Background: To evaluate the usefulness of PCR in peripheral blood leukocytes for the diagnosis of CMV infection and for prognosis of CMV disease in patients with heart transplantation.
Patients and methods: A total of 54 heart transplant recipients included in a protocolized virological follow-up with blood samples (total samples: 594). Mean time of follow-up: 14.8 months (range 1-34 months). We compared a qualitative nested PCR with tube culture (CC), shell vial culture (SV) and pp65 quantitative antigenemia test (AGC).
Results: PCR was the most sensitive test (89.9%) followed by AGC (68.1%), SV (42.6%) and CC (33.4%). Specificity: 80 samples were positive only by PCR, 77 of which form patients with virologically documented CMV active infection, so they were considered as true positives. Three samples were from 2 patients in which the unique positive marker was PCR. If we considered these results as false positive, the calculated specificity was 99.0%. PCR was the first positive marker in 44 out of 45 patients with active CMV infection. In 9 of these patients no other viral marker was positive in the first positive sample, except for PCR. A total of 16 episodes of CMV disease were observed along the study, and a positive PCR result was detected in 15 of them. The remaining patient did not show amplification with the set of primers used in this study, but it gave a positive PCR by amplifying with a different primer pair. Positive predictive value of PCR for CMV disease was low (33.3%). Thus, a positive PCR result did not allow to distinguish between asymptomatic infection and CMV disease.
Conclusions: In heart transplantation recipients CMV-PCR is a highly sensitive, specific and early marker of CMV infection but its positive predictive value for CMV disease seems unsatisfactory.