In a patient with chronic atrial fibrillation with a regular beat of 60/min, the most probable cause is-
The health care provider may hear a fast heabeat while listening to your hea with a stethoscope. Your pulse may feel fast, uneven, or both. The normal hea rate is 60 to 100 beats per minute. In atrial fibrillation or flutter, the hea rate may be 100 to 175 beats per minute Digoxin toxicity is a life-threatening condition. ... The classic arrhythmias seen during digoxin toxicity include atrial tachycardia with a 2:1 conduction, bidirectional ventricular tachycardia and atrial fibrillation with a slow ventricular response Ref Harrison 20th edition pg 1436
Sleep
Digitalis toxicity
Sino nodal block
Hypothyroidism
C.V.S