Complete heart block in myocardial infarction presents with distinct preceding conduction abnormalities depending on the infarct location, attributing CHB to an A-V node lesion in posterior MI and bilateral bundle-branch block in anteroseptal MI.
CHB localization by infarct site may guide ECG surveillance; leaves open relevance under modern reperfusion.
Complete heart block (CHB) was observed in 24 of 350 patients with myocardial infarction who were studied under conditions of continuous electrocardiographic monitoring. CHB occurred predominantly in posterior and anteroseptal infarctions. In posterior infarction CHB was observed in patients who also developed first degree (1°) and types I and II second degree (2°-I and 2°-II) atrioventricular (A-V) block but not bundle-branch block (BBB). In anteroseptal infarction CHB was found in patients with BBB, occasionally in patients with 2°-II A-V block, but not in patients with 1° and 2°-I A-V block. Right BBB with a Q wave in lead V 1 was the usual form of BBB observed in patients with CHB and anteroseptal infarction. One mechanism for sudden death in anteroseptal infarction is the abrupt development of CHB following the onset of BBB. Evidence is presented attributing CHB to a lesion in the A-V node in posterior infarction and to bilateral BBB in anteroseptal infarction.
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Stock et al. (1968) studied this question.
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