Technetium-99m Methoxyisobutyl Isonitrile Stress MPI in Suspected Coronary Artery Disease Patients: A Prospective Study to Evaluate Clinical Significance of Adenosine-induced ECG Changes.

Purpose: The purpose of this study is to evaluate the adenosine pharmacological stress-induced electrocardiogram (ECG) changes and their association with stress-induced ischemic defects on myocardial perfusion scintigraphy (MPS) in the evaluation of coronary artery disease (CAD) and to evaluate event-free survival among patients with positive and negative ECG/MPS image findings.

Methods: A total of 100 patients were examined using stress MPS from March 2020 to August 2021. Stress-induced ECG changes during adenosine infusion were evaluated. The summed stress score (SSS) was evaluated to identify ischemic defects in myocardium. Association of stress ECG changes and scintigraphic results was evaluated.

Results: Out of 100 patients, stress ECG changes during adenosine infusion were seen among 34 patients, whereas 66 patients had normal ECG findings. Positive stress MPS findings with SSS >3 were seen in 22 patients, whereas 78 patients had SSS ≤3. There was no agreement between stress ECG changes and MPS findings with Cohen's kappa coefficient (κ) = -0.023, whereas there was mild agreement between stress ECG changes and SSS >7 with κ = 0.105. Median follow-up of 11 months showed more events among patients with positive ECG changes than negative ECG changes.

Conclusion: Adenosine, pharmacological stress is safe to use, but few patients might experience some minor and transient symptoms. Adenosine may induce ECG changes in patients with or without positive MPS findings. Patients with concordant positive findings need aggressive cardiac care, whereas patients with small or no defects on MPS need close monitoring.