Impact of gender on rest Tc-99m sestamibi-gated left ventricular ejection fraction.
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Timothy F Christian
Publications and source records attributed to Timothy F Christian.
Effects of adjustment for referral bias on the sensitivity and specificity of single photon emission computed tomography for the diagnosis of coronary artery disease.
PURPOSE: Referral bias, in which the result of a diagnostic test affects the subsequent referral for a more definitive test, influences the accuracy of noninvasive tests for coronary artery disease. This study evaluates the effect of referral bias on the apparent accuracy of single photon emission computed tomography (SPECT). METHODS: Over a 10-year period, 14,273 patients without known coronary artery disease underwent stress SPECT. Coronary angiography was performed within 3 months after the stress test in 1853 patients (13%). The apparent sensitivity, specificity, and likelihood ratios of SPECT were determined in these patients, and then adjusted for referral bias using two different formulas. RESULTS: The overwhelming majority (95%) of patients who underwent angiography had abnormal SPECT images. Apparent values for test indices were a sensitivity of 98%, a specificity of 13%, a likelihood ratio for a positive test of 1.1, and a likelihood ratio for a negative test of 0.15. Test indices adjusted for referral bias (using the two methods) were a sensitivity of 65% or 67%, a specificity of 67% or 75%, a likelihood ratio for a positive test of 2.0 or 2.7, and a likelihood ratio for a negative test of 0.44 or 0.52. CONCLUSION: Referral bias has a marked effect on the apparent accuracy of stress SPECT for the diagnosis of coronary disease. Adjustment for referral bias yields estimates for sensitivity and specificity and likelihood ratios that better reflect the accuracy of the technique.
Adenosine↗
The prognostic value of pharmacologic stress myocardial perfusion imaging in patients with permanent pacemakers.
BACKGROUND: The aim of this study is to assess the prognostic value of pharmacologic stress (adenosine or dipyridamole) myocardial perfusion imaging in patients with permanent electronic ventricular pacemakers. METHODS AND RESULTS: Between October 1986 and December 1995, 93 patients with pacemakers underwent pharmacologic stress testing with myocardial perfusion single photon emission computed tomography imaging. Follow-up information on 91 patients (98%) was obtained. Mean follow-up was 5.6 +/- 2.4 years. Previously published clinical and image variables were analyzed for their prognostic significance with regard to cardiac death, cardiac death/nonfatal myocardial infarction, and cardiac death/nonfatal myocardial infarction/late revascularization. The presence of a high-risk scan was a significant predictor of subsequent cardiac death by both univariate (chi 2 = 9.4, P < .001) and multivariate analysis (chi 2 = 6.5, P = .01) after adjustment for clinical score. Clinical score was not a significant predictor of cardiac death. CONCLUSION: This study demonstrates that pharmacologic stress myocardial perfusion imaging provides significant prognostic information in patients with permanent pacemakers. In this population, pharmacologic stress myocardial perfusion imaging can differentiate patients at high risk of a subsequent cardiac event from those at low risk. These results support the American College of Cardiology/American Heart Association guideline recommendations for pharmacologic stress perfusion imaging in patients with permanent pacemakers.
Adenosine↗
Prognostic significance of ischemic electrocardiographic changes during vasodilator stress testing in patients with normal SPECT images.
BACKGROUND: Patients with ischemic electrocardiographic (ECG) findings during exercise stress testing but normal perfusion images generally have a low risk of cardiac death or myocardial infarction (<1% per year). During vasodilator stress testing, however, the prognostic significance of the combination of normal perfusion images and ischemic ECG changes is unknown. METHODS AND RESULTS: Among 5526 patients who underwent vasodilator stress single photon emission computed tomography (SPECT), 49 (0.9%) had normal images but ischemic ECG changes. A unique feature of this population was that 43 (88%) were women with a mean age of 67 +/- 10 years. Ischemic ECG changes occurred at a mean heart rate of 101 +/- 15 beats per minute and persisted for 6.8 +/- 4.7 minutes after termination of drug infusion. During follow-up of 28 +/- 20 months, cardiac death occurred in 2 patients and nonfatal myocardial infarction in 4 patients. The rate of cardiac death or nonfatal myocardial infarction was 4% at 1 year, 10% at 2 years, and 14% at 3 years. Of the 12 patients who underwent coronary angiography or autopsy during follow-up, 11 had multivessel coronary artery disease, indicating that these patients likely had false-negative SPECT image results. Eight patients required coronary revascularization. CONCLUSIONS: The finding of ischemic ECG changes with normal SPECT images during vasodilator infusion is uncommon, occurs primarily in older women, and is associated with a higher subsequent cardiac event rate than is customarily associated with normal images.
Adenosine↗