[Late potentials--endocardial lead following myocardial infarct]

In 27 patients with myocardial infarction, late potentials were sought by means of diagnostic heart catheterization with endocardial left and right ventricular mapping. Signals of late potentials were amplified between 100 and 10,000 times at low noise level using bipolar electrode catheters. Late potentials were recorded reproducibly in 19 patients (70%). Their amplitudes ranged from 50 to 600 microV. The coupling interval in each individual patient was constant and in the total group ranged between 100 and 520 ms. There were no differences of amplitude, form, and coupling interval in patients with and without ventricular tachycardia. In conclusion, late potentials can be found by endocardial mapping in the majority of patients after myocardial infarction. Their clinical relevance, however, has not yet been sufficiently investigated.