Value of electrocardiographic scoring systems for the assessment of thrombolytic therapy in acute myocardial infarction

The value of the Selvester and Cardiac Infarction Injury Scores was assessed in a randomized, placebo-controlled study of intravenous recombinant tissue plasminogen activator (rt-PA) in 721 patients with acute myocardial infarction. Electrocardiograms (ECG) obtained at admission, 6 h and 10 to 22 days after the start of therapy were analysed. Patients with prior myocardial infarction or QRS duration greater than or equal to 120 ms were excluded, leaving 322 in the rt-PA group and 333 in the placebo group. Cumulative 72-h release of alpha-hydroxybutyrate dehydrogenase (HBDH) and global ejection fraction derived from angiography and nuclear scintigraphy were used as independent measures of infarct size. Predischarge results demonstrated a net benefit of rt-PA therapy, with the Selvester Score 11% lower (P less than 0.01) and the Cardiac Infarction Injury Score 5.4% lower (P = NS) in the rt-PA than the control group. Total enzyme release was reduced by 19.2% (P less than 0.001) in the rt-PA group. In patients with inferior infarction, neither enzyme release (r = 0.30 to 0.40) nor ejection fraction (r = 0.22 to 0.31) correlated well with the ECG indices of infarct size. In anterior infarction, the correlations were better, especially between the Selvester Score and enzyme release (r = 0.40 to 0.48) as well as ejection fraction (r = -0.48 to -0.67). It is concluded that ECG scoring systems, especially the Selvester Score, although imperfect are useful to assess thrombolytic therapy in clinical trials. However, their value for the management and assessment of thrombolytic therapy in individual patients is still limited.