Hercules sculpture, Florence, Italy. Medical bills are leaving “a lasting imprint on families’ balance sheets,” JP Morgan Chase concludes from its recent analysis of the anonymous checking and credit card account activity of some 250,000 bank customers. With little available cash on hand, 53 percent of these families prepare to pay large, one-time medical expenses by waiting for an uptick in their income. Nevertheless, a year after the bill is paid, they are still struggling to patch the hole blown in their household budgets, according to the report, “Coping with Costs: Big Data on Expense Volatility and Medical Payments.” The 2013-2015 account data show that family incomes tend to be 4 percent higher, on average, in the month a medica…