Exercise-induced ST-elevation is related to left ventricular dysfunction but not to myocardial viability in patients with healed myocardial infarction

Background: Exercise-induced ST-segment elevation was proposed as a marker of myocardial viability after a recent myocardial infarction. Aims: The aim of this study was to evaluate whether exercise-induced ST segment elevation is related to viability or to left ventricular dysfunction in patients with history of old Q wave myocardial infarction. Methods: Fifty patients (43 men, age 57 +/- 11 years) were studied 31 +/- 49 months after a Q wave myocardial infarction. They all underwent stress, reinjection-redistribution, and late redistribution Tl-201 SPECT, completed by equilibrium radionuclide angiography. Viability was defined by defect reversibility or significant (> 60%) persistent Tl-201 uptake in dyssinergic segments on late redistribution SPECT. Relative post-exercise and reinjection-redistribution LV volumes were calculated using validated software (QGS). Results: Twenty-one out of 50 patients (42%, GI) had significant stress-induced ST-elevation (> 1 mm 80 ms after J point in at least 2 ECG leads with Q wave), and 29/50 (58%, G2) did not. Seventeen out of 50 patients (34%) demonstrated myocardial viability on late redistribution scan. The diagnostic accuracy of exercise-induced ST-elevation was only 52% for viability assessment. Significant LVEF reduction and increased relative LV volumes were observed in GI compared to G2 (LVEF: 39 +/- 10% vs. 49 +/- 11%, P = 0.003; post-stress LV volume: 134 +/- 98 ml vs. 81 +/- 41 ml, P < 0.02; reinjection-redistribution LV volume: 123 +/- 86 ml vs. 79 +/- 40 ml; P < 0.02). Perfusion defects were similar in G1 and G2 (post-exercise: 38 +/- 12% vs. 37 +/- 14%, ns; reinjection-redistribution: 31 +/- 11% vs. 30 +/- 11%, ns; late redistribution: 30 10% vs. 28 +/- 11%, ns). Conclusion: These results suggest that, in patients with history of myocardial infarction, exercise-induced ST-segment elevation is not related to persistent myocardial viability but is associated to left ventricular dysfunction. (C) 2001 European Society of Cardiology. All rights reserved.