A 79-year-old man presents as a referral for evaluation of a systolic murmur. He reports decreased activity level over the last year to an extent that he now feels tired and short of breath walking to the mailbox. He does not report any chest pain at rest or with exertion. He has long-standing diabetes mellitus, hypertension, dyslipidemia, and benign prostatic hypertrophy, all of which have been adequately treated with medications. He is a life-long nonsmoker. He used to work as an accountant, but has been retired for more than 10 years. He lives with and takes care of his wife, who has been undergoing treatment for metastatic breast cancer for the last 8 years. Prior to the current referral, he has not been aware of having a heart murmur. He denies any cardiac evaluation in the past including echocardiography, and denies any history of rheumatic fever.
On physical examination, his blood pressure is 116/70 mm Hg and his heart rate is 89 bpm and irregularly irregular. He has a high-pitched holosystolic murmur that is best heard at the apex and radiates to the left sternal border. The intensity of the murmur is constant from beat to beat. Carotid upstrokes are brisk. Jugular vein pulsation is normal. Peripheral pulses are normal, and there is no edema.
Two-dimensional echocardiography showed mitral regurgitation (MR) with an estimated effective regurgitant orifice of 0.5 cm2. There is inferior hypokinesis and the left ventricular ejection fraction (LVEF) is calculated to be 56% with the biplane Simpson's method. The LV end-diastolic dimension measures 61 mm and end-systolic dimension measures 43 mm. The left atrium is dilated, measuring 41 ml/m2.
Which of the following is the best management option at this time?
Show Answer
The correct answer is: D. Evaluation for ischemic heart disease.
MR can result from abnormalities of the valve leaflets (rheumatic heart disease, infective endocarditis, mitral valve prolapse [MVP], cleft leaflet), mitral annulus (calcification, dilation), chordae tendineae (rupture, MVP), or the papillary muscles (dysfunction, infarction, rupture), and these causes can generally be grouped into ischemic and nonischemic. It is important to realize that nonorganic MR (functional MR) is also associated with a worse outcome.
The prevalence of MR is known to increase with age. Echocardiographically diagnosed MR is the most common valvular heart disease (VHD) in older adults, occurring in approximately one-third of individuals ages >75 years. Although most of this MR is mild to moderate, MR is the second most common indication, after aortic stenosis (AS), for valvular surgery in older individuals. The most common causes of significant MR in the elderly include ischemic papillary muscle dysfunction, MVP, and mitral annular calcification. Mitral annular calcification is quite prevalent in older adults, particularly in women, and is known to share common risk factors with atherosclerosis. Although usually mitral annular calcification has no hemodynamic consequences, it can impinge on the mitral valve leaflets, which can lead to MR if severe.
The most prevalent cause of MVP is myxomatous degeneration of the mitral leaflets, which results in the abnormal movement of the leaflets into the left atrium in systole (Video 1). Severe MVP may result in a flail mitral valve leaflet due to chordae rupture (Video 2). Ischemic MR may be acute (papillary muscle infarction and rupture), but is more commonly chronic, occurring in patients who have previously sustained a myocardial infarction. In this setting, the mitral valve leaflets and subvalvular apparatus are usually normal, and the abnormality is in the papillary muscle, the underlying myocardium, or the geometry of the LV. It is imperative to evaluate for the presence of ischemic heart disease in the older adult presenting with severe MR, especially if no clear organic cause of MR is evident on echocardiography.
Video 1
Video 2
The American College of Cardiology (ACC)/American Heart Association (AHA) guidelines on VHD consider coronary angiography as a Class I indication in patients in whom ischemia is suspected as an etiological factor in MR, when surgery is contemplated for MR in patients with one or more risk factors for coronary artery disease, and when mitral valve surgery is contemplated in patients with angina or prior myocardial infarction. The only patients in whom coronary angiography should not be considered prior to mitral valve surgery are those ages <35 years with no clinical suspicion of coronary disease. Therefore, all older adults should undergo coronary angiography if mitral valve surgery is being contemplated, especially if there is suspicion that MR is ischemic in nature, like in this case. Coronary revascularization may be sufficient treatment for ischemic MR, especially in older adults with multiple comorbidities who have a higher risk from combined surgery (coronary artery bypass grafting and mitral valve surgery).
On physical examination, it is important to differentiate the systolic murmur of MR from that of AS. The murmur of MR is usually heard best at the apex, but it can radiate toward the axilla or the left sternal border. Similarly, a component of AS can be heard best at the apex, as explained in Case 1, Question 2 of Essentials for Cardiovascular Care in Older Adults, making geographic differentiation of the murmurs unreliable. The MR murmur is holosystolic, constant in intensity, and does not vary with variation of stroke volume, unlike AS (as with atrial fibrillation in this patient). The assessment of MR severity is usually gauged with Doppler echocardiography, and is similar between younger and older adults. A detailed discussion of the assessment of MR severity is beyond the scope of this module, but it is clear that this patient has severe MR that is evidenced by the estimated effective regurgitant orifice area (severe is ≥0.4 cm2), dilated left atrium, presence of symptoms and LV dysfunction (LVEF <60% and/or LV end-systolic dimension ≥40 mm).
More recently, it has been shown that three-dimensional echocardiography may provide a better load-independent assessment of MR severity than two-dimensional echocardiography. Therefore, it is inappropriate to ignore the presence of MR in this patient or to search for other causes to explain his symptoms. In this patient, symptoms may be related to the development of LV dysfunction, or alternatively, due to atrial fibrillation, which is known to precipitate symptoms in patients with severe MR who have preserved LV function. An attempt at cardioversion can thus be contemplated to verify if symptoms resolve when the patient reverts to sinus rhythm.
Although medical therapy with afterload-reducing agents such as ACE inhibitors is beneficial in acute MR, the value of such treatment in chronic MR is controversial, especially in the presence of normal blood pressure. Nevertheless, in patients with ischemic MR, treatment with ACE inhibitors and/or beta-blockers is indicated in the presence of LV dysfunction. Also, if surgical treatment is not feasible in patients with severe chronic MR, such therapy is probably warranted.
References
Enriquez-Sarano M, Akins CW, Vahanian A. Mitral regurgitation. Lancet 2009;373:1382-94.
Zipes DP, Braunwald E. Aortic valve diseases. In: Bonow RO, Mann DL, Zipes DP, Libby P. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia: Saunders; 2011, Chapter 66.
Agricola E, Oppizzi M, Pisani M, Meris A, Maisano F, Margonato A. Ischemic mitral regurgitation: mechanisms and echocardiographic classification. Eur J Echocardiogr 2008;9:207-21.
Bonow RO, Carabello BA, Chatterjee K, et al. 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1998 guidelines for the management of patients with valvular heart disease). Endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol 2008;52:e1-142.
Hage FG, Nanda NC. Real-time three-dimensional echocardiography: a current view of what echocardiography can provide? Indian Heart J 2009;61:146-55.
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