Abstract
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Objectives SPECT-CT allows the simultaneous evaluation of functional (MPI) and morphoanatomical (CCS) aspects of the atherosclerosis. This study aims to assess the additional prognostic value of CCS in patients with intermediate-risk of CAD, undergoing MPI.
Methods we evaluated 351 patients (232 men, 68±13 years) presenting with an intermediate Framingham risk of CAD. All subjects underwent contextual rest MPI and CCS evaluation as a part of a standard two-days MPI protocol, acquiring images with an hybrid Siemens Symbia tomograph. Summed Stress Scores (SSS) and Agatston data were calculated for all patients and MPI studies were considered “positive” (+) if SSS>3.
Results the study population was followed for 63±10 months considering cardiac death, non-fatal MI, hospitalization for unstable angina and late (>90 days) coronary revascularization as outcome events. Subjects were divided into four groups on the basis of tests results: MPI- and CCS<400 (group A - 134), MPI- and CCS≥400 (group B - 62), MPI+ and CCS<400 (group C - 34), and MPI+ and CCS≥400 (group D - 121). The global cardiac event rate was 2.7%/year. Annual event rates for overall cardiac events in group A, B, C and D were 0.3, 1.4, 4.4 and 5.7%/year respectively. Patients with normal MPI had higher survival free of cardiac events (p<0.01) and an increase in predicting all cardiac events occurred when CCS data were added to MPI information. Kaplan-Meier curves showed significant differences in event-free survival at 5 years in the four groups.
Conclusions this study outlines that an hybrid approach, combining anatomic assessment of coronary plaque burden (better estimating longer-term prognosis) with functional evaluation of ischemia (more closely related to a “short-term risk”) may contribute to refine temporal risk stratification among subjects at intermediate likelihood of CAD.