Hi...I'm 67 Years Old Female And I Had Been Experiencing

Hi...I'm 67 years old female and I had been experiencing palpitation for years at first once a month...but this past month, it's everyday and I. Had been taking 50mg Atenolol but it seems like it doesn't me anymore. It's worst when I bend to wash dishes and when I life something heavy. Is there a meds I can take other than Atenolol? Thank you.