supraventricular tachycardia
"Prescribed 50mg day for post AFib/flutter ablation rate control while healing for a month or so.  I've taken the regular non ER version before for similar reasons after coming out of AFib/flutter but usually had to stop very soon due to dropping rate and BP below the low end of the normal ranges.  So far the ER tabs seem to be not as aggressive on that, but I'm not sure if I'll make the full recovery time with them.    I haven't had any of the "loopiness" or fog that I've had with the non ER version which were 25's cut in half 2x day."