Cardiac magnetic resonance (CMR) imaging demonstrated moderate to good agreement with measurement of fractional flow reserve (FFR) in evaluating nonculprit lesions after ST-segment elevation myocardial infarction (STEMI) in reperfused patients with multivessel coronary artery disease (CAD), according to study results published in JACC: Cardiovascular Imaging.
In this subanalysis of the Reducing Micro Vascular Dysfunction in Acute Myocardial Infarction by Ticagrelor trial (ClinicalTrials.gov identifier: NCT02422888), 77 patients with STEMI postrevascularization (mean age, 60±10 years; 86.0% men) who had multivessel CAD were enrolled. Participants had ≥1 intermediate nonculprit lesion (50%-90% diameter stenosis), and had a CMR performed 30 days after percutaneous coronary intervention and an invasive coronary angiography with FFR measurement within 1 day of CMR.
Perfusion (at rest and under stress), late gadolinium enhancement, and cine imaging were all evaluated blindly on CMR. Myocardial perfusion was assessed by visual, semiquantitative, and fully quantitative analysis and compared with an FFR reference measurement. An FFR ≤0.80 was considered indicative of hemodynamically obstructive CAD.
There were 94 nonculprit vessels identified in this cohort, with hemodynamically obstructive lesions detected in 36 vessels (38%) in 31 patients (40%). The median FFR in nonculprit vessels was 0.87, with 36 vessels (38%) with an FFR ≤0.80.
In the visual CMR analysis, the area under the curve (AUC) for identification of ≥1 obstructive lesion in a nonculprit vessel was 0.74 (95% CI, 0.62-0.83), which yielded a per patient sensitivity and specificity of 73% and 70%, respectively.
In the semiquantitative analysis of CMR, the AUC of the relative upslope of the stress signal intensity time curve was 0.66 (95% CI, 0.54-0.77), resulting in a sensitivity of 76% and a specificity of 65%. The relative upslope of the myocardial flow reserve (MFR) had an AUC of 0.71 (95% CI, 0.59-0.81), with a sensitivity of 61% and a specificity of 83%. The relative upslopes were lower in the myocardium, where FFR was ≤0.80, compared with tissues, where FFR was >0.80 (P =.04 for the stress curve; P =.009 for MFR).
Fully quantitative CMR analysis was not found to enhance diagnostic performance compared with the other methods (P >.05 for all). The AUC for MFR was 0.82 (95% CI, 0.71-0.90), and the AUC for myocardial blood flow was 0.76 (95% CI, 0.64-0.85), yielding respective sensitivities of 82% and 69% and respective specificities of 71% and 77%.
Study limitations include possible underpowering, small sample size, and possible inaccurate analysis of CMR images in patients with microvascular dysfunction.
“To implement perfusion quantification into the clinic, image acquisition and post-processing have to be accelerated and automated,” noted the authors. They recommended that future research compare imaging- and physiology-guided approaches to the treatment of nonculprit lesions in patients with STEMI.
Disclosures: This is a substudy of the REDUCE-MVI trial, which was initiated by the Amsterdam UMC, Amsterdam, the Netherlands, with financial support from AstraZeneca through an unrestricted research grant. In addition, the study was financed by the Ministry of Economic Affairs of the Netherlands by means of a PPP Allowance made available by the Top Sector Life Sciences & Health to stimulate public-private partnerships. Dr van Royen reports research grants from AstraZeneca, Abbott, Philips, Biotronik, and Top Sector Life Sciences & Health during the conduct of the study. Dr van Leeuwen has received research grants from AstraZeneca. Dr Nijveldt has received research grants from Philips and Biotronik; and financial support from the Netherlands Organization for Health Research and Development (grant 9071544). Dr Demirkiran has received a research grant from the postdoctoral international research fellowship program of the Scientific and Technological Research Council of Turkey (ref: 53325897-115.02-170549). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Everaars H, Hoeven NWVD, Janssens GN, et al. Cardiac magnetic resonance for evaluating nonculprit lesions after myocardial infarction. JACC Cardiovasc Imaging. 2020;13(3):715-728.