The Clinical, Angiographic, and Prognostic Significance of Patients with Exercise Induced ST-segment Elevation

Doo, Young Cheoul; Park, Tae Rim; Suh, Joong San; Koh, Soon Hee; Oh, Dong Jin; Rim, Chong Yun; Koh, Young Bahk; Lee, Young

Abstract

BACKGROUND
The exercise stress testing(Treadmill Test) is one of the preferred noninvasive methods of identifying patients with coronary artery disease. ST-segment elevation during or immediately after exercise is uncommon and in most patients, it was associated with prior infarction, left ventricular hypertrophy or left bundle branch block, Exercise-induced ST-segment elevation has been attributed to ventricular wall motion abnormalities, and ischemia due to either coronary vasospasm or ervere proximal coronary stenosis. We examined the clinical, angiographic, and prognostic significance of 16 patients with exercise induced ST-segment elevation.
METHODS
16 patients with exercise-induced ST-segment elevation were retrospectively reviewed. The symptom-limited exercis testing was performedn using a modified Bruce protocol and in patients with acute myocardial infarction(AMI), low level exercise testing(Myocardial infarction protocol) was used. The significant ST-segment elecation was defined as a > or =1mm change present in >1 lead measured at 0.08 sec after J point and in > or =3 consecutive beats. Coronary arteriogram and percutaneous transluminal coronary angioplasty(PTCA) was performed using standard techniques within 7 days of initial exercise testing and a luminal diameter stenosis of >50% was considered significant.
RESULTS
1) We have studied 2076 exercise tests and 16 patients(M/F:15/1, Mean age : 58 years) developed exercise-induced ST-segment elevation. The initial diagnosis were acute myoca rdial infarction(AMI) in 12, variant angina in 2, effort angina in 1 and unstable angina in 1 patient. 9 of 12 patients with AMI were treated with thrombolytic agent(Urokinase 2.5 to 3 million unit) within 6 hours from the onset of chest pain. 2) Mean maximal ST-segment elevation was 2.6mm(range 1-5mm). The leads which showed exercise-induced ST-segment elevation were corresponded to the location of severe coronary stenosis in typical effort angina, to spasm site in variant angina, and to infarction site in AMI. 11 Patients had follow-up exercise testing and showed abolition of exercise-induced ST-segment elevation in 4 of 5 patients with AMI and 1 patient with effort angina after PTCA, and 1 patient with variant angina and 3 of 4 patient with AMI after medication. 3) In 12 patients, coronary angiography was performed, and showed 95% and 90% stenosis at proximal LAD in 2 patients with effort angina and >80% stenosis at proximal or mid lesion of infarct-related artery in 7 patients with AMI. In variant angina, one patient showed normal coronary artery and another patient showed 60% stenosis at mid LAD. On LV angiogram, there were moderate to severe hypokinesia instead of akinesia or dyskinesia at infarction site in all patients with AMI and showed normal LV contractility in patients with effort or variant angina. PTCA were successfully performed in 7 patients(effort angina 2, AMI 5). 4) The clinical follow up for 16 patients were obtained for mean follow-up duration of 17 months and during the clinical follow-up, 1 variant angina patient with mild stenosis at proximal LAD was died with ventricular fibrillation after discontinution of medication. There were CABG due to restenosis in 1 patient and cerebrovascular accident in 1 patient.
CONCLUSION
1) The exercise-induced ST-segment elevation signifies severe ischemia due to either severe proximal coronary stenosis or coronary arterial spasm. In AMI, this findings suggests the residual ischemia(or residual viable myocardium) in addition to left ventricular dyssynergy or aneurysm. 2) Adverse cardiac events can be provented by revascularization in patients who had critical coronary stenosis and by medical therapy in those with coronary vasospasm or mild coronary stenosis.