Is it ok to add a small dose of Cartia X-R ( 60 mg) PRN when pulse stays above 100 by-FOR A PERSON WHO ALREADY TAKES 120 mg ER X, 2 qd. Co ncern is that if pulse leveled out, PR MIGHT THEN DIP LOW, person might get dizzy and fall. Pulse has recently gone up to over 100bpm with fairly wide range, Ps person is 89, Afib x3 years, recently worsened heart failure prob Stage 3