Accelerated idioventricular rhythm (AIVR) has a rate of

• A. 100-140 bpm
• B. 25-45 bpm
• C. 50-100 bpm
• D. 140-180 bpm

Answer: (C)

Accelerated idioventricular rhythm is a ventricular rhythm where the pacing comes from ventricular tissue at a moderate rate—faster than a typical idioventricular rhythm but not fast enough to be ventricular tachycardia. The rate that defines AIVR is about 50–100 beats per minute. This places it above the slower idioventricular escape (which is typically under 50 bpm) and below the threshold for VT (usually over 100 bpm). In practice, AIVR is often seen after reperfusion or during recovery from myocardial injury and is usually self-limited and well tolerated unless the patient is unstable. The other ranges correspond to rhythms outside this middle zone: 100–140 bpm is more consistent with ventricular tachycardia, 25–45 bpm is a slower idioventricular/escape rhythm, and 140–180 bpm indicates VT as well. So the rate 50–100 bpm best matches AIVR.