Open Journal Systems

ORIGINAL CONTRIBUTIONS

Received: April 22^nd 2015

Accepted: July 21^st 2015

Infective endocarditis. 5-years experience in a third-level reference center in Yucatan, Mexico

Angel Emmanuel Vega-Sánchez,^a Miguel Santaularia-Tomas,^b Diana Isabel Pérez-Román,^a Arturo Cortés-Telles^c

^aServicio de Medicina Interna

^bServicio de Cardiología e Imagen Cardiovascular

^cServicio de Medicina Interna-Neumología

Hospital Regional de Alta Especialidad de la Península de Yucatán, Secretaría de Salud, Mérida, Yucatán, México

Communication with: Angel Emmanuel Vega-Sánchez

Telephone: (999) 942 7600, extensión 54302

Email: angelemmanuelvega@gmail.com

Background: Infective endocarditis is a disease with high morbidity and mortality. The clinical characteristics differ among populations. Therefore it is important to know the characteristics of the disease in our region.

Methods: This is an observational study that included all patients diagnosed with infective endocarditis from 1 January 2009 until 31 December 2014. The data are showed as frequencies and percentages altogether with medians with interquartile range.

Results: 10 cases were included. The median age was 34 years (IQR 26-41). Several risk factors were identified and included: previous valvular heart disease, patients with chronic kidney disease who have had a vascular access and previous history of immunological disease. The native mitral valve was the most affected. The size of vegetations had a median length of 14 mm (IQR 9.3-16). Streptococcus alpha hemolytic was the most common organism. In-hospital mortality rate was 10 %.

Conclusions: The behavior of the disease is similar to other national series. We identify risk factors that could be related to the type of morbidities in the region.

Keywords: Bacterial endocarditis; Epidemiology; Surgery; Mitral valve; Diagnosis

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Infective endocarditis (IE) is a disease that can be fatal if not given adequate treatment; in industrialized countries, the incidence is 3 to 9 cases per 100,000 people.¹ The age of onset is between the fifth and seventh decade of life with a male: female ratio of 2:1.^2-4 However, this relationship generates no differences in mortality at 1 year of follow-up.⁵

The valves most affected are native (72%) and, depending on the study, mitral or aortic affectation are the most common.^5-7 Over time the etiology has changed; at present, Staphylococcus aureus is the most common microorganism. Next in frequency are coagulase-negative Staphylococcus and Enterococcus species; however, descriptions will vary according to the regional epidemiology.²

In Mexico there are few reports of IE.^8-11 The first report dates back to 1979;⁸ Díaz Davies et al. analyzed the survival of patients with native and prosthetic valve endocarditis. Interestingly, patients with native valve disease had a higher survival rate (88% vs. 56%); the central associated factor, greater structural affectation in prosthetic valves and the paravalvular insertion site; also notable was the time delay for specialized attention.8 Souto Meirino et al. focus on the clinical course and outcome with emphasis on the treatment of 130 patients with IE, of which 67% had native valve endocarditis. The study’s novel finding was the increased mortality in patients who received medical treatment versus those surgically resolved.10 Finally, Pérez-Gordillo¹¹ ​​et al. describe a series of 38 cases diagnosed over 16 years. The age at presentation ranged from 30 to 40 years (63%). The male to female ratio was 1:1, and the frequency of IE in patients with prosthetic valves was higher.

Based on these findings we can mention that the information available in our country has regional boundaries, since studies are limited to north-central areas. We know of no reports coming from other regions; so the aim of our study is to report confirmed cases of IE to see if the data remains homogeneous or if we can identify some characteristics that guide diagnosis and treatment strategies and thus improve the prognosis of the disease in the region. The justification for our report is based on international reports where the importance of epidemiological knowledge for decisions is emphasized in daily clinical practice.⁷

Methods

This observational study included all patients admitted to the Hospital Regional de Alta Especialidad of the Yucatan Peninsula (HRAEPY), diagnosed with IE during the period from January 1, 2009 to December 31, 2014. Due to the retrospective nature of the study it was not necessary to obtain a letter of informed consent; however, at all times the confidentiality of the data was based on existing laws derived from the Helsinki Declaration.¹²

To carry out the data analysis, records were included from patients with the diagnosis of IE based on the Duke criteria, and the demonstration of vegetations was confirmed by transthoracic echocardiography.^13-16

Once the diagnosis of IE was confirmed in the clinical record, the following variables were recorded systematically: age and gender; history of comorbidities considered risk factors, such as diabetes mellitus, chronic renal disease, immune diseases; intravenous drug use; cardiovascular history including rheumatic fever, congenital heart disease, valvular disease; placement of cardiac devices and chronic vascular access and clinical manifestations (fever, weight loss, skin lesions) and time of evolution; use of antimicrobial drugs prior to hospital admission; microbiology; echocardiographic characteristics (left ventricle ejection fraction, valves affected, number, length, and width of vegetations, maximum heart valve gradients); surgical procedures; length of hospital stay; and outcome.

Statistical analysis

Because most continuous variables had an asymmetric distribution, they were described as medians with interquartile range (IQR). On the other hand, the categorical variables are described as frequencies with percentages. The data analysis was performed using the statistical package of Microsoft Excel (Version 2013, Microsoft Office. USA.).

Results

10 cases were identified during the set period. The median age was 34 years (IQR 26-41), the male: female ratio was 1:1. The relevant background found that a history of heart valve disease, chronic kidney disease on hemodialysis, and previous history of vascular access had a similar frequency of 40%; other risk factors are presented in Table I.

Clinically, the median time to symptoms prior to hospital admission was 18 days (IQR 15-60). The cardinal symptom was fever (90% of cases), followed in order of frequency by weight loss and skin lesions (Table I).

All patients had transthoracic echocardiography demonstrating one or more vegetations. Notably, 60% of patients showed a second vegetation. Overall, the median length of vegetations was 14 mm (IQR 9.3-16) and for those who had a second vegetation, median length was 13 mm (IQR 13-15). The site with greatest compromise was the native mitral valve (80% of cases); however, 2 out of 10 patients had 2 valves affected simultaneously.

Finally, 80% of patients showed data of valvular insufficiency, and left ventricle ejection fraction was preserved (Simpson). The rest of the echocardiographic features are found in Table II.

Microbiology

The rate of isolation by blood culture was 60%. The most common organism was hemolytic Staphylococcus alpha (50%); others included Salmonella (16%), Histoplasma capsulatum (16%), and Streptococcus spp (16%). Primary treatment schemes used during the hospital stay were based on the combination of Vancomycin and Gentamicin. It is worth mentioning that 60% of patients received some antimicrobial before being hospitalized; cephalosporins were the most common type of antibiotic (50%) among the drugs used.

Finally, 80% of our patients underwent surgical treatment. The median time between hospital admission and surgical resolution was 12 days (IQR 8-18). Complications included cerebrovascular events of embolic origin (60%), Buckley A aortic dissection (10%), and postoperative myocardial infarction (10%). Mortality was 10% in the study, associated with valvular insufficiency and cardiogenic shock.

Discussion

The main findings of our study were as follows. 1) a young population with a male: female ratio of 1:1; 2) the background risk included: preexisting valvular abnormalities, chronic vascular access, and immunological diseases; 3) microbiological behavior; 4) 70% of cases with vegetations larger than 10 mm; 5) mortality rate of 10%.

International reports tell that the median age of cases with IE varies between 45 and 58 years with a 3:1 ratio, predominantly male.2-7 However, our population recorded a median age 10 years younger and the male: female ratio was similar (1:1). It is interesting that the results disagree with those of other reports in the world, but are nonetheless consistent with the national literature.9-11 This finding, generated in a different geographical area than it was published, suggests a similar behavior of IE in Mexico. It may be interesting to analyze subsequently if differences with other reports in the world are linked to the effect of race, among other factors. Additionally, the presentation of IE in our hospital may be related to the frequency of local and regional risk factors that may contribute to early development of endocarditis (congenital heart disease, valvular heart disease, chronic vascular access, and immunological factors).17-19

Based on the microbiological isolation, the yield of blood cultures was lower than previously reported, where isolation is about 85%.1 It is clear from the data presented by our group that they are vulnerable, as 60% of the population had received antimicrobial therapy prior to admission. This aspect is crucial, as it is widely reported that the use of antibiotics jeopardizes the effectiveness of microbial isolation.19 In cases with negative blood cultures, it is advisable to send the tissue obtained during surgery for pathological anatomical analysis.20 Notably, Lamas et al. emphasize the importance of such analysis. In 2 out of 3 patients with negative blood work, microorganism isolation was achieved in the valve tissue or cardiac devices.21 Unfortunately we could not corroborate the microbiology of cases with negative blood cultures, since we did not get histological reports.

The microbiological trend in southeastern Mexico is similar to that reported in the rest of the country.2,8-11 However, it is not clear what factors are relevant in the epidemiological transition of recent years. Answering this question requires more cases in which to identify them.

Based on the echocardiographic findings, 80% of patients underwent surgery in an average time of 12 days. A recent study by Galvez-Acebal et al. showed that surgical treatment within the hospital reduces mortality at 1 year.22 The results are constant in confirmed cases and subject to surgical intervention in the first 14 days of hospital stay.22

Among the complications, the most frequently seen was the rate of central nervous system embolism associated with the time of surgical delay and the size of the vegetation in our patients, which is higher compared to international reports.22,23. We cannot make a comparison with the other Mexican studies cited, since data are not available.8-11 Duk-Hyun et al. analyzed the overall frequency of adverse events in patients with vegetations greater than 10 mm that received surgery before and after 48 hours of hospital admission. The frequency of central nervous system embolism was 3% versus 28% when carrying out the procedure within the first 48 hours.22

Finally, the mortality rate in this study is similar to that in previous studies. The common denominator is the early surgical resolution (< 12 days) that impacts on this aspect, but not on morbidity.5,10,22,23

Limitations

Because of the retrospective nature of the study there may be multiple confounders, however, the data come from a referral center in southeastern Mexico. Similarly, the sample size does not allow deep analysis, however, we can say that the data are close to those described in other regions of our country, so the behavior and natural history of the disease may possibly be constant.

Conclusions

The presentation of IE in the southeast of the country is similar to that reported by other Mexican studies. In our center the presence of structural risk factors is a common denominator, however, we believe this trend should be evaluated by prospective studies. Early recognition of the disease made it possible to carry out operations causing lower frequency of morbidity and mortality.

References

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