Acute vs Subacute Bacterial Endocarditis : A Comprehensive Guide to Symptoms, Causes, and Prognosis

Bacterial endocarditis is the infection of the endocardial surface of the heart and usually involves heart valves. There are two types of bacterial endocarditis, which include acute bacterial endocarditis and subacute bacterial endocarditis.

Read further to know the differences between acute and subacute bacterial endocarditis.

Bacterial endocarditis is a life-threatening inflammation that is more common in men than women and is more common with growing age.^{(1, 2)}

Acute bacterial endocarditis is a febrile illness that damages cardiac structures rapidly and spreads in a hematogenous manner, which, if left untreated, can ultimately progress to death within weeks.

However, subacute bacterial endocarditis has comparatively a slower disease process and can be present in a person for weeks to months with gradual progression, unless gets complicated by ruptured structure or major embolic events.⁽³⁾

Symptoms of acute bacterial endocarditis generally begin suddenly with a high fever (102 degrees F to 104 degrees F), fast heart rate (greater than 100 beats per minute), fatigue, and extensive damage to the heart valve, causing symptoms of heart failure.

Symptoms of subacute bacterial endocarditis usually develop slowly and the symptoms might be different for each individual. However, chest pain with breathing, fatigue, flu-like symptoms, muscle and joint pain, shortness of breath, night sweats, different heart murmur, and unexplained weight loss are some of the common symptoms of subacute bacterial endocarditis.

Most cases of acute bacterial endocarditis are caused by Staphylococcus aureus, though people infected with this organism will occasionally run a subacute course. However, most cases of subacute bacterial endocarditis are caused by Streptococcus viridans, which is penicillin-sensitive. This organism will probably never produce acute endocarditis.

Enterococci are versatile and might produce either subacute or acute bacterial endocarditis. The pneumococcus bacteria nearly always produces an acute infection.

Acute bacterial endocarditis starts abruptly, usually explosively, and might even progress to death within less than a week. By contrast, the onset of subacute bacterial endocarditis is subtle and most patients with this type of bacterial endocarditis have difficulty dating their first symptom.

Mostly, the diagnosis of acute bacterial endocarditis is missed because it is mimicked by several other acute infections. A few such mimics are pyelonephritis, poliomyelitis, meningococcemia, influenza, acute rheumatic fever, infectious mononucleosis, and thrombotic thrombocytopenic puerpera.

Though the diagnosis of subacute bacterial endocarditis is not always immediately apparent, it usually becomes easy to establish in time for an effective treatment to take place.

The prognosis, both for eradication of infection and for life is poor in acute bacterial endocarditis, generally because the diagnosis is made too late. Thus, acute bacterial endocarditis is a medical emergency that demands immediate empiric therapy.

On the other hand, the prognosis, both for eradication of infection and for life is pretty good in subacute bacterial endocarditis.

Many patients with acute bacterial endocarditis are more apt to die of cardiac failure within months or even weeks of the time of recovery from the bacterial infection. This is particularly obvious when the aortic valve is involved.

However, patients with subacute bacterial endocarditis, emerge from the bacterial infection with no additional cardiac damage.

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