I am on coreg and altace, as I have a Cardiomyopathy with tachycardia and pvc's. Since being on the meds, my heart rate is sometimes in the 40's. I have also been told this is ok as long as I feel ok, but under 40 I need to seek medical attention. Probably your meds doing it. I find when it gets that low I just get up and so something, that helps.