Done aortic valve replacement. Increased heart rate, anxiety. Prescribed Atenolol

Hello, my name is Loren & I m 32. I had an aortic valve replacement 3 years ago having been born with bicuspid valve. Things were going good until about a year later when I started getting these episodes of fast heart rythym & feelings of anxiety usually the day after consuming alcohol, so I tried just cutting out the drinking. Now it s progressed to after eating dinner (usually starts while sleeping) & oddly enough usually will slow down if I urinate, bowel movement ect. But sometimes this event will happen during the day & my anxiety has gotten way out of control. While having theses episodes I truly feel I m about to die. My cardiologist has prescribed me atenalol & told me to take a low dose aspirin along with my usual warfarin . After a another year of suffering episodes there s still no change. If you have any info it would be so much appreciated! Thanks