Non-invasive detection of acute rejection after cardiac transplantation by means of body surface potential mapping

Results are presented of monitoring 16 patients after orthotopic heart transplantation (OHT). In 377 examinations the grade of rejection was determined by endomyocardial biopsy (EMB). The QRS voltage was measured by noninvasive body surface potential mapping (BSPM) within 4 hours of EMB. Sixty-three acute rejections necessitating additional medical therapy, graded A-3b or A-4 according to the Hannover classification scheme, were detected by EMB. Only 13 of these acute rejections could be identified by QRS reduction in the standard electrocardiogram (ECG) (sensitivity of 21%). However, 48 of them showed positive BSPM-ECG. In 93 of 314 negative biopsies BSPM showed a significant drop in voltage, indicating BSPM was false positive. Thus the sensitivity of BSPM to detect acute rejection was 76% with a specificity of 70%. Only 22 of 200 BSPM-ECG of normal subjects shows a significant drop of QRS voltage (specificity of 89% in the control group). It is concluded that QRS voltage reduction in a localized area measured by BSPM is a useful screening method for moderate or severe acute rejection