Is Bacterial Endocarditis Curable?
Before the antibiotic era, mortality due to endocarditis was practically 100%. In the last decades, the most important advances in the field of infectious endocarditis have been the following:
- The improvement in the identification of the causative agent, the study of antibiotic sensitivity and the monitoring of antibiotic therapy.
- The appearance of echocardiography, constituting an unquestionable diagnostic aid and allowing a very precise follow-up of the valvular lesion secondary to endocarditis and its impact on hemodynamics. Currently, transesophageal echocardiography is the most appropriate technique for the study of patients with endocarditis.
- The finding that there are three types of endocarditis that must be evaluated and treated in a differentiated manner: endocarditis on the native valve, endocarditis on valvular prostheses and endocarditis in injecting drug users.
- The indications for surgical treatment have been outlined, achieving a significant reduction in mortality figures.
The treatment can be easily summarized: 4 to 6 weeks of intravenous administration of one or more bactericidal antibiotics for the infecting microorganism. We must use bactericidal drugs, parenterally, at sufficiently high doses and for a long enough time to achieve the sterilization of vegetation, which are usually found in endocarditis, in addition to prevent recurrence and eradication of possible metastatic foci. The general principles of treatment are: identification of the causative organism, in vitro determination of sensitivity and use of the antibiotic of choice.
The therapy with antibiotics is initially empirical (when the causal microorganism is unknown). Later, the treatment is selected in order to attack the specific bacteria isolated in blood cultures. Blood culture is a microbiological culture of the blood. This is used for discovering causal microorganisms.
The most adequate antibiotic is chosen according to the type of bacteria located in the valves.
Bacteriological cure depends directly on the sensitivity of the microorganism to the antibiotic. In uncomplicated bacterial endocarditis, it is not usually difficult to obtain a favorable response in terms of a symptomatic improvement, negativization of blood cultures and disappearance of fever. The cure, however, is more difficult to obtain, because inside the vegetations there is a large bacterial population (of the order of 108-1010 microorganisms per gram of tissue) with a reduced metabolic activity and protected from the phagocytic cells due to the accumulations of platelets and fibrin, this influences that bacteria considered sensitive to several antibiotics, in the context of a relatively resistant endocarditis.
In the most serious cases, when there is destruction of the heart valve due to an infection, valve change surgery is necessary, which means implanting an artificial valve.
Surgery, associated with antibiotic treatment, has contributed to the improvement of the prognosis of certain forms of endocarditis.
At this time, surgery indications are considered in the active phase of the infection, the appearance of one of the following major criteria:
- Progressive or severe heart failure.
- Germ infection difficult to treat or uncontrolled sepsis.
- Abscesses or other intracardiac suppurative complications.
- Multiple embolic episodes.
- Dehiscence or obstruction of the prosthetic valve.
Early surgical treatment, the timely determination of the causative agent, the effectiveness of antibiotic treatments and the advances achieved in extracorporeal circulation and myocardial protection techniques have allowed long periods of anoxic cardiac arrest without ischemic damage and, with it, performing safe and effective repairs of extensive cardiac injuries.
Mortality due to surgery is over 26%, the most important mortality risk factors are: the presence of a myocardial abscess and renal failure. Survival at 5 years among discharged patients is 71%, the 10 years of 60%, with the risk of reoperation at 5 and 10 years of 23% and 36%, respectively.