Prediction of Post-revascularization Ejection Fraction in Patients with CoronoryArtery Disease Using Cavity-to-Myocardial Ratio of Thallium Reinjection Image(Multicenter Trial)

Abstract

Background: We reported the high correlation between cavity-to-myocardial (C/M) count ratio at stress and rest thallium SPECT, and stress-rest EF calculated by MUGA test, this was confirmed by others. This correlation was explained partially by the functional mass. On the other hand, two important prognostic parameters should be considered before any revascularization technique: (1) Identification of viable myocardium and its amount, (2) Prediction of EF improvement post revascularization. Aim of the study: Correlating EF (C/M) on RD and RI image (EFRD & EFRI) image to actual EF (prevascularization EF1) and 1 year post revascularization EF2. Patients and methods: 78 patients with CAD (68 males and 10 females with mean age of 54.2+9 years) had been subjected to: (1) St-RD-RI thallium SPECT with assessment of reversible or fixed perfusion defects and calculation of C/M and consequently the EFC/M at the three settings. (2) Assessment of EF by MUGA at rest pre and 1 year post revascularization EF1 & EF2 respectively. These patients had been subjected to revascularization either by PTCA and stent (23/78 i.e., 29.5%) or by CABG (55/78, i.e., 70.5%). Results: Out of the 1560 myocardial segments (20 segments × 78 patients), 780 (50%) segments had abnormal resting wall motion. 441/780 (56.5%) of these segments were either of normal thallium uptake or with reversible perfusion defects while the rest (43.5%) showed fixed defects. 233/441 (52.8%) of those normal uptake or reversible segments showed recovery of wall motion post revascularization (PRV) while only 29/339 (15.1%) showed similar improvements. EFRI was found higher than EFRD in 44/78 of patients, no change in 23/78 patients and worsened in 11/78 patients with total agreements of 63/78 (80.8%) with EF2. On the other hand, EFRD was matched with EF1 in 64/78 of patients. 30/64 (46.9%) showed higher EF2, 23/64 (35.9%) showed similar EF2 while 11/64 (17.2%) showed lower EF2. The rest of cases 14/78 showed mismatch between EFRD and EF1 with higher values of EFRD. These patients still had higher values of EFRI and EF2 than EFRD. Conclusion: (1) Mismatch between EFRD and EF1 is an indication of presence of stunning myocardium and of good prognosis. (2) EFRI can be used to predict EF2 and so helps on selecting patients who can benefit from revascularization.