Bigeminal AIVR: Inferoposterolateral MI

Report:

Sinus bradycardia (rate uncertain)

Accelerated idioventricular rhythm 77/min

Bigeminy ? exit block

Nonspecific ST/T changes

Comment:

The infarction cannot of course be diagnosed in the original tracing and what was left of its evidence after angioplasty is shown below (Fig 82a). Electrocardiographically, the evidence for inferior MI is strong, posterior MI reasonable and anterolateral one presumptive (with only T waves inverting). The overall gestalt is as stated in the title: inferoposterolateral MI. Paul Wood once said, somewhere, that it does not matter where the infarct is, but whether one had occurred.

The interesting feature is the AIVR, itself a marker of reperfusion. It shows a bigeminal pattern, presumably reflecting 3:2 conduction of the impulses from its focus to the ventricles. The focus may be somewhere in the left anterior-superior division of the left bundle branch since the QRS morphology resembles RBBB with LPHB. The rhythm slows in both the long and the short cycles and is followed by a sinus escape (rather than capture, as in the preceding two cases) beat. The last beat is again of the AIVR focus origin and comes rather quickly, with the same cycle length as at the beginning of the trace. The focus has “recovered”.