Use of treadmill score to quantify ischemic response and predict extent of coronary disease.

Abstract

In this study we assessed whether various responses to exercise testing could be quantified in order to derive the probabilities of presence of coronary disease, and if present, to assess its severity. A treadmill score based on the exercise response was determined in 405 patients who had both treadmill tests and coronary angiograms. The score was derived using discriminant function analysis, by weighting and combining depth and configuration of ST depression (downsloping, horizontal or slowly upsloping), timing onset and duration of ischemia, grading ventricular arrhythmias, heart rate and blood pressure change, coexistence of exercise-induced chest pain and sex. The treadmill score was effective in detecting coronary disease (lesions with an greater than or equal to 50% narrowing), with a predictive accuracy (PA) (probability that a subject manifesting a positive test has disease) of 87%, a true negative rate (TNR) (probability of a subject with a negative test having no disease) of 80%, and sensitivity of 94%. The treadmill score also detected severe disease (triple-vessel, main left and/or greater than 90% proximal occlusion of the left anterior descending artery), with a PA of 73%, TNR of 79% and sensitivity of 82%. We conclude that the exercise response, expressed numerically as a treadmill score, permits analysis of most of the relevant data from exercise testing, increases test accuracy by 10-15% compared with standard criteria for treatmill test interpretation, and enables the derivation of probability statements for presence and severity of coronary disease. The validity of any prediction on the basis of exercise performance may thus be quantitatively judged.

Features of the exercise test that reflect the activity of ischemic heart disease out of hospital.

“…Furthermore, recent work in which regional myocardial perfusion was assessed with rubidium-82 and positron-emission tomography in conjunction with electrocardiographic observations has further validated the use of ST segment depression as a marker of ischemia in such patients, even in the absence of symptoms.9 ' 10 The ambulatory monitoring studies in the group I patients with inducible ischemia on exercise confirmed the findings of several previous studies '13 on solved by 5 or less minutes after exercise have very little or no ischemic activity out of hospital, which may also be reflected in a better prognosis.3-7 (4) In contrast, patients who develop ischemia after 6 min of exercise or less or at heart rates of less than 150 beats/ min, and those in whom ischemic changes persist for more than 5 min after exercise, are likely to have much more active myocardial ischemia out of hospital, which may in turn be related to an adverse prognosis. [3][4][5][6][7] There is no indication that ambulatory monitoring of ischemic ST segment changes is superior to the exercise test for detection of ischemic heart disease, but it has provided a different picture of the pathophysiology of active transient myocardial ischemia, which is one of the potentially damaging aspects of coronary artery disease. The greater frequency and duration of transient ischemia out of hospital shown in our patients with lower ischemic thresholds and more persistent ischemia during exercise testing may explain the poorer prognosis in such patients.3 7 However, there was a wide range of ischemic activity out of hospital in these patients, which raises the possibility that characterizing such disease activity during daily life may be Vol.…”

“…[3][4][5][6][7] There is no indication that ambulatory monitoring of ischemic ST segment changes is superior to the exercise test for detection of ischemic heart disease, but it has provided a different picture of the pathophysiology of active transient myocardial ischemia, which is one of the potentially damaging aspects of coronary artery disease. The greater frequency and duration of transient ischemia out of hospital shown in our patients with lower ischemic thresholds and more persistent ischemia during exercise testing may explain the poorer prognosis in such patients.3 7 However, there was a wide range of ischemic activity out of hospital in these patients, which raises the possibility that characterizing such disease activity during daily life may be Vol. 74, No.…”

Risk stratification with low-level exercise testing 2 weeks after acute myocardial infarction.

“…The exercise evaluation was performed 1 or 2 days before anticipated hospital discharge. Patients with unstable angina, orthostatic systolic blood pressure less than 90 mm Hg, and an unsteady gait (1) to rank exercise duration, number of VPDs during exercise and ST depression in terms of strength of association with cardiac death 1 year after infarction; (2) to test the independence of the association of each of the three exercise variables with 1-year mortality; (3) to determine the combined ability of the three exercise variables to predict 1-year cardiovascular mortality; and (4) No patient died within 24 hours of the exercise examination. Two nonfatal reinfarctions occurred in the 24 hours after the exercise test, one in a patient who completed the 9-minute protocol without symptoms and the other in a patient who stopped after 6.5 minutes because of fatigue.…”

The Severity of Myocardial Ischemia Can Be Predicted by the Exercise Electrocardiogram

“…Cohn et al [6] also designed a score based on the timing of onset and duration of ischemia, ST configuration, heart rate and blood pressure changes, chest pain and sex. They reported a predictive accuracy for three-vessel disease of 73% and a sensitivity of 83%.…”

“…Within a few more years, attempts to quantitate the severity of coronary disease by examining various aspects of the test were reported as well [6, 7]. Although these reports claim their methods to be quite reliable, they have never been broadly utilized.…”