The Journal of Thoracic and Cardiovascular Surgery
Volume 139, Issue 3 , Pages 795-796, March 2010

Regional wall motion abnormalities and scarring in severe functional ischemic mitral regurgitation: A pilot cardiovascular magnetic resonance imaging study

Department of CT Surgery, ISMETT (Mediterranean Institute for Transplantation and Advanced Specialized Therapies), Palermo, Italy

Article Outline

CTSNet classification: 23, 30, 35

 

To the Editor:

We read with interest Flynn and colleagues' article1 concerning preoperative evaluation with cardiac magnetic resonance imaging (MRI) in patients undergoing coronary artery bypass grafting and mitral valve annuloplasty for ischemic mitral valve regurgitation (IMVR).

In our experience, cardiac MRI has been advocated for preoperative routine evaluation of patients with IMVR since 2006.2 In a cohort of patients with coronary artery disease and depressed left ventricular ejection fraction, IMVR seemed to occur mainly whenever a transmural area of delayed enhancement (necrosis) was present at cardiac MRI within the inferior myocardial segments.3

On the contrary, we did not notice any significant difference in the geometric mitral valve and papillary muscle parameters (as documented at MRI) when comparing patients with and without IMVR. Furthermore, myocardial necrosis distribution was the sole determinant for IMVR occurrence.3

This confirms that IMVR is not resulting from an abnormal valve/apparatus but from a malfunctioning ventricular muscle (in its segmental aspects), and for this reason, surgical decision making cannot be adequately performed just on the basis of a simple rest echocardiography.

We agree with Flynn and colleagues1 that patients with excessive scar burden (at MRI) in the inferior myocardial segments (particularly those segments close to the posterior papillary muscles) will possibly have recurrent IMVR even after annuloplasty. Within this group of patients, we think some distinctions should be made. In fact, in our surgical practice we still perform a simple annuloplasty if a segmental geometric remodeling has not yet taken place and vital areas are present within the delayed enhancement (necrotic) zone. In this case, we should emphasize that standard MRI will not be able to detect hibernated myocardium that could, once the coronary target has been revascularized, prevent the geometric remodeling and the consequent IMVR recurrence.

In this context, dynamic echocardiography (with dobutamine or semi-supine physical stress) may assist in further surgical stratification and identification of “recoverable” myocardium.

In a different context, identification of large areas of MRI delayed enhancement in the inferior myocardium should trigger further evaluation even in patients with mild IMVR. In particular, physical stress echocardiography may enhance severe IMVR even in patients with mild regurgitation at rest.4 This finding could support a broader application of mitral valve annuloplasty, especially when the myocardial remodeling has not yet taken place.

In conclusion, together with Flynn and colleagues,1 we agree that IMVR is an elusive occurrence and adequate surgical stratification cannot be performed with sole rest echocardiography. IMVR is a disease of the ventricular muscle, and surgical outcomes should be reinterpreted in the light of preoperative evaluation with global morphofunctional and perfusion-vitality studies, such as those achievable with MRI. The presence of extensive necrosis in the inferior myocardial segments may suggest a high rate of postoperative IMVR recurrence. Further investigation with preoperative stress echocardiography may identify viable myocardium and trigger IMVR in those patients with mild regurgitation at rest. In both cases, myocardial surgical revascularization together with mitral valve annuloplasty may be a valid option if adequate coronary targets are present and myocardial remodeling has not yet taken place.

Back to Article Outline

References 

  1. Flynn M, Curtin R, Nowicki ER, Rajeswaran J, Flamm SD, Blackstone EH, et al. Regional wall motion abnormalities and scarring in severe functional ischemic mitral regurgitation: a pilot cardiovascular magnetic resonance imaging study. J Thorac Cardiovasc Surg. 2009;137:1063–1070
  2. D'Ancona G, Mamone G, Marrone G, Pirone F, Santise G, Sciacca S, et al. Ischemic mitral valve regurgitation: the new challenge for magnetic resonance imaging. Eur J Cardiothorac Surg. 2007;32:475–480
  3. D'Ancona G, Biondo D, Mamone G, Marrone G, Pirone F, Santise G, et al. Ischemic mitral valve regurgitation in patients with depressed ventricular function: cardiac geometrical and myocardial perfusion evaluation with magnetic resonance imaging. Eur J Cardiothorac Surg. 2008;34:964–968
  4. Lancellotti P, Gérard PL, Piérard LA. Long-term outcome of patients with heart failure and dynamic functional mitral regurgitation. Eur Heart J. 2005;26:1528–1532

PII: S0022-5223(09)01350-6

doi:10.1016/j.jtcvs.2009.08.061

Refers to article:

  • Regional wall motion abnormalities and scarring in severe functional ischemic mitral regurgitation: A pilot cardiovascular magnetic resonance imaging study , 18 March 2009

    Michael Flynn, Ronan Curtin, Edward R. Nowicki, Jeevanantham Rajeswaran, Scott D. Flamm, Eugene H. Blackstone, Tomislav Mihaljevic
    The Journal of Thoracic and Cardiovascular Surgery May 2009 (Vol. 137, Issue 5, Pages 1063-1070.e2)

The Journal of Thoracic and Cardiovascular Surgery
Volume 139, Issue 3 , Pages 795-796, March 2010

Article Tools