The Massachusetts treasurer said Tuesday that Congress will “threaten to wipe out the American economy within four years” if it adopts a health-care overhaul modeled after the Bay State’s. Treasurer Timothy P. Cahill – a former Democrat running as an independent for governor – said the local plan enacted in 2006 has succeeded only because of huge subsidies and favorable regulatory changes from the federal government. ..................................................... He also gave reporters a copy of a recent state ledger sheet, showing the state’s Medicaid program ballooning from $7.5 billion to a projected $9.2 billion since the plan was adopted. Meanwhile, of...