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Mitral regurgitation : Risk stratification by echo

Author: Dr Martin Swaans.


 

Optimal timing of surgery is fundamental in the management of patients with mitral regurgitation. The only treatment in patients with mitral regurgitation is mitral valve surgery since no medical therapy is available. The current guidelines have been largely defined based on preoperative determinants of long-term postoperative outcome. The main indications for surgery include the onset of symptoms, left ventricular dysfunction (LVEF < 60%) and left ventricular enlargement (LVESD ≥ 45mm). If patients who are asymptomatic with preserved left ventricular function should be operated is still controversial.(1-2) Surgery should be considered in asymptomatic patients and preserved left ventricular function with new onset AF or pulmonary hypertension (systolic pulmonary arterial pressure > 50 mmHg at rest).

Management of severe chronic mitral regurgitation. ESC guidelines of the management of valvular disease (3).

 

Studies are now focussing on these asymptomatic patients with preserved left ventricular function to identify these patients who are at higher risk and who might benefit from early surgery.Several risk factors for an unfavourable outcome have been identified:

  • Pulmonary hypertension at exercise (sPAP > 60 mmHg). This might be more accurate than resting sPAP to predict the occurrence of symptoms in patients with asymptomatic chronic degenerative MR.(4) Exercise PHT is associated with a 3.4-fold increase in risk of developing symptoms in 3 years. Nevertheless, exercise echocardiography might not always be available and it can be difficult in patients with poor acoustic windows, severe tricuspid regurgitation and inability to exercise. Exercise sPAP is impossible to obtain in the absence of tricuspid regurgitation. In these cases the exercise sPAP can be calculated with the following predictive calculation(5):
    • Predicted exercise sPAP = 0.13 x Age + 0.05 x LVED Vol + 0.7 x E/Ea ratio – (TP.Sa/10) + 51mmHg
    • LVED Vol = LV end-diastolic volume by biapical Simpson disc method
    • E = Early diastolic filling velocity measured with pulsed wave
    • Ea = Early diastolic mitral annulus velocity measured by pulsedwave tissue Doppler imaging (average from septal and lateral wall)
    • Tp.Sa = Time to peak Sa velocity using color tissue Doppler imaging (marker of LV longitudinal myocardial function)
  • Severe left atrial dilatation (volume index ≥60 ml/m² BSA).(6)
  • Elevated BNP levels. A cut-off BNP value ≥105 pg/ml helped to identify asymptomatic patients at higher risk of developing HF, LV dysfunction or death on mid-term follow-up. (7) Low-plasma BNP has a high negative predictive value and may be helpful for the follow-up of asymptomatic patients. (8)
  • Global longitudinal strain (GLS) < - 18%. (9)
  • Exercise-induced right ventricular dysfunction (exercise TAPSE < 17.6mm). (10)

Furthermore when considering surgery in a patient with a severe mitral regurgitation the probability of a durable valve repair is of crucial importance. A major contributing factor to successful repair is the hospital volume. Patients with predictable complex repair should undergo surgery in experienced repair centers with high repair rates and low operative mortality. When repair is not feasible, mitral valve replacement with preservation of the subvalvular apparatus is preferred.

 

  1. Mascle S et al. Predictive value of global longitudinal strain in a surgical population of organic Mitral regurgitation. J Am Soc Echocardiogr 2012;25:766-72.
  2. Kusunose K et al. Prognostic significance of exercise-induced right ventricular dysfunction in asymptomatic degenerative mitral regurgitation. Circ Cardiovasc Imaging 2013;6:167-176.

References

  1. Enriques-Sarano M et al. Quantitative determinants of the outcome of asymptomatic mitral regurgitation. N Engl J Med 2005;352:875-83.
  2. Rosenhek R et al. Outcome of watchful waiting in asymptomatic severe mitral regurgitation. Circulation 2006; 113:2238-44.
  3. Vahanian et al. Guidelines on the management of valvular heart disease (version 2012). European Heart Journal 2012; 33:2451-2496.
  4. Magne J et al. Exercise pulmonary hypertension in asymptomatic degenerative mitral regurgitation. Circulation 2010;122:33-41.
  5. Magne J et al. Prediction of Exercise pulmonary hypertension in asymptomatic degenerative mitral regurgitation. J Am Soc Echocardiogr 2011;24:1004-12.
  6. Le Tourneau T et al. Impact of left atrial volume on clinical outcome in organic mitral regurgitation. J Am Coll Cardiol 2010;56:570–78.
  7. Pizarro R et al. Prospective validation of the prognostic usefulness of brain natriuretic peptide in asymptomatic patients with chronic severe mitral regurgitation. J Am Coll Cardiol 2009;54:1099-106.
  8. Klaar U et al. Prognostic value of serial B-type natriuretic peptide measurement in symptomatic organic mitral regurgitation. Eur J Heart Fail 2011;13:163–169.
  9. Mascle S et al. Predictive value of global longitudinal strain in a surgical population of organic Mitral regurgitation. J Am Soc Echocardiogr 2012;25:766-72.
  10. Kusunose K et al. Prognostic significance of exercise-induced right ventricular dysfunction in asymptomatic degenerative mitral regurgitation. Circ Cardiovasc Imaging 2013;6:167-176.