Contribution of mitral valve reserve capacity to sustained symptomatic improvement after balloon valvulotomy in mitral stenosis: implications for restenosis

Late results of percutaneous mitral commissurotomy up to 20 years: development and validation of a risk score predicting late functional results from a series of 912 patients

BACKGROUND

Long-term follow-up after percutaneous mitral commissurotomy enables predictive factors of late results to be identified.

METHODS AND RESULTS

Late results of percutaneous mitral commissurotomy were assessed in 1024 consecutive patients. Good immediate results, defined as valve area ≥1.5 cm(2) without mitral regurgitation >2/4, were obtained in 912 patients (89%). These 912 patients were randomly split into 2 cohorts comprising 609 and 303 patients that were used to develop and validate, respectively, a scoring system predicting late functional results. The 20-year rate of good functional results (survival without cardiovascular death, mitral surgery, or repeat percutaneous mitral commissurotomy and in New York Heart Association class I or II) was 30.2 ± 2.0%. A multivariable Cox model identified 7 predictive factors of poor late functional results: higher final mean gradient (P<0.0001), interaction between age and final mitral valve area (P<0.0001) showing that the impact of valve area decreases with age, interaction between sex and valve calcification (P<0.0001) showing that the impact of valve anatomy is stronger in men, and interaction between rhythm and New York Heart Association class showing an impact of New York Heart Association class only in patients in atrial fibrillation (P<0.0001). A 13-point score enabled 3 risk groups to be defined, corresponding to predicted good functional results of 55.1%, 29.1%, and 10.5% at 20 years in the validation cohort.

CONCLUSIONS

Twenty years after percutaneous mitral commissurotomy in a population of patients with varied characteristics, 30% still had good functional results. Prediction of late functional results is multifactorial and strongly determined by age and the quality of immediate results. A simple validated scoring system is useful for estimating individual patient outcome.

Pulmonary hypertension in older adults

Pulmonary hypertension is a frequently encountered problem in older patients. True idiopathic pulmonary arterial hypertension can also be seen and requires careful exclusion in older patients. Institution of therapies must be tempered with an appreciation of individual comorbidities and functional limitations that may affect patients' ability to comply and benefit from the complex treatments available for pulmonary arterial hypertension. This article reviews the existing data on the various forms of pulmonary hypertension presenting in older patients and on appropriate therapy in this challenging population.

Mitral Valve Resistance as a Determinant of Resting and Stress Pulmonary Artery Pressure in Patients with Mitral Stenosis: A Dobutamine Stress Study

BACKGROUND

Severity of mitral stenosis (MS) is assessed by means of mitral valve area and mean transmitral gradient. However, these conventional stenosis indexes poorly reflect the major hemodynamic consequence of MS, which is increase in pulmonary artery pressure (PAP). Valve resistance (VR) is a physiologic expression of stenosis because it incorporates both the pressure gradient and flow data. Previously, in patients with aortic stenosis, hemodynamic burden on the left ventricle has been shown to be closely related to aortic VR but not to aortic valve area. Accordingly, we hypothesized that mitral VR may also better reflect the hemodynamic burden of MS and, hence, be an important determinant of PAP in patients with MS. This study sought to evaluate the relation between several echocardiographic parameters of MS severity, in particular mitral VR and the resting and stress PAP in patients with MS. Determinants of exercise capacity were also assessed.

METHODS

Twenty patients with pure MS were studied by Doppler echocardiography. Mitral valve area, mean transmitral gradient, mitral VR, net atrioventricular compliance, and left atrial diameter were derived from resting Doppler echocardiographic examination as possible determinants of resting and stress PAP. PAP was measured by Doppler echocardiography at rest and during dobutamine-induced stress. Patients completed a symptom-limited exercise test to determine exercise capacity. Determinants of resting and stress PAP and exercise capacity were analyzed.

RESULTS

Systolic PAP increased significantly from 39.2 +/- 9.4 mm Hg at rest to 59.5 +/- 18.4 mm Hg during dobutamine-induced stress. Mitral VR was the most closely correlated stenosis index with the resting and stress PAP (r = 0.80, P < .001 and r = 0.93, P < .001, respectively) and it was an independent predictor for both with multivariate analysis. Exercise capacity was mostly and equally correlated with stress PAP (r = -0.62, P = .004) and mitral VR (r = -0.62, P = .004). Multivariate analysis revealed stress PAP as the only significant independent predictor of exercise capacity.

CONCLUSION

Mitral VR is the strongest and the independent predictor of both resting and stress PAP in patients with MS and by this aspect it is superior to mitral valve area and mean transmitral gradient in the expression of stenosis severity. These results underline the importance of mitral VR as a severity index in patients with MS.

Is the mitral valve area flow-dependent in mitral stenosis? A dobutamine stress echocardiographic study

OBJECTIVES

The purpose of this study was to compare the effect of changes in flow rate on the mitral valve area (MVA) derived from two-dimensional echocardiographic planimetry and Doppler pressure half-time (PHT) methods in patients with mitral stenosis (MS).

BACKGROUND

Dobutamine stress echocardiography has been proposed as a means of assessing the severity of MS. However, data regarding the effect of an increase in flow rate on MVA are limited. If MVA is indeed flow-dependent, this has important implications for the assessment of the severity of MS, particularly in the setting of reduced cardiac output (CO).

METHODS

Dobutamine echocardiography was performed in 57 patients with isolated MS who were in sinus rhythm. The MVA was determined by planimetry and Doppler PHT methods.

RESULTS

Cardiac output increased by > or =50% in 27 patients (group I) and by <50% in 30 patients (group II). In group I, the MVA by planimetry increased by only 10.6 +/- 2% and the MVA by PHT increased by 21.9 +/- 4.8%. These changes were similar to those observed in group II (10.7 +/- 3% and 14.8 +/- 4%, respectively; p = NS), despite a much smaller increase in CO. A clinically important change (from the severe to mild category) occurred in only one patient when using the PHT method and in none by planimetry.

CONCLUSIONS

Changes in flow rate result in small but clinically insignificant changes in echocardiographic MVA measurement. These methods provide an accurate assessment of MS severity in a majority of patients, independent of changes in flow rate.

Late results of percutaneous mitral commissurotomy for calcific mitral stenosis

The aim of this study was to assess late results of percutaneous mitral commissurotomy (PMC) in calcific mitral stenosis and to identify predictors to improve patient selection. We analyzed 422 patients who underwent PMC for calcific mitral stenosis. The extent of calcium was graded from 1 to 4 by fluoroscopy: 227 patients (53%) were graded 1, 125 (30%) graded 2, 55 graded 3 (13%), and 15 graded 4 (4%). The procedure failed in 15 patients, used a single balloon in 11, a double balloon in 126, and the Inoue balloon in 270. In-hospital mortality was 1.2%. Good immediate results (valve area >/=1.5 cm(2) without mitral regurgitation >2/4), were obtained in 321 patients (76%). Multivariate analysis identified 5 predictors of good immediate results: a younger age (p = 0.0004), a lesser degree of stenosis (p = 0.0005), a smaller extent of calcium (p = 0.04), the use of the Inoue balloon (p = 0.015), and a larger effective balloon dilating area (p = 0.006). Good functional results, defined as survival with no further intervention and in New York Heart Association class I or II, were 36 +/- 4% at 8 years. The predictors of good functional results after good immediate results were a younger age (p = 0.04), a lower pre-PMC New York Heart Association class (p <0.0001), sinus rhythm (p = 0.0006), a smaller extent of calcium (p = 0.02), and a lower gradient after PMC (p <0.0001). Despite a frequent deterioration on follow-up after PMC for calcific mitral stenosis, the predictive analysis suggests that PMC may be useful in deferring surgery in selected patients with mild to moderate calcific deposits, who have otherwise favorable characteristics.

Valve Resistance in Mitral Stenosis: Its Determinants and its Role in the Evaluation of the Disease

To evaluate the value and the determinants of valve resistance in mitral stenosis, 95 patients with pure mitral stenosis were examined by Doppler echocardiography during their clinical follow-up, measuring cavity dimensions, left ventricular function, mitral area (by planimetry and pressure half time), mean transmitral pressure gradient, aortic flow, and pulmonary artery systolic pressure. The mitral resistance was calculated as mean transmitral pressure gradient/aortic flow ratio. To graduate the severity of the morphological abnormalities in valvular structure, we used a point score system with evaluation of leaflet and subvalvular thickness, calcification, and valvular mobility. The functional class was determined according to NYHA classification. In this study, both mitral area (r = -0.79, P < 0.001 and r(p) = -0.60, P < 0.001) and mitral score (r = 0.68, P < 0.001 and r(p) = 0.25, P = 0.013) were independent determinants of mitral resistance. In multivariate analysis, mitral resistance and female gender were selected by multiple linear regression analysis as determinants of pulmonary artery systolic pressure, and mitral area and pulmonary artery systolic pressure were selected by logistic linear regression analysis as determinants of NYHA functional class. In patients with moderate or severe mitral stenosis, the estimated probability for III and IV NYHA functional class considering mitral area 1 cm(2) or below went from 51.1-86.4% when mitral resistance below or above 130 dynes.sec.cm(-5), respectively, was considered together. Thus, mitral valve resistance should be used as a complement to the mitral area method in assessment of mitral stenosis, adding the effects of the reduction in mitral area and the damage in mitral valve apparatus.

Comparison of exercise and dobutamine stress echocardiography in assessing mitral stenosis

Dobutamine elicited similar hemodynamic response to exercise in 20 consecutive patients with mitral stenosis, and significantly altered management in 6 of them (30%). Dobutamine stress echocardiography is a safe and feasible alternative to exercise in patients with mitral stenosis of mild-to-moderate severity and ambiguous symptoms.

Balloon mitral commissurotomy in patients with previous annuloplasty. Our experience

Balloon mitral commissurotomy is an alternative to surgical commissurotomy in the treatment of mitral stenosis and different studies have shown its usefulness for restenosis following surgical commissurotomy. We describe our experience in balloon mitral commissurotomy in five patients with previous commissurotomy and annuloplasty. Among 360 balloon commissurotomies performed in our hospital up to December 1993, 29 procedures were performed on patients with restenosis after surgical commissurotomy, five of whom also had an annuloplasty (flexible ring in four and rigid in one). The balloon commissurotomy was performed without complications using the Inoue single balloon technique. Mitral valve area increased from 0.9 +/- 0.1 cm2 to 1.0 +/- 0.1 cm2 by pressure half-time, and from 1.0 +/- 0.2 cm2 to 1.3 +/- 0.1 cm2 by Gorlin formula. Two patients in functional class III underwent mitral valve replacement, 32 and 11 months later; the other three patients were in class II 38, 10 and 7 months later. The presence of a mitral ring should not constitute a contraindication to balloon commissurotomy. However, the haemodynamic results are not favourable in our patients, probably due to the practical absence of commissural fusion and the ring's restrictive effect on valvular stretching.