Reversibility of cardiac dysfunction after valve replacement in elderly patients with severe aortic stenosis

Clinical profile, prognostic implication, and response to treatment of pulmonary hypertension in patients with severe aortic stenosis

The incidence, correlates, and prognostic implications of pulmonary hypertension (PH) are unclear in patients with severe aortic stenosis (AS). We studied 509 patients with severe AS evaluated for transcatheter aortic valve implantation (TAVI). Patients were divided into groups based on pulmonary artery systolic pressure (PASP): group I, 161 (31.6%) with PASP <40 mm Hg; group II, 175 (34.3%) with PASP 40 to 59 mm Hg; and group III, 173 (33.9%) with PASP ≥ 60 mm Hg. Group III patients were more symptomatic and had higher creatinine levels and higher left ventricular end-diastolic pressure. Transpulmonary gradient was >12 mm Hg in 17 patients (10.5%), 31 patients (17.7%), and 80 patients (46.2%) in groups I through III, respectively. In a median follow-up of 202 days (73 to 446) mortality rates were 35 (21.7%), 69 (39.3%), and 85 (49.1%) in groups I through III, respectively (p <0.001). Immediately after TAVI, in patients with PASP >40 mm Hg there was significant decrease in PASP (63.1 ± 16.2 to 48.8 ± 12.4 mm Hg, p <0.0001), which remained at 1 year (50.1 ± 13.1 mm Hg, p = 0.04). After surgical aortic valve replacement there was a significant immediate decrease in PASP (66.1 ± 16.3 to 44.7 ± 14.2 mm Hg, p <0.0001), which persisted at 3 to 12 months (44.8 ± 20.1 mm Hg, p <0.001). In patients who underwent balloon aortic valvuloplasty, PASP decreased immediately after the procedure (63.2 ± 14.8 to 51.8 ± 17.1 mm Hg, p <0.0001), yet at 3 to 12 months pressure returned to baseline levels (57.4 ± 17.0 mm Hg, p = 0.29). In conclusion, patients with severe AS have a high prevalence of PH, and in patients with severe AS increased PASP is associated with increased mortality. Surgical aortic valve replacement and TAVI are effective treatments for these patients and result in a significant PASP decrease.

Factors affecting left ventricular remodeling after valve replacement for aortic stenosis. An overview

Although a small percentage of patients with critical aortic stenosis do not develop left ventricle hypertrophy, increased ventricular mass is widely observed in conditions of increased afterload. There is growing epidemiological evidence that hypertrophy is associated with excess cardiac mortality and morbidity not only in patients with arterial hypertension, but also in those undergoing aortic valve replacement. Valve replacement surgery relieves the aortic obstruction and prolongs the life of many patients, but favorable or adverse left ventricular remodeling is affected by a large number of factors whose specific roles are still a subject of debate. Age, gender, hemodynamic factors, prosthetic valve types, myocyte alterations, interstitial structures, blood pressure control and ethnicity can all influence the process of left ventricle mass regression, and myocardial metabolism and coronary artery circulation are also involved in the changes occurring after aortic valve replacement. The aim of this overview is to analyze these factors in the light of our experience, elucidate the important question of prosthesis-patient mismatch by considering the method of effective orifice area, and discuss surgical timings and techniques that can improve the management of patients with aortic valve stenosis and maximize the probability of mass regression.

[Aortic stenosis with left ventricular dysfunction: evaluation and management]

Aortic stenosis is the most frequent valvulopathy in France today. Valve replacement has transformed the prognosis, when indications are present before the appearance of irreversible left ventricular dysfunction. However, some patients are still not seen before this time or their surgery was deferred. Thus, the postoperative prognosis depends on the reversibility of this dysfunction which can occur even when the stenosis is severe and essentially reflects the elevated afterload. The prognosis is less favorable once myocardial fibrosis has developed in response to left ventricular hypertrophy or when ischemic cardiopathy contributes to this dysfunction. The diagnosis and prognosis are based on the confirmation of the presence of a severe stenosis and that the removal of this obstacle will lead to regression of the dysfunction. For this, Doppler echocardiography is determinant, as combined with a dobutamine test, it is able to evaluate the tightness of the stenosis, the severity of the left ventricular dysfunction and its reversibility. When the stenosis is severe with contractile reserve, indicating a better postoperative prognosis, dobutamine does not induce an appreciable change of the aortic area, but the mean pressure gradient, often low prior to dobutamine administration, rises. Although the surgical risk remains higher in the presence of left ventricular dysfunction, the ultimate prognosis is more favorable when the test suggests regression is possible.

Influence of St. Jude medical valve in patients with aortic stenosis and small aortic annulus on cardiac function and late survival result

This clinical study analyzes our experience of postoperative cardiac function and long-term survival rate in patients with aortic stenosis and small-size St. Jude Medical (SJM) valve. Sixty-eight patients who underwent aortic valve replacement by SJM valve were divided into two groups by preoperative aortic annulus diameter. Group 1 consisted of 44 patients with small aortic annulus and small-size SJM valve (19 mm or 21 mm). In Group 1, small SJM standard valves were implanted in 16 patients, and small SJM Hemodynamic Plus (HP) valves were implanted in 28 patients. Group 2 consisted of 24 patients with large-size SJM standard valve (23 mm or larger). Preoperative left ventricular mass index, left ventricular dimension, the dimension of ascending aorta, and body surface area were significantly smaller in Group 1 than in Group 2. Average age at surgery was older in Group 1 than in Group 2. Effective orifice area index of the SJM valve measured by the manufacturer's data was smaller in Group 1 than in Group 2. Postoperative left ventricular mass indexes of Group 1 (standard valve or HP valve) and Group 2 significantly decreased in comparison with the preoperative mass indexes. Postoperative left ventricular ejection fraction and the peak ejection rate of Group 1 were not different from those of Group 2. The 10 year survival rate of Group 1 was 79%, and the rate of Group 2 was 77%. At 10 years after surgery, freedom from valve-related complication of Group 1 was 80%, and freedom from complication of Group 2 was 81%. Our results demonstrated that small-size SJM valve afforded satisfactory long-term survival rate and valve-related event-free rate for elderly patients with small body surface area and small aortic annulus.

Changes in left and right ventricular cardiac function after valve replacement for aortic stenosis determined by cine MR imaging

The purpose of this study was to determine the changes in function of both the left and the right ventricles (LV, RV) before and after aortic valve replacement (AVR), compared with age-matched healthy volunteers using magnetic resonance (MR) imaging. Fourteen patients with aortic stenosis underwent MR imaging (1.5 T) before and 3 (n = 14) and 12 (n = 9) months after surgical valve replacement. An electrocardiographically triggered two-dimensional cine fast low-angle shot sequence was used for the evaluation of absolute values and indices related to 1 m(2) body surface area for function, mass, and LV wall thickening. Fourteen age-matched healthy volunteers served as controls. Before surgery, all patients showed significant abnormalities of LV mass and function, whereas RV mass and function were not different from those of volunteers and remained mostly unchanged. After surgery, normalization of LV ejection fraction, absolute mass, and end-systolic wall thickness was observed, whereas the LV mass index failed to normalize, and LV volumes remained elevated. Aortic stenosis combined with a significant, but not severe reduction in LV function only affects the LV, whereas the RV remains unaffected at this stage of disease. AVR leads to improved LV function and reduced hypertrophy, but without normalization of LV volumes or the LV mass index within 1 year.

Patient-prosthesis mismatch is negligible with modern small-size aortic valve prostheses

BACKGROUND

Concern has been raised about residual significant gradients when small aortic prostheses are used, particularly in patients with large body surface areas. We studied the performance of six types of small aortic prostheses using dobutamine stress echocardiography.

METHODS

Sixty-three patients (mean age, 67 +/- 7 years) who had undergone aortic valve replacement 17 +/- 6 months previously were studied. Two bileaflet mechanical prostheses (St. Jude Medical and CarboMedics: sizes, 19 mm and 21 mm) and two biological prostheses (Medtronic Intact and St. Jude BioImplant: size, 21 mm) were evaluated. A graded infusion of dobutamine was given and Doppler studies of valve performance were carried out.

RESULTS

All prostheses except one biological valve had acceptable hemodynamic performance under stress. Using regression modeling, gradient at rest was the only variable found to predict gradient under stress (p < 0.001). Moreover, the most important predictor of gradient at rest was valve design, which accounted for 72% of the variance (p < 0.001). This relationship was independent of valve size (19 mm or 21 mm) or material (ie, mechanical or biological). Body surface area accounted for 4% of the variance in gradient only.

CONCLUSIONS

The main predictor of transprosthetic gradient is the inherent characteristics of each particular prosthesis, with relatively insignificant contribution from variations in body surface area. Patient-prosthesis mismatch is not a problem of clinical significance when certain modern valve prostheses are used.