Increased myocardial performance index correlates with biopsy-proven rejection in pediatric heart transplant recipients.

TLDR: Increased LVMPI correlated with biopsy-proven rejection, and frequent serial assessments using this technique may provide a relatively sensitive non-invasive means of rejection surveillance after pediatric cardiac transplantation.

Abstract: Background To date, cardiac catheterization and endomyocardial biopsy have been considered the "gold standard" for rejection surveillance after heart transplantation. Factors such as patient size (i.e., infant transplantation), loss of vascular access after repeated catheterizations, and anesthesia requirements all present unique problems and risks related to pediatric rejection surveillance. Therefore, additional methods to monitor for rejection in a non-invasive, reliable and frequent manner have been sought. We studied the utility of echocardiographic measurement of the left ventricular myocardial performance index (LVMPI), a reproducible measure of combined systolic and diastolic performance, in pediatric heart transplant recipients as a method of identifying acute rejection. Methods Two-dimensional/Doppler echocardiographic studies ( n = 36) were performed on 21 cardiac transplant patients (ages 6.2 to 21.9 years) at the time of endomyocardial biopsy. The LVMPI, the sum of the isovolumic contraction time and isovolumic relaxation time divided by aortic ejection time, was determined at each study, as well as other echocardiographic measures of systolic and diastolic function. Patients were grouped by concurrent histologic rejection grade and the results compared between groups. Results Significant differences in LVMPI ( p n = 23) and those with moderate to severe rejection (Grade 3; n = 5), as well as between those with no rejection and those with focal moderate (Grade 2; n = 8) rejection ( p n = 7). No significant differences were noted between groups for left ventricular ejection fraction or shortening fraction, percent septal or posterior wall thickening, left ventricular mass index or mitral valve deceleration time. In addition, for those individual patients with multiple studies, the LVMPI consistently increased with higher rejection grades and decreased after therapy. Conclusions In this series, increased LVMPI correlated with biopsy-proven rejection, and frequent serial assessments using this technique may provide a relatively sensitive non-invasive means of rejection surveillance after pediatric cardiac transplantation. False positive results may be encountered, likely due to alterations in diastolic function that have been previously observed in transplant recipients.