Objectives Early detection of microvascular dysfunction after acute myocardial infarction (AMI) could identify patients at high risk of adverse clinical outcome, who may benefit from adjunctive treatment. Our objective was to compare invasively measured coronary flow reserve (CFR) and hyperaemic microvascular resistance (HMR) for their predictive power of long-term clinical outcome and cardiac magnetic resonance (CMR)-defined microvascular injury (MVI).
Methods Simultaneous intracoronary Doppler flow velocity and pressure measurements acquired immediately after revascularisation for AMI from five centres were pooled. Clinical follow-up was completed for 176 patients (mean age 60±10 years; 140(80%) male; ST-elevation myocardial infarction (STEMI) 130(74%) and non-ST-segment elevation myocardial infarction 46(26%)) with median follow-up time of 3.2 years. In 110 patients with STEMI, additional CMR was performed.
Results The composite end point of death and hospitalisation for heart failure occurred in 17 patients (10%). Optimal cut-off values to predict the composite end point were 1.5 for CFR and 3.0 mm Hg cm−1•s for HMR. CFR <1.5 was predictive for the composite end point (HR 3.5;95% CI 1.1 to 10.8), but not for its individual components. HMR ≥3.0 mm Hg cm−1 s was predictive for the composite end point (HR 7.0;95% CI 1.5 to 33.7) as well as both individual components. HMR had significantly greater area under the receiver operating characteristic curve for MVI than CFR. HMR remained an independent predictor of adverse clinical outcome and MVI, whereas CFR did not.
Conclusions HMR measured immediately following percutaneous coronary intervention for AMI with a cut-off value of 3.0 mm Hg cm−1 s, identifies patients with MVI who are at high risk of adverse clinical outcome. For this purpose, HMR is superior to CFR.
- Acute myocardial infarction
- Cardiac magnetic resonance (CMR) imaging
- Percutaneous coronary intervention
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GAW and GF contributed equally.
Contributors GAdW, GF, PFAT, DdW, NP, MS, RW and HK performed study procedures and ascertained follow-up. RK, SU, PK, NvR, TA and DP supervised the study at the respective sites. GAdW and NvR drafted the manuscript. GAdW and PvdV performed statistical analysis. All authors critically reviewed the manuscript and made revisions.
Funding This study was funded by institutional grants from the Oxford Biomedical Research Centre, Volcano Corporation, Biotronik, Turkish Academy of Sciences and National Institute for Health Research.
Competing interests GAdW, DP, RK and NvR have received speaking/advisory board honoraria from Volcano Corporation. The other authors report no conflicts of interest pertaining to this study.
Patient consent Obtained.
Ethics approval VU University Medical Center.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice Since this paper first published online the Oxford Acute Myocardial Infarction (OxAMI) Study investigators have been added to the author line.