Usefulness of exercise SPECT-thallium to detect asymptomatic restenosis in patients who had angina before coronary angioplasty

The usefulness of exercise single photon emission computed tomography (SPECT)-thallium for detecting asymptomatic restenosis was assessed prospectively in 62 patients with angina before angioplasty, who underwent ≤6-month reangiography and exercise SPECT-thallium imaging. Among patients with restenosis, nine had recurrence of angina but eight did not. These two subgroups had equivalent percentages of restenosis (71 ± 16% vs 64 ± 16%, NS) and extent of reversible thallium defects (2.8 ± 1.7 vs 4.1 ± 2.6, NS), and both subgroups had poorer hemodynamic responses to exercise compared with patients without restenosis (maximal rate-pressure product [× 100], 258 ± 54 and 239 ± 33 vs 302 ± 61; p < 0.05 and p < 0.01, respectively). Exercise testing detected fewer patients with restenosis compared to exercise SPECT-thallium imaging, especially among asymptomatic patients (25% vs 100%, p < 0.005). Asymptomatic restenosis occurs frequently, induces an amount of stress ischemia equivalent to that of symptomatic restenosis, and is efficiently detected by exercise SPECT-thallium with rest-reinjection but not by exercise testing.