An echocardiographic method for selecting high risk patients shortly after acute myocardial infarction, for inclusion in multi-centre studies (as used in the TRACE study)

Abstract

The aim of our study was to examine if echocardiography can reproducibly be used in a multicentre study to select high risk patients with reduced left ventricular function early after an acute myocardial infarction (MI). In the TRAndolapril Cardiac Evaluation Study (TRACE) patients with reduced left ventricular systolic function were randomized 3–7 days post MI to receive either the ACE inhibitor trandolapril, or placebo. Twenty-seven Danish centres participated and 7001 consecutive MI patients were screened for entry. Local doctors and technicians who had received a brief but thorough training course recorded a two-dimensional echocardiographic examination on videotape 2–6 days after MI. Within 24 h, wall motion index (WMI) was visually assessed by one of two cardiologists (examiners) with considerable experience in echocardiography. A WMl of ≤l.2 (corresponding to a left ventricular ejection fraction (LVEF) ≤0.35) meant that the patient was eligible for randomization in the TRACE study. Two other experienced cardiologists with substantial experience in echocardiography (controllers) performed blind reassessment of 155 randomly chosen videotapes. We showed that 93% of the 7001 screened Mis had an assessable echocardiogram. WMl was ≤1.2 in 37% of patients. The one-year mortality was inversely related to WMl, being 60%, 30%, 14% and 11% in patients with a WMIl.6, respectively. In the random sample of 155 videorecordings that were reevaluated, 97% were found to be technically adequate for analysis both by the examiners and the controllers. Comparing the examiners with the controllers, the reproducibility analysis showed 95% confidence limits for a single estimate of LVEF of ± 0.13. Comparison between the two examiners showed corresponding confidence limits of ±0.10. Using WMl of 12 (LVEF∼0.35) as a discriminative value the concordance between examiners and controllers was 80%. Thus, evaluation by experienced cardiologists of videotaped echocardiographic examinations recorded by briefly but thoroughly trained investigators appears to be a reliable and reproducible method for the selection of high risk patients shortly after MI in multicentre studies.