Responds to cardioversion — rate control — rhythm control
Why It's NOT the Similar Diseases
NOT atrial flutter — flutter is REGULAR with sawtooth baseline at 240 to 320 bpm — typically around 300 bpm — with fixed conduction ratios. AFib is IRREGULARLY irregular with chaotic fibrillatory baseline. Flutter looks organized — AFib looks chaotic.
NOT SVT — SVT is a regular narrow complex tachycardia — often terminated by vagal maneuvers or adenosine. AFib is irregularly irregular — adenosine may transiently slow ventricular rate and unmask fibrillatory waves but does not terminate AFib.
NOT sinus tachycardia — sinus tach has normal P waves before every QRS — regular rhythm — identifiable cause. AFib has no P waves and is irregularly irregular.
NOT ventricular tachycardia — VTach is WIDE complex regular tachycardia. AFib is narrow complex irregularly irregular.
NOT premature atrial contractions — PACs cause occasional irregular beats but overall rhythm remains regular. AFib is continuously irregularly irregular.
Differential Diagnosis List
Atrial flutter — ruled out by irregularly irregular rhythm and chaotic baseline versus organized sawtooth at 300 bpm
SVT — ruled out by irregular rhythm and absence of abrupt termination
Sinus tachycardia with PACs — ruled out by continuously irregular rhythm
VTach — ruled out by narrow complex and irregular rhythm
Multifocal atrial tachycardia — ruled out by absence of three distinct P wave morphologies
Key Distinguishing Test
ECG — absence of discrete P waves — irregularly irregular rhythm — fibrillatory baseline. Holter monitor captures paroxysmal episodes. Echocardiogram evaluates left atrial size and underlying structural heart disease.