I have been having a lot of irregular heartbeats; have been checked by cardiologist in the past, was told my heart was in good shape. I am currently taking 11.25 mg mirtazapine, 1 mg lorazepam, 600 to 900 mg gabapentin, either 3 mg lunesta or 10 to 20 mg zaleplon. I also take 25 to 50 mg atenolol, not because I have high blood pressure but for anxiety and the irregular heartbeats. I have also been prescribed Seroquel, anywhere from 6.25 to 25 milligrams for sleep but I don t like taking it so I don t usually. It makes my heart beat much faster; the mirtazapine makes it beat faster too although the psychiatrist says it shouldn t do so at the dose I m on. Could the mirtazapine be causing irregular heartbeats? I think maybe it is, although it also could be that I still don t get enough sleep although I try to. Am also concerned because my cholesterol is higher and I ve heard that mirtazapine can raise it. Thanks for your help.