Overview of indications and timing for surgery
The indications and timing of surgery for infective endocarditis (IE) is complex and nuanced. General considerations in deciding whether to operate and when to operate include the difference between left- and right-sided pathology, the impact of the pathology on patient’s hemodynamic status, risk of thromboembolic complication, and the likelihood that source control requires invasive treatment. Therefore, response to antibiotics therapy and infectious organism also dictate the indication and timing of intervention. Special considerations in terms of whether and when to intervene include history of drug use, recent stroke, and the extent of the disease requiring high-risk reconstruction such as commando operation. Increasing popularity of percutaneous aspiration thrombectomy device for right-sided vegetation also warrants consideration, although the evidence on its long-term efficacy is limited. Patient’s underlying clinical condition and comorbidities as well as expected short- and long-term survival will affect decision-making independent of indications. This chapter summarizes current evidences on surgical indication in various situations.
Indications and timing to intervene on left-sided endocarditis
Broadly, there are three conceptual purposes of surgical indications in left-sided endocarditis: (1) to address hemodynamics/heart failure, (2) to control infectious source, and (3) to prevent thromboembolic complications. Indications for left-sided disease involving mitral or aortic valve are much better defined compared with those of right-sided disease. Distinction between right- and left-sided endocarditis is useful because the nature of the disease differs considerably. For example, aortic and mitral valves are closely related to left ventricular function and the compromise of either valve manifests more dramatically than right-sided valve pathology. The risk of systemic thromboembolic event is much higher in the left-sided pathology. Distinction between native- or prosthetic-valve endocarditis (PVE) matters with regard to the operative risk, with PVE having a substantially higher operative mortality risk [ ]. However, there is not a guideline-directed pathway specific to PVE.
It is important to acknowledge that the appropriate timing of intervention is poorly defined, with guidelines from major societies using different definition of what constitutes ‘early’ or ‘emergent’ intervention. The 2015 European Society of Cardiology (ESC) guideline defines ‘elective’ as those that can be treated within 2 weeks, ‘urgent’ as those requiring intervention within a few days of diagnosis, and ‘emergent’ as those requiring treatment in less than 24 h [ ]. In contrast, the 2014 American Heart Association and American College of Cardiology (AHA/ACC) guidelines distinguishe between whether the endocarditis should be treated during the same hospitalization or could be treated on a different admission [ ]. A randomized controlled trial published in 2012 on surgical intervention on left-sided endocarditis used 48 h since the time of randomization as the threshold to define early and late intervention [ ]. In this trial 76 patients with native-valve left-sided endocarditis at a high risk of embolism were randomized to surgery within or after 48 h. The rate of composite event of death or embolic event at 6 months was 3% in the early surgery arm and 28% in the late surgery arm ( P = .02). Therefore, early surgery may be beneficial when feasible.
Hemodynamic/heart failure indications
Complications of endocarditis, including severe acute aortic or mitral regurgitation, obstruction, or shunt physiology related to fistula, leading to cardiogenic shock and pulmonary edema meet emergent indication for operative management. Medical management in such severe cases of hemodynamic compromise related to structural damage is futile and the prognosis of such patients without operative intervention is extremely poor. When the hemodynamic compromise is less severe (i.e., symptoms of heart failure without shock), such cases may be managed on urgent basis. Both of such situations are class I indications by the ESC 2015 guideline [ ].
Heart failure is common in endocarditis, present in about 40%–60% of hospital cases [ , ], and the indication is met when there is either a symptom of heart failure or echocardiographic finding of hemodynamics stress [ , ]. Aortic valve pathology more commonly manifests in symptomatic heart failure compared with mitral valve pathology [ ]. The onset is most often acute, related to leaflet destruction or perforation, vegetation interfering with proper valve coaptation, or chordal rupture. When surgery is indicated based on heart failure, the status of infection (negative culture) is irrelevant and the patient requires surgery on urgent to emergent basis depending on the severity of hemodynamic compromise. Importantly, surgery is indicated even in patients with cardiogenic shock as long as the hemodynamic compromise is related to the valvular lesions from endocarditis. Such significant and acute hemodynamic compromise is the only situation where emergent operation is indicated for endocarditis [ ]. Other manifestations are treated on urgent or elective basis.
Uncontrolled infection despite antibiotics is also a common indication for operation for the purpose of source control. Persistent infection is often caused by highly resistant and virulent organism. The definition of persistent infection varies but is often defined as positive culture despite 7–10 days of antibiotics treatment. Intracardiac infectious source, most often involving perivalvular extension, requires operative debridement. Perivalvular extension may manifest in a fistula, abscess, or pseudoaneurysm and the potential for the extension to evolve rapidly warrants early intervention. As the conduction system resides in the area, conduction abnormality is a common manifestation of perivalvular extension. PVE tends to have such perivalvular extension requiring more complex reconstruction, driving the significant mortality and morbidity associated with operations for PVE [ ].
Locally uncontrolled infection manifesting as abscess, false aneurysm, fistula, or enlarging vegetation requires operative intervention on an urgent basis. It must be noted that local invasion and tissue destruction is a dynamic process, and fistula and root abscess could develop into hemodynamically devastating destruction of the fibrous skeleton and other integral structures [ ]. On that basis, such manifestations comprise urgent indication that should be intervened within 2–3 days of diagnosis. Similarly, infections of resistant organisms or those with low likelihood of being controlled by antimicrobial therapy alone forms indication for surgical source control. These organisms are methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, gram-negative bacterial infection, and PVE caused by staphylococci or non-HACEK gram-negative organisms [ , ].
Prevention of thromboembolic complications
Thromboembolic complications are common and have different consideration for left- versus right-sided endocarditis. Systemic thromboembolism from left-sided source tends to be much more morbid, including stroke and end-organ infarction, compared with pulmonary septic emboli from right-sided source. Importantly, substantial portion of such embolic events is silent, meaning without clinical manifestation and only discovered with imaging. Factors that increase the risk of embolic event are: within 2 weeks of antibiotic therapy initiation, larger size, and more mobile vegetation. Consequently, operative indications are formed based on such factors related to the risk of embolic event.
Vegetation size appears to have dose–response relationship between the risk of stroke, and the threshold of >10 mm is commonly used as an indication. Importantly, associated valve regurgitation or stenosis increases the recommendation for operative intervention. In the absence of any other valvular abnormalities with isolated presence of vegetation, >15 mm is proposed as a threshold to undergo surgical debridement (Class IIb recommendation). There is a calculator that outputs risk of embolic event based on clinical features [ ].
Indications and timing to intervene on right-sided endocarditis
Right-sided IE (RSIE) accounts for 5%–10% of all IE cases and the epidemiology is changing with the opioid epidemic in the United States [ ]. Most often, RSIE involves tricuspid valve and occurs in the settings of intravenous drug use [ ], intracardiac devices such as ICD and pacemaker [ , ], and patients with congenital heart disease. All of these risk factors have become more prevalent in the United States over the past 20 years [ , ]. Nevertheless, data to inform the optimal timing and type of treatment remain limited in RSIE.
Surgical management: indications and timing
Up to one-third of patients with RSIE is treated surgically [ , ]. Principles driving the surgical indications are the same as those of left-sided endocarditis, namely to treat heart failure, to control infection, and to prevent thromboembolic event. Right-sided disease may have a higher threshold for intervention than the left-sided disease, partly owing to the nature of the disease that is better tolerated and a substantially lower risk of systemic embolization [ ]. Operations for tricuspid endocarditis should be considered in the below conditions:
Persistent bacteremia for more than 7 days despite adequate antibiotic therapy, or blood cultures positive for microorganisms difficult to eradicate (e.g., fungal or multidrug-resistant organism).
Right heart failure secondary to severe tricuspid regurgitation not responsive to diuretic treatment.
Presence of vegetations on the tricuspid valve greater than 20 mm which persist after recurrent pulmonary embolism, regardless of the right ventricular function.
In a meta-analysis by Yanagawa et al. the most common reasons that patients with right-sided IE underwent surgery were the development of septic pulmonary embolism, concomitant left-sided IE, right heart failure, and persistent bacteremia [ ]. The three most frequently performed strategies for the management of RSIE are tricuspid valvectomy, tricuspid valve repair, and tricuspid valve replacement [ ]. Other possible techniques are tricuspid annuloplasty, bicuspidization, and vegectomy (i.e., removal of the vegetation only).
Earlier intervention prevents the development of embolic complications and further disruption of the leaflet tissue [ ]. However, the optimal timing to intervene in RSIE remains unclear. Some authors proposed to evaluate the optimal timing for surgery based on the following [ ]: etiology (urgent in device-related IE or prosthetic tricuspid IE); microbiology (urgent if fungal, Pseudomonas spp., MRSA); coexistence with left-sided IE; response to antibiotic treatment and risk for antibiotic-related hepatic and renal toxicity; presence of related complications (i.e., abscesses, fistulas). Other authors recommend operating on urgent basis in the presence of concomitant atrial septal defect, infected indwelling catheters, or intracardiac leads or prosthetic valves [ ].
Proposed diagnostic flowcharts of surgical management of LSIE and RSIE are shown in Figs. 14.1 and 14.2 , respectively.