Prevalence and functional significance of transient ST-segment depression during daily life activity: comparisons of ambulatory ECG with stress redistribution thallium 201 single-photon emission computed tomographic imaging.
To assess the prevalence and functional significance of ischemic ambulatory ECG responses, we prospectively performed ambulatory ECG monitoring in 244 patients (mean age 61 +/- 10 years) referred for stress redistribution thallium 201 myocardial perfusion scintigraphy. The prevalence of ST-segment depression during ambulatory ECG was 33% among patients with a positive exercise ECG, but prevalence varied in selected patient subgroups. Among three groups with coronary artery disease (CAD), the group with ambulatory ECG ischemia (group 1) had a greater frequency of ischemic thallium responses (p = 0.07), a greater median number of reversible thallium defects (p < 0.05), and a greater summed thallium "reversibility" score (p < 0.05) than did the group with a positive exercise ECG but negative ambulatory ECG response (group 2) or that with negative exercise and ambulatory ECG responses (group 3). Exercise ST depression in group 1 versus group 2 was significantly greater (p = 0.002), occurred at a lower heart rate threshold (p = 0.002), and lasted longer after exercise (p = 0.001). Notably, one third of group 1 patients also manifested evidence of transient ischemic dilation of the left ventricle after exercise (p < 0.01 vs groups 2 and 3), a sign of severe ischemia. However, although functionally less "sick" than group 1 patients, 66% of group 2 patients and 50% of group 3 patients still had an ischemic thallium response, which was sometimes severe. Thus transient ischemia during ambulatory ECG monitoring identifies a functionally sicker cohort of patients with CAD and occurs in approximately one third of CAD patients with positive results of exercise tests. A negative ambulatory ECG response, however, does not exclude functionally significant disease among CAD patients. These results imply that caution should be applied in the interpretation of a negative ambulatory ECG response for the purpose of patient risk stratification.
Klein
J
J
Division of Cardiology, Cedars Sinai Medical Center, Los Angeles, Calif.
Rodrigues
E A
EA
Berman
D S
DS
Prigent
F
F
Chao
S Y
SY
Maryon
T
T
Rozanski
A
A
D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D011446:Prospective Studies; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon
D013794:Thallium Radioisotopes