Document Detail

Is 'silent' myocardial ischemia really as severe as symptomatic ischemia? The analytical effect of patient selection biases.
MedLine Citation:
PMID:  8181118     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The clinical significance of exercise-induced chest pain remains controversial, as reflected by sharply discordant clinical results within the medical literature. Thus, we developed a prospective study to compare the functional significance of silent versus symptomatic ischemia and to evaluate whether patient selection biases influence this analysis. METHODS AND RESULTS: We evaluated 117 patients (mean age, 63 +/- 9 years) with ischemic ST-segment depression during treadmill testing. Each patient underwent Tl-201 myocardial perfusion single-photon emission computed tomography (SPECT) after exercise followed by 24-ambulatory ECG monitoring. Patients were divided into silent versus symptomatic cohorts and were compared for the degree of hemodynamic, exercise and ambulatory ECG, and thallium abnormalities during stress testing. Analyses were repeated as the patient population became increasingly restricted. Compared with the silent patients, patients with chest pain during exercise had a shorter exercise duration (P < .009), lower peak heart rate (P = .009) and double product (P = .005), lower heart rate threshold for ST depression (P < .05), more episodes of ambulatory ST-segment depression (P < .05), a higher frequency of ischemia abnormalities during Tl-201 SPECT (P = .02), and higher summed Tl reversibility scores (P = .002). As the population became increasingly restricted, the relative magnitude of differences in silent versus symptomatic cohorts diminished, whereas the absolute magnitude of ischemic abnormalities progressively increased in both cohorts. For example, within the restricted group having ischemia on both exercise and ambulatory ECG, 50% of the silent cohort had severe ischemia on Tl SPECT (five or more reversible defects) and more than one third demonstrated the ominous finding of transient left ventricular dilation after exercise. CONCLUSIONS: The induction of chest pain is associated with substantially more functional abnormalities when it is analyzed in a relatively "broad-spectrum" coronary artery disease population; by contrast, chest pain tends to lose its apparent value as a clinical test parameter when its analysis is restricted to coronary artery disease populations with a greater a priori likelihood of manifesting inducible ischemia. These findings may help resolve some of the previous discordant literature reports.
J Klein; S Y Chao; D S Berman; A Rozanski
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Circulation     Volume:  89     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1994 May 
Date Detail:
Created Date:  1994-06-14     Completed Date:  1994-06-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1958-66     Citation Subset:  AIM; IM    
Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, Calif.
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MeSH Terms
Angina Pectoris / diagnosis,  epidemiology*
Coronary Angiography
Electrocardiography, Ambulatory
Exercise Test
Exercise Tolerance / physiology
Heart / radionuclide imaging
Middle Aged
Myocardial Ischemia / diagnosis,  epidemiology*
Prospective Studies
Selection Bias
Thallium Radioisotopes / diagnostic use
Tomography, Emission-Computed, Single-Photon
Reg. No./Substance:
0/Thallium Radioisotopes

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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