C23 ELECTROCARDIOGRAPHIC PREDICTORS OF PRIMARY VENTRICULAR FIBRILLATION DURING A FIRST ACUTE MYOCARDIAL INFARCTION

Abstract

Abstract Introduction Few small studies evaluated electrocardiographic (ECG) predictors of ventricular fibrillation (VF) before reperfusion during a first acute myocardial infarction (AMI). None accounted for the time between symptom onset and ECG. Objectives To evaluate the ECG predictors of primary VF in the PREDESTINATION (PRimary vEntricular fibrillation and suDden dEath during a firST myocardIal iNfArcTION) population. Patients and methods: PREDESTINATION is an ongoing, prospective, multicenter, case–control study (1:2 match for sex and age) enrolling patients aged 18–80 with a first AMI, whether complicated (cases) or not (controls) by primary VF before reperfusion. For the present analysis, we matched 1:1 for age, sex, infarct site, and symptom–ECG time, the ECGs of cases before VF and those of controls revascularized at least 60 minutes after symptom onset. ECG traces were digitized in pdf and enlarged by 400%. Three blind analyzes were performed: on the entire population, on only anterior and only non–anterior AMI. Results PREDESTINATION currently includes 1478 patients (mean 59 years, 83% male), 533 of whom are cases. Among the cases, only 59 (58 ± 11 years, 10% females, 64% with anterior AMI, mean symptoms–ECG time 78±60 minutes, mean ECG–VF time 23±15 minutes) had a pre–VF ECG of adequate quality. Both in the general population (118 ECGs) and in anterior AMIs subgroup (76 ECGs), the presence of ventricular (VEB) or supraventricular ectopic beats (SVEB) was associated with an increased risk of developing VF (maximum OR 8.35 for VEBs in anterior AMIs). In the subgroup of anterior AMIs, the Tpeak–Tend interval in non–infarction leads, both corrected for the RR interval (Bazett) and for the QT interval (TpTe/QT) was significantly longer in cases compared to controls. A TpTe/QT ≥0.33 in non–infarction leads was associated with an OR of 4.6 (p=0.02) of developing VF. Conclusions the present analysis, aimed at identifying ECG predictors of primary VF, is the first to perform a rigorous case–control matching including symptom–ECG time. In addition to ectopic beats, a well–known marker and promoter of electrical instability, we identified, only for anterior AMIs, a single additional predictor (TpTe/QT), which correlates with an increased dispersion of repolarization and consequently of ventricular refractoriness.