Abstract
This study aims to apply a CCTA-derived territory-based patient-specific estimation of boundary conditions for coronary artery fractional flow reserve (FFR) and wall shear stress (WSS) simulation. The non-invasive simulation can help diagnose the significance of coronary stenosis and the likelihood of myocardial ischemia. FFR is often regarded as the gold standard to evaluate the functional significance of stenosis in coronary arteries. In another aspect, proximal wall shear stress (mathrm{{WSS}_{prox}}) can also be an indicator of plaque vulnerability. During the simulation process, the mass flow rate of the blood in coronary arteries is one of the most important boundary conditions. This study utilized the myocardium territory to estimate and allocate the mass flow rate. 20 patients are included in this study. From the knowledge of anatomical information of coronary arteries and the myocardium, the territory-based FFR and the mathrm{{WSS}_{prox}} can both be derived from fluid dynamics simulations. Applying the threshold of distinguishing between significant and non-significant stenosis, the territory-based method can reach the accuracy, sensitivity, and specificity of 0.88, 0.90, and 0.80, respectively. For significantly stenotic cases (mathrm{FFR}_{m}le 0.80), the vessels usually have higher wall shear stress in the proximal region of the lesion.
Highlights
Cardiovascular disease is the top leading cause of death worldwide
The values can be compared with the catheter measured Fractional flow reserve (FFR), which is denoted as FFRm
We proposed the Territory-based method that utilized myocardium territory allocation and Murray’s law to estimate the coronary blood flow rate to accurately simulate the pressure field within coronary arteries with adequate boundary conditions
Summary
Cardiovascular disease is the top leading cause of death worldwide. Total deaths associated with cardiovascular diseases had increased by 21.1% from 2007 to 2017 and claimed 17.8 million deaths in 20171. An increase in blood pressure or mechanical stress can cause a vulnerable plaque rupture and subsequent coronary occlusion, resulting in myocardial necrosis. A 15-year follow-up study showed that the deferred percutaneous coronary intervention (PCI) after the safety evaluation by FFR for functionally nonsignificant stenosis demonstrated a lower rate (2.2%) of myocardial infarction than those who underwent revascularization (10%)[4]. Such an invasive procedure poses certain risks to patients because of potential allergic reactions to vasodilators such as adenosine and possible complications during the prolonged procedure[5,6]. Proximal WSS becomes an incremental prognostic index over FFR in predicting myocardium ischemia in recent y ears[26,27]
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