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Prognostic significance of silent myocardial ischemia on a thallium stress test
L I Heller1, M Tresgallo, R R Sciacca
1Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, New York 10032.
Insights
Silent ischemia, or lack of chest pain during a positive thallium stress test, did not predict worse cardiac outcomes compared to patients experiencing angina. This finding suggests chest pain presence is not a key indicator of adverse events in ischemic patients.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Diagnostic Imaging
Background:
- The clinical significance of silent ischemia remains unclear.
- Thallium stress testing is a common diagnostic tool for myocardial ischemia.
Purpose of the Study:
- To determine if angina presence during a thallium stress test predicts adverse cardiac outcomes in patients with ischemia.
Main Methods:
- Prospective study of 234 patients with thallium stress test-positive ischemia.
- Patients categorized into those with (n=129) and without (n=105) angina during the test.
- Follow-up for adverse events (myocardial infarction, revascularization, death) over a mean of 5.2 years.
Main Results:
- 82 patients had angina (Group A), 74 had silent ischemia (Group S).
- No significant differences in sex, prior infarction, or multi-vessel disease between groups.
- Cardiac event rates were similar: 45% in Group A vs. 38% in Group S.
- Mortality rates were also comparable between groups.
Conclusions:
- The presence or absence of angina during a positive thallium stress test is not an independent predictor of adverse cardiac outcomes.
- Silent ischemia carries a similar prognosis to ischemic events accompanied by angina.
Abstract:
The clinical significance of silent ischemia is not fully known. The purpose of this study was to determine whether the presence or absence of angina during a thallium stress test positive for ischemia was independently predictive of an adverse outcome. Two hundred thirty-four consecutive patients with ischemia on a thallium stress test were identified. Ischemia was defined as the presence of defect(s) on the immediate postexercise scans not in the distribution of prior infarctions that redistributed on 4-hour scans. During the test 129 patients had angina, defined as characteristic neck, jaw, arm, back or chest discomfort, while the remaining 105 patients had no angina. Follow-up ranged from 2 to 8.2 years (mean 5.2 +/- 2.1) and was successfully obtained in 156 patients. Eighty-two of the 156 patients had angina (group A) and 74 had silent ischemia (group S). Group A patients were significantly older (62 +/- 8 vs 59 +/- 8 years, p less than 0.05). There was no significant difference between the 2 groups in terms of sex, history of prior infarction or presence of left main/3-vessel disease. A larger percentage of patients in group A were receiving beta blockers (60 vs 41%, p less than 0.05) and nitrates (52 vs 36%, 0.05 less than p less than 0.10). There was a large number of cardiac events (myocardial infarction, revascularization and death) in both groups (37 of 82 [45%] in group A; 28 of 72 [38%] in group S) but no statistically significant difference between the groups. Similarly, life-table analysis revealed no difference in mortality between the 2 groups.(ABSTRACT TRUNCATED AT 250 WORDS)