My 73 Year Old Mother Fainted And Seems To Have

My 73 year old mother fainted and seems to have irregular heart beat. She's seen her Primary and she's on Diltiazem for her high blood pressure (135/78 when she's seen the Primary and 157/80 when she's seen the Cardiologist). The Cardiologist or Primary had her wear a heart monitor for about a month and also did a night time monitor, and she's done a stress test. She passed her stress test but her heart stopped for 2 seconds and another time for 1 second as indicated on the heart monitor. So the Cardiologist wants to double her Dilitazem dosage and put her on Eliquis to thin her blood to prevent a heart attack. My mom is 5 ft 5in and probably 130 to 140 pounds and general in good health, strong and eats healthy. The doctors have not explained what is causing her irregular heart beats and I've read that several things (thyroid, nutrient imbalance, stress, etc.) could cause it. As far as I can tell neither doctors checked for other causes. My concern is the Cardiologist is "preventing" a heart attack but not trying to fix the irregular heart beats and heart stopping. Is her heart stopping for a couple of seconds the same as heart palpitations? What should we be asking the Primary and Cardiologist? Any additional insight or recommendations is greatly appreciated.