Prognostic significance of ischemic electrocardiographic changes during vasodilator stress testing in patients with
Elizabeth Klodas1, Todd D Miller, Timothy F Christian
1Division Cardiovascular, Mayo Clinic and Foundation, Rochester, Minn 55905, USA.
Insights
Ischemic ECG changes with normal SPECT images during vasodilator stress testing are uncommon, primarily affecting older women. This combination indicates a higher cardiac event risk than previously understood for normal perfusion imaging.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Diagnostic Imaging
Background:
- Exercise stress testing with normal perfusion imaging and ischemic ECG changes indicates low cardiac event risk.
- The prognostic significance of this finding during vasodilator stress testing is not well-established.
Purpose of the Study:
- To investigate the clinical significance and outcomes of patients with ischemic ECG changes and normal single-photon emission computed tomography (SPECT) perfusion images during vasodilator stress.
Main Methods:
- Retrospective analysis of 5526 patients undergoing vasodilator stress SPECT.
- Identification of patients with normal perfusion images and ischemic ECG changes.
- Follow-up for cardiac death and myocardial infarction.
Main Results:
- 0.9% of patients (49) had normal SPECT images with ischemic ECG changes, predominantly older women (88%).
- Cardiac death or myocardial infarction occurred in 14% of patients within 3 years.
- Multivessel coronary artery disease was found in 11 of 12 patients who underwent angiography/autopsy, suggesting false-negative SPECT results.
Conclusions:
- Ischemic ECG changes with normal vasodilator stress SPECT are rare, seen mainly in older women.
- This finding is associated with a significantly higher cardiac event rate than expected with normal perfusion imaging.
- These results suggest potential underestimation of coronary artery disease in such cases.
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.
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