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

Abstract

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 Ž . 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.Ž . 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 Ž . Ž . Ž software QGS . Results: Twenty-one out of 50 patients 42%, G1 had significant stress-induced ST-elevation ) 1 mm 80 ms . Ž . Ž . after J point in at least 2 ECG leads with Q wave , and 29r50 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 G1 Ž compared to G2 LVEF: 39 " 10% vs. 49 " 11%, Ps 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 Žpost-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. ᮊ

Vagal Enhancement as Evidence of Residual Ischemia After Inferior Myocardial Infarction

“…During the past decade, however, ST‐segment elevation in Q‐wave leads has attracted clinical attention concerning its diagnostic potential for residual ischemia in MI patients 24 . Some investigators reported that ST‐segment elevation in Q leads was a highly specific marker of residual ischemia, 25,26 while others presented negative evidence 27–29 . Combination of exercise‐induced ST‐segment elevation and pseudonormalization of negative T waves 30 or ST‐segment depression 31 have been reported to indicate residual ischemia within the infarct‐related area.…”

“…24 Some investigators reported that ST-segment elevation in Q leads was a highly specific marker of residual ischemia, 25,26 while others presented negative evidence. [27][28][29] Combination of exercise-induced ST-segment elevation and pseudonormalization of negative T waves 30 or ST-segment depression 31 have been reported to indicate residual ischemia within the infarct-related area.…”