Survivors of community-acquired pneumonia (CAP) are at increased risk of cardiovascular disease, cognitive and functional decline, and death but the mechanisms remain unknown.Do CAP survivors have evidence of increased inflammatory activity in their lung parenchyma on 18FDG-PET/CT after clinical resolution of infection?and Methods: We performed 18FDG-PET/CT scans in 22 CAP-survivors during their hospitalization with pneumonia (acute-CAP) and 30-45 days after the hospital discharge (post-CAP). We assessed the lungs for foci of increased 18FDG uptake by visual interpretation and by the total pulmonary glycolytic activity (tPGA), a background-corrected measure of total metabolic activity (as measured by 18FDG uptake) of the lungs on both scans. We also measured the glycolytic activity of lung areas of volumes exactly similar to the areas of increased 18FDG uptake in the post-CAP studies of CAP participants in 28 matched historical controls without pneumonia.Overall, (68%, confidence interval 45% to 85%) CAP-survivors had distinct residual areas of increased 18FDG uptake in their post-CAP studies. tPGA decreased from 821.5 (standard deviation [SD], 1140.2) in the acute-CAP period to 80.0 (SD, 81.4) in the post-CAP period (p=0.006). The tPGA post CAP was significantly higher than that in lung areas of similar volume in controls (80.0 [SD, 81.4] versus -19.4 [SD, 5.9]; p<0.001).An important proportion of CAP survivors have persistent pulmonary foci of increased inflammatory activity beyond resolution of their infection. As inflammation contributes to cardiovascular disease, cognitive decline, functional waning and mortality risk in the general population, this finding provides a plausible mechanism for the increased morbidity and mortality that has been observed post-CAP.
Vicente F Corrales-Medina, Robert A deKemp, Julio A Chirinos, Wanzhen Zeng, Jerry Wang, Grant Waterer, Rob S B Beanlands, Girish Dwivedi