CHANGES IN THE SIGNAL-AVERAGED ELECTROCAR DIOGRAM AFTER MYOCARDIAL REVASCULARIZATION - COMPARISON BETWEEN CORONARY-BYPASS SURGERY AND ANGIOPLASTY

The signal-averaged electrocardiogram (SA-ECG) was studied in 148 pati ents undergoing myocardial revascularisation either by coronary bypass surgery (CBS) (64 cases) or transluminal angioplasty (PTCA) (84 cases ). The investigation was performed before the procedure, at day 7 (D7) and after 3 months (D120). No difference was observed in the SA-ECG b etween the two groups before revascularisation. The CBS population was older, more symptomatic and had more severe lesions than the PTCA pop ulation. One hundred and thirty-nine patients were followed up until t he end of the study protocol (CBS = 63; PTCA = 76). Two criteria of th e SA-ECG were significantly modified after CBS : QRS duration (p < 0.0 5) and Under 40 (p < 0.01). No significant changes were observed after PTCA. In the patients with late potentials (LP) before revascularisat ion, the mean value of these criteria (Under 40 and Last 40) were sign ificantly modified after CBS (U40 = 54.3 +/- 16 to 35.4 +/- 15; p < 0. 01) (L40 = 11.9 +/- 4.7 to 26.1 +/- 24.3; p < 0.01). No changes in the se criteria were observed after PTCA. The value of negativation of the criteria of LP for patients with two criteria of positivity was 71.1 % after CBS compared with 25 % after PTCA (not significant). These obs ervations support the hypothesis of a favourable modification of the a rrhythmogenic substrate after myocardial revascularisation, especially by CBS.