ST-segment elevation on Q leads at rest and during exercise: Relation withmyocardial viability and left ventricular remodeling within the first 6 months after infarction

Background Resting ST-segment elevation on Q leads after an acute myocardia l infarction has been related to a greater infarct size. Otherwise, the rel ation between exercise-induced ST-segment elevation and myocardial viabilit y is controversial. We investigated the relation between ST-segment elevati on on Q leads at rest and during exercise and regional dysfunction and its evolution, contractile reserve, left ventricular dilation, and coronary pat ency. Methods and Results Exercise testing and cardiac catheterization were perfo rmed at the first week after infarction in 51 patients. The study group was divided according to the existence (in 2 or more Q leads; n = 36) or not ( n = 15) of resting ST-segment elevation and according to the existence (n = 28) or not (n = 23) of exercise-induced ST-segment elevation. Left ventric ular end-diastolic and end-systolic volumes (mL/m(2)), regional wall motion (SD/chord), contractile reserve (wall motion percentage improvement with l ow-dose dobutamine), and coronary potency in the culprit artery were analyz ed. Cardiac catheterization was repeated at the sixth month in 35 patients; systolic recovery (wall motion percentage improvement), left ventricular v olumes, and coronary patency were again evaluated. Patients with resting ST -segment elevation showed poorer wall motion (2.1 +/- 0.8 SD/chord vs 1.2 /- 1 SD/chord, P = .002), lesser contractile reserve (17% [0% to 39%] vs 41 % [4% to 92%], P = .04), greater end-systolic volume (32 +/- 15 mL/m(2) vs 23 +/- 11 mL/m(2), P = .04), and higher percentage of occlusion (36% vs 7%, P = .04) than did patients without ST-segment elevation. likewise, patient s with exercise-induced ST-segment elevation showed lesser contractile rese rve (8% [0% to 40%] vs 35% [12% to 86%], P = .03) than did patients without exercise-induced ST-segment elevation. The only independent predictors of contractile reserve were wall motion <2 SD/chord (odds ratio [OR] 7.1, conf idence interval [CI] 6.3 to 7.9, P = .01) and the absence of exercise-induc ed ST-segment elevation (OR 5.7 CI 4.9 to 6.5, P = .02). There were no sign ificant differences between patients with and those without ST-segment elev ation (at rest or during exercise) in systolic recovery or left ventricular volumes at the sixth month. Conclusions ST-segment elevation on Q leads at rest is related to a poorer systolic function (more severe regional dysfunction, greater end-systolic v olume, and less response to dobutamine). ST-segment elevation during exerci se is independently related to a lesser contractile reserve. ST-segment ele vation (at rest or during exercise) is not related to the evolution of volu mes or regional dysfunction during the first 6 months after infarction.