HISTOMORPHOMETRIC FEATURES PREDICT 1-YEAR OUTCOME OF PATIENTS WITH IDIOPATHIC DILATED CARDIOMYOPATHY CONSIDERED TO BE AT LOW PRIORITY FOR CARDIAC TRANSPLANTATION

Cardiac transplantation for patients with idiopathic dilated cardiomyo pathy (IDC) and poor left ventricular function usually is postponed un til symptoms have become intolerable. However, the short-term prognosi s of this subset of patients has been defined poorly. Accordingly, the 1-year outcome was investigated in 30 patients with IDC with an eject ion fraction less than or equal to 25% who showed a stabilized clinica l condition at assessment for transplantation and were therefore consi dered at low priority for surgery. During follow-up, 10 patients (grou p A) showed a poor outcome: 2 died suddenly, and 8 had hemodynamic fai lure (4 of whom underwent transplantation and 4 of whom died from hear t failure while on the waiting list). The remaining 20 patients (group B) had a benign outcome. At assessment for cardiac transplantation, c linical and electrocardiographic features, left ventricular dimension, and ejection fraction were similar between the two groups. However, g roup A patients had higher left ventricular end-diastolic pressure (p < 0.03) and lower cardiac index (p < 0.02) and stroke volume index (p < 0.03) with respect to group B patients. In addition, the former had a lower myofibril volume fraction (p < 0.001) and a higher nuclear are a (p < 0.001) compared with the latter. Multivariate analysis selected myofibril volume fraction (p < 0.001) and nuclear area (p < 0.005) as the only independent predictors of a poor 1-year outcome. The combina tion of myofibril volume fraction less than or equal to 89% and nuclea r area >50 mu m(2) was found in all group A patients (sensitivity 100% ) but in only 2 group B patients (specificity 90%). It is concluded th at in patients with IDC considered at low priority for cardiac transpl antation: (1) the 1-year freedom from a cardiac event is lower than th at currently expected with surgery; (2) histomorphometric features, th at is, the concurrency of low myofibril volume fraction and increased nuclear area, predict short-term outcome; and (3) endomyocardial biops y at assessment for cardiac transplantation might improve the rational ization of the timing of the procedure.