On propranolol 20 mg 2x a day for svt (wpw), &hbp. i need one that lasts longer but can't take er. toprol (metoprolol) was to strong even at 25 mg. any suggestion?

Lots of options: There are lots of other options for controlling palpitations besides Propranolol and toprol (metoprolol) xl. Given your history of wpw, however, it requires being careful; sometime these medications can actually make the palpitations worse. It'd be important to see your electrophysiologist or general cardiologist to try another medication, or consider other treatment options (e.g., ablation therapy).

Switch propranolol?: You need to discuss your problem with the physician (p) who is prescribing your Propranolol to you. It is best for p, who knows your history and you best, to make any changes in cardiac therapy, especially for a patient with a svt. Good luck.