Overall and gender-based negative predictive value of a normal gated myocardial perfusion SPECT study: a single center experience

Abstract

A normal gated myocardial perfusion imaging (GMPI) has been found to have high diagnostic and negative predictive value (NPV) in western population. The goal of the present study was to evaluate the overall and gender-based NPV of a normal GMPI in local population. This is a prospective study conducted at Nuclear Cardiology Department of Karachi Institute of Heart Diseases (KIHD), Karachi from December 2008 till May 2009. All patients (with intermediate risk) with a normal GMPI with adequate dynamic or dipyridamole stress were included and followed up for 18 months (mean 15 ± 3 months) for fatal or non-fatal infarctions. The mean ejection fraction (EF) of studied population was 69 ± 8% while mean end diastolic (EDV) and end systolic volume (ESV) were 71 ± 19 and 22 ± 11 ml, respectively. In studied female cohort, the mean EF (%), EDV (ml) and ESV (ml) were 71 ± 08, 64 ± 15 and 19 ± 09, respectively. In studied male cohort, the mean EF (%), EDV (ml) and ESV (ml) were 66 ± 06, 82 ± 18 and 27 ± 11, respectively. At 18 months follow-up, one fatal (male patient) and one non-fatal MI (male patient) were reported. The overall NPV was 99.4% over 18 months follow-up with an event rate of 0.6% (95% CI 0.03-1.16%) and annualized event rate of 0.3%. The NPV and annualized event in subgroup analyses, was similar for female and male (P = 0.213). We conclude that a normal GMPI with adequate stress in our population has high NPVs for major cardiac events as in western population. In addition, the prognostic utility of GMPI is similar for both men and women.