A new technology that allows doctors to quantify blood flow in the heart can help improve their ability to diagnose potentially deadly coronary artery disease (CAD), according to an international study, led by School of Medicine investigators.
The technique, which is an advancement in cardiac magnetic resonance imaging (CMR) combined with stress testing as a diagnostic test of coronary artery disease, up to 70% or more people aged 60 or older. Doctors use CMR stress testing, to assess how the heart is working and if there are any blockages in the blood flow that will be harmful.
CMR stress testing can identify coronary artery disease, but the new research from Amit Patel (Cardiologist and imaging expert, University of Virginia Health System, USA) and colleagues suggests that ‘quantitative’ CMR with blood flow data is even better. The research is published in the journal JACC: Cardiovascular Imaging.
Amit Patel et al. conducted an assessment of quantitative myocardial blood flow (MBF) using a CMR (AQUA-MBF) study. It is a retrospective, observational, and international multi-center study involving 10 medical centers across North America, Europe, and Asia. They compare the quantitative stress MBF (sMBF) and myocardial perfusion reserve (MPR), with qualitative assessment (QA) of stress CMR for the identification of obstructive CAD (obCAD). A total of 127 patients with a mean age of 62 ± 16 years who underwent stress CMR were included in this research.
Less common but more likely to need treatment to unblock a coronary artery with coronary artery bypass or heart stent surgery is obstructive. obCAD is often regarded as more serious than the nonobstructive because it does not, usually, need to be treated surgically, but still could result in heart attacks and will have to be treated with medications. Adding information on blood flow improved CMR’s ability to spot obstructive coronary artery disease, the researchers found. Overall, 44% of the study group had obstructive CAD, and 71 had nonobstructive. This enhanced CMR was also shown to be more effective at detecting obstructive CAD than traditional CMR or even human physician reading scans.
Researchers explained that stress CMR-based sMBF and MPR quantification can efficiently differentiate obCAD and noCAD at both the patient and coronary artery territory levels. Levels of sMBF (<2.04 mL/g/min) and MPR (<1.61) prove strong diagnostic performance for the detection of obCAD at the patient level. Furthermore, the probability of obCAD decreased logarithmically as sMBF increased beyond 2.04 mL/g/min. This correlation was independent of cardiovascular risk factors and largely unchanged by variations in acquisition methods. Particularly, global sMBF outperformed qualitative assessments by some experts in detecting obCAD.
Finally concluded that quantitative perfusion using stress CMR has higher reproducibility than QA. Quantification of MBF and MPR can identify obCAD more precisely than qualitative assessment performed by CMR experts. Although this study was neither meant to nor will not expand out to the diagnosis of other heart problems like heart failure, future studies will be necessary to see how these blood flow measurements will impact patients with other cardiac problems.
Reference: Wang S, Kim P, Wang H, et al. Myocardial blood flow quantification using stress cardiac magnetic resonance improves detection of coronary artery disease. JACC Cardiovasc Imaging. 2024;17(12):1428-1441. doi:10.1016/j.jcmg.2024.07.023‌
