Review Question - QID 204207

The clinical presentation and the new holosystolic murmur at the apex are consistent with mitral regurgitation associated with papillary muscle rupture, a life-threatening complication of acute myocardial infarction.

In acute mitral regurgitation, an abrupt elevation of left atrial pressure in the setting of normal atrial size and compliance causes back flow into the pulmonary circulation, and resultant pulmonary edema. Cardiac output decreases because of decreased forward flow, and hypotension or shock may also occur. The murmur of mitral regurgitation is characterized by a holosystolic murmur loudest at the apex, which radiates to the axilla and becomes softer with decreased blood flow to the heart (Valsalva maneuver, standing). Causes of acute mitral regurgitation include infective endocarditis and papillary muscle rupture (given their attachment to the atrioventricular valves via the chordae tendineae). Causes of chronic mitral regurgitation include rheumatic fever, degenerative valvular disease (e.g. from mitral valve prolapse), and cardiomyopathy.

Shipton and Wahba review the diagnosis and management of common valvular abnormalities in the primary care setting. They discuss how patients with chronic, compensated mitral regurgitation should have an ejection fraction measured by echocardiogram that is above 60 percent. Indications for surgery to repair the valvular abnormality include moderate to severe symptoms (e.g. hypotension, palpitations, dyspnea), ejection fraction less than 60 percent, or an end-systolic dimension approaching 45 mm, even in the absence of symptoms.

Li et al. found that in individuals older than 80 years of age with acute coronary syndrome, the presence of mitral regurgitation was independently associated with long-term all-cause mortality. They also found that percutaneous coronary intervention was significantly associated with improved long-term survival in older patients with acute coronary syndrome and mitral regurgitation.

Illustration A depicts the systolic blood flow pattern associated with mitral regurgitation.

Incorrect Answers:
Answer 1: Aortic stenosis is associated with a mid-to-late systolic murmur and diminished carotid upstrokes.
Answer 2: Aortic regurgitation is associated with a blowing diastolic murmur, wide pulse pressure, systolic hypertension, and hyperdynamic circulation.
Answer 3: Mitral valve prolapse is associated with a mid-systolic click and a mid-to-late systolic murmur, which increases with standing.
Answer 4: Mitral stenosis is associated with a diastolic murmur and, sometimes an opening snap.