Only few data exist on discrepancies between positive ECG exercise test (ExT) results and single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) without ischemia, in patients with suspected or known coronary artery disease (CAD).

The aim was to assess coronary angiography results and early clinical outcome in patients with suspected or known CAD with discrepancy between an abnormal ECG ExT and a MPI without ischemia.

In total, 30,620 consecutive patients with suspected or known CAD referred between May 2010 and October 2016 for exercise SPECT MPI with CZT camera were retrospectively evaluated. “True discrepancy” was defined in presence of exercise ECG changes highly suggestive of ischemia in contrast to SPECT MPI without ischemia. Significant stenosis on coronary angiography (CAG) performed within 3 months after MPI and major cardiovascular events (cardiac death, nonfatal myocardial infarction and revascularization) during follow-up were collected. The Kaplan–Meier and log-rank test was used to compare the time to cardiac event-free survival.

Among 270 patients with true discrepancy, invasive coronary angiography and coronary CT angiography data were available in 142 patients with suspected (S group; 60 patients) or known (K group; 89 patients) CAD. No significant coronary stenosis and significant stenosis was present in 30 patients (50%) versus 30 patients (50%) in S group and in 42 patients (47%) versus 47 patients (55%) in K group, respectively. Major cardiac event rate was significantly different between patients with or without revascularization after CAG in S group (respectively, 17% versus 0%; P=0.003), contrary to K group (15% versus 9.5%; P=0.49).

True discordant results occurred in 1% of exercise SPECT MPI and half of patients with anatomy assessment were associated in 50% of the cases with the presence of significant coronary stenosis.