PROGNOSTIC VALUE OF STRESS-ONLY GATED SPECT MYOCARDIAL PERFUSION IMAGING: TIME FOR PARADIGM SHIFT

Abstract

Prognostic value of a normal rest-stress gated SPECT myocardial perfusion imaging (MPI) is well documented. A normal stress-only MPI study saves time, cost and avoids significant radiation exposure but its safety is questioned. AIM: Compare the prognostic value of normal stress-only and rest-stress MPIs. PATIENTS AND METHODS: This is a prospective study conducted at Nuclear Cardiology Department of Karachi Institute of Heart Diseases (KIHD) from December 2008 till May 2009. A rest-stress (same day) protocol was used in all patients but patients with lower pre-test probability for CAD in which stress (stress-only if MPI is normal) followed by a resting study (same day) if stress study is positive or equivocal. The protocol was decided by a board certified nuclear cardiologist. A dual head dedicated (Cardio MD, Philips) camera was used to acquire data. These patients / families were questioned on telephone regarding fatal or non-fatal myocardial infarction at 12-18 month. RESULTS: Study included 265 patients (104 males and 161 females, mean age of 52 – 10 years) having a normal GSPECT studies (normal LV perfusion and function parameters). The stress-only cohort included 47 patients (13 males and 34 females, mean age of 51 – 08 years) while rest-stress cohort had 218 patients (91 males and 127 females, mean age of 50 – 10 years). On follow up (12-18 months, mean 15 –3.4) only one death was reported among 265 patients (in rest-stress group due to fatal myocardial infarction). Negative predictive value (NPV) for stress-only cohort was 100% while it was 99.5% for stress-rest cohort (p =0.382). CONCLUSION: We conclude that a normal stress-only GSPECT MPI has an excellent and comparable short term prognosis with a normal rest-stress study. We recommend using this protocol as routine in low risk patients to save time, reduce cost and avoid significant radiation exposure. Key Words: GSPECT, Stress-Only, MPI, rest-stress, 99mTc MIBI