Background: Although line source attenuation correction (AC) in SPECT MPI studies improves diagnostic accuracy, its prognostic value is less understood.
Methods: Consecutive patients (n = 6,513) who underwent rest/stress AC ECG-gated SPECT MPI were followed for cardiac death or non-fatal myocardial infarction (MI). A 17-segment model and AC summed stress score (SSS) were used to classify images.
Results: Of the 6,513 patients, cardiac death or non-fatal MI occurred in 267 (4.1%), over 2.0 ± 1.4 years. The AC-SSS in patients with a cardiac event (5.6 ± 7.8) was significantly higher than in those without (1.9 ± 4.6, P < .001). The annualized cardiac event rate in patients with an AC-SSS 1-3 (3.6%) was significantly higher than in those with an AC-SSS = 0 (1.1%, P < .001) but similar to that in those with an AC-SSS 4-8 (2.9%, P = .4). Accordingly, patients were classified to AC-SSS = 0, 1-8, and >8 with annualized cardiac event rates of 1.1%, 3.2%, and 8.5%, respectively (P < .0001). In multivariate analysis, an AC-SSS 1-8 and >8 emerged as independent predictors of cardiac events (P < .02 and P < .0001, respectively).
Conclusion: Rest/stress ECG-gated SPECT MPI with line source AC provides highly effective and incremental risk stratification for future cardiac events.