ABSTRACT
OBJECTIVES: We sought to assess the prognostic value and risk classification improvement using contemporary single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) to predict all-cause mortality. BACKGROUND: Myocardial perfusion is a strong estimator of prognosis. Evidence published to date has not established the added prognostic value of SPECT-MPI nor defined an approach to detect improve classification of risk in women from a developing nation. METHODS: A total of 2,225 women referred for SPECT-MPI were followed by a mean period of 3.7 ± 1.4 years. SPECT-MPI results were classified as abnormal on the presence of any perfusion defect. Abnormal scans were further classified as with mild/moderate reversible, severe reversible, partial reversible, or fixed perfusion defects. Risk estimates for incident mortality were categorized as <1%/year, 1% to 2%/year, and >2%/year using Cox proportional hazard models. Risk-adjusted models incorporated clinical risk factors, left ventricular ejection fraction (LVEF), and perfusion variables. RESULTS: All-cause death occurred in 139 patients. SPECT-MPI significantly risk stratified the population; patients with abnormal scans had significantly higher death rates compared with patients with normal scans, 13.1% versus 4.0%, respectively (p < 0.001). Cox analysis demonstrated that after adjusting for clinical risk factors and LVEF, SPECT-MPI improved the model discrimination (integrated discrimination index = 0.009; p = 0.02), added significant incremental prognostic information (global chi-square increased from 87.7 to 127.1; p < 0.0001), and improved risk prediction (net reclassification improvement = 0.12; p = 0.005). CONCLUSIONS: SPECT-MPI added significant incremental prognostic information to clinical and left ventricular functional variables while enhancing the ability to classify this Brazilian female population into low- and high-risk categories of all-cause mortality.
Subject(s)
Heart Diseases/diagnostic imaging , Heart Diseases/mortality , Myocardial Perfusion Imaging/methods , Tomography, Emission-Computed, Single-Photon , Aged , Analysis of Variance , Brazil , Chi-Square Distribution , Coronary Circulation , Female , Heart Diseases/physiopathology , Humans , Kaplan-Meier Estimate , Middle Aged , Predictive Value of Tests , Prognosis , Proportional Hazards Models , Prospective Studies , Risk Assessment , Risk Factors , Sex Factors , Stroke Volume , Ventricular Function, LeftABSTRACT
Os níveis plasmáticos de LDL-colesterol (LDL-C), HDL-colesterol (HDL-C), apolipoproteínas B (apo B) e A-I (apo A-I) foram estimados em 38 indivíduos hiperlipidêmicos (HL) e 42 normolipidêmicos (NL). Coeficientes de correlação, entre essas variáveis e os níveis de TG, foram calculados, em cada grupo. O teor de LDL-C, apo B e as razões LDL-C/HDL-C e apo B/apo A-I apresentaram-se significativamente maiores (p>0,001) nos HL do que nos NL. Entretanto, utilizando-se análise discriminante, observamos que a discriminação mais acentuada, nos hl, foi obtida pela razão apo B/apo A-I, que classificou 87% dos pacientes no grupo correto. O teor de HDL-C foi significativamente menor no grupo dos HL do que no de NL (p0,05). No grupo de NL, os resultados da correlação entre os níveis de TG com as outras variáveis fora: a) positiva e significativa com os níveis de LDL-C e apo B; b) negativa e significativa com os níveis de HDL-C; c) não significativa com o nível de apo A-I. No grupo de HL, encontramos correlações negativas entre os níveis de TG com os de LDL-C, HDL-C, não havendo correlação significativa com apo B e apo A-I.