Correlation of endomyocardial biopsy findings with electrocardiogram voltage in pediatric cardiac allografts

Endomyocardial biopsy is said to be the gold standard for the diagnosis of cardiac rejection. In the pediatric age group endomyocardial biopsy is more difficult, and technically may be unsatisfactory. It is therefore desirable to correlate the biopsy finding with non-invasive studies so that patients may be monitored meaningfully, and endomyocardial biopsy may be used in a more selective manner. Ten pediatric patients (age range 2-16 years, mean 11.1 yr) underwent endomyocardial biopsy and electrocardiography simultaneously during their post-transplant course (2-24 biopsies, mean 14 biopsies). All patients were treated with triple-drug therapy including cyclosporine, azathioprine and prednisone. Biopsies were classified according to the working formulation of the International Society for Heart Transplantation. The total electrocardiographic voltage (summation of leads 1, 2, 3, V1 and V6) and the limb lead voltage (summation of leads 1, 2, and 3) were calculated. The measurements were then converted into percentage of the highest voltage for each patient, and these values were then compared in the different biopsy groups by analysis of variance. Both the total voltage and the limb lead voltage were significantly lower in the group with grade 3 biopsies versus all other groups (p<0.0005). At a level of 10% decline in total voltage, changes in EKG voltage had low specificity (87%) and positive predictive value (51%) but high sensitivity (94%) and negative predictive value (99%). We conclude that, although strong correlation is present between rejection and low voltage, a decline in voltage is not specific for rejection. However, lack of change from baseline EKG values is an excellent indicator that rejection is not present. Therefore, the EKG may be used as a screening test for rejection but is not a definitive diagnostic test.