PET Assessment of Myocardial Perfusion Reserve Inversely Correlates with Intravascular Ultrasound Findings in Angiographically Normal Cardiac Transplant Recipients

Abstract

Cardiac allograft vasculopathy (CAV) is the major determinant of long-term survival after heart transplantation. We aimed to evaluate the efficacy of PET as a noninvasive way to assess the early stages of CAV. Methods: Twenty-seven consecutive patients (20 men and 7 women; mean age 6 SD, 46 6 12 y) who had normal results on coronary angiography and normal left ventricular systolic function (ejection fraction $ 60%) were enrolled at 2.5 6 2.1 y after transplantation. Myocardial blood flow (MBF) was assessed using dynamic 13 N-ammonia PET at rest and during adenosine-induced hyperemia, and myocardial perfusion reserve (MPR) was calculated as the ratio of hyperemic MBF to resting MBF. Regional 13 N-ammonia PET was assessed using a 5-point scoring system. The intravascular ultrasound (IVUS) measurements for the extent of intimal hyperplasia, including plaque volume index (calculated as [total plaque volume/total vessel volume] · 100%) and maximum area of stenosis, were compared with MPR by linear regression analysis. Results: In 27 angiographically normal cardiac transplant recipients, MBF at rest and during adenosine stress and MPR of the left anterior descending artery distribution correlated strongly with the other 2 coronary artery distribution territories (r $ 0.97, P , 0.0001). Summed stress score and summed difference score showed a moderate inverse correlation with MPR (r 5 20.41 and 20.49, respectively; P , 0.05) but not with IVUS measurements. MPR correlated inversely with plaque volume index (r 5 20.40, P , 0.05) but not with maximal luminal stenosis as assessed by IVUS. In addition, MPR and IVUS measurements gradually inversely changed after heart transplantation (all P , 0.05). Conclusion: This study confirms that CAV is a progressive process, diffusely involving the epicardial and microvascular coronary system. Plaque burden as determined by IVUS agrees well with MPR as assessed by PET in recipients with normal coronary angiography results. This finding suggests that dynamic 13 N-ammonia PET is clinically feasible for the early detection of CAV and can be used as a reliable marker of disease progression. Cardi ac allograft vasculopathy (CAV) is one of the leading causes of late mortality after heart transplantation (1,2). Early CAV is clinically silent, and ischemia is usually not evident until the disease is far advanced. The traditional annual coronary angiogram for surveillance is of limited value because CAV is characterized by diffuse concentric intimal thickening of both epicardial and intramyocardial arteries and may thus be overlooked on a coronary angiogram. Intravascular ultrasound (IVUS) has been proposed to be the most sensitive method for diagnosis of early CAV (3-8). However, the invasiveness and the physical bulkiness of IVUS catheters make the widespread application of IVUS in the detection of CAV difficult (2-5).Stress myocardial perfusion images, including SPECT and PET, have been recognized as key diagnostic methods to evaluate coronary artery disease (9-12). Stress myocardial SPECT,...

Usefulness of Magnetocardiography to Detect Coronary Artery Disease and Cardiac Allograft Vasculopathy

“…CI, confidence interval. mined on IVUS agrees well with myocardial perfusion reserve assessed on PET in OHT recipients, 12 it can be used as a marker of inducible ischemia burden and disease severity. In the present study, QTc on ECG and MCG was significantly higher in OHT patients than in those with patent coronary angiogram (both P<0.0001), but did not correlate well with any IVUS parameters.…”

“…For each subject, namic perfusion positron emission tomography (PET) has been considered superior to invasive coronary angiography and SPECT in the detection of CAV. 12 The complexity of production and delivery of short-lived PET tracers, high cost and radiation exposure, however, hinder wide utilization. Therefore, the need for a sensitive and non-invasive surveillance diagnostic tool is of clinical importance.…”

Diagnosis and management of coronary allograft vasculopathy in children and adolescents

“…As well as myocardial perfusion reserve, perfusion of the epicardial arteries and the microvasculature can be determined [85,86] . In patients after heart transplantation, myocardial perfusion reserve measured with PET has been performed in a few studies [87][88][89] . Wu et al [88] found good correlation between IVUS and myocardial perfusion reserve even in the absence of angiographic lesions.…”

“…In patients after heart transplantation, myocardial perfusion reserve measured with PET has been performed in a few studies [87][88][89] . Wu et al [88] found good correlation between IVUS and myocardial perfusion reserve even in the absence of angiographic lesions. Published data is very limited even in adults, related to the limited availability of the technique and the expertise required.…”

Myocardial perfusion imaging for cardiac allograft vasculopathy assessment: Evidence grows, but questions remain

“…16 PET, while expensive and not widely available, may also quantify myocardial blood flow and can demonstrate early CAV in patients who have angiographically normal coronary arteries. 17 If the purpose of the test is to evaluate for severe CAV which would mandate angiography and revascularization, gated SPECT appears to be sufficiently sensitive, and the high negative predictive value of a normal test may safely allow delay or decrease in frequency of angiograms in the short term. If the purpose is to assess overall prognosis, for example for clinical trials, gated SPECT integrates macrovascular, microvascular, and functional data and provide information not available from CAG.…”