Computational assessment of the fractional flow reserve from intravascular ultrasound and coronary angiography data: a pilot study

Clinical outcomes of various continued antiplatelet therapies in patients who were administered DAPT following the implantation of drug-eluting stents and developed gastrointestinal hemorrhage

Although an increasing number of patients accept dual antiplatelet therapy (DAPT) following implantation of drug-eluting stents (DES) for coronary heart disease (CHD), the proportion of patients with DAPT who subsequently develop gastrointestinal hemorrhage continues to increase. To ensure the clinical outcomes from DES, it is important to formulate a novel continued antiplatelet therapy for patients who were administered DAPT and subsequently develop gastrointestinal hemorrhage following DES implantation. The present study aimed to evaluate the effects of continued aspirin, clopidogrel or DAPT use on the incidence of clinical adverse events and gastrointestinal rebleeding in patients who received DAPT and subsequently developed gastrointestinal hemorrhage following implantation of DES for CHD. Between 2004 and 2010, 108 consecutive patients receiving DAPT developed gastrointestinal hemorrhage following DES implantation for CHD at Liuzhou General Hospital (Liuzhou, Guangxi). These patients were divided into three groups according to the novel antiplatelet therapy. The occurrence of major adverse cardiac events (MACE), including cardiac death, non-fatal myocardial infarction, heart failure or target vessel revascularization, net adverse clinical events (NACE), including major bleeding, stroke or MACE, and gastrointestinal rebleeding during clinical follow-up following the initial procedure were compared among these three groups. The results of this analysis demonstrated that the occurrence rate of MACE, NECE and gastrointestinal rebleeding was not significantly different among these groups (P>0.05). Furthermore, survival analysis was performed and although the survival curves of MACE and NECE were not significantly different among these groups, gastrointestinal rebleeding was demonstrated to be significantly different among the three groups (P<0.05), and continued aspirin or clopidogrel use was superior to continued DAPT. In conclusion, the results of the present study indicated that there were no significant differences in the clinical effectiveness and safety of continuing antiplatelet monotherapy or DAPT in patients who are administered DAPT and experience gastrointestinal hemorrhage following DES implantation. As for the prevention of recurrent bleeding, antiplatelet monotherapy was demonstrated to be superior to DAPT. Moreover, the treatment of patients who are administered DAPT and experience gastrointestinal hemorrhage following DES implantation must involve an evaluation of the risk of complications, including stent thrombosis, continuous bleeding and recurrent hemorrhage.

Patient-specific coronary stenoses can be modeled using a combination of OCT and flow velocities to accurately predict hyperemic pressure gradients

Computational fluid dynamics (CFD) is increasingly being developed for the diagnostics of arterial diseases. Imaging methods such as computed tomography (CT) and angiography are commonly used. However, these have limited spatial resolution and are subject to movement artifact. This study developed a new approach to generate CFD models by combining high-fidelity, patient-specific coronary anatomy models derived from optical coherence tomography (OCT) imaging with patient-specific pressure and velocity phasic data. Additionally, we used a new technique which does not require the catheter to be used to determine the centerline of the vessel. The CFD data were then compared with invasively measured pressure and velocity. Angiography imaging data of 21 vessels collected from 19 patients were fused with OCT visualizations of the same vessels using an algorithm that produces reconstructions inheriting the in-plane (10 μm) and longitudinal (0.2 mm) resolution of OCT. Proximal pressure and distal velocity waveforms ensemble averaged from invasively measured data were used as inlet and outlet boundary conditions, respectively, in CFD simulations. The resulting distal pressure waveform was compared against the measured waveform to test the model. The results followed the shape of the measured waveforms closely (cross-correlation coefficient = 0.898 ± 0.005, ), indicating realistic modeling of flow resistance, the mean of differences between measured and simulated results was -3. 5 mmHg, standard deviation of differences (SDD) = 8.2 mmHg over the cycle and -9.8 mmHg, SDD = 16.4 mmHg at peak flow. Models incorporating phasic velocity in patient-specific models of coronary anatomy derived from high-resolution OCT images show a good correlation with the measured pressure waveforms in all cases, indicating that the model results may be an accurate representation of the measured flow conditions.