Reliability of myocardial perfusion gated SPECT for the reproducible evaluation of resting left ventricular functional parameters in long-term follow-up.

PURPOSE: Perfusion gated single photon emission computed tomography (SPECT) can assess with good reproducibility left ventricular (LV) volumes and ejection fraction (EF). Whether this reproducibility is maintained in long-term follow-up is unknown. METHODS: We compared LV end-diastolic (ED) and end-systolic (ES) volumes (V) as well as EF calculated using gated SPECT and QGS software in 103 coronary artery disease patients studied twice at > 1-year interval because of standard clinical indications. Patients were divided into two groups: (A) 67 patients without major clinical changes and with stable resting perfusion and (B) 36 with modified clinical status or resting perfusion. RESULTS: The relationship between gated SPECT 2 EF (=y) and gated SPECT 1 EF (=x) was for group A: y=0.91 x + 5.34, r=0.92, p<0.0001, SEE=4 and for group B: y=0.67 x + 13.6, r=0.63, p<0.0001, SEE=10. The 95% limit of agreement was 8 EF units for group A and 20.6 EF units for group B. For EDV, the 95% limit of agreement was 22 ml for group A and 52 ml for group B. For ESV, the 95% limit of agreement was 13 ml for group A and 44 ml for group B. CONCLUSION: In stable patients with an unmodified resting perfusion pattern the functional parameters derived from perfusion gated SPECT have good reproducibility even after a prolonged time interval. This supports the value of gated SPECT for serial evaluations of LV function.