Relationship between Obesity and Coronary Artery Disease Defined by Coronary Computed Tomography Angiography

Abstract Background: Although associated with traditional cardiovascular risk factors, it is unclear whether obesity alone is associated with coronary artery disease (CAD). Objective: To investigate the role of obesity as a risk factor for CAD, defined by coronary computed tomography angiography (CCTA). Methods: This study retrospectively included 1,814 patients referred for CCTA in a hospital in São Paulo, from August 2010 to July 2012. CAD was identified by coronary calcium score and presence of coronary stenosis > 50%. Images were analyzed by two specialists, and the coronary findings were compared between obese and non-obese groups. A multivariate analysis model was used to assess obesity as an independent variable for the occurrence of obstructive CAD. Results: Among the study population, mean age was 58.5 +/- 11.5 years, 22.8% were obese (BMI = 30 kg/m2) and 66.3% were male. The prevalence of obstructive CAD was 18.4% in both groups. Obese patients had higher median calcium score compared to non-obese subjects (14.7 vs. 1.4, respectively, p = 0.019). In the multivariate analysis, obesity was not an independent factor for obstructive CAD (coefficient = -0.035, p = 0.102). Conclusion: Although no differences were observed in the prevalence of obstructive CAD between obese and non-obese individuals, coronary calcium scores were significantly in lower the latter group.

Desempenho diagnóstico da reserva de fluxo fracionado por tomografia na detecção de estenoses coronárias hemodinamicamente significativas / Fractional flow reserve by tomography diagnostic performance in the detection of coronary stenoses hemodynamically significant

BACKGROUND: Coronary computed tomography angiography is a noninvasive anatomic test for the diagnosis of coronary artery disease. The coronary fractional flow reserve is the gold standard method to determine if coronary stenosis is hemodynamically significant but requires an invasive procedure. Fractional flow reserve measurement by tomography is a new method to determine the hemodynamic significance of coronary luminal reduction. OBJECTIVE: To compare the accuracy of the invasive fractional flow reserve with the fractional flow reserve measurement by tomography. METHOD: Patients submitted to invasive coronary computed tomography angiography and fractional flow reserve were included in the study. Flow-restricted stenosis was defined by fractional flow reserve measurement by tomography and fractional flow reserve ≤ 0.8, and anatomically significant coronary artery disease was defined as stenosis ≥ 50%. Diagnostic performance of fractional flow reserve measurement by tomography and stenosis by coronary computed tomography angiography was accessed with invasive fractional flow reserve as the gold standard. RESULTS: Among the patients, 33% had fractional flow reserve ≤0.8. There was no significant difference between the fractional flow reserve measurement by tomography and fractional flow reserve averages (0.87 versus 0.84; p = 0.4). The correlation between the values of the methods was r = 0.77, and concordance was moderate (k = 0.54). When fractional flow reserve ≤ 0.75 was analyzed, the concordance between the methods was absolute. The sensitivity, specificity, positive predictive value and negative predictive value of fractional flow reserve measurement by tomography were, respectively, 50%, 100%, 100% and 75%, for the threshold of 0.8. The mean difference between fractional flow reserve and fractional flow reserve measurement by tomography was -0.033 (95%CI -0.072-0.007), with concordance limits between -0.176 and -0.1111. CONCLUSION: Fractional flow reserve measurement by tomography is a new method with high diagnostic performance in the detection of hemodynamically significant coronary stenoses and significantly elevates the specificity of the isolated coronary computed tomography angiography.

FUNDAMENTO: A angiotomografia de coronárias é um teste anatômico não invasivo para diagnóstico de doença arterial coronariana. A reserva de fluxo fracionado coronariano é o método padrão-ouro para determinar se a estenose coronariana é hemodinamicamente significativa e requer procedimento invasivo. A mensuração da reserva de fluxo fracionado por tomografia é um novo método para determinar a significância hemodinâmica da redução luminal coronária. OBJETIVO: Comparar a acurácia da reserva de fluxo fracionado invasiva com a reserva de fluxo fracionado por tomografia. MÉTODO: Pacientes submetidos à angiotomografia de coronárias e à reserva de fluxo fracionado invasiva foram incluídos neste estudo. Estenose com limitação de fluxo foi definida por reserva de fluxo fracionado por tomografia e reserva de fluxo fracionado ≤ 0,8. Doença arterial coronariana anatomicamente significativa foi definida por estenose ≥ 50%. O desempenho da reserva de fluxo fracionado por tomografia e da estenose pela angiotomografia de coronárias foi acessado com a reserva de fluxo fracionado invasiva como padrão-ouro. RESULTADOS: Dentre os pacientes, 33% tinham reserva de fluxo fracionado ≤ 0,8. Não houve diferença significativa entre as médias de reserva de fluxo fracionado por tomografia e reserva de fluxo fracionado (0,87 versus 0,84; p=0,4). A correlação entre os valores dos métodos foi r = 0,77, com concordância moderada (k=0,54). Quando analisada a reserva de fluxo fracionado ≤ 0,75, a concordância entre os métodos foi absoluta. Sensibilidade, especificidade, valor preditivo positivo e negativo da reserva de fluxo fracionado por tomografia foram, respectivamente, 50%, 100%, 100% e 75%, para o limiar de 0,8. A média da diferença entre reserva de fluxo fracionado e reserva de fluxo fracionado por tomografia foi de -0,033 (IC95% -0,072-0,007), com limites de concordância entre -0,176 e -0,111. CONCLUSÃO: A reserva de fluxo fracionado por tomografia é um novo método, com alto desempenho diagnóstico na detecção de estenoses coronárias hemodinamicamente significativas, e eleva significativamente a especificidade da angiotomografia de coronárias isolada.

Image Quality and Radiation Exposure Comparison of a Double High-Pitch Acquisition for Coronary Computed Tomography Angiography Versus Standard Retrospective Spiral Acquisition in Patients With Atrial Fibrillation.

OBJECTIVE: The aim of this study was to compare image quality and radiation dose of coronary computed tomography (CT) angiography performed with dual-source CT scanner using 2 different protocols in patients with atrial fibrillation. METHODS: Forty-seven patients with AF underwent 2 different acquisition protocols: double high-pitch (DHP) spiral acquisition and retrospective spiral acquisition. The image quality was ranked according to a qualitative score by 2 experts: 1, no evident motion; 2, minimal motion not influencing coronary artery luminal evaluation; and 3, motion with impaired luminal evaluation. A third expert solved any disagreement. RESULTS: A total of 732 segments were evaluated. The DHP group (24 patients, 374 segments) showed more segments classified as score 1 than the retrospective spiral acquisition group (71.3% vs 37.4%). Image quality evaluation agreement was high between observers (κ = 0.8). There was significantly lower radiation exposure for the DHP group (3.65 [1.29] vs 23.57 [10.32] mSv). CONCLUSIONS: In this original direct comparison, a DHP spiral protocol for coronary CT angiography acquisition in patients with atrial fibrillation resulted in lower radiation exposure and superior image quality compared with conventional spiral retrospective acquisition.

Métodos de imagem na pesquisa de perfusão miocárdica / Imaging methods in the search of myocardial perfusion

As doenças cardiovasculares são a principal causa de morte em todo o mundo, resultando em importante repercussão social social e econômica e impondo questionamentos a respeito de qual seria a melhor forma de diagnostica-las de forma precoce e acurada e, desta forma, tentar reduzir as consequências do diagnóstico tardio ou não realizado. Neste capítulo, apresentamos uma breve introdução da fisiologia da perfusão miocárdica e uma breve descrição dos métodos de imagem não invasivos disponíveis para avaliação da perfusão miocárdica, porém com maior enfoque na ressonância magnética cardiovascular e na tomografia computadorizada cardiovascular. Por meio de ensaios clínicos controlados, mostramos a importância de cada método e sua utilização na prática clínica, desde a cintilografia de perfusão miocárdica pela tomografia computadorizada. A utilização destes métodos possibilita uma estratificação não invasiva da doença coronariana e o seu diagnóstico, tanto anatomico como funcional, possibilitando, assim, um planehjamento terapêutico adequado e direcionado para cada grupo de pacientes. Apresentamos, também, as mais modernas e recentes técnicas da perfusão miocárdica por ressonância magnética e a recentemente validada perfusão miocárdica por tomografia computadorizada associada à angiotomografiacoronária, métodos que tem o potencial de mudar o algoritmo atual de investigação da doença arterial coronária em futuro breve

Cardiovascular disease remain the biggest cause of death worldwide, resulting in significant social and economic impact. As a result, the most effective ways to diagnose them early and accurately need to be understood in order to reduce the consequences of a late or unrealized diagnosis. In this chapter, we briefly introduce the physiology of myocardial perfusion and provide a brief description of noninvasive imaging methods available for its assessment, with an emphasis on Cardiovascular Magnetic Resonance and Cardiac Computed Tomography . Throught clinical trials, we see the importance of each method and its use in clinical practice, since the myocardial perfusion scintigraphy to never methods such as computed tomography myocardial perfusion. The use of these methods provides a noninvasive stratification of coronary disease and its diagnosis, both anatomical and functional, thus enabling appropriate and specific treatment planning for each patient group. We further explore the most modern and recent techniques of Myocardial Perfusion by Magnetic Resonance Imaging and, the recently validated Myocardial Perfusion by Computed Tomography combined to Coronary Computed Tomography combined to Computed Tomography Angiography, methods that have the potential to change the current algoritm of coronary artery disease investigation in the near future.

Correlação da calcificação arterial coronária e necesidade de revascularização em pacientes sem diagnóstico prévio de doença arterial coronariana / Correlation of coronary artery calcification and necessity of coronary revascularization in patients without prior diagnosis of coronary artery disease

Introdução: Cerca de metade das mortes por doença coronariana (DAC) não são precedidas por sintomas cardíacos ou diagnóstico prévio. A quantificação da calcificação arterial coronariana (CAC) por tomografia é um preditor de eventos e reestratifica o risco de ocorrência desses eventos baseado no Escore de Risco de Framingham. Objetivo: Avaliar a capacidade do escore de cálcio de predizer revascularização em pacientes (pts) sem o diagnóstico prévio de DAC. Método: Estudo retrospectivo em pts sem diagnóstico prévio de DAC com quantificação da CAC, realizada em 2.009. A CAC foi obtida em tomografia multislice de 64 cortes, sem contraste, com aquisição sincronizada ao ECG, 120kV, 80-100mA, radiação < 1mSv, e medida pelo escore de cálcio de Agatston (EC) (limiar de 130 HU). Média, mediana e testes diagnósticos foram utilizados. Resultados: Avaliamos 263 pts (171 homens), com 59±13 anos, IMC = 27,7kg/m2 e seguimento médio de 18 ± 3 meses. O EC total foi 199,5 ± 24,39. Nos pacientes diabéticos (DM), o EC foi de 320,5 ± 67,56 e de 166 ± 24,47 nos não DM. Os 23 pacientes que foram revascularizados apresentaram EC médio de 692 ± 72,3 versus 134,7 ± 21,35 dos pacientes não revascularizados (p< 0,001). Dos 47 pts com EC ≥ 400, 17 (36,1%) foram revascularizados e dos 216 pts com EC< 400, 6 (2,6%) foram revascularizados (p< 0,001). Dos pts revascularizados, 15 sem DM tiveram EC médio de 672,7 ± 92,04 versus 728,3 ± 11 dos DM (8pts). Nos pts não revascularizados e sem DM (191 pts), apenas 18 pts tinham EC ≥ 400. Conclusão: O EC ≥ 400 foi forte preditor de revascularização com boa performance diagnóstica em pacientes sem diagnóstico prévio de DAC, no seguimento de 18 meses.