Future Cardiac Events in Patients with Ischemic ECG Changes during Adenosine Infusion as a Myocardial Stress Agent and Normal Cardiac Scan

Abstract

Background: We sought to determine the prognostic importance of adenosine-induced ischemic ECG changes in patients with normal SPECT myocardial perfusion images. Methods: We performed a retrospective analysis of 765 patients undergoing adenosine MPI between January 2013 and January 2015. Patients with baseline electrocardiographic (ECG) abnormalities and/or abnormal scan were excluded. Results: Overall, 67 patients (8.7%) had ischemic ECG changes during adenosine infusion in the form of ST depression of ≥1mm. Of these, 29 (43% [3.8% of all patients]) had normal MPI (positive (+) ECG group). An ageand sex-matched group of 108 patients with normal MPI without ECG changes served as control subjects (negative (-) ECG group). During a mean follow-up of 33.3 ± 6.1 months, patients in the +ECG group had no significantly more adverse cardiac events than those in the –ECG group. One (0.9%) patient within the negative ECG group had a nonfatal MI (0.7% annual event rate after a negative MPI). A case only was admitted due to heart failure in the (-) ECG group) that proved to be secondary to pulmonary cause and not of CAD. A case in this (+) ECG group admitted as a CAD that ruled out by coronary angiography. Conclusion: Patients with normal myocardial perfusion scintigraphy in whom ST-segment depression develops during adenosine stress test appear to be with no increased risk for future cardiac events compared with similar patients without ECG evidence of ischemia.