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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Murmur: holosystolic (pansystolic) at apex radiating to axilla. Louder with increased preload (squatting) and afterload (hand grip)
- Primary MR: intrinsic valve pathology (degenerative/prolapse, rheumatic, endocarditis). Secondary MR: functional from LV dilation/remodeling
- Acute severe MR (e.g., papillary muscle rupture post-MI): pulmonary edema, cardiogenic shock — emergent surgery
- Chronic severe primary MR: surgical repair preferred over replacement (better outcomes). Indications: symptomatic, or asymptomatic with LVEF <=60% or LVESD >=40 mm
- Secondary MR: optimize HFrEF GDMT first. TEER (MitraClip) for symptomatic secondary MR refractory to GDMT (COAPT trial)
Overview
Mitral regurgitation is the most common valvular heart disease. Primary (degenerative) MR results from intrinsic valve pathology — the most common cause in developed countries is mitral valve prolapse (myxomatous degeneration). Secondary (functional) MR occurs when LV dilation or dysfunction displaces papillary muscles and tethers leaflets, despite structurally normal valve tissue. The distinction is critical because primary MR is treated surgically while secondary MR is managed primarily with HF therapy.
Clinical Features
Symptoms
Chronic: dyspnea on exertion, fatigue, palpitations (AF), progressive exercise intolerance
Acute (papillary rupture, flail leaflet): sudden pulmonary edema, cardiogenic shock
Signs
Holosystolic murmur at apex radiating to axilla (posterior leaflet prolapse radiates to sternum/aortic area)
Increases with squatting (preload) and hand grip (afterload)
Laterally displaced PMI (LV volume overload)
S3 gallop in severe MR (volume overload)
MVP: mid-systolic click followed by late systolic murmur; standing/Valsalva causes earlier click + longer murmur
Investigations
First-line
Transthoracic echocardiogramDiagnostic: assess MR severity (jet area, vena contracta, regurgitant volume, EROA), mechanism (primary vs secondary), leaflet morphology, LVEF, LVESD, LA size, pulmonary pressures. Severe MR: EROA >=0.4 cm2 (primary) or >=0.2 cm2 (secondary), regurgitant volume >=60 mL
ECGLAE (P mitrale), LVH, AF
Second-line
TEEPre-surgical planning: detailed leaflet analysis, suitability for repair vs replacement
Exercise stress echoIf symptoms discordant with resting echo severity — may unmask dynamic MR or exercise-induced pulmonary HTN
Cardiac catheterizationCoronary assessment pre-surgery; invasive hemodynamics if non-invasive discordant
1
Chronic severe primary MR
- Mitral valve REPAIR preferred over replacement (lower operative mortality, better long-term outcomes, no anticoagulation needed)
- Surgical indications: symptomatic severe MR, OR asymptomatic with LV dysfunction (LVEF <=60% or LVESD >=40 mm), OR new-onset AF, OR pulmonary HTN (PASP >50)
- Asymptomatic severe MR + normal LV function + high likelihood of successful repair at an experienced center: early repair may be considered
2
Secondary (functional) MR
- Optimize HFrEF GDMT (ARNi, BB, MRA, SGLT2i) — MR often improves with LV reverse remodeling
- CRT if eligible (LBBB, LVEF <=35%) — may reduce functional MR
- TEER (transcatheter edge-to-edge repair, MitraClip): for symptomatic severe secondary MR despite GDMT — COAPT trial showed reduced HF hospitalizations and mortality vs medical therapy alone
3
Acute severe MR
- Hemodynamic stabilization: vasodilators (nitroprusside), IABP for afterload reduction, inotropes if cardiogenic shock
- Emergent surgical repair/replacement
USMLE Step 2 CK Exam Tips
- 1Holosystolic murmur at apex radiating to axilla = MR. This is the most tested murmur description
- 2MVP: mid-systolic click + late systolic murmur. Standing/Valsalva = earlier click, longer murmur. Squatting = later click, shorter murmur
- 3Acute MR post-MI (papillary muscle rupture, day 2-7): sudden pulmonary edema + new murmur = emergent surgery
- 4Repair > replacement for primary MR. Key surgical trigger: LVEF <=60% or LVESD >=40 mm (do NOT wait until LVEF is severely reduced)
- 5Secondary MR: treat the HF first. MitraClip if refractory (COAPT trial)
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