I Was Hospitalized For Congestive Heart Failure; That Was Taken

I was hospitalized for congestive heart failure; that was taken care of in the hospital, but a 'weakened heart muscle' (low ejection fraction) and one instance of atrial fibrillation sent me home with a 'life-vest', which monitors my heart rate. I've been recording my weight, heart rate and blood pressure since my release in mid-August. In recent days, I'm noticing an increase in heart rate. . . I believe I've improved, but I'm concerned about the heart rate. Should I take my pulse more often (or is that anxiety?) Can you help me figure out possible causes and how to determine if one is serious?