|Year : 2019 | Volume
| Issue : 2 | Page : 610-617
Surgical management of infective endocarditis: risk factors affecting early outcome
Mohamed O Mahmoud1, Ahmed L Dokhan2, Amr M Allama1, Mohamed OM Mostafa2
1 Department of Cardiothoracic Surgery, Faculty of Medicine, Menoufia University, Shebin El Kom, Egypt
2 Department of Cardiothoracic Surgery Department, National Heart Institute, Giza, Egypt
|Date of Submission||06-Mar-2018|
|Date of Acceptance||21-May-2018|
|Date of Web Publication||25-Jun-2019|
Mohamed OM Mostafa
Shebin El Kom, Menoufia
Source of Support: None, Conflict of Interest: None
To evaluate the risk factors affecting the early outcome of surgical treatment of infective endocarditis (IE).
IE represents a series of clinical conditions with high in-hospital mortality, so early diagnosis and treatment can improve outcomes. Diagnosis depends on constant history and classic manifestations like sustained bacteremia or fungemia or active valvulitis. IE is a medical-surgical disease in which surgical treatment is a part of the therapeutic process rather than a result of the failure of medical treatment.
Patients and methods
A prospective cohort study was conducted on 50 consecutive patients diagnosed with definite IE and underwent cardiac surgery after being admitted to the Cardiothoracic Surgical Department, National Heart Institute, Giza, Egypt, during the period from December 2015 till March 2017. Preoperative, intraoperative, and postoperative data as potential predictors of mortality were tested.
Our results showed that rheumatic heart disease was the most common underlying cardiac disease. Native valve endocarditis was present in 31 (62%) and prosthetic valve endocarditis in 19 (38%) patients. Mean Euro SCORE II was 5.71%. The hospital mortality was 22%, whereas the 6-month mortality was 10%. Congestive heart failure, embolization, and periannular extension of infection are the most powerful predictors of hospital mortality and also 6-month mortality.
Surgery for IE continues to be challenging. Euro SCORE II has a good discrimination ability to predict in-hospital mortality in IE surgery. Satisfactory results can be obtained with valve repair in IE.
Keywords: infective endocarditis, mortality, predictors, risk factors, surgery
|How to cite this article:|
Mahmoud MO, Dokhan AL, Allama AM, Mostafa MO. Surgical management of infective endocarditis: risk factors affecting early outcome. Menoufia Med J 2019;32:610-7
|How to cite this URL:|
Mahmoud MO, Dokhan AL, Allama AM, Mostafa MO. Surgical management of infective endocarditis: risk factors affecting early outcome. Menoufia Med J [serial online] 2019 [cited 2019 Sep 17];32:610-7. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/610/260888
| Introduction|| |
Infective endocarditis (IE) is defined as any condition in which an infective process affects a structure of the heart. The valves are the most common location for endocarditis, but the process may also involve atrial or ventricular septal defects, patent ductus arteriosus, or any of a wide range of congenital heart defects including the aorta and great vessels. IE is a serious clinical condition with an annual incidence in the general population of ∼1.7–6.2 cases per 100 000 patients. Despite recent advances in diagnosis and treatment, IE is still a hazardous condition with high in-hospital mortality, reaching 12.6% in the Euro Heart Survey program. Early diagnosis and treatment can improve outcomes. Low suspicion of IE (owing to the nonspecificity of the symptoms) can delay effective treatment and increase mortality. The diagnosis of IE is straightforward in the minority of patients who present with a consistent history and classic Oslerian manifestations: sustained bacteremia or fungemia, evidence of active valvulitis, peripheral emboli, and immunological vascular phenomena. In most patients, however, the 'textbook' history and physical examination findings may be few or absent. The variability in clinical presentation of IE and the importance of early accurate diagnosis require a diagnostic strategy that is both sensitive for disease detection and specific for its exclusion across all forms of the disease. In 1994, Durack and colleagues from the Duke University Medical Center proposed a diagnostic schema that stratified patients with suspected IE into three categories: definite, possible, and rejected cases. Decisions on surgical intervention are complex and depend on many clinical and prognostic factors that vary among patients, including infecting organism, vegetation size, presence of perivalvular infection, presence of embolism or heart failure, age, noncardiac comorbidities, and available surgical expertise. Surgery is the treatment of choice in complicated prosthetic valve endocarditis and sterilization. Cure by medical treatment alone is rarely possible in active IE on native valves. Residual valve damage may be associated with significant hemodynamic changes leading to a decreased life expectancy. Therefore, the aim of the work was to evaluate the risk factors affecting the early outcome of surgical treatment of IE.
| Patients and Methods|| |
A prospective cohort study was conducted on 50 consecutive patients diagnosed with definite IE and required cardiac surgery. The study was approved by the local medical ethical committee.
All patients were admitted to the Cardiothoracic Surgical Department, National Heart Institute, Giza, Egypt, during the period from December 2015 to March 2017.
All patients participating in this investigation signed an informed written consent before surgery initiation. Approval was recorded from Research Ethics Committee of Faculty of Medicine, Menoufia University.
Selection criteria for the patients
Diagnosis was based on strict case definition fulfilling modified Duke's criteria in association with assessments by the endocarditis team in our hospital. The participants included in this study were selected according to inclusion and exclusion criteria.
All patients with native valve endocarditis or those with prosthetic valve endocarditis with involvement of mitral, aortic, or tricuspid valve either isolated or combined were included.
Patients presenting with irreversible septic shock with failed medical treatment, patients with neurological insult such as deep coma or intracranial hemorrhage, patients with severe comorbidities such as mycotic aneurysm, and patients with poor ejection fraction (<30%) were excluded from the study.
All patients were subjected to the following:
- Preoperative assessment involved full history taking; clinical examination; co morbidities, including diabetes mellitus, renal failure, chronic obstructive pulmonary disease (COPD), liver dysfunction, anemia, and intravenous addiction; Euro score; chest radiography; echo findings valve (description and pathology); left ventricle (LV) function; pulmonary hypertension and associated congenital lesions; presence of abscesses; pseudoaneurysms or intracardiac fistulae; laboratory data including erythrocyte sedimentation rate (ESR), C reactive protein (CRP), and three sequent blood cultures at least 1 h. apart added to the routine investigations; and complications, including embolization (e.g., cerebrovascular accidents and peripheral), heart failure, and pericardial effusion
- Operative assessment: including timing of surgery (emergency, urgent or elective); surgical procedure (valve replacement with mechanical or biological prosthesis, valve repair or combined replacement and repair and for which valve); first do or redo surgery; intraoperative findings with description of the pathological affection of the endocardium (site and nature of valvular affection, periannular extension, and presence and size of vegetations); bypass time; cross-clamp time; total operative time; method of cardioplegia; weaning off cardiopulmonary bypass, use of inotropes; and culture and sensitivity from excised infected tissue
- Postoperative assessments included duration of mechanical ventilation; inotropic support; complications such as re-exploration for bleeding, low cardiac output syndrome, neurological complications, arrhythmias, deep wound infection, and mortality; ICU stays; laboratory workup, including serial total leucocyte count and C-reactive protein, blood culture, and sensitivity detecting residual infection; and hospital stays
- Follow-up: 6-month follow-up by echocardiography for assessment of cardiac condition and detection of relapse.
Results were tabulated and statistically analyzed by using personal computer using Microsoft Excel 2016 and SPSS, version 22 (SPSS Inc., Chicago, Illinois, USA). Statistical analysis was done using descriptive, for example, percentage, mean, and SD, and analytical analyses, which included Student's t-test for comparison of means and the Fisher's exact or χ2-tests for comparison of categorical parameters. A value of P less than 0.05 was considered statistically significant.
| Results|| |
Regarding the indications of surgery, our results showed that the most common indications for surgery were congestive heart failure owing to valve dysfunction in 32 (64%) and large vegetation (>10 mm in size) in 23 (46%). Regarding echocardiographic findings, it showed that type of IE were native valve (62%) and prosthetic valve (38%), whereas the tricuspid valve (32%) and mitral valve alone (28%) were the most common site of IE. Severe mobility (46%) and mobile vegetation (30%) were the most vegetations. Moreover, abscess (16%), pseudoaneurysm (16%), and fistula (2%) were considered the most periannular extension of infection [Table 1].
|Table 1: Indications of surgery and echocardiographic findings in patients with infective endocarditis|
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Regarding, preoperative data, Euro SCORE II ranged from 1.23 to 36.99%, with a mean value of 5.71%. Preoperative complications included congestive heart failure in 25 (50%) patients; embolization was evident in 18 (36%) patients, where the sites of embolization were the CNS (nine patients), upper/lower extremities (seven patients), spleen (four patients), lung (four patients), and kidney (two patients); and renal impairment developed in 17 (34%) patients, of which six patients were on dialysis. Concerning intraoperative data, ischemic time (aortic cross-clamp time) ranged from 28 to 191 min, with a mean value of 79.47 min, and cardiopulmonary bypass time ranged from 40 to 253 min, with a mean value of 106.45 min. Successful primary weaning off cardiopulmonary bypass was achieved in 45 (90%) patients, whereas in the remaining five (10%) patients, reinstitution of cardiopulmonary bypass was needed. In four of these five patients, the weaning succeeded in the second trial after administration of inotropic support at high doses including adrenaline and noradrenaline. The remaining patient died intraoperatively owing to persistent low CO with failure to wean off cardiopulmonary bypass (CPB) despite high inotropic support. Forty-five (90%) patients needed intraoperative inotropic support. Total operative time ranged from 110 to 360 min, with a mean value of 205.3 ± 63.4 min [Table 2].
|Table 2: Operative procedures, types of implanted valves, causes of hospital mortality, and major postoperative complications and morbidities in patients with infective endocarditis|
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Regarding hospital mortality and morbidity, the in-hospital mortality was 11 (22%) patients. Twenty-two (44%) patients experienced one or more postoperative complications. The period of mechanical ventilation ranged from 5 to 280 h, with a mean value of 30.65 h. The period of mechanical ventilation was less than 24 h in 34 (68%) patients, 24–48 h in three (6%), and more than 48 h in 12 (24%). Forty-three (86%) patients were kept on inotropic support [19 (38%) of them required inotropic support for >48 h]. The duration of ICU stays ranged from 2 to 12 days, with a mean value of 2.85 days. Predictors of hospital mortality were as follows: of regarding preoperative predictors, 65 variables were analyzed by univariate analysis to identify significant predictors for hospital mortality, and only nine variables were found to have statistical significance as predictors of hospital mortality, whereas regarding operative predictors, 16 variables were analyzed by univariate analysis to identify significant predictors for hospital mortality, and only three variables were found to have statistical significance as predictors of hospital mortality [Table 3].
Fourteen postoperative variables were analyzed by univariate analysis to identify significant predictors for hospital mortality. Only eight variables were found to have statistical significance as predictors of hospital mortality.
Six-month follow-up data
Five patients died during the follow-up period [13.6% (39) among hospital survivors], yielding an overall 6-month mortality of 30%. Two patients experienced permanent neurological disability, and four patients had dyspnea (NYHA FC Ш–IV). Of the four patients with dyspnea, one patient developed severe aortic paravalvular leak without endocarditis and underwent redo aortic valve replacement. Another two patients experienced a relapse. The offending microorganism was Staphylococcus aureus in both cases. One of them showed involvement of mechanical aortic prosthesis and died of sepsis before reoperation. The other patient showed involvement of mechanical mitral prosthesis. This patient underwent redo mitral valve replacement with a mechanical prosthesis and survived. The other 29 patients had no detected comorbidity. In the group of patients selected for valve repair strategy, none had recurrence of endocarditis, and at follow-up, echocardiography did not show more than mild residual regurgitation. Predictors of 6-month mortality were as follows: by univariate analysis, only five preoperative variables were found to have statistical significance as predictors of 6-month mortality, and only one operative variable (emergency surgery, P = 0.049) was found to have statistical significance as a predictor of 6-month mortality. However, all the postoperative variables were found to be insignificant predictors of 6-month mortality [Table 4].
|Table 4: Preoperative and operative predictive variables and causes for 6-month mortality, in patients with IE regarding surviving group after 6 months of follow-up|
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| Discussion|| |
The ESC published guidelines on the prevention and treatment of IE in 2015 including helpful recommendations concerning the indications for surgery. We followed these guidelines to detect the main indications for surgery. In this study, we found that the most common findings leading to surgical treatment for both native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE) was severe valvular regurgitation with intractable heart failure (50%). Rekik et al. found that the main indication for surgery was severe valvular dysfunction with congestive heart failure (52.3%).
In this study, Euro SCORE II had a good discrimination ability to predict in-hospital mortality and 6-month mortality in IE surgery. This agreed with studies by Di Dedda et al. and Borracci et al. in which Euro SCORE II showed satisfactory prediction of mortality in patients undergoing heart valve surgery. Moreover, PVE was a univariate predictor of in-hospital mortality. From 10 patients who died during hospital period, five had PVE. PVE is frequently complicated by perivalvular extension of infection and in many of these cases, infection spreads behind the site of attachment of the valve prosthesis, resulting in valve dehiscence in most of cases which increases volume overload on corresponding ventricle precipitating heart failure. PVE was found to be a significant risk predictor of mortality also in the following studies: David et al. and Manne et al.. Periannular extension of infection was an independent predictor of hospital mortality and 6-month mortality in the current study. Half of the dead patients had periannular extension of infection of the total eight patients with periannular extension of infection preoperatively (5/8; 62.5%). Musci et al. found abscess formation as a significant risk factor for early mortality (≤30 days) in the univariate analysis.
In this study, the strategy we followed in treating renal impaired patients was trying to avoid fluid overload in congested patients with diseased kidneys by shortening the length of CPB circuits and priming by colloids as plasma or packed RBCs rather than crystalloids, and maintaining mean blood pressure above 60 during CPB. Rekik et al. stated that high creatinine was strongly associated with mortality.
In this study, congestive heart failure (CHF) was a strong independent predictor of in-hospital mortality. It was found in 90% of the hospital mortality patients. In severe cases of endocarditis, infection spread results in destruction of perivalvular tissue causing acute regurgitation in NVE or dehiscence and paravalvular leak in PVE, both causing volume overload on corresponding ventricle precipitating heart failure. Moreover, large vegetations obstruct blood outflow causing CHF. Associated myocarditis causes pump failure. Heart failure is agreed as a contributing factor in the mortality of IE as shown in several studies. Ohara et al. found high C-reactive protein level as a univariate predictor of in-hospital mortality. It is a sign of active infection, which makes the tissues friable, increasing operative technical difficulty. Similarly, high CRP values (≥100 mg/l) on admission significantly predicted both short-term and 1-year mortality in the study of Heiro et al..
This study showed that emergency surgery was a significant univariate predictor of hospital mortality and 6-month mortality. Our strategy in surgical IE treatment was not to rush surgery until patient is stabilized. So, the majority of our patients were operated upon on urgent basis (50%). Five patients with IE could not be stabilized. They all presented with CHF with hemodynamic instability despite high inotropic support. Two of them had NVE with new-onset acute regurgitant lesions whereas other three had PVE with new-onset sudden valve dehiscence and severe paravalvular leak. These five patients were operated upon on emergency basis. Of these five patients with IE, three (60%) patients had hospital mortality. This high hospital mortality may be contributed to deficient patient preparations, antibiotic therapy, and infection control; failure of controlling patient risky comorbidities before surgery such as toxemia, CHF, and pulmonary edema; and lack of time needed for preparations of different blood products. Our results come in line with the study by Musci et al., where emergency surgery was a significant predictor of in-hospital mortality.
This study showed that redo surgery was a significant univariate predictor of in-hospital mortality. Overall, 50% of mortality patients had PVE with risky redo operations. In redo surgery, presence of PVE increases time needed for valve excision increasing CPB time and consequently the ischemic time. Similarly, redo surgery was a predictor of in-hospital mortality in study. This study showed that prolonged cardiopulmonary bypass time was a significant univariate predictor of hospital mortality. This prolonged CPB time may be contributed to increased time needed for dissection and prosthetic valve extraction in cases with PVE. However, in cases with NVE, there is increased time needed for good debridement and valve repair. Moreover, the presence of friable tissues makes operations technically more difficult owing to difficulty in suturing, increasing the ischemic time. Klieverik et al. and Nayak et al. showed that bypass time and cross-clamp time were significant univariate predictors of 30-day mortality and long-term mortality.
In this study, four patients had postoperative fever. All incidences started in the first postoperative day. Two patients had hectic fever and the other two patients had a continuous fever. Of those four patients, three died during the hospital period (75%). In agreement to our result, postoperative fever was found as a good predictor of mortality by Rostagno et al..
In this study, of all six patients who had postoperative chest infection and respiratory failure, only one patient survived during the hospital period (mortality 84%). Postoperative atelectasis or pneumonia commonly causes postoperative chest infection which is associated with fever. In severe cases, this infection may progress to respiratory failure which is associated with prolonged ventilation, need to inotropic support, and prolonged length of ICU stay. Sheikh et al. and Smith et al., stated that postoperative pulmonary complications were good predictors of mortality.
Systemic sepsis was found a significant predictor of hospital mortality in this study. All the three patients who had systemic sepsis died during hospitalization (mortality 100%). Sepsis results in severe vasodilatation and hypotension and concurrently decreased peripheral perfusion and low cardiac output syndrome, which lead to different organ ischemia (e.g., renal ischemia and pulmonary ischemia). Presence of fever, pulmonary ischemia, and low cardiac output leads to prolonged ventilation. Finally, prolonged ventilation and high doses of inotropic support prolong the length of ICU stay. In the study by Sheikh et al., postoperative sepsis was a good predictor of mortality.
In this study, five patients experienced postoperative low cardiac output syndrome. Of these five patients, three (60%) died during the hospital period. Presence of postoperative low COP increases mortality risk owing to decreased peripheral perfusion making different organs at ischemic risk, especially the kidneys, decreasing renal perfusion predisposing to renal impairment which may progress to renal failure in severe cases. Moreover, low cardiac output increases the need for inotropic support which prolongs the duration of ICU stay. Decreased peripheral perfusion predisposes to different organ infection, and together with associated postoperative mechanical ventilation predisposes to chest infection, which in turn leads to prolonged period of mechanical ventilation, which in severe cases may progress to respiratory failure.
In the current study, we found that presence of new renal impairment was a significant predictor of postoperative mortality. Seven patients had postoperative new renal impairment (serum creatinine >1.3 g/dl). Only two patients required hemodialysis. Four patients (of these seven patients; 57%) died during hospital period with only one patient died of renal failure after hemodialysis, whereas the other three patients died of low COP syndrome. Similarly, Smith et al., stated renal complications as a predictor of in-hospital mortality. Sheikh et al., also stated postoperative renal failure as a predictor of mortality.
Prolonged period of mechanical ventilation was found as a significant predictor of hospital mortality in current study. In agreement with several studies, this study showed that period of mechanical ventilation, inotropic support more than 48 h, and duration of ICU stay were all significant univariate predictors of in-hospital mortality. Perrotta et al. showed that prolonged intubation was an independent predictor of hospital mortality.
This study showed that presence of inotropic support for more than 2 days was a significant predictor of postoperative mortality. Moreover, only six patients did not need inotropic support. Of 24 patients who needed inotropic support for less than 2 days, only one patient died. Of 17 patients who needed inotropic support for more than 2 days, six (35%) patients died during hospital period. Of these six patients who died, three had α-inotropic medication and the other three had β-inotropic support. These results agree with Perrotta et al. who stated that prolonged inotropic support was an univariate predictor of early mortality.
This study showed that high white blood cell count was a univariate predictor of 6-month mortality. Elevated white blood cell count is an indicator of presence of active infection. Similarly, Rostagno et al. found that patients with white blood cells count outside the normal range were at a significantly greater risk of death at both discharge and 6 months, whereas elevated white blood cells count did not predict in-hospital or 1-year mortality. Only one operative variable (emergency surgery) was found to have statistical significance as a predictor of 6-month mortality. All the postoperative variables were found to be insignificant predictors of 6-month mortality. However, the data analysis during follow-up period showed that five patients died during this period, yielding an overall 6-month mortality of 30%. An increased rate of relapse may be owing to inadequate antibiotic treatment, resistant microorganisms, polymicrobial infection, empirical antimicrobial therapy for bacterial culture negative endocarditis, periannular extension, PVE, persistent metastatic foci of infection (abscesses), resistance to conventional antibiotic regimens, positive valve culture, persistence of fever at the seventh postoperative day, and chronic dialysis. Moreover, recurrence of infection occurred in the study by Sheikh et al..
| Conclusion|| |
Surgery for IE continues to be challenging and is found to be associated with high mortality. Risk factors for in-hospital mortality were prosthetic valve IE, periannular extension of infection, high serum creatinine, congestive heart failure, embolization, emergency surgery, prolonged cardiopulmonary bypass time, period of mechanical ventilation, inotropic support for more than 48 h, ICU stay, and postoperative complications. Congestive heart failure, embolization, and periannular extension of infection were the most powerful predictors of hospital mortality. Risk factors for 6-month mortality were periannular extension of infection, high serum creatinine, and emergency surgery. Euro SCORE II has a good discrimination ability to predict both in-hospital and 6-month mortality in IE surgery. Satisfactory results can be obtained with valve repair in IE.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]