Heart allograft rejection: detection with breath alkanes in low levels (the HARDBALL study).
BACKGROUND
We evaluated a new marker of heart transplant rejection, the breath methylated alkane contour (BMAC). Rejection is accompanied by oxidative stress that degrades membrane polyunsaturated fatty acids, evolving alkanes and methylalkanes, which are excreted in the breath as volatile organic compounds (VOCs).


METHODS
Breath VOC samples (n = 1,061) were collected from 539 heart transplant recipients before scheduled endomyocardial biopsy. Breath VOCs were analyzed by gas chromatography and mass spectroscopy, and BMAC was derived from the abundance of C4-C20 alkanes and monomethylalkanes. The "gold standard" of rejection was the concordant set of International Society for Heart and Lung Transplantation (ISHLT) grades in biopsies read by 2 reviewers.


RESULTS
Concordant biopsies were: Grade 0, 645 of 1,061 (60.8%); 1A, 197 (18.6%); 1B, 84 (7.9%); 2, 93 (8.8%); and 3A, 42 (4.0%). A combination of 9 VOCs in the BMAC identified Grade 3 rejection (sensitivity 78.6%, specificity 62.4%, cross-validated sensitivity 59.5%, cross-validated specificity 58.8%, positive predictive value 5.6%, negative predictive value 97.2%). Site pathologists identified the same cases with sensitivity of 42.4%, specificity 97.0%, positive predictive value 45.2% and negative predictive value 96.7%.


CONCLUSIONS
A breath test for markers of oxidative stress was more sensitive and less specific for Grade 3 heart transplant rejection than a biopsy reading by a site pathologist, but the negative predictive values of the 2 tests were similar. A screening breath test could potentially identify transplant recipients at low risk of Grade 3 rejection and reduce the number of endomyocardial biopsies.
Phillips
Michael
M
Menssana Research, Inc. Fort Lee, New Jersey, USA. menssana@bellatlantic.net
Boehmer
John P
JP
Cataneo
Renee N
RN
Cheema
Taseer
T
Eisen
Howard J
HJ
Fallon
John T
JT
Fisher
Peter E
PE
Gass
Alan
A
Greenberg
Joel
J
Kobashigawa
Jon
J
Mancini
Donna
D
Rayburn
Barry
B
Zucker
Mark J
MJ
D000328:Adult; D000368:Aged; D000473:Alkanes / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests; D016022:Case-Control Studies; D005260:Female; D006084:Graft Rejection / Q000378:metabolism* / Q000473:pathology; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology; D011650:Pulmonary Alveoli / Q000378:metabolism*; D012680:Sensitivity and Specificity
D000473:Alkanes; D015415:Biomarkers