Author + information
- Received July 7, 1986
- Revision received October 11, 1986
- Accepted November 3, 1986
- Published online May 1, 1987.
- David E. Haines, MD1,
- George A. Beller, MD, FACC1,
- Denny D. Watson, PhD1,
- Donald L. Kaiser, Dr PH1,
- Sharon L. Sayre, BSN1 and
- Robert S. Gibson, MD*,1
- ↵*Address for reprints: Robert S. Gibson, MD, University of Virginia Medical Center. Division of Cardiology, Box 468, Charlottesville, Virginia 22908.
To define the prevalence and clinical significance of exercise-induced ST segment elevation during predis-charge treadmill testing after uncomplicated acute myocardial infarction confirmed by serum MB creatine kinase (CK) activity, 241 consecutive patients were prospectively investigated with quantitative exercise thallium-201 scintigraphy, rest radionuclide ventriculography and coronary angiography at 10 ± 3 days. All patients received customary care, and in none was thrombolytic therapy or emergency coronary angioplasty employed.
Eighty-two patients (34%) had exercise-induced ST segment elevation of ≥ mm above rest baseline. These patients were similar to the 159 patients without this finding with respect to history of prior infarction, the Norris coronary prognostic index, exercise duration, metabolic equivalents (METs) achieved and peak heart rate-blood pressure product. The frequency of inducible myocardial ischemia and extent of angiographic coronary disease was also comparable in the two groups. Findings associated with larger infarct size and transmural extent of infarction were more common in patients with exercise-induced ST segment elevation than in those without, including higher peak CK values (1,235 ± 1,037 versus 942 ± 915 μmol/min per liter, p < 0.026), lower left ventricular ejection fraction (43 ± 12 versus 51 ± 10%, p < 0.001), a higher prevalence of pathologic Q waves in ≥2 contiguous infarct-related leads (80 versus 55%, p < 0.001), more persistent thallium-201 defects (2.2 ±1.1 versus 1.4 ± 1.1, p < 0.001), abnormally increased lung uptake of thallium (33 versus 18%, p < 0.01) and a greater number of akinetic or dyskinetic segments (3.2 ± 2.5 versus 1.4 ± 1.9, p < 0.001). Among all variables subjected to stepwise discriminant function analysis, the severity of wall motion abnormalities at rest was the strongest independent predictor of exercise ST segment elevation. During a median follow-up of 34 months individual nonfatal cardiac event rates were similar in the two groups, and mortality was 22% in patients with exercise ST segment elevation compared with 11% in those without this finding (p = 0.10, Kaplan-Meier method).
It is concluded that exercise-induced ST segment elevation 10 ± 3 days after uncomplicated myocardial infarction is common and associated with greater impairment of global and regional left ventricular function due to more extensive damage, rather than extent of underlying coronary artery disease or residual ischemia as assessed by exercise test or quantitative thallium-201 scintigraphic criteria.
- Received July 7, 1986.
- Revision received October 11, 1986.
- Accepted November 3, 1986.
- American College of Cardiology Foundation