Background: We evaluated the diagnostic and prognostic value of quantification of myocardial flow reserve (MFR) with positron emission tomography (PET) in orthotopic heart transplant patients.

Methods and Results: We retrospectively identified orthotopic heart transplant patients who underwent rubidium-82 cardiac PET imaging. The primary outcome was the composite of cardiovascular death, acute coronary syndrome, coronary revascularization, and heart failure hospitalization. Cox regression was used to evaluate the association of MFR with the primary outcome. The relationship of MFR and cardiac allograft vasculopathy severity in patients with angiography within 1 year of PET imaging was assessed using Spearman rank correlation and logistic regression. A total of 117 patients (median age, 60 years; 71% men) were identified. Twenty-one of 62 patients (34%) who underwent angiography before PET had cardiac allograft vasculopathy. The median time from orthotopic heart transplant to PET imaging was 6.4 years (median global MFR, 2.31). After a median of 1.4 years, 22 patients (19%) experienced the primary outcome. On an unadjusted basis, global MFR (hazard ratio, 0.22 per unit increase; 95% confidence interval, 0.09–0.50; P<0.001) and stress myocardial blood flow (hazard ratio, 0.48 per unit increase; 95% confidence interval, 0.29–0.79; P=0.004) were associated with the primary outcome. Decreased MFR independently predicted the primary outcome after adjustment for other variables. In 42 patients who underwent angiography within 12 months of PET, MFR and stress myocardial blood flow were associated with moderate–severe cardiac allograft vasculopathy (International Society of Heart and Lung Transplantation grade 2–3).

Conclusions: MFR assessed by cardiac rubidium-82 PET imaging is a predictor of cardiovascular events after orthotopic heart transplant and is associated with cardiac allograft vasculopathy severity.

背景：我们评估了正位发射断层扫描（PET）对原位心脏移植患者心肌血流储备（MFR）定量的诊断和预后价值。

方法和结果：我们回顾性地确定了接受rub 82心脏PET显像的原位心脏移植患者。主要结果是心血管死亡，急性冠状动脉综合征，冠状动脉血运重建和心力衰竭住院的综合结果。Cox回归用于评估MFR与主要结局的相关性。使用Spearman秩相关和Logistic回归评估了PET显像后1年内血管造影患者的MFR与心脏同种异体血管病变严重程度的关系。总共确定了117例患者（中位年龄为60岁；男性为71％）。在PET之前接受血管造影的62例患者中有21例（34％）患有心脏同种异体血管病变。从原位心脏移植到PET成像的中位时间为6.4年（全球MFR中位数为2.31）。在中位1.4年之后，22名患者（19％）经历了主要结局。在未经调整的基础上，全球MFR（危险比，每单位增加0.22； 95％置信区间，0.09-0.50；P <0.001）和应激性心肌血流（危险比，每增加0.48； 95％置信区间，0.29-0.79；P = 0.004）与主要结局相关。调整其他指标后，MFR降低可独立预测主要结局。在PET的12个月内接受血管造影的42例患者中，MFR和应激性心肌血流与中度至重度心脏同种异体移植血管病变（国际心肺移植协会2-3级）相关。

结论：通过心脏rub 82 PET成像评估的MFR是原位心脏移植术后心血管事件的预测指标，并且与心脏同种异体血管病变的严重程度有关。