Prognostic Implications of Discordant Results of Myocardial Perfusion Single-Photon Emission Computed Tomography and Exercise ECG Test in Patients with Stable Angina.

Abstract

ECG exercise treadmill test (ExT) and myocardial perfusion SPECT (single photon emission computed tomography) study are widely used for the non-invasive evaluation of patients with coronary artery disease (CAD). To assess long-term prognosis in patients with suspected or known coronary artery disease (CAD), in whom ECG exercise treadmill test (ExT) and myocardial perfusion single photon emission computed tomography (SPECT) provided discordant results are lacking. Four hundred eighty three patients with suspected or known stable CAD underwent 99mTc-methoxyisobutylisonitrile SPECT and ExT. SPECT was considered positive (+) if inducible or mixed perfusion defects were detected. ExT was evaluated using widely accepted criteria. Based on the results of both examinations the patients were divided into 4 subgroups: group 1 - SPECT (+) and ExT (+), group 2 - SPECT (+) and ExT (-), group 3 - SPECT (-) and ExT (+), group 4 - SPECT (-) and ExT (-). After a mean follow-up of 59 ± 7 months, major cardiac events (cardiac death and nonfatal myocardial infarction combined) and revascularizations were more prevalent in groups 1 and 2 than in groups 3 and 4. However, the statistical significance (p ≤ 0.01) was reached only for the following differences: in major cardiac events - group 1 vs group 3 and group 1 vs group 4; in revascularizations - group 1 vs. group 3, group 1 vs. group 4 and group 2 vs group 4 and in cardiac hospitalizations - group 1 vs. group 4 and group 2 vs. group 4. Positive myocardial perfusion SPECT result is associated with similar clinical outcome irrespectively of ExT result in long-term follow-up.