Validation of a physics-based computational model of epicardial and microvascular coronary physiology against continuous infusion thermodilution

Introduction Coronary microvascular dysfunction is associated with myocardial ischaemia and an adverse prognosis, but accurate invasive assessment is technically challenging, requires dedicated hardware and increases procedure time and cost. Assessment can be performed with three-dimensional (3D) computational fluid dynamics (CFD) modelling, but this technique lacks robust in-vivo validation. In this study, we compared the accuracy of a 3D CFD method against continuous thermodilution.

Patients with acute and chronic coronary syndromes, undergoing continuous thermodilution and angiography-derived assessment, were recruited from two tertiary cardiac centres. Microvascular resistance reserve (MRR) and absolute flow were computed using 3D CFD in reconstructed coronary arteries. Invasive pressure measurements informed the CFD boundary conditions.

Paired flow results were available for 131 arteries from 89 patients. Median computed MRR was 2.31 [1.83 – 3.00], which was significantly lower than continuous thermodilution assessed MRR (2.79 [2.21 – 3.52], z = 3.57, p = 0.0004). There was evidence of a moderate relationship between computed and measured MRR (ρ = 0.58, p<0.0001) and area under the receiver operator characteristic curve was 0.77 (95% CI 0.68–0.86), indicating fair classification. There was a modest relationship between computed and measured hyperaemic vessel inlet flow (ρ=0.44, p<0.0001). For both MRR and flow, agreement improved at lower, more clinically relevant, values.

In this clinical validation study, when compared with continuous thermodilution, the novel CFD method demonstrated a moderate correlation, and fair diagnostic accuracy. This CFD method may be a useful, low-cost and less-invasive tool in the assessment of microvascular physiology that could complement current invasive techniques. Competing Interest Statement The authors have declared no competing interest. Funding Statement DT was funded by Sheffield Biomedical Research Centre. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Data collection for research purposes was approved by Regional Ethics Committees (OxAMI REC number 10/H0408/24, Essex-SAAMI REC reference 22/EE/0016), compliant with the Declaration of Helsinki and all patients gave written informed consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability Available on reasonable request