It was useless for me. Very disappointing. I am 84 and now in permanent a-fib. My first a-fib episode occurred in 2017 following knee replacement surgery, which I was very uptight about. Cardioversion restored rhythm. It had to be repeated 10 months later. Simultaneously I took diltiazem, then sotalol. When they stopped working, I was given Tikosyn and then amiadarone, neither of which worked. Finally I was given metoprolol, which controls my tachycardia pretty well, but I I am hardly back to my old vigor. I ride a bike, walk a mile or so, try to do what I can, but the old high energy and confidence are gone. I recently got a second opinion from a highly regarded EP, who feels it's too late to do an ablation, and wonders why my primary cardiologist didn't recommend an ablation when my tachycardia first appeared. I wonder, too.