What is the management approach for a patient with Hypertrophic Obstructive Cardiomyopathy (HOCM) and mitral regurgitation who develops infective endocarditis with vegetation seen on Transthoracic Echocardiogram (TTE)?

Management of HOCM with Mitral Regurgitation and Infective Endocarditis

Patients with hypertrophic obstructive cardiomyopathy (HOCM) who develop infective endocarditis with mitral regurgitation due to vegetation require urgent surgical intervention to prevent mortality and serious complications.

Pathophysiology of HOCM with Infective Endocarditis

• HOCM creates a unique environment for endocarditis development, with the anterior mitral leaflet being the most frequent site of vegetative lesions due to chronic endocardial trauma from systolic anterior motion 1
• Mitral regurgitation in this setting can occur through several mechanisms:
  • Leaflet perforation from direct infection 2
  • Chordal rupture leading to flail leaflet 2
  • Interference of vegetation mass with leaflet closure 2
  • Aneurysm formation on the atrial side of the mitral leaflet that may lead to perforation 2
• The combination of HOCM's dynamic obstruction and new/worsening mitral regurgitation from endocarditis creates a particularly high-risk hemodynamic state 1

Diagnostic Approach

• Transthoracic echocardiography (TTE) should be performed as the initial diagnostic test in all suspected cases of IE 2
• TTE has limited sensitivity (40-70%) for detecting vegetations in native valve endocarditis, with specificity around 90% 3
• Transesophageal echocardiography (TEE) is mandatory when:
  • Initial TTE is negative but clinical suspicion remains high 2
  • Complications are suspected (abscess, pseudoaneurysm, fistula) 2
  • Better visualization of vegetation size and mobility is needed 2
• TEE has significantly higher sensitivity (90-100%) compared to TTE, particularly for detecting perivalvular complications 3
• Repeat TEE should be performed within 3-5 days if initial TEE is negative but clinical suspicion remains high 2

Management Approach

Indications for Urgent Surgical Intervention

Surgery is indicated urgently (within a few days) for patients with HOCM and IE with any of the following:

• Heart failure due to severe mitral regurgitation 2
• Large vegetation (>10 mm) on the mitral valve, especially on the anterior leaflet 2
• Locally uncontrolled infection (abscess, false aneurysm, fistula, enlarging vegetation) 2
• Persistent vegetation after embolic episode despite appropriate antibiotic therapy 2

Timing of Surgery

• Emergency surgery (within 24 hours) is required for:

  • Severe acute regurgitation causing refractory pulmonary edema or cardiogenic shock 2
  • Vegetation with evidence of ongoing embolization despite appropriate antibiotics 2

• Urgent surgery (within a few days) is indicated for:

  • Severe regurgitation with symptoms of heart failure 2
  • Large vegetation (>10 mm) on the anterior mitral leaflet 2
  • Perivalvular extension of infection 2

• Elective surgery (after 1-2 weeks of antibiotic therapy) may be considered for:

  • Stable patients with smaller vegetations and controlled infection 2
  • Cases where more time on antibiotics may facilitate valve repair rather than replacement 4

Surgical Options

• For HOCM with IE affecting the mitral valve, surgical options include:

  • Septal myectomy with concomitant valve repair or replacement 5
  • Valve repair is preferred when feasible, especially for discrete vegetations on valve leaflets 4
  • Valve replacement is necessary when there is extensive tissue destruction 4, 5

• Factors favoring valve replacement over repair:

  • Large defects of the anterior leaflet due to transmural infection 4
  • Lesions encompassing greater than one-third of the posterior leaflet with annular abscess 4
  • Unstable preoperative hemodynamics requiring immediate intervention 4

Antimicrobial Therapy

• Appropriate antibiotic therapy should be initiated immediately after blood cultures are obtained 2
• Treatment duration is typically 4-6 weeks, depending on the causative organism 2
• Persistent fever and positive blood cultures after 7-10 days of appropriate antibiotic therapy indicate uncontrolled infection and may necessitate surgical intervention 2

Monitoring and Follow-up

• Repeat echocardiography is essential when:
  • Clinical features suggest new development of intracardiac complications 2
  • There is unexplained progression of heart failure symptoms 2
  • New cardiac murmurs or conduction abnormalities develop 2
• Monitoring for vegetation size changes is important as:
  • Increasing vegetation size under therapy indicates higher risk of embolic events 2
  • Lack of increase in echo density of vegetations may indicate poor healing 6

Prognosis and Complications

• Valvular complications of IE add complexity to surgical management of HOCM 5
• There is an increased need for concomitant valve repairs, prosthetic replacements, and reoperation 5
• The 5-year and 10-year survival rates after surgery for HOCM complicated by IE are approximately 94% and 78%, respectively 5
• Heart failure is the most frequent complication of IE and represents the most common indication for surgery 2

Pitfalls and Caveats

• Delayed diagnosis and treatment significantly impact clinical outcomes 2
• False positive TTE findings may occur with degenerative valve disease, Libman-Sacks lesions, and thrombi 3
• TTE may miss perivalvular complications, particularly in early stages of infection 3
• Orodental procedures are a common source of infection in HOCM patients who develop active IE 5