A 64-year-old man is admitted to the hospital because of fever, chills, and progressive fatigue. Eight months ago, he underwent surgical aortic valve replacement with a bioprosthetic valve for severe aortic stenosis. His medical history also includes hypertension and type 2 diabetes mellitus. Medications include aspirin, metformin, lisinopril, and atorvastatin. On admission, temperature is 39.1°C (102.4°F), blood pressure is 118/68 mm Hg, pulse is 104/min, and respiratory rate is 18/min. Cardiac examination reveals a systolic ejection murmur at the right upper sternal border. There are several tender erythematous nodules on the fingertips. The lungs are clear, and there is no peripheral edema. Three sets of blood cultures grow Staphylococcus aureus. Transesophageal echocardiography demonstrates a mobile vegetation attached to the prosthetic aortic valve. Intravenous antibiotics are initiated according to culture susceptibilities. On hospital day 3, the patient develops worsening fatigue and lightheadedness. Temperature is 38.7°C (101.7°F), blood pressure is 104/62 mm Hg, and pulse is 48/min. Cardiac examination now reveals a new early diastolic murmur along the left sternal border. ECG demonstrates progressive prolongation of the PR interval followed several hours later by complete atrioventricular block. Repeat transesophageal echocardiography shows new severe paravalvular aortic regurgitation, but the vegetation is unchanged in size.
Which of the following is the most appropriate next step in management?
The correct answer is:
D) Perform urgent surgical debridement and valve replacement
This patient has prosthetic aortic valve endocarditis complicated by a perivalvular abscess. The most important clue is the development of new atrioventricular conduction disease. The AV node and proximal His bundle lie near the aortic root and membranous interventricular septum. Extension of infection beyond the valve annulus into surrounding tissue can therefore injure the conduction system, causing progressive PR prolongation, bundle branch block, or complete heart block.
The new severe paravalvular aortic regurgitation provides additional evidence of destructive periannular infection. A perivalvular abscess is unlikely to be eradicated with antibiotics alone because infected and necrotic tissue has poor antimicrobial penetration. Urgent surgery is required to remove infected tissue, drain the abscess, and repair or replace the affected prosthetic valve. Intravenous antimicrobial therapy must continue, but it is not sufficient as the sole treatment.
Several complications of infective endocarditis mandate early surgical evaluation. These include acute heart failure from severe valvular dysfunction, perivalvular abscess or fistula formation, prosthetic valve infection with invasive complications, persistent bacteremia despite appropriate antibiotics, fungal or highly resistant infection, and recurrent embolization from large vegetations. In this case, both invasive infection and severe paravalvular regurgitation support urgent surgery.
Temporary pacing may be required if the complete heart block causes hemodynamic instability. However, pacing treats only the electrical consequence of the abscess and does not control the underlying infection. Permanent pacemaker implantation is generally deferred until infected tissue has been surgically managed and blood cultures have cleared, when clinically feasible.
Answer choice A: Continue intravenous antibiotics and repeat echocardiography after completion of therapy, is incorrect.
Antibiotic therapy alone may be appropriate for uncomplicated native-valve endocarditis without heart failure, uncontrolled infection, or invasive complications. This patient has developed complete heart block and severe paravalvular regurgitation, indicating extension of infection beyond the prosthetic valve into the aortic annulus. Delaying surgery would increase the risk of progressive tissue destruction, aortic root rupture, fistula formation, heart failure, and death.
Answer choice B: Implant a permanent pacemaker and continue medical therapy, is incorrect.
Complete heart block may require temporary pacing for immediate stabilization, but pacemaker placement does not treat the perivalvular abscess causing the conduction abnormality. Implanting permanent hardware during active bloodstream infection may also seed the device and create an additional focus of infection. Source control with surgical debridement and valve intervention is the priority.
Answer choice C: Initiate systemic anticoagulation to prevent embolization, is incorrect.
Anticoagulation does not prevent septic embolization from an infected vegetation and may increase the risk of intracranial hemorrhage, particularly if cerebral emboli or mycotic aneurysms are present. Prosthetic valve endocarditis involving a bioprosthetic valve does not independently require anticoagulation. The urgent problem is invasive periannular infection.
Answer choice E: Switch to oral antibiotic therapy after blood cultures become negative, is incorrect.
Selected clinically stable patients with uncomplicated endocarditis may eventually complete part of their treatment with carefully chosen oral therapy. This patient is not stable and has developed an invasive complication requiring surgical source control. Negative blood cultures would not exclude a persistent perivalvular abscess or reverse the structural damage.
Key Learning Point
A new atrioventricular conduction abnormality in a patient with aortic valve endocarditis strongly suggests extension of infection into the periannular tissue with abscess formation. Perivalvular abscess, prosthetic valve destruction, or acute severe regurgitation requires urgent surgical debridement and valve repair or replacement.
