Influence of valve prosthesis type on the recovery of ventricular dysfunction and subendocardial ischaemia following valve replacement for aortic stenosis

Abstract

Background Long-standing aortic stenosis (AS) causes significant progressive left ventricular (LV) dysfunction and may result in subendocardial ischaemia. Following aortic valve surgery, LV function may improve and this may be accompanied by reversal of ischaemia. There is debate about the differential effects of valve substitutes. Methods We studied 33 patients with significant AS and impaired LV systolic function. Patients underwent trans-thoracic Doppler echocardiography and 12-lead electrocardiography pre-operatively, prior to discharge from hospital and at 2.5 (range 1.5–3) years follow-up. Results Twenty patients received a stentless valve and 13 a stented valve. No patient had significant aortic regurgitation, other valvular disease or coronary artery disease. LV fractional shortening (FS) increased from 19±6% to 26±7% post-operatively and to 33±12% at follow-up in the stentless group ( p<0.001). In the stented group, no significant change was seen in the post-operative FS, although it improved at follow-up and at this point did not differ from the stentless group. LV mass fell from 338±72 to 265±64 g post-operatively and to 170±77 g at follow-up ( p<0.001) in the stentless group, whereas in the stented group a significant fall was seen only at follow-up (329±51 g pre-operatively, 304±68 g post-operatively, 166±28 g at follow-up, p=0.01). LV free wall excursion increased from 0.8±0.3 to 1.1±0.4 cm ( p=0.05) and to 1.4±0.3 cm ( p=0.02 compared with pre-operative values) in the stentless group. In the stented group, values were 1.0±0.4, 1.0±0.3 and 1.3±0.2 cm ( p=0.05 compared with pre-operative) at the three time points, respectively. QRS duration fell from 113±36 ms pre-operatively to 99±12 ms at follow-up in the stentless group and from 117±28 to 99±19 ms in the stented group, p=0.01 for both comparisons. QT interval fell from 385±54 ms pre-operatively to 366±39 ms at follow-up ( p=0.04) in the stentless group with no significant change in the stented group (387±52 and 375±33 ms, p=0.24). There was reversal of LV strain pattern in 11 (55%) of the stentless group and 6 (46%) of the stented group and normalisation of the inverted U wave in two thirds of patients. Conclusion In patients with AS and severe LV dysfunction, there is a more rapid improvement in LV function following aortic valve replacement with a stentless prosthesis. Improvements in those receiving stented valves appear delayed, although there were no differences between the groups in LV function or mass at follow-up. Normalisation of LV free wall systolic behaviour, narrowing of the QRS complex and a reduction in the QT interval suggest that AS is associated with subendocardial ischaemia that reverses following valve replacement.