NORMALIZATION OF DIASTOLIC DYSFUNCTION IN AORTIC-STENOSIS LATE AFTER VALVE-REPLACEMENT

Background The remodeling of the left ventricle in patients with aorti c stenosis after aortic valve replacement (AVR) is a complex process i nvolving structural and functional changes. Methods and Results Twenty -two patients were included in the present analysis. Twelve patients w ith severe aortic stenosis were studied before surgery, early (22+/-8 months) and late (81+/-22 months) after AVR using left ventricular bip lane angiograms, high-fidelity pressure measurements, and endomyocardi al biopsies. Ten healthy subjects were used as controls. Left ventricu lar systolic function was assessed from biplane ejection fraction, and diastolic function from the time constant of relaxation, the peak fil ling rate, and the myocardial stiffness constant. Left ventricular str ucture was evaluated from interstitial fibrosis, fibrous content, and muscle fiber diameter. Left ventricular muscle mass was significantly increased before surgery in patients with aortic stenosis and remained increased early after surgery, although there was a 35% decrease. Lat e after AVR, muscle mass decreased significantly but remained slightly (P=NS) elevated. Left ventricular ejection fraction increased slightl y after AVR. Left ventricular relaxation was significantly prolonged b efore surgery and returned toward normal early and late after AVR. Pea k filling rates remained unchanged before and after surgery. Myocardia l stiffness constant was increased before surgery in patients with aor tic stenosis compared with controls and increased even further early a fter AVR but was normalized late after surgery. Muscle fiber diameter was elevated in patients with aortic stenosis before and after surgery compared with controls; however, it decreased significantly early and late after AVR with respect to preoperative data but remained hypertr ophied even late after surgery. Interstitial fibrosis and fibrous cont ents were larger before surgery than in control subjects and increased even more early but decreased significantly late after AVR. Conclusio ns Diastolic stiffness increases in aortic stenosis early after AVR pa rallel to the increase in interstitial fibrosis, whereas relaxation ra te decreases with a reduction in left ventricular muscle mass. Late af ter AVR, both diastolic stiff ness and relaxation are normalized due t o the regression of both muscular and nonmuscular tissue. Thus, revers al of diastolic dysfunction in aortic stenosis takes years and is acco mpanied by a slow regression of interstitial fibrosis.