I have been taking Metoprolol Succ ER 50 mg, one at night, for about 5 years, for HCM after an ASD closure procedure in 2010. I recently needed a short term refill while out of town and received Metoprolol Tartrate 50 mg, told to take 2 times a day because of different half life . I will go back to previous medicine tomorrow, but will have been taking the tartrate version for 4 days. Are there any concerns about this switch in medicine?