Endocardial late potentials recorded during sinus rhythm in man: incidence in different cardiac disease states.

In a prospective study, 100 patients with various cardiac diseases not selected on the basis of previous ventricular arrhythmias underwent left ventricular endocardial mapping. With 10 different positions of the quadripolar catheter per patient, 90 of the 100 patients showed late potentials. These findings were documented in 50 of 52 patients with coronary heart disease compared to 26 of 34 patients with dilative cardiomyopathy (p less than 0.025). Late potentials in diastole were the most frequent type of abnormal electrogram, found in 82 patients. Fractionated electrograms were documented in 43 patients. They were seen in 27 (52%) coronary patients more often than in 8 (24%) patients with dilative cardiomyopathy (p less than 0.025). Onset of fractionated electrograms in coronary patients was somewhat later (301 +/- 177 ms after the QRS) than in the cardiomyopathy group (263 +/- 141 ms). The duration was longer (189 +/- 114 ms) in the former group than in the latter (148 +/- 87 ms). Thus, endocardial late potentials are not uncommon in patients with various cardiac diseases. The more frequent occurrence in coronary heart disease and the higher frequency of fractionated electrograms may indicate a more inhomogeneous, patchy type of fibrosis in the ischemically diseased myocardium.