Infective endocarditis (IE) is a potentially lethal condition, the incidence and mortality of which has not been reduced in the last 50 years. This is because of reduced compliance of the use of prophylactic therapy and the increased incidence of more virulent organisms and antibiotic-resistant organisms.
Dr K Taubert (Dallas, US) emphasised that there is increased questioning of which patients need antibiotic prophylaxis, but there is no questioning of the need for antibiotic prophylaxis in high risk patients. High risk patients are those who have a prosthetic heart valve, those with previous IE, those with complex cyanotic congenital heart disease and those with surgically constructed bypass procedures in congenital heart disease. In practice, patients with rheumatic heart disease and mitral valve prolapse are more frequently seen, in whom the issue of prophylaxis becomes important. There is also agreement that such patients must maintain good oral hygiene and must be educated regarding the need for antibiotic prophylaxis.
Dr B D Prendergast ( Manchester, GB) discussed the difficulties that are encountered in diagnosing IE, particularly in the early stages of the disease. The clinical assessment of the patient is the single most important feature in making the diagnosis and this is supplemented with microbiological techniques (blood cultures), imaging techniques and newer novel markers. With regard to the clinical features, in addition to the usual clinical findings which were described by Osler in 1885, the issues that need special consideration are positive blood cultures with staphylococcus, drug resistance, intravenous drug users, patients with HIV and culture negative. He cited a study of 500 consecutive echocardiograms for IE in which the incidence of IE was only 5%, thus emphasising the need to keep the clinical picture in perspective. Patients who are most likely to have IE are those with vasculitis, those with intravenous lines, those who abuse intravenous drugs and those with prosthetic heart valves, if the clinical picture is not diagnostic. In different reports culture negative IE has been reported to occur in 2.5% to 30% of patients and its commonist cause is antibiotic administration prior to obtaining blood cultures. The newer imaging techniques that include 3D echocardiogram, intracardiac echocardiogram, CT and CMR as well as novel markers, for example troponin, protein S-100 and procalcitonin, have to be put in perspective as their precise clinical use at the present time is still being investigated. He ended by emphasising that sound clinical judgement and clinical experience are of paramount importance.
Dr G Habib (Marseille, France) pointed out that no combination of clinical features or tests are either 100% sensitive or 100% specific. For diagnosing, the Von Reyn and Duke criteria have a sensitivity of diagnosing IE of 56% and 76% respectively. Clinically, echocardiography is one of the most important tests. Transthoracic and transoesophogeal echocardiography have a sensitivity of 58% and 90% respectively. The principle difficulty arises in those patients who have small vegetations of less than 2mm, non-vegetative endocarditis, those with prosthetic heart valves or pacemakers, mitral valve prolapse and where the vegetations are either not yet present or have embolised. For diagnosis of an abscess by transthoracic and transoesophageal echocardiogram sensitivities are 29% and 87% respectively and both of these techniques may be mandatory for small abscesses. Repeat echocardiograms are needed in a proportion of patients. Dr Habib ended by emphasising “Don’t forget clinical judgement”.
Dr J C A Morais (Leiria, Portugal) pointed out that it is appropriate to treat patients with IE in a peripheral hospital, but what were needed were clinicians with experience and knowledge of IE and its treatment, appropriate facilities for laboratory testing, intensive care units, close collaborations between cardiologists and microbiologists and easy access to cardiac surgeons for consultation, and for easy transportation to a hospital where cardiac surgery is available.
Dr C Selton-Suty pointed out data from the EURO Heart Surveys. Of 159 patients with IE surgery had been performed in 52%. The indications for surgery were heart failure in 60%, persistent sepsis in 40%, embolis in 18% and vegetation size in 48%. Heart failure was the most frequent complication. It was the first cause of death and first indication for surgery. The occurrence of an embolus was related to increased vegetation size and its mobility. It was most frequent in those who had had a previous embolus and in those in whom the organism was staphylococcus aureus and streptococcus bovis. Most emboli occurred prior to initiation of antibiotic therapy. In those with a neurologic event surgery, if needed for the usual indications, can be performed within three days and the risk of an untoward event occurring was less than 20%. This progressively decreased with the passage of time, so that after four weeks the risk was very low and stable. Dr Selton-Suty emphasised the importance of early surgery for the usual indications, and especially for heart failure, and ideally before structural damage occurs.