Comparison of clinical features of left-sided infective endocarditis involving previously normal versus previously abnormal valves

Infective Endocarditis and Antithrombotic Therapy

BACKGROUND

Incidence of infective endocarditis (IE) is progressively raising because of the increasing number of cardiovascular invasive procedures, support treatment and devices, awareness in the medical community, and improved diagnostic modalities. IE pathophysiology is a unique model of immunothrombosis, and the clinical course is often complicated by either embolic or hemorrhagic events. Managing antithrombotic treatment is challenging and the level of supporting evidence scant. The aim of this review was to discuss and present the embolic and bleeding complication associated with IE and review the available evidence on antithrombotic treatment in patients with IE with and without a previous indication to antithrombotic drugs.

SUMMARY

Embolic events occur in 20-40% of patients with IE and are associated with high morbidity and mortality. Acute ischemic stroke is the most common neurological complication. A beneficial effect of antithrombotic therapy in preventing ischemic stroke for patients with IE has never been formally tested in adequately powered randomized clinical trials. Atrial fibrillation is a common complication associated with severe infections, requiring anticoagulation. Furthermore, patients with IE have a high risk of unprovoked and anticoagulation treatment-related bleeding. In particular, intracerebral bleeding is the most severe complication in about 5% of patients with IE. Single antiplatelet therapy with low-dose aspirin after hospitalization for IE has been shown to reduce causes mortality within 90 days without an increase of hemorrhagic strokes. In the absence of bleeding complications, recent guidelines recommend to maintain low-dose aspirin. No data are available on the management of patients with IE while on dual antiplatelet therapy.

KEY MESSAGES

Several gaps in knowledge remain about antithrombotic management in patients with IE and most of the evidence relies on observational studies. Individualized strategies based on clinical evaluation, comorbidities, patient engagement, and shared decisions strategies are encouraged.

Early versus Delayed Surgery in Patients with Left-Sided Infective Endocarditis and Stroke

BACKGROUND

Timing of surgery remains controversial in patients with infective endocarditis and stroke. Guidelines on infective endocarditis suggest delaying surgery for up to 4 weeks. However, with early heart failure due to progression of the infection or recurrent septic embolism, urgent surgery becomes imperative.

METHODS

Out of 688 patients who were surgically treated for left-sided infective endocarditis, 187 presented with preoperative neurological events. The date of cerebral stroke onset was documented in 147 patients. The patients were stratified according to timing of surgery: 61 in the early group (0-7 days) vs. 86 in the delayed group (>7 days). Postoperative neurological outcome was assessed by the modified Rankin Scale.

RESULTS

Preoperative sepsis was more prevalent in patients with preoperative neurological complications (46.0% vs. 29.5%, p < 0.001). Patients with haemorrhagic stroke were operated on later (19.8% vs. 3.3%, p = 0.003). Postoperative cerebrovascular accidents were comparable between both groups (p = 0.13). Overall, we observed good neurological outcomes (p = 0.80) and a high recovery rate, with only 5% of cases showing neurological deterioration after surgery (p = 0.29). In-hospital mortality and long-term survival were not significantly different in the early and delayed surgery groups (log-rank, p = 0.22).

CONCLUSIONS

Early valve surgery in high-risk patients with infective endocarditis and stroke can be performed safely and is not associated with worse outcomes.

Infective Endocarditis during Pregnancy-Keep It Safe and Simple!

The diagnosis of infective endocarditis (IE) during pregnancy is accompanied by a poor prognosis for both mother and fetus in the absence of prompt management by multidisciplinary teams. We searched the electronic databases of PubMed, MEDLINE and EMBASE for clinical studies addressing the management of infective endocarditis during pregnancy, with the aim of realizing a literature review ranging from risk factors to diagnostic investigations to optimal therapeutic management for mother and fetus alike. The presence of previous cardiovascular pathologies such as rheumatic heart disease, congenital heart disease, prosthetic valves, hemodialysis, intravenous catheters or immunosuppression are the main risk factors predisposing patients to IE during pregnancy. The identification of modern risk factors such as intracardiac devices and intravenous drug administration as well as genetic diagnostic methods such as cell-free deoxyribonucleic acid (DNA) next-generation sequencing require that these cases be addressed in multidisciplinary teams. Guiding treatment to eradicate infection and protect the fetus simultaneously creates challenges for cardiologists and gynecologists alike.

Neutrophils Protect Against Staphylococcus aureus Endocarditis Progression Independent of Extracellular Trap Release

BACKGROUND

Infective endocarditis (IE) is characterized by an infected thrombus at the heart valves. How bacteria bypass the immune system and cause these thrombi remains unclear. Neutrophils releasing NETs (neutrophil extracellular traps) lie at this interface between host defense and coagulation. We aimed to determine the role of NETs in IE immunothrombosis.

METHODS

We used a murine model of Staphylococcus aureus endocarditis in which IE is provoked on inflamed heart valves and characterized IE thrombus content by immunostaining identifying NETs. Antibody-mediated neutrophil depletion and neutrophil-selective PAD4 (peptidylarginine deiminase 4)-knockout mice were used to clarify the role of neutrophils and NETs, respectively. S. aureus mutants deficient in key virulence factors related to immunothrombosis (nucleases or staphylocoagulases) were investigated.

RESULTS

Neutrophils releasing NETs were present in infected thrombi and within cellular infiltrates in the surrounding vasculature. Neutrophil depletion increased occurrence of IE, whereas neutrophil-selective impairment of NET formation did not alter IE occurrence. Absence of S. aureus nuclease, which degrades NETs, did not affect endocarditis outcome. In contrast, absence of staphylocoagulases (coagulase and von Willebrand factor binding protein) led to improved survival, decreased bacteremia, smaller infiltrates, and decreased tissue destruction. Significantly more NETs were present in these vegetations, which correlated with decreased bacteria and cell death in the adjacent vascular wall.

CONCLUSIONS

Neutrophils protect against IE independent of NET release. Absence of S. aureus coagulases, but not nucleases, reduced IE severity and increased NET levels. Staphylocoagulase-induced fibrin likely hampers NETs from constraining infection and the resultant tissue damage, a hallmark of valve destruction in IE.

Characteristics and outcome of acute heart failure in infective endocarditis: focus on cardiogenic shock

BACKGROUND

Studies investigating the impact of cardiogenic shock (CS) on endocarditis are lacking. We aimed to investigate the characteristics and outcomes of endocarditis patients presenting with acute heart failure (AHF), particularly of those developing CS.

METHODS

Prospectively collected cohort from 35 Spanish centers (2008-2018). Logistic regression analyses were performed to identify risk factors for developing CS and predictors of mortality.

RESULTS

Amongst 4,856 endocarditis patients, 1,652 (34%) had AHF and 244 (5%) CS. Compared to patients without AHF and AHF but no CS, patients with CS presented higher rates of surgery (40.5%, 52.5% and 68%,p<.001) and in-hospital mortality (16.3%,39.1%, and 52.5%). Compared to patients with septic shock, CS patients presented higher rates of surgery (42.5% vs. 68%, p<.001), and lower rates of in-hospital and 1-year mortality (62.3% vs. 52.5%,p.008;and 65.3% vs. 57.4%,p.030). Severe aortic and mitral regurgitation (OR 2.47, 95%CI 1.82-3.35 and OR 3.03, 95%CI 2.26-4.07, both p<.001), left-ventricle ejection fraction<60% (OR 1.72, 95%CI 1.22-2.40, p.002), heart block (OR 2.22, 95%CI 1.41-3.47, p.001), tachyarrhythmias (OR 5.07,95%CI 3.13-8.19, p<.001) and acute kidney failure (OR 2.29, 95%CI 1.73-3.03,p<.001) were associated to a higher likelihood of developing CS. Prosthetic endocarditis (OR 2.03, 95%CI 1.06-3.88, p.032), S. aureus (OR 3.10, 95%CI 1.16-8.30, p.024), tachyarrhythmias (OR 3.09,95%CI 1.50-10.13, p.005), and not performing cardiac surgery (OR 11.40, 95%CI 4.83-26.90, p<.001) were associated to a higher risk of mortality.

CONCLUSIONS

Acute heart failure is common among patients with endocarditis. Cardiogenic shock is associated to very high mortality and should be promptly identified and assessed for cardiac surgery.

Blockage of extracorporeal circulation during emergency surgery for fulminant infective endocarditis

A 37-years-old man with a history of alcohol abuse and pancreatitis, presented to the emergency department with a 1-week history of progressively worsening dyspnoea with a fever up to 39°C. Echocardiography revealed bicuspid aortic valve with additional mobile structure and perforation of leaflet with acute aortic regurgitation. Due to rapidly deteriorating condition of the patient, a decision about immediate surgery was made. In the operating room, cardiac arrest in the asystole mechanism occurred. Extracorporeal circulation was turned on during direct heart massage. After opening of the aorta, the circulation was blocked by total clogging of the arterial line filter by fibrine deposits. The oxygenator was replaced which resulted a break in extracorporeal circulation lasting about 10 min. Patients survived surgery and was discharged after 6 week antibiotic therapy.

Staphylococcus aureus endocarditis: distinct mechanisms of bacterial adhesion to damaged and inflamed heart valves

AIMS

The pathogenesis of endocarditis is not well understood resulting in unsuccessful attempts at prevention. Clinical observations suggest that Staphylococcus aureus infects either damaged or inflamed heart valves. Using a newly developed endocarditis mouse model, we therefore studied the initial adhesion of S. aureus in both risk states.

METHODS AND RESULTS

Using 3D confocal microscopy, we examined the adhesion of fluorescent S. aureus to murine aortic valves. To mimic different risk states we either damaged the valves with a surgically placed catheter or simulated valve inflammation by local endothelium activation. We used von Willebrand factor (VWF) gene-deficient mice, induced platelet and fibrinogen depletion and used several S. aureus mutant strains to investigate the contribution of both host and bacterial factors in early bacterial adhesion. Both cardiac valve damage and inflammation predisposed to endocarditis, but by distinct mechanisms. Following valve damage, S. aureus adhered directly to VWF and fibrin, deposited on the damaged valve. This was mediated by Sortase A-dependent adhesins such as VWF-binding protein and Clumping factor A. Platelets did not contribute. In contrast, upon cardiac valve inflammation, widespread endothelial activation led to endothelial cell-bound VWF release. This recruited large amounts of platelets, capturing S. aureus to the valve surface. Here, neither fibrinogen, nor Sortase A were essential.

CONCLUSION

Cardiac valve damage and inflammation predispose to S. aureus endocarditis via distinct mechanisms. These findings may have important implications for the development of new preventive strategies, as some interventions might be effective in one risk state, but not in the other.

Coagulation: At the heart of infective endocarditis

Infective endocarditis is a life-threatening and enigmatic disease with a mortality of 30% and a pathophysiology that is poorly understood. However, at its core, an endocarditis lesion is mainly a fibrin and platelet blood clot infested with bacteria, clinging at the cardiac valves. Infective endocarditis therefore serves as a paradigm of immunothrombosis gone wrong. Immunothrombosis refers to the entanglement of the coagulation system with innate immunity and the role of coagulation in the isolation and clearance of invading pathogens. However, in the case of infective endocarditis, instead of containing the infection, immunothrombosis inadvertently creates the optimal shelter from the immune system and allows some bacteria to grow almost unimpeded. In every step of the disease, the coagulation system is heavily involved. It mediates the initial adhesion of bacteria to the leaflets, fuels the growth and maturation of a vegetation, and facilitates complications such as embolization and valve destruction. In addition, the number one cause of infective endocarditis, Staphylococcus aureus, has proven to be a true manipulator of immunothrombosis and thrives in the fibrin rich environment of an endocarditis vegetation. Considering its central role in infective endocarditis, the coagulation system is an attractive therapeutic target for this deadly disease. There is, however, a very delicate balance at play and the use of antithrombotic drugs in patients with endocarditis is often accompanied with a high bleeding risk.

[Septicemia and endocarditis with multiple implants : CIED, TAVI, MK clip and LAA occluders]

Infective endocarditis (IE) as well as septicemia in patients with implanted cardiac devices are severe diseases and diagnosis is often delayed due to a variety of misleading symptoms. Imaging with transesophageal echocardiography (TEE) and also microbiology play a key role in both the diagnosis and management. They are also useful for the prognostic assessment of patients with IE, for follow-up during treatment, during extraction of the implant and after surgery. In addition to antibiotic treatment, removal of the implant is also necessary, at least if vegetation is detected. Not only the removal of the implant but also the underlying cardiac disease, the frequently occurring severe cardiac insufficiency, the advanced age and the not uncommon high degree of fragility of the patients mean that decision making for treatment and management as well as renewed implantation after completion of treatment are a challenge. The optimal treatment is only possible with a close cooperation between various specialist disciplines and should therefore be carried out in experienced centers.

[Infective endocarditis in Morocco through the experience of a hospital department]

Infective endocarditis is a grave disease because of a high level of morbidity and mortality. We conducted a retrospective analysis of 100 patients hospitalized for infective endocarditis from January 2009 until December 2015. The mean age was 41 years with a male predominance. Infective endocarditis occurs on a native valve (77 patients), prosthetic valves (12 patients), Pacemaker (7 patients) and congenital heart disease (4 patients). The diagnostic delay was 77 days on average. The fever was present in 85 patients. Blood cultures were negative in 54 patients. Echocardiography allowed visualizing the vegetations in 95 patients. In patients with prosthetics valves, a paraprosthetic regurgitation was diagnosed in 54 % of these patients and vegetation in 18 %. The main complications are heart failure (42), neurological (19), spleen (10) and renal (23) complications. The evolution under medical treatment was marked by the clinical-laboratory improvement in 57 patients, the lack of improvement with persistent fever in 21 patients. The mortality rate of our series is 23 %. Only seven patients underwent urgent surgery for hemodynamic and infectious indications. At the end of this work, it is emphasized that the epidemiological profile of infective endocarditis does not follow the changes of Wold. Its management is difficult in our context (significant diagnostic delay, often negative blood cultures, high level of morbidity, lack of recourse to early surgery). The improvement of this disease consistes of the prevention of acute articular rhumatism and the establishment of an heart team endocarditis to adapt international recommendations to our context.

Infective endocarditis prophylaxis: a review

INTRODUCTION

Guidelines for prophylaxis against infective endocarditis (IE) have changed significantly due to a lack of evidence for its efficacy and increasing concerns about safety and antibiotic resistance. The impact of these changes on clinical practice and IE hospitalisation trends and outcomes has become a focus of research. Areas covered: We review the rationale for and against IE prophylaxis, highlight significant changes in guidelines since 2002, and discuss literature examining the impact of these changes on antibiotic prescription rates for IE prophylaxis, IE incidence, morbidity, and mortality. We included English articles published since 2002 relevant to IE prophylaxis. Expert commentary: Existing guidelines recommend limited to no prophylaxis against IE but differ on which patient populations would benefit most. Antibiotic prescription rates for IE prophylaxis have declined as a result of newer restrictive guidelines, most significantly in the UK where IE prophylaxis is not recommended. However, conflicting data exists on the impact of these changes on the trends of IE hospitalisation and clinical outcomes. Definitive studies to resolve this controversy do not seem feasible in the near future but well designed prospective observational studies may provide novel information on the long term impact of the new guidelines.

[Left-sided native valve infective endocarditis: Influence of age and the presence of underlying heart disease]

INTRODUCTION AND OBJECTIVES

Left-sided native valve infective endocarditis (LNVIE) epidemiology has been modified as a result of the increase in average age. The aim of our study is to analyze the influence of age and the presence of predisposing heart disease in the prognosis of these patients.

METHODS

We analyzed a series of 257 cases of LNVIE depending on their age (greater than or equal to 70 years old), both in the overall series and in the subgroup of patients without predisposing heart disease.

RESULTS

Mean age was 54.6 (18.6) years. There was an increase in the percentage of cases of older patients between 1987-2000 and 2001-2014 (9.8 vs. 34.8%, P<.001). These patients present higher prevalence of degenerative valves (50 vs. 22.8%) or not predisposing heart disease (50 vs. 39.9%), P<.001, health-care associated episodes (41.8 vs. 23.6%, P=.016), lower rate of surgery (43.7 vs. 63.8%, P=.005) and higher in-hospital mortality (39.1 vs. 20.7%, P=.003), with no differences in comorbidities. Older patients who did not have predisposing heart disease also suffered higher in-hospital mortality (47 vs. 22%, P=.01). Age greater than or equal to 70 years old is an independent predictor of mortality in patients with LNVIE (OR 2.53, 95% CI 1.24-5.15, P=.011), as in those without previous heart disease (OR 3.98, 95% CI 1.49-10.62, P=.006).

CONCLUSIONS

Patients of age greater than or equal to 70 years old and who suffer an LNVIE are becoming more frequent and have a worse prognosis with a lower rate of surgery and higher rates of in-hospital mortality.

[Which patients with infective endocarditis require emergency surgery?]

Half of patients with infectious endocarditis have surgery during the active phase of infective endocarditis (before the end of antibiotic therapy). The American Heart Association and the European Society of Cardiology, independently from each other, have published guidelines in September 2015. As regards surgical indications, these guidelines are similar. The surgical indication must be a common decision of a multidisciplinary team of experts in cardiology, cardiac surgery, imaging and infectious diseases. The main indications are heart failure, non-infectious process control and prevention of embolisms.

Predisposing cardiac conditions, interventional procedures, and antibiotic prophylaxis among patients with infective endocarditis

Efficacy and safety of antibiotic prophylaxis (AP) for prevention of infective endocarditis (IE) in patients with predisposing cardiac condition (PCC) undergoing invasive procedures is still debated. We sought to assess the prevalence of PCC, the type of interventional procedures preceding the onset of symptoms, and the usefulness of AP in a large cohort of consecutive patients with definite IE.

METHODS

We examined 677 (median age 65.34 years; male 492 [73%]) consecutive patients with IE enrolled from July 2007 through 2010 into the Italian Registry of Infective Endocarditis.

RESULTS

Predisposing cardiac condition was present in 341 patients (50%).Thirty-two patients (4.7%) underwent dental procedures. Of 20 patients with PCC undergoing dental procedure, 13 had assumed AP. Viridans group streptococci were isolated from blood cultures in 8 of 20 patients with PCC and prior dental procedure. Nondental procedures preceded IE in 139 patients (21%). They were significantly older and had more comordibities compared with patients undergoing dental procedures. Predisposing cardiac condition was identified in 91 patients. Perioperative antimicrobial prophylaxis was administered to 67 patients. Staphylococcus aureus was the most frequent causative agent. Cardiac surgery was necessary in 85 patients (20 with prior dental and 65 with nondental procedure). Surgical mortality (12% vs 0%, P = .03) and hospital mortality (23% vs 3%, P = .001) were significantly larger among patients with nondental procedures.

CONCLUSIONS

In a large unselected cohort of patients with IE, the incidence of preceding dental procedures was minimal. The number of cases potentially preventable by means of AP was negligible. Nondental procedures were more frequent than dental procedures and were correlated with poorer prognosis.

Staphylococcus lugdunensis Endocarditis in a 35-Year-Old Woman in Her 24th Week of Pregnancy

Background. Infective endocarditis is associated with considerable morbidity and mortality. Guidelines addressing prophylaxis and management of infective endocarditis do not extensively deal with concomitant pregnancy, and case reports on infective endocarditis are scarce. This is the first published report of infective endocarditis by Staphylococcus lugdunensis in a pregnant woman. Case Presentation. We report a single case of a 35-year-old woman in her 24th week of pregnancy who was admitted to our intensive care unit with fever and suspected infectious endocarditis. Blood culture detected Staphylococcus lugdunensis. A vegetation and severe mitral regurgitation due to complete destruction of the valve confirmed the diagnosis. An interdisciplinary panel of cardiologists, maternal-fetal medicine specialists, cardiac and plastic surgeons, infectiologists, anesthesiologists, and neonatologists was formed to determine the best therapeutic strategy. Conclusions. Timing and indications for surgical intervention to prevent embolic complications in infective endocarditis remain controversial. This original case report illustrates how managing infective endocarditis by Staphylococcus lugdunensis particularly in the 24th week of pregnancy can represent a therapeutic challenge to a broad section of specialties across medicine. Critical cases like this require a thorough weighing of risks and benefits followed by swift action to protect the mother and her unborn child.

Shear-Resistant Binding to von Willebrand Factor Allows Staphylococcus lugdunensis to Adhere to the Cardiac Valves and Initiate Endocarditis

BACKGROUND

Staphylococcus lugdunensis is an emerging cause of endocarditis. To cause endovascular infections, S. lugdunensis requires mechanisms to overcome shear stress. We investigated whether platelets and von Willebrand factor (VWF) mediate bacterial adhesion to the vessel wall and the cardiac valves under flow.

METHODS

S. lugdunensis binding to VWF, collagen, and endothelial cells was studied in a parallel flow chamber in the absence and presence of platelets. In vivo adhesion of S. lugdunensis was evaluated in a mouse microvasculature perfusion model and a new mouse model of endocarditis.

RESULTS

Contrary to other coagulase-negative staphylococci, S. lugdunensis bound to VWF under flow, thus enabling its adhesion to endothelial cells and to the subendothelial matrix. In inflamed vessels of the mesenteric circulation, VWF recruited S. lugdunensis to the vessel wall. In a novel endocarditis mouse model, local inflammation and the resulting release of VWF enabled S. lugdunensis to bind and colonize the heart valves.

CONCLUSIONS

S. lugdunensis binds directly to VWF, which proved to be vital for withstanding shear forces and for its adhesion to the vessel wall and cardiac valves. This mechanism explains why S. lugdunensis causes more-aggressive infections, including endocarditis, compared with other coagulase-negative staphylococci.

Genomics, evolution, and molecular epidemiology of the Streptococcus bovis/Streptococcus equinus complex (SBSEC)

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a group of human and animal derived streptococci that are commensals (rumen and gastrointestinal tract), opportunistic pathogens or food fermentation associates. The classification of SBSEC has undergone massive changes and currently comprises 7 (sub)species grouped into four branches based on sequences identities: the Streptococcus gallolyticus, the Streptococcus equinus, the Streptococcus infantarius and the Streptococcus alactolyticus branch. In animals, SBSEC are causative agents for ruminal acidosis, potentially laminitis and infective endocarditis (IE). In humans, a strong association was established between bacteraemia, IE and colorectal cancer. Especially the SBSEC-species S. gallolyticus subsp. gallolyticus is an emerging pathogen for IE and prosthetic joint infections. S. gallolyticus subsp. pasteurianus and the S. infantarius branch are further associated with biliary and urinary tract infections. Knowledge on pathogenic mechanisms is so far limited to colonization factors such as pili and biofilm formation. Certain strain variants of S. gallolyticus subsp. macedonicus and S. infantarius subsp. infantarius are associated with traditional dairy and plant-based food fermentations and display traits suggesting safety. However, due to their close relationship to virulent strains, their use in food fermentation has to be critically assessed. Additionally, implementing accurate and up-to-date taxonomy is critical to enable appropriate treatment of patients and risk assessment of species and strains via recently developed multilocus sequence typing schemes to enable comparative global epidemiology. Comparative genomics revealed that SBSEC strains harbour genomics islands (GI) that seem acquired from other streptococci by horizontal gene transfer. In case of virulent strains these GI frequently encode putative virulence factors, in strains from food fermentation the GI encode functions that are pivotal for strain performance during fermentation. Comparative genomics is a powerful tool to identify acquired pathogenic functions, but there is still an urgent need for more physiological and epidemiological data to understand SBSEC-specific traits.