Executives of three of the nation's largest health insurers told federal lawmakers in Washington on Tuesday that they would continue canceling medical coverage for some sick policyholders, despite withering criticism from Republican and Democratic members of Congress who decried the practice as unfair and abusive. The hearing on the controversial action known as rescission, which has left thousands of Americans burdened with costly medical bills despite paying insurance premiums, began a day after President Obama outlined his proposals for revamping the nation's healthcare system. An investigation by the House Subcommittee on Oversight and Investigations showed that health insurers WellPoint Inc.,...