Correlation of cumulative ST elevation with left ventricular ejection fraction and 30-day outcome in patients with ST elevation myocardial infarction.

Background: The electrocardiogram (ECG) is the first and often the only investigation available prior to definitive therapy in patients with ST elevation myocardial infarction (STEMI). A good prognostic marker is the left ventricular ejection fraction (LVEF) on ECG. Our aim was to assess the correlation between ST elevation (STE) in ECG and the LVEF and thereby aid the prognosis of patients with STEMI.

Methods: This was a prospective cohort study of 230 patients with STEMI. A baseline 12-lead ECG was taken to calculate the sum of STE at the J point in all the leads showing elevation. The STE was measured 90 min after revascularization to calculate the ST resolution percentage (STR%). All patients underwent echocardiography, and the LVEF was measured using biplane Simpson's method.

Results: A total of 136 patients with anterior myocardial infarction (MI), 35 with inferior MI, and 59 with inferoposterior MI were included in the study. Mean STE was 13 mm and was significantly higher among patients with anterior MI. There was a good inverse correlation between the STE and the LVEF with a correlation coefficient of -0.64. STR% had a correlation coefficient of 0.59 to the LVEF. A formula was generated to calculate the LVEF based on the STE as follows: LVEF = (37.34 - STE)/0.567. An STE ≥15 mm predicted an LVEF < 35% with a sensitivity and specificity of 70%.

Conclusion: The STE and STR% are useful surrogate markers in prognosticating patients irrespective of the type of STEMI.