961-78 Importance of Left Ventricular Ejection Fraction and Signal Averaged Electrocardiogram but not of Coronary Artery Patency nor Holter Monitoring to Predict Severe Arrhythmic Events After a First Myocardial Infarction in the Thrombolytic Era

Abstract

We followed-up 244 consecutive patients (210 men, mean age 56 ± 9 yrs) who survived the acute phase (alive after day 7) of a first anterior (N = 102) or inferior (N = 142) myocardial infarction (MI) with a mean follow-up (FU) delay of 57 ± 18 months. In the acute phase, 97/244 patients (40%) received a thrombolytic therapy. Within the second and third week after admission, all patients underwent a Holter ECG monitoring graded by the Lown classification, a signal averaged electrocardiogram (SAECG) and a coronary angiography. Three parameters were measured by SAECG (predictor system, 40 Hz high-pass filter): total QRS duration (QRSd), root mean square voltage of the last 40 ms (RMS) and duration of the terminal low (<40 uV) amplitude signal (LAS). The number of diseased vessels as well as the infarct related artery (IRA) patency was evaluated by TIMI grading (TIMI 2 or 3 = patent) and left ventricular ejection fraction (LVEF) was measured angiographically. Cox proportional hazards model was used for the statistical analysis. We observed 18 arrhythmic events (AE): 10 sudden cardiac death and 8 ventricular tachycardia during the FU period. Statistical analysis identified 3 independent factors predictive of the occurence of an AE: 1) LVEF, with a risk multiplied by 1.9 for each 0.10 decrease in the LVEF value, 2) LAS, with a risk multiplied by 1.3 for each 5 ms increase in LAS value and 3) absence of thrombolysis, with a risk multiplied by 3.9. After MI in the thrombolytic era the Holter ECG monitoring and the results of the coronary angiography do not predict the risk of an AE. LVEF, SAECG and absence of thrombolysis are the 3 independent predictors of such a risk.