Exercise-induced ST-segment depression in patients without restenosis after coronary angioplasty. Relation to preprocedural impaired left ventricular function.

Background: ST-segment depression during exercise testing is frequently observed in the absence of restenosis after coronary angioplasty.
Methods and Results: We studied the determinants of this phenomenon in 70 consecutive patients with unstable angina related to a single left anterior descending coronary artery lesion who had successful angioplasty without restenosis (< 50% stenosis by quantitative angiography). We compared preangioplasty clinical, angiographic, and hemodynamic variables in the group with positive (ExT Pos, n = 35; ST depression, 2.3 +/- 0.9 mm) and negative (ExT Neg, n = 35; ST depression, 0.3 +/- 0.5 mm) results on exercise testing at follow-up angiography. At this time, minimal lumen diameter (1.7 +/- 0.4 mm) and mean residual stenosis (34 +/- 11%) in the ExT Pos group were not significantly different from the values (1.9 +/- 0.5 mm, 38 +/- 10%) in the ExT Neg group. Before angioplasty, the ExT Pos group had a lower ejection fraction (63 +/- 8% versus 68 +/- 9%, P < .05), more marked anterior hypokinesis estimated by the extent of anterior wall contraction on quantitative ventriculography (P < .05), and a greater end-systolic volume (30 +/- 11 versus 25 +/- 9 mL/m2, P < .05) than the ExT Neg group. At follow-up angiography, regional anterior wall motion was normal in 68 patients (97%). Anterior hypokinesis before angioplasty was strongly associated (P < .01) with a positive exercise test at control (71% compared with 31% in patients with normal wall motion before angioplasty).
Conclusions: In the absence of significant epicardial stenosis after angioplasty, ST-segment depression is strongly associated with the presence of preprocedural regional ventricular dysfunction that has recovered at follow-up angiography.