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Increased myocardial performance index correlates with biopsy-proven rejection in pediatric heart transplant
Glenn T Leonard1, F Jay Fricker, Debra Pruett
1Department of Pediatrics (Cardiology), University of Florida College of Medicine, Gainesville, Florida 32610, USA.
Insights
The left ventricular myocardial performance index (LVMPI) can help detect acute rejection in pediatric heart transplant recipients. This non-invasive echocardiographic measure shows promise for frequent, reliable rejection surveillance.
Area of Science:
- Cardiology
- Transplantation immunology
- Pediatric medicine
Background:
- Cardiac catheterization and endomyocardial biopsy are standard for heart transplant rejection surveillance.
- Pediatric heart transplant recipients face unique challenges with invasive monitoring methods.
- Non-invasive, reliable methods for rejection surveillance are needed.
Purpose of the Study:
- To evaluate the utility of left ventricular myocardial performance index (LVMPI) for identifying acute rejection in pediatric heart transplant recipients.
- To assess LVMPI as a non-invasive alternative to traditional surveillance methods.
Main Methods:
- Echocardiographic studies, including LVMPI calculation, were performed on 21 pediatric heart transplant patients concurrently with endomyocardial biopsy.
- Patients were categorized based on histologic rejection grade (Grade 0, 2, and 3).
- LVMPI and other echocardiographic parameters were compared between rejection and non-rejection groups.
Main Results:
- A significant difference in LVMPI was observed between non-rejection (Grade 0) and rejection groups (Grade 2 and 3) (p < 0.001).
- LVMPI values were consistently higher in patients with moderate to severe rejection.
- LVMPI >or= 0.64 was associated with significant rejection in all cases; other echocardiographic measures did not show significant differences between groups.
Conclusions:
- Increased LVMPI correlates with biopsy-proven rejection in pediatric heart transplant recipients.
- Serial LVMPI assessments may offer a sensitive, non-invasive method for rejection surveillance.
- Potential for false positives exists, possibly due to diastolic function alterations.
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 < 0.001) were noted between patients with no rejection (Grade 0; 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 < 0.05). The LVMPI was 0.42 +/- 0.03 (mean +/- SEM) for the group without rejection, 0.57 +/- 0.06 for those with Grade 2 rejection and 0.73 +/- 0.05 for those with Grade 3 rejection. Although 9 of the 23 studies in the non-rejection group had LVMPI values exceeding 0.44 (upper threshold value), 12 of 13 patients in the rejection groups exceeded this threshold. LVMPI >or= 0.64 was associated with significant rejection in all cases in this study (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.
