Acute mitral regurgitation treatment

# Overview
Surgery is the main treatment of symptomatic acute severe primary mitral regurgitation (MR) and it should be performed urgently without any delay. Although some patients with moderate acute MR develop some compensatory mechanisms, surgery remains the treatment of choice for the majority of patients with acute MR. Medical therapy with vasodilators might be needed to  decrease the afterload and thereby decrease the regurgitant fraction until surgery can be performed. Prior to the surgical procedure, an intra-aortic balloon pump or percutaneous circulatory assist device might also be used to stabilize the patient.

# Medical Therapy
The main treatment of acute mitral regurgitation is urgent surgery.  Medical therapy should be provided to stabilize the patient during the diagnostic work up and before surgery.  Surgery should not be delayed.
- Vasodilators, such as nitroprusside or nicardipine, may be of use in acute MR to decrease the afterload and thereby decrease the regurgitant fraction. However, the use of vasodilators is limited by hypotension. ACE inhibitors may be useful as oral therapy.
- Prior to the surgical procedure, an intra-aortic balloon pump may be placed in order to improve perfusion of the organs and to reduce afterload and thereby decrease the degree of mitral regurgitation.
- Among patients with hemodynamic compromise, percutaneous circulatory assist device can also be used to stabilize the patient before surgery.
- In patients with acute mitral regurgitation secondary to myocardial ischemia/infarction, early coronary revascularization should be performed.

# 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines
In acute MR, vasodilator treatment enhances hemodynamic compensation. The rationale behind the use of vasodilators in acute MR is the decrease in aortic flow impedance, which preferentially directs flow away from the LV-to-LA channel, decreasing MR while concurrently enhancing forward output to the LV-to-aortic pathway. 1,2 Typically, a simple-to-titrate drug, like sodium nitroprusside or nicardipine, is infused to do this. Systemic hypotension, which is increased when peripheral resistance is reduced, frequently restricts the use of vasodilators. To treat acute severe MR, intra-aortic balloon counterpulsation may be beneficial. Intra-aortic balloon counterpulsation reduces LV afterload by lowering systolic aortic pressure, boosting forward output and lowering regurgitant volume. In order to promote the systemic circulation, intra-aortic balloon counterpulsation simultaneously raises mean and diastolic aortic pressures. Before the procedure, a patient with acute hemodynamic compromise may be stabilized by the use of a percutaneous circulatory assist device.

# Surgery
Surgery is the main treatment of symptomatic acute severe primary mitral regurgitation and it should be performed urgently without any delay. Although some patients with moderate acute MR develop some compensatory mechanisms, surgery remains the treatment of choice for the majority of patients with acute MR.
In comparison to elective surgeries, the mortality rate is higher in emergency mitral valve surgery with a mortality rate of 23% at 30 days following surgery.  There was no difference in mortality between mitral valve repair or mitral valve replacement.
The choice between mitral valve repair and mitral valve replacement depends upon the etiology and extent of the valvular damage.
- Patients with rupture of the chordae tendineae should preferably undergo early mitral valve repair if possible because it associated with less operative mortality and better lon-term survival in comparison to mitral valve replacement.
- The choice of the valvular surgery in infective endocarditis depends on the extent of destruction of the mitral valve.  When possible, mitral valve repair is the preferred surgical approach.
In patients with acute mitral regurgitation due to endocarditis, early valve replacement surgery during hospitalization is recommended in the following conditions:
- Heart failure due to the valve dysfunction (Class I, level of evidence B)
- Left sided infective endocarditis due to staphylococcus aureus, fungal or highly resistant organisms (Class I, level of evidence B)
- Heart block, annular or aortic abscess or destructive lesions (Class I, level of evidence B)
- Persistent bacteremia or fever 5 to 7 following the initiation of the antibiotics (Class I, level of evidence B)
- Relapse of the infection depsite a complete course of antibiotics in prosthetic valve endocarditis when no portal of infection can be identified (Class I, level of evidence C)
- Recurrent emboli and persistent vegetations despite antibiotic therapy (Class IIa, level of evidence B)
- Mobile vegetations with a length more than 10 mm in native valve endocarditis(Class IIb, level of evidence B)
In the absence of these conditions, elective surgery may be appropriate.

# 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines
"Prompt  mitral  valve  surgery,  preferably  mitral  repair  if  possible,  is  lifesaving  in  the  symptomatic  patient  with  acute  severe  primary  MR.  The  severity  of  acute  primary  MR  is  variable,  and  some  patients  with  more  moderate  amounts  of  MR  may  develop  compensation  as  LV  dilation  allows  for  lower  filling  pressure  and  increased  for-ward cardiac output. However, most patients with acute severe MR require surgical correction for reestablishment of normal hemodynamics and for relief of symptoms.15This is especially true for a complete papillary muscle rupture that causes very severe MR, which is poorly tolerated."