SIGNAL-AVERAGED ECG IN PATIENTS AFTER ANTHRACYCLINE THERAPY FOR CHILDHOOD-CANCER

Late cardiac complications after anthracycline therapy is an increasin gly common problem among survivors of childhood cancer, Routine clinic al examination may be normal, but subclinical cardiac abnormalities, w hich may progress with time, are documented in high percentage of thes e patients. Microstructural myocardial alterations may result in produ ction of micropotential level signals (late potentials, LP) and altere d frequency components of signal-averaged ECGs (SAECG). SAECG abnormal ities are valuable in risk stratification of patients with various hea rt diseases culminating in fatal arrhythmias or heart failure. Forty-f ive pediatric oncologic patients (mean age 14.4 +/- 4.1 years) were in cluded in the study. SAECG was performed 3 months - 12 years (median 5 .5 years) following completion of anthracycline therapy. The total cum ulative doses of anthracyclines were 90-555 (median 230) mg/m(2). The control group consisted of 30 healthy age-matched volunteers. LP were present in six (13.3%) patients after anthracycline therapy at 40 Hz h igh-pass filter setting. Using frequency-domain analysis within the QR S complex, area ratio 1 (area of 20 to 50 Hz/ area of 0 to 20 Hz) and area ratio 2 (area of 40 to 100 Hz/area of 0 to 40 Hz) were calculated . Twenty (44.4%) and fourteen (31.1%) had abnormal values in area rati os 1 and 2, respectively, within the QRS complex. Area ratios 1 and 2 of patients after anthracycline therapy were significantly higher than those in control group (p = 0.0187 and p = 0.0043). Our preliminary r esults suggest that chemotherapy with anthracyclines, even in low dosa ge, is associated with increased incidence of SAECG abnormalities. The potential of this simple, noninvasive method to detect subclinical an thracycline-induced myocardial alterations and facilitate prognostic s tratification of cancer survivors is promising, however: the clinical value of SAECG remains to be established in a larger and a longer stud y.