Does Normal Perfusion Scan Mean Low Annual Risk of Hard Cardiac Event? Patients With Adenosine-Induced ST-Segment Depressions and Normal Myocardial Perfusion Imaging: Cardiac Outcomes at 24 Months. Sharma J, Roncari C, et al: J Nucl Cardiol 2010; June 10 (): epub ahead of print Patients with a normal myocardial perfusion scan have a low risk of adverse cardiac events, even when the adenosine stress electrocardiography test is positive. Background: Patients able to exercise adequately with normal myocardial perfusion imaging (MPI) have an annual hard cardiac event rate of approximately 1% per year. This rate increases to 1.3% to 2.3% per year in those assessed using adenosine who have normal MPI. In patients with both an abnormal adenosine stress electrocardiogram (ECG) test and an abnormal adenosine stress perfusion scan, the risk is greater than an abnormal scan alone. Objective: To determine if an abnormal adenosine stress ECG test in patients with normal MPI carries a worse prognosis. Design: Retrospective cohort study. Participants: Patients presenting for clinical reasons for MPI were retrospectively reviewed; 76 patients met inclusion criteria of a normal myocardial perfusion scan, abnormal adenosine stress ECG, no known coronary artery disease, and follow up >6 months. Methods: A 6-minute infusion adenosine stress ECG test was performed. Ischemic ECG was defined as either ≥1.5 mm upsloping ST-depression or ≥1.0 mm horizontal or downsloping ST-depression at 80 ms beyond the J-point in at least 3 consecutive beats in at least 2 contiguous leads. Post-stress imaging started at 45 to 60 minutes post-infusion. Cardiovascular events were defined as cardiac death, nonfatal myocardial infarction (MI), or coronary revascularization. Results: The mean age of participants was 66 years; 87% were women and 30% were diabetic. Follow-up was 24 ± 13 months. There were no cardiac deaths or nonfatal MIs in the cohort. Twenty two patients underwent angiography as a result of the adenosine stress myocardial perfusion scan. There were 11 patients who underwent revascularization; 10 occurred as a direct result of the initial perfusion scan, and 1 occurred 19 months later. Conclusions: The rate of cardiac death and MI was 0% at a mean follow-up interval of 24 months in this cohort of patients with adenosine stress-induced ST-depression but normal MPIs. The authors state that, "In the presence of normal MPI, the specificity of ischemic ECG changes during adenosine infusion for the detection of severe obstructive coronary artery disease is poor, although patients with multiple coronary risk factors, particularly diabetes mellitus, should undergo further investigation." Reviewer's Comments: The authors state that patients with an abnormal adenosine stress ECG but normal myocardial perfusion and who have multiple risk factors should undergo further investigation. Why? The rate of hard cardiac events (cardiac death or nonfatal MI) was 0% over 2 years in this cohort and in all subgroups of this cohort. They did not show that angiography was of benefit or that revascularization was of benefit in patients with a normal myocardial perfusion scan. On the contrary, the best conclusion from their data is that patients with a normal perfusion scan have a very low annual risk of a hard cardiac event, even if the stress adenosine test is positive. (Reviewer-Thomas F. Heston, MD). © 2010, Oakstone Medical Publishing Keywords: Myocardial Perfusion Imaging, Adenosine, Pharmacologic Stress Testing Print Tag: Refer to original journal article