "structure". But the threat ups the ante and further complicates the Symbion takeover battle. Bateman does not have enough shares to block the share-exchange sale of Symbion's diagnostic businesses to Healthscope, which needs only 50 per cent shareholder approval. But he can bring down the sale of the rest of Symbion to the private equity firms, which needs 75 per cent. Symbion's board approved the two-stage deal knowing that Bateman might do this, and it believes the Healthscope bit is worth doing anyway. Bateman will argue that half a deal is worse than no deal.