Know your heart conditions: endocarditis

Resource post for December

In this day and age when stroke and heart attacks are the most common forms of cardiovascular diseases reported about, we sometimes need to be reminded that there are other heart disorders out there, albeit less common, that we have to be aware of. That’s why I am tackling endocarditis (IE) in this month’s resource post.

What is endocarditis?

According to the Medline Medical Encyclopedia,

endocarditis is an inflammation of your heart’s inner lining. The most common type, bacterial endocarditis, occurs when germs enter your heart. These germs come through your bloodstream from another part of your body, often your mouth. Bacterial endocarditis can damage your heart valves. If untreated, it can be life-threatening. It is rare in healthy hearts.

What are the risk factors for IE?

The risk factors for IE are as follows:

• Heart valves which are abnormal or damaged
• Prolapse of the mitral valve (the valve that separates the left atrium and the left ventricle to prevent the back flow of the blood)
• An artifical heart valve
• Other heart defects, such as congenital heart defects

Recently, the factor of age and other underlying conditions also came up in connection with IE. Studies observed that elderly patients have four times the risk of having IE and double the risk of dying from it compared to younger patients.

It seems that the incidence of IE is increasing across all age group among the elderly in particular and is associated with other aging-related conditions. The data was taken from the study International Collaboration on Endocarditis which looked at 2759 IE patients aged 18 to 64 years old from 2000 to 2005.

The researchers found a number of medical conditions that seem to be associated with elderly IE, primarily diabetes mellitus and abdominal cancers…They also discovered a changing microbiological profile of the causative agent of IE. The prevalence of Staphylococcus aureus decreases with age, they found, although the opposite trend was observed for methicillin-resistant S aureus. And enterococci and Streptococcus bovis are emerging as major players of spontaneous IE in the elderly, possibly in relation to higher rates of genitourinary or gastrointestinal-tract disorders.

What causes IE?

The most common cause of this heart infection is bacteria entering the blood stream which then attach to heart valves and tissues. However, other microbes such as fungi can also cause IE. Now, how could microbes enter the bloodstream? You’d be surprised how easy it is. In a previous post, I’ve written about how poor oral hygiene can increase your risk for a heart infection. Normal daily activities such as eating and brushing your teeth can actually allow bacteria in especially if you have unhealthy teeth and gums. Other bodily infections, however, can spread to the heart as well.

In addition, medical procedures that are supposed to be done under aseptic conditions can also cause IE. This can happen when needles, catheters, and dental instruments which are supposedly sterile are actually contaminated.

However, in general, our immune system is strong enough to withstand microbes entering our body. It is those people with weakened hearts which are highly at risk.

How is IE prevented?

IE is an infection and is therefore treated as such – with antibiotics. For this reason, those with high risk receive prophylaxis treatment with antibiotics prior to any medical procedure that can potentially cause IE, including dental treatments.

Recently, however, questions have arisen whether the use of antibiotics under these conditions is justified. In a report  at heartwire, three schools of thought about IE prophylaxis, namely:

• The traditionalists are the extra-careful doctors who insist on the necessity of prophylaxis for all patients.
• The anti-prophylaxis practitioners claim that there is no medical evidence that antibiotics provide protection against IE.
• The middle ground practitioners believe that risk assessment should be done first to determine whether prophylactic treatment is justified.

According to IE expert Dr Bernard Prendergast of the John Radcliffe Hospital, Oxford, UK,

“the scientific evidence for the use of antibiotics to prevent endocarditis is weak and that new guidelines indicating that no one needs antibiotics any longer make things much simpler. However, he admits to still having some reservations about omitting prophylaxis in patients at higher risk of endocarditis.”

Professional medical groups seem to agree with him. Here is what they have to say:

• The British Society of Antimicrobial Chemotherapy (BSAC) “issued new recommendations that also took the middle ground, advising that antibiotics be given only to those at very high risk of IE” in 2006.
• The American Heart Association (AHA) … concluded that prophylactic antibiotic therapy for dental procedures was unlikely to prevent many cases of infective endocarditis and should be restricted to patients at highest risk from the infection, issuing updated guidelines to this effect.
• German and French doctors are of a similar opinion.
• This year, an extreme view came from the British National Institute for Health and Clinical Excellence (NICE) stated “that there is no evidence of any benefit of antibiotic prophylaxis against IE for any patient undergoing dental or respiratory procedures and that nobody should receive preventive antimicrobials for these purposes any longer.”

Researchers involved in International Collaboration on IE believe that the high rate of IE among the elderly is associated with healthcare procedures.

“The data show that healthcare procedures are currently placing the increasing population of frail, elderly, disabled people at high risk of IE. In this setting, appropriate antibiotic prophylaxis and higher adherence to aseptic technique should be strongly pursued.” However, the group, too does not recommend prophylactic treatment for all elderly patients but only those with high risk profiles.

To read more about IE, check out:

• Endocarditis twice as likely to kill the elderly
• Is prophylaxis for endocarditis essential, or just a habit that’s hard to break?
• Mayo Clinic

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