Change of c-myc expression and cardiac hypertrophy in patients with aorticvalve replacement

Background. Long-term volume overload to the left ventricle (LV) due to aor tic regurgitation (AR) fends to cause severe impairment in LV function that cannot be reversed even with aortic valve replacement (AR). Recently, we r eported that the protooncogene c-myc is related to the onset of the cardiac hypertrophy and LV dysfunction in patients with chronic AR. However, it is still unclear whether c-myc is related to reversibility of the cardiac hyp ertrophy or LV dysfunction after AVR. Methods and Results. Twenty patients with isolated chronic AR who underwent AVR were included in this study. LV function was calculated before and aft er AVR. After AVR, end-systolic volume index (ESVI) and end-diastolic volum e index (EDVI) were improved, but not mass index (LVMI). However, normaliza tion of ESVI and EDVI was observed only in 12 and 9 patients, respectively. Preoperatively, c-Myc protein was expressed in the myocardium of 16 out of 20 patients with an average point count of 35 +/- 30%. After AVR, c-Myc pr otein was observed only in 2 patients. Preoperative ejection fraction (EF), ESVI, and postoperative end-systolic stress (ESS)/ESVI had significant cor relation to postoperative cell diameter (CD). Percent c-Myc protein express ion before the operation was significantly correlated to post-operative CD, ESVI, and ESS/ESVI. Average c-Myc expression was higher in patients who sh owed normalization of CD and ESS/ESVI after AVR than the patients who did n ot. Conclusions. These data suggest that preoperative expression of c-Myc can b e indicative of the reversibility of myocardial cellular hypertrophy and LV dysfunction. (C) 2001 by The Society of Thoracic Surgeons.