Treatment suggestions for very symptomatic inappropriate sinus tach? no success at 25-50mg: diltiazem(calcium chan. blocker), atenolol + propranolol.

Try Nadolol: An older, generic (cheap) treatment option that is often very successful in IAST is Nadolol, a non-selective, longer acting B-blocker that allows you to take it once daily. Since nadolol is an older generic, many physicians are not familiar with its use. Atenolol and propranolol are shorter acting B-blockers and rarely work for IAST. Diltiazem and other calcium channel blockers almost never work.