Rb-82 PET is accurate for the detection of obstructive CAD and, despite advances in SPECT technology, remains superior. More widespread use of Rb-82 PET may be beneficial to improve CAD detection.

Background-Positron emission tomography using 18 F-Fluorodeoxyglucose (FDG) is an emerging modality for diagnosis of cardiac sarcoidosis (CS). We compared the location and degree of FDG uptake in CS patients presenting with either advanced atrioventricular block (AVB) or ventricular tachycardia (VT

CAV results in diffuse concentric intimal thickening of the epicardial vessels affecting both the proximal and distal vessels as well as the microcirculation.3 This progressive luminal narrowing and loss of vasodilatory capacity culminates in myocardial ischemia and contractile dysfunction. Immunemediated injury plays a significant role in the development of epicardial vessel stenosis in addition to traditional risk factors. 4 Clinical symptoms such as angina are typically absent in cases of CAV because of allograft denervation, and therefore annual screening is used in most centers.Recent guidelines recommend periodic invasive coronary angiography for at least the first 3 to 5 years after transplantation. 5 However, this is inconvenient and adds risk. Hence, many centers have elected to monitor patients with noninvasive testing, but this strategy may be suboptimal because of the lower sensitivity for the detection of early CAV. 6,7 Rubidium-82 (Rb-82) positron emission tomography (PET) myocardial perfusion imaging is a noninvasive imaging modality that has the ability to quantify myocardial blood flow (MBF) 8 and has been shown to have prognostic value in patients being assessed for ischemia.9-11 This technique may facilitate earlier detection of CAV and thus may have prognostic value in HT patients. The objective of this study was to evaluate the prognostic value of Rb-82 PET in patients with a history of HT.Background-Cardiac allograft vasculopathy is a key prognostic determinant after heart transplant. Detection and risk stratification of patients with cardiac allograft vasculopathy are problematic. Positron emission tomography using rubidium-82 allows quantification of absolute myocardial blood flow and may have utility for risk stratification in this population. Methods and Results-Patients with a history of heart transplant undergoing dipyridamole rubidium-82 positron emission tomography were prospectively enrolled. Myocardial perfusion and left ventricular ejection fraction were recorded. Absolute flow quantification at rest and after dipyridamole stress as well as the ratio of mean global flow at stress and at rest, termed myocardial flow reserve, were calculated. Patients were followed for all-cause death, acute coronary syndrome, and heart failure hospitalization. A total of 140 patients (81% men; median age, 62 years; median follow-up, 18.2 months) were included. There were 14 events during follow-up (9 deaths, 1 acute coronary syndrome, and 4 heart failure admissions). In addition to baseline clinical variables (estimated glomerular filtration rate, previously documented cardiac allograft vasculopathy), relative perfusion defects, mean myocardial flow reserve, and mean stress myocardial blood flow were significant predictors of adverse outcome. Conclusions-Abnormalities on rubidium-82 positron emission tomography were predictors of adverse events in heart transplant patients. Larger prospective studies are required to confirm these findings. (Circ Cardiovasc Imaging. 2014;7:930-937.)

In this prospective study, four of 14 (28%) patients presenting with MMVT (without idiopathic VT, ischemic VT, or known sarcoidosis) had CS as the underlying etiology. Clinicians should consider screening for CS in patients with unexplained MMVT.