Biological factors and overestimation of left ventricular ejection fraction by gated SPECT.

BACKGROUND: Some patients present an overestimated left ventricular ejection fraction (LVEF) on electrocardiogram-gated myocardial scintigraphy (gated SPECT). OBJECTIVE: To establish the relationship between biological factors and overestimated LVEF. METHODS: We selected 3838 patients who underwent gated SPECT between May 20, 2000 and September 16, 2005 with normal perfusion images and LVEF > or =50%. The following variables were analyzed: gender (29.4% females and 70.6% males), age (from 20 to 94 years - mean: 56 years), weight (from 33.5 to 150 kg - mean: 79.6 kg), height (from 138 to 220 cm - mean: 171 cm) and BMI (from 13.9 to 54 - mean: 27.2). In a subgroup of 1002 patients who underwent echocardiogram, the diastolic diameter (from 36 to 68 mm - mean 47.5 mm) and systolic diameter (from 22 to 41 mm - mean 29.8 mm) variables were included. The patients were divided into two groups: normal LVEF (< or =80%) and overestimated LVEF (>80%). The odds ratio (OR) for presenting an overestimated LVEF was calculated for each variable using logistic regression. RESULTS: The following odds ratios were found (p < 0.005): female gender OR = 3.585 (95%CI: 2.745 to 4.683), age in years OR = 1.020 (95%CI: 1.011 to 1.029) and height in cm OR = 0.893 (95%CI: 0.829 to 0.962). Weight and BMI were not significantly associated with LVEF (p>0.2). In the subgroup of 1002 patients, a statistically significant influence was found in overestimated LVEF values for the systolic diameter, gender and height variables. CONCLUSION: Although systolic diameter influences the overestimation of LVEF, the gender and height variables have an independent influence on LVEF overestimation by gated SPECT.

Fatores biológicos e superestimação da fração de ejeção do ventrículo esquerdo no gated SPECT / Biological factors and overestimation of left ventricular ejection fraction by gated SPECT

FUNDAMENTO: Alguns pacientes apresentam fração de ejeção do ventrículo esquerdo (FEVE) superestimada na cintilografia miocárdica com sincronização eletrocardiográfica (gated SPECT). OBJETIVO: Estabelecer a relação entre fatores biológicos e FEVE superestimada. MÉTODOS: Selecionamos 3.838 pacientes que realizaram gated SPECT entre 20/5/2000 e 16/9/2005, com imagens normais de perfusão e FEVE >50 por cento. Analisamos as variáveis: sexo (29,4 por cento feminino e 70,6 por cento masculino), idade (de 20 a 94 anos - média: 56 anos), peso (de 33,5 a 150 kg - média: 79,6 kg), altura (de 138 a 220 cm - média: 171 cm) e IMC (de 13,9 a 54 - média: 27,2). Em um subgrupo de 1.002 pacientes que realizaram ecocardiograma, incluímos as variáveis diâmetros diastólico (de 36 a 68 mm - média 47,5 mm) e sistólico (de 22 a 41 mm - média 29,8 mm). Dividimos os pacientes em dois grupos: FEVE normal (<80 por cento) e superestimada (>80 por cento). A Razão de Chances (RC) para apresentar FEVE superestimada foi calculada para cada variável por regressão logística. RESULTADOS: Encontramos as seguintes Razões de Chances (p < 0,005): sexo feminino RC = 3,585 (IC95 por cento: 2,745 a 4,683), idade em anos RC = 1,020 (IC95 por cento: 1,011 a 1,029) e altura em cm RC = 0,893 (IC95 por cento: 0,829 a 0,962). O peso e o IMC não se associaram a FEVE significativamente (p>0,2). No subgrupo de 1.002 pacientes, encontramos influência estatisticamente significativa na obtenção da FEVE superestimada para as variáveis diâmetro sistólico, sexo e altura. CONCLUSÃO: Apesar de o diâmetro sistólico influenciar na obtenção da FEVE superestimada, as variáveis sexo e altura apresentam influência independente na superestimação da FEVE pelo gated SPECT.

BACKGROUND: Some patients present an overestimated left ventricular ejection fraction (LVEF) on electrocardiogram-gated myocardial scintigraphy (gated SPECT). OBJECTIVE: To establish the relationship between biological factors and overestimated LVEF. METHODS: We selected 3838 patients who underwent gated SPECT between May 20, 2000 and September 16, 2005 with normal perfusion images and LVEF >50 percent. The following variables were analyzed: gender (29.4 percent females and 70.6 percent males), age (from 20 to 94 years - mean: 56 years), weight (from 33.5 to 150 kg - mean: 79.6 kg), height (from 138 to 220 cm - mean: 171 cm) and BMI (from 13.9 to 54 - mean: 27.2). In a subgroup of 1002 patients who underwent echocardiogram, the diastolic diameter (from 36 to 68 mm - mean 47.5 mm) and systolic diameter (from 22 to 41 mm - mean 29.8 mm) variables were included. The patients were divided into two groups: normal LVEF (<80 percent) and overestimated LVEF (>80 percent). The odds ratio (OR) for presenting an overestimated LVEF was calculated for each variable using logistic regression. RESULTS: The following odds ratios were found (p < 0.005): female gender OR = 3.585 (95 percentCI: 2.745 to 4.683), age in years OR = 1.020 (95 percentCI: 1.011 to 1.029) and height in cm OR = 0.893 (95 percentCI: 0.829 to 0.962). Weight and BMI were not significantly associated with LVEF (p>0.2). In the subgroup of 1002 patients, a statistically significant influence was found in overestimated LVEF values for the systolic diameter, gender and height variables. CONCLUSION: Although systolic diameter influences the overestimation of LVEF, the gender and height variables have an independent influence on LVEF overestimation by gated SPECT.