Usefulness of the QTc interval in predicting acute allograft rejection.

BACKGROUND

Endomyocardial biopsy (EMB) is the gold standard for detecting cardiac allograft rejection. However, EMB is invasive, costly, and unsuitable for frequent monitoring. Recent studies have shown that acute allograft rejection causes ventricular conduction disturbances. Therefore we tested the hypothesis that the electrocardiographic QTc interval correlates with the histopathologic degree of allograft rejection.

METHODS

Between January 1994 and April 1997, 65 adult cardiac allograft recipients (mean age 52.1 +/- 1.7 years) were studied from transplantation until hospital discharge. During EMB, a 12-lead electrocardiogram was obtained. In grading acute allograft rejection, we used both the Texas Heart Institute (THI) scale and the International Society for Heart and Lung Transplantation (ISHLT) scale. 212 paired biopsy specimens and QTc intervals (mean 3.3 per patient) were obtained. We considered an increase of more than 10% of the QTc interval a rejection.

RESULTS

Of the biopsy specimens 177 showed no or mild rejection (THI grade 0-5; ISHLT grade O-IIIA), and 35 showed moderate to severe rejection (THI grade 6-10; ISHLT IIIA-IV). The mean QTc interval was 449 +/- 2 msec for the first group and 517 +/- 11 msec for the second group (p = 0.0001). The correlation between the biopsy grades and the percentage of the changes in the QTc interval was r = 0.73 (p = 0.001). The QTc interval had a sensitivity of 86% (30/ 35) in predicting rejection and a specificity of 88% (1551177) in predicting the absence of rejection.

CONCLUSIONS

Determination of the QTc interval is an accurate, noninvasive means of detecting acute cardiac rejection. Adoption of QTc testing may allow EMB to be used less frequently and more selectively.