Prevalence of coronary artery disease requires sensitive diagnostic methods for screening and follow-up. The sensitivity of stress-ECG is low, 201-thallium scintigraphy is more sensitive but has the disadvantages of radiation and costs. Improved echocardiographic resolution with better identification of endocardial border as well as digital imaging technique have increased the interest in stress echocardiography as a diagnostic tool in coronary artery disease since a decade ago the clinical usefullness of stress echocardiography has been demonstrated. For stress echocardiography a semisupine bicycle position for continuous recording of echocardiographic images from the apical position in the two-chamber- and RAO-view was developed (Figure 1). Echocardiographic images were digitized with a frame rate of 30/s and stored on optical discs with a storage capacity of 1 Gbyte. Rest and exercise images were analysed simultaneously for newly-occurring wall motion abnormalities or deterioration of already present hypokinesia or extension of existing wall motion abnormalities. Segmental wall motion was scored according to the scheme in Figure 2. In addition end-diastolic, end-systolic volume, and ejection fraction were calculated. In a patient population of 150, 30 female and 120 male, age 56.6 +/- 8.3 years, we could confirm the results reported by other working groups (Table 3) and demonstrate a high sensitivity in the diagnosis of single vessel disease. Our technique with the patient cycling in semi-supine position allows continuous echocardiographic registration during exercise and offers adequate image quality. The mean workload at peak stress was 127 +/- 30 watts, the maximal heart rate 137 +/- 18 bpm. Digital cine-loop imaging allowed evaluation of the examinations in about 90% of the cases. The sensitivity in the whole study group was 87%, the specificity 80%. Under full antianginal medication, 43% of the patients developed angina pectoris during exercise and 58% had a positive stress-ECG. The sensitivity in single-vessel coronary artery disease was 93% for the left anterior descending, 80% for the left circumflex, and 83% for the right coronary artery (Table 1, Figure 3). These results in single-vessel disease were superior compared to findings of other authors using different techniques of stress echocardiography. In addition to the qualitative analysis, quantitative measurement of end-systolic volume and ejection fraction seems to be important. We found a significantly more pronounced decrease of ejection fraction at peak exercise in patients with multivessel disease compared to those with single-vessel disease. In single-vessel disease ejection fraction was 61 +/- 12% at rest and 57 +/- 17% during exercise, this difference was not significant. Ejection fraction decreased significantly in two-vessel disease from 64 +/- 7% to 56 +/- 13% (p < 0.05), in three-vessel disease from 61 +/- 12% to 48 +/- 10% (p < 0.05, Table 2, Figure 6). In single-vessel disease end-systolic volume changed only slightly during exercise (26 +/- 15 ml/m2 at rest and 29 +/- 17 ml/m2 during peak exercise). In two-vessel disease it increased from 24 +/- 9 ml/m2 to 31 +/- 13 ml/m2 (p < 0.05) and in three-vessel disease from 26 +/- 6 ml/m2 to 36 +/- 10 ml/m2 (p < 0.05, Table 2, Figure 5). These findings suggest that patients with single vessel disease can compensate hypo- or akinesia in one region with a hyperkinetic response in the contralateral region. The rest and exercise values for end-diastolic volume were not significantly different in all groups (Table 2, Figure 4). Score values increased significantly from rest to peak exercise in each group, but exercise scores did not differ significantly between the groups (Table 2). The wall motion abnormalities persisted after the end of exercise (Figure 7). In one-vessel disease wall motion abnormalities were only present up to 58 +/- 49 s after exercise, in two-vessel disease 96 +/- 55 s, in three-vessel disease 152 +/- 33 s. Thus, recordings taken only at the end of exercise can miss transient wall motion abnormalities, especially in one-vessel disease. Major indications for stress echocardiography are negative stress-ECG tests, but positive history, risk stratification after myocardial infarction, and follow-up diagnostics in patients who underwent percutaneous transluminal angioplasty or aorto-coronary bypass grafting.
