The prevalence and predictive accuracy of quantitatively defined transient ischemic dilation of the left ventricle on otherwise normal SPECT myocardial perfusion imaging studies

TID in the setting of otherwise normal MPI has been suggested as a marker of high risk CAD. In this study we estimate the variance of TID in a normal population and the statistical frequency of false positive TID. This will provide an indirect measurement of predictive accuracy (PA) in a mixed referral population. To study the PA of TID in otherwise normal MPI. 688 consecutive patients were studied. We defined TID according to the standard method at 2 cut-off values; 1SD and 2SD, and also by a BSA normalized volume difference with gender-specific 2SD limits (NrVD). 457 patients with otherwise normal MPI were analyzed. PA of TID at 1SD was 4% and 26% at 2SD. PA was slightly higher (42%) using the NrVD, however, still too low to be clinically useful as a high-risk marker. PA of TID in patients with perfusion abnormalities was 58% at 1SD, 80% at 2SD and slightly higher (93%) by NrVD. In the setting of otherwise normal MPI, elevated TIDr has a low prevalence and poor predictive accuracy and should not be considered summarily as a marker of high risk CAD.