Prognostic interplay between cardiac allograft vasculopathy and coronary vascular function by hybrid rubidium-82 PET/CT imaging in heart transplant population

Purpose: We evaluated the interrelation of cardiac allograft vasculopathy (CAV) and both coronary artery calcium and coronary vascular function, as assessed rubidium-82 (82Rb) positron emission tomography (PET)/computed tomography (CT) imaging, in heart transplant population with respect to prediction of clinical outcomes. Methods: A total of 100 (mean age 60 ± 13 years) consecutive patients were studied. CAC score was measured according to the Agatston method and patients were categorized into 2 groups (< 100, and ≥100). Baseline and hyperemic MBF were automatically quantified. MPR was calculated as the ratio of hyperemic to baseline MBF and it was considered reduced when < 2. Results: During the mean time of 27 ± 8 months, 35 events occurred. Patients with events showed a higher prevalence of CAV, MPR impairment and CAC score > 100 as compared to patients without events. At multivariable COX analysis, CAC score, CAV and reduced MPR were independent predictors of events. In patients without previous CAV, the presence of reduced MPR was associated with higher event rate compared to normal MPR. Conclusions: In heart transplanted patients, the presence of CAV and reduced MPR were associated with a poor prognosis and higher risk of adverse events. In patients without CAV the presence of reduced MPR was associated with worst prognosis. Thus, the early noninvasive evaluation of microcirculatory dysfunction in HT patients has important clinical implication, providing a better risk stratification and subsequent modification of treatment strategies, with a potential impact on patient management at follow-up. Clinical trial number: not applicable