RESUMO
BACKGROUND: It has been demonstrated that a new reconstruction algorithm for myocardium perfusion imaging (MPI) allows faster acquisition with similar accuracy. The prognostic value of MPI performed with this software and short acquisition time is unknown. METHODS: To determine the prognostic value we followed 3184 consecutive MPI patients between March 2008 and March 2010. A 2-day protocol with low dose 99mTc-MIBI (10-12 mCi) and a 6-minute acquisition was used. Exercise stress was used in 62.6% of the studies. Scans were reconstructed using the software "Evolution for cardiac". Perfusion defects were quantified by summed stress score (SSS) and categorized in four groups: SSS0 = 0; SSS1 = 1-3; SSS2 = 4-8; and SSS3 ≥ 9. Patients were phone contacted every 6 months for follow up and hard events were defined as death or myocardial infarction (MI) and total events as hard events plus late revascularization. RESULTS: The mean radiation dose was <7 mSv/patient. Mean F/U was 33 ± 20 months; 140 of the patients were lost to follow up and 86 were censored due early revascularization (<60 days after MPS). There were 140 hard events: 89 deaths and 51 MI. Mean age was 61.5 ± 12.3 years and 57.7% were male. Hard event rate was 0.8%/year in patients with normal MPS and 3.7%/year in those with abnormal MPS. Patients with larger defects had nine times more hard events than patients with SSS = 0 (14.2% vs 1.6%). Revascularization was more frequent in patients with abnormal MPS than normal MPS (21.7% vs 3.9%; P < 0.001). Cox proportional hazard analysis showed that SSS was an independent predictor of hard events and revascularization. CONCLUSIONS: The use of reduced-dose, fast myocardial perfusion SPECT and the new processing algorithm lowers acquisition time and radiation exposure compared to conventional SPECT without compromising the well-established prognostic value of MPI.
