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

Updated knowledge and practical implementations of stress echocardiography in ischemic and non-ischemic cardiac diseases: an expert consensus of the Working Group of Echocardiography of the Hellenic Society of Cardiology

Stress echocardiography (SE) is a well-established and valid technique, widely-used for the diagnostic evaluation of patients with ischemic and non-ischemic cardiac diseases. This statement of the Echocardiography Working Group of the Hellenic Society of Cardiology summarizes the consensus of the writing group regarding the applications of SE, based on the expertise of their members and on a critical review of current medical literature. The main objectives of the consensus document include a comprehensive review of SE methodology and training, focusing on the preparation, the protocols used and the analysis of the SE images and an updated, evidence-based knowledge about SE applications on ischemic and non-ischemic heart diseases, such as in cardiomyopathies, heart failure and valvular heart disease.

Pulmonary Artery Systolic Pressure Response to Exercise in Patients with Rheumatic Mitral Stenosis: Determinants and Prognostic Value

BACKGROUND

Pulmonary hypertension in response to exercise is a marker of the hemodynamic severity of mitral stenosis (MS). However, the factors related to elevated pulmonary pressure with exercise are not well defined. The aim of this study was to assess the parameters associated with the pulmonary pressure response to exercise in patients with pure rheumatic MS. An additional aim was to determine the impact of exercise-induced pulmonary hypertension on clinical outcome.

METHODS

One hundred thirty patients with MS (94% women; mean age, 45 ± 11 years) underwent exercise echocardiography. A range of echocardiographic parameters were obtained at rest and at peak exercise. Symptom-limited graded ramp bicycle exercise was performed in the supine position. The primary end point was mitral valve intervention, either percutaneous or surgical.

RESULTS

In the overall population, systolic pulmonary artery pressure (SPAP) increased from 38.3 ± 13.4 mm Hg at rest to 65.8 ± 20.7 mm Hg during exercise. Increases in mean mitral gradient, right ventricular function, left atrial volume, and net atrioventricular compliance were independently associated with SPAP at peak exercise, after adjusting for changes in heart rate. During the follow-up period (median, 17 months; range, 1-45 months), 46 adverse clinical events were observed. By multivariate Cox proportional-hazards analysis adjusted for age and sex, SPAP achieved at peak exercise was an important predictor of adverse outcome (adjusted hazard ratio, 1.025; 95% CI, 1.010-1.040; P = .001). New York Heart Association functional class (adjusted hazard ratio, 2.459; 95% CI, 1.509-4.006; P < .001) and the interaction between valve area and net atrioventricular compliance (P = .001) were also significant predictors of adverse events. Time-dependent areas under the receiver operating characteristic curve for the model with SPAP during exercise were better than for the model with SPAP at rest, with a significant improvement from 3 years onward.

CONCLUSIONS

In patients with MS, the pulmonary artery pressure response to exercise is determined by a combination of factors, including transmitral mean gradient at exercise, net atrioventricular compliance, left atrial volume, and right ventricular function. Pulmonary artery pressure at peak exercise is a predictor of clinical outcomes and adds incremental prognostic value beyond that provided by standard resting measurements, including valve area.

Pulmonary vascular resistance and proper timing of percutaneous balloon mitral valvotomy

It is frequent to see pulmonary hypertension (PH) in patients with mitral stenosis (MS) secondary to increased pulmonary vascular resistance (PVR), data about the effect of PVR on the results of percutaneous balloon mitral valvotomy (PBMV) are insufficient. To detect the role of PVR in predicting residual PH immediately after PBMV. This prospective study comprised 49 consecutive patients with moderate to severe MS who were investigated pre and within 48 h post a successful PBMV for the first time. Echocardiography was used to assess the mitral valve area (MVA), mean transmitral pressure gradient (MPG), mitral valve resistance (MVR), right ventricular systolic pressure (RVSP) and PVR. Patients were classified into two groups according to the pre PVR (≥ 1.6 WU as group I and < 1.6 as group II). At baseline compared to group II (32 patients), Group I (17 patients) had higher MPG (13.6 ± 5.2 vs. 11.7 ± 3.7 mmHg, P < 0.05), RVSP (45.6 vs. 37.9 mmHg, P < 0.001) and PVR (2.2 ± 0.1 vs. 1.2 ± 0.1WU, P < 0.001) with no significant difference regarding age, gender, MVS, MVA and MVR. Patients of group I had comparatively lower improvement immediate post procedural of RVSP and PVR with no significant difference in immediate post procedural improvement in NYHA classification, MVA, MPG and MVR. Basal PVR > 1.8WU was proved to be a highly specific (91%), a good predictor (AUC 0.78) of persistent elevation of RVSP > 50 mmHg post PMV. Pathological rise of PVR that associates MS had provided a strong and an independent predictor of persistent pulmonary hypertension post PBMV and by this aspect it could be used as a valuable tool as MVA and MPG to send patients earlier for PBMV even with less severe MS. PVR > 1.81 WU could be used as a noninvasive parameter for predicting regression of PH immediately after PBMV.

Net atrioventricular compliance can predict persistent pulmonary artery hypertension after percutaneous mitral balloon commissurotomy

Background

Pulmonary hypertension is a common complication of rheumatic mitral stenosis (MS). Patients with similar mitral valve (MV) areas may have different pulmonary artery pressures. Net atrioventricular compliance (Cn) was found to play an important role in the development of pulmonary hypertension.

Aim

To test the value of Cn in predicting persistent pulmonary artery hypertension (PPAH) after percutaneous mitral balloon commissurotomy (PMBC).

Patients and Methods

Eighty patients with severe MS, suitable for PMBC were included in the study. We excluded patients with contraindication to PMBC, atrial fibrillation, failure of PMBC, and restenosis. All patients had undergone electrocardiography, echocardiography with measurement of MV area, systolic pulmonary artery pressure (SPAP), and Cn, PMBC, and follow-up echocardiography.

Results

Patients were divided into two groups: Group I: Cn < 4.2 mL/mmHg (36 patients), Group II: Cn ≥ 4.2 mL/mmHg (44 patients). Group I patients had significantly higher SPAP, and significantly lower SPAP reduction. Sensitivity of Cn < 4.2 mL/mmHg in prediction of PPAH was 88.9%, specificity was 88.6%, and accuracy was 88.8%. Independent predictors for PPAH were baseline Cn (p = 0.0027), and Cn improvement after PMBC (p = 0.0085). There was a significant negative correlation between Cn and baseline SPAP (r = −0.349, p = 0.0015), and a significant positive correlation between Cn and percent SPAP reduction (r = 0.617, p < 0.00001).

Conclusion

Measuring Cn can predict PPAH in MS patients after PMBC. It also may add value in evaluating MS patients undergoing PMBC and may help in predicting their prognosis.

Mitral valve resistance determines hemodynamic consequences of severe rheumatic mitral stenosis and immediate outcomes of percutaneous valvuloplasty

INTRODUCTION

The mitral valve area (MVA) poorly reflects the hemodynamic status of (MS). In this study, we compared the MVA with mitral valve resistance (MVR) with regard to the determination of hemodynamic consequences of MS and the immediate outcomes of percutaneous balloon mitral valvuloplasty (PBMV).

METHODS

In a prospective study, 36 patients with severe rheumatic MS with left ventricular ejection fraction (LVEF) >50% were evaluated. They underwent transthoracic echocardiography (TTE) and catheterization. The MVA was measured by two-dimensional planimetry and pressure half-time (PHT), and the MVR was calculated using the equation: 1333 × transmitral pressure gradient mean transmitral diastolic flow rate.

RESULTS

The patients' mean age was 47.8±10.5 years. MVR ≥140.6 dynes·s/cm⁵ detected systolic pulmonary arterial pressure (sPAP) >55 mm Hg with a sensitivity of 100% and a specificity of 74%. The sensitivity and specificity of MVA<0.75 cm² to discriminate elevated sPAP were 81% and 89%, respectively. PHT ≥323.5 mseconds had a sensitivity of 78% and a specificity of 96% to detect an elevated sPAP. To predict a successful PBMV, preprocedural MVR ≥106.1 dynes·s/cm⁵ had a sensitivity of 100% and a specificity of 67% (area under the curve [AUC]=0.763; 95% confidence interval [CI]=0.520-1.006; P=.034); preprocedural MVA <0.95 cm² had a sensitivity of 78% and a specificity of 73% (AUC=0.730; 95% CI=0.503-0.956; P=.065); and preprocedural PHT ≥210.5 mseconds had a sensitivity of 73% and a specificity of 78% (AUC=0.707; 95% CI=0.474-0.941; P=.095).

CONCLUSIONS

MVR seems to be more accurate than MVA in determining the hemodynamic consequences of severe MS as determined by sPAP. In addition, preprocedural MVR detected successful PBMVs.

Serum N-terminal brain natriuretic peptide indicates exercise induced augmentation of pulmonary artery pressure in patients with mitral stenosis

INTRODUCTION

To determine whether elevated N-terminal pro-BNP (NT pro-BNP) predicts pulmonary artery systolic pressure increase on exercise stress echocardiography in asymptomatic or mildly symptomatic patients with moderate to severe mitral stenosis.

METHODS AND RESULTS

Forty-one asymptomatic or mildly symptomatic patients with moderate to severe mitral stenosis and 21 age- and sex-matched healthy subjects. Transthoracic echocardiography was performed in all patients to assess the severity of the valve disease and to measure pulmonary artery pressure before and immediately after treadmill exercise. Blood samples for NT pro-BNP were also collected before and immediately after treadmill exercise at the time of echocardiographic examination. The plasma concentrations of NT pro-BNP levels were significantly higher in patients with mitral stenosis than in control subjects before and after exercise (P < 0.001). Patients with atrial fibrillation had significantly higher NT pro-BNP levels compared to those with sinus rhythm (P < 0.001). Pre- and postexercise NT pro-BNP levels correlated statistically significantly with the left atrial (LA) dimension, right ventricle enddiastolic diameter, exercise duration, heart rate, rest, and exercise pulmonary artery systolic pressure, after exercise mitral valve mean gradient. Area under the receiver-operating characteristic curve for NT pro-BNP as an exercise induced augmentation of pulmonary artery pressure was 0.78. Using an optimized cutoff value of 251 pg/mL for NT pro-BNP, sensitivity was 89.47%. The independent determinants of higher pulmonary artery pressure were LA diameter and pretest NT pro-BNP levels in multivariante analysis.

CONCLUSION

NT pro-BNP levels correlate with functional class and echocardiographic findings in patients with mitral stenosis and indicate exercise induced augmentation of peak PAP > 60 mmHg. (Echocardiography 2011;28:8-14).