Type 4 chemokine receptor (CXCR4) plays an important role in immune cell migration during the atherosclerosis progression. We aimed to evaluate [⁶⁸Ga]Pentixafor positron emission tomography (PET) in combination magnetic resonance imaging (MRI) for in vivo quantification of CXCR4 expression in carotid plaques.

BACKGROUND: Microvascular obstruction (MVO) is associated with heart failure (HF) following ST-segment–elevation myocardial infarction. Angiography-derived microcirculatory resistance (AMR), a wire- and adenosine-free measure, may facilitate early assessment of microvascular function post-primary percutaneous coronary intervention. This study aimed to evaluate the ability of AMR to detect MVO and its prognostic value for predicting HF in patients with ST-segment–elevation myocardial infarction post-primary percutaneous coronary intervention. METHODS: Patients with consecutive ST-segment–elevation myocardial infarction undergoing primary percutaneous coronary intervention with a cardiac magnetic resonance examination 2 to 7 days post-procedure between April 2016 and February 2023 were retrospectively reviewed. AMR was computed from coronary angiography. MVO was identified and quantified via cardiac magnetic resonance. The end point was new-onset HF during follow-up. RESULTS: Overall, 475 patients (aged 56.8±11.7 years; 399 men) were included. The area under the curve for AMR to detect MVO was 0.821 (95% CI, 0.782–0.859), with an optimal cutoff value of 2.7 mm Hg*s/cm. During a median follow-up of 37.3 months, 121 (25.5%) patients developed HF. AMR, whether as a continuous (per 0.5-mm Hg*s/cm increase; hazard ratio, 1.29 [95% CI, 1.10–1.52]; P =0.002) or categorical (AMR >2.7 mm Hg*s/cm; hazard ratio, 2.15 [95% CI, 1.43–3.22]; P <0.001) variable, was independently associated with HF after adjusting for traditional risk factors (age, symptom-to-balloon time, left anterior descending coronary artery, and ejection fraction) and late gadolinium enhancement-cardiac magnetic resonance parameters. AMR improved prognostication over traditional risk factors and late gadolinium enhancement-cardiac magnetic resonance parameters (net reclassification improvement, 0.533; P <0.001; integrative discrimination index, 0.023; P =0.005). CONCLUSIONS: AMR showed good diagnostic performance in detecting MVO and was an independent and incremental predictor of HF in patients with ST-segment–elevation myocardial infarction post-primary percutaneous coronary intervention.