General approach to the clinical diagnosis of endocarditis

General signs and symptoms

The initial symptoms of infectious endocarditis, regardless of their acuity, are often nonspecific and include fevers, chills, malaise, anorexia, night sweats, dyspnea, headache, and weight loss [ ]. Fever is the most commonly reported symptom and may be present in 90% of patients [ , ]. The degree of fever may vary significantly and cannot be used to rule in or rule out the diagnosis. Notably, patients >60 years of age are more likely to present without fever, which is relevant given that more than half of all endocarditis cases occur in patients over 60 [ ]. The duration of fever, particularly after initiation of appropriate antimicrobial therapy, has been shown to correlate with increased mortality and in 1 series of 26 patients with >2 weeks of fever 27% were found to have an intracardiac abscess [ ]. Dyspnea and cough are frequently reported symptoms and may be associated with congestive heart failure and/or septic pulmonary emboli in cases of right-sided endocarditis.

Musculoskeletal symptoms, including arthralgias (17% of patients) and low back pain (up to one-third of patients), are closely associated with endocarditis and in many cases may precede other symptoms [ , ]. Synovitis both with and without septic arthritis has also been reported in up to 14% of patients [ ]. Additionally the overlapping incidence of spontaneous vertebral osteomyelitis and infectious endocarditis has been reported to be as high as 30.8% [ ]. Consequently, in the absence of an alternative explanation, it is prudent to consider a concomitant diagnosis of endocarditis in patients with vertebral osteomyelitis.

Cardiovascular signs and symptoms

The most common abnormality on physical examination is the presence of a cardiac murmur which can be heard in 85% of patients [ ]. However, this finding is more representative of the patient population who are most commonly diagnosed with endocarditis, many of whom have underlying valvulopathies. In only 8%–15% of cases is a new murmur identified or a worsening murmur detected [ ]. In addition, the proportion of patients with symptoms of heart failure can vary widely. In one series of 40 patients from 1986, 78% of patients were noted to have presented with symptoms of heart failure [ ]. However, in a more recent retrospective data review of 234,731 patients with a primary diagnosis of endocarditis, only 28.9% of patients were found to have a secondary diagnosis of heart failure [ ]. The difference may be accounted for by a variety of changing factors, including the standardization of heart failure definitions and the availability of large electronic databases that allow for data abstraction of a high volume of cases without chart review.

Neurologic signs and symptoms

In addition to cardiac manifestations, neurologic abnormalities secondary to embolic strokes can be found in 10%–35% of left-sided endocarditis patients [ , ]. Given that anywhere from 15% to 70% of all strokes are thought to be embolic and the high morbidity of undiagnosed endocarditis, current American Society of Echocardiography guidelines recommend transthoracic echocardiography or TEE in all patients diagnosed with ischemic stroke [ ]. An area for further study is whether routine blood cultures in the evaluation of stroke could lead to earlier diagnoses of endocarditis. Additionally, approximately 75% of patients will have clinically inapparent neurologic complications of endocarditis including silent emboli, microhemorrhage, mycotic aneurysms, or brain abscess seen on advanced imaging [ ]. Radiographic evaluation for these silent complications will be addressed later in the chapter.

Although not classically considered as a presentation manifestation of endocarditis, meningitis or a meningeal reaction (elevated cerebrospinal fluid white blood cell count with negative cultures) can be seen in 1%–20% of patients [ , ]. It is more commonly associated with Staphylococcus aureus blood stream infection [ , ]. In cases where patients present with clinical signs and symptoms of meningitis it is appropriate to pursue lumbar puncture as the presence of positive cerebrospinal fluid cultures will impact antibiotic selection. Conversely, only approximately 2% of all patients with bacterial meningitis are found to have concurrent endocarditis [ ]. Finally, many patients may present with encephalopathy which may be the result of any of the previously described neurologic phenomenon such as stroke, intracranial hemorrhage, mycotic aneurysm, and brain abscess or could be secondary to a multitude of other factors including illness severity and/or uremia [ ].

Ophthalmologic signs and symptoms

While patients with endocarditis rarely present with primary ocular symptoms, central retinal artery occlusion with associated vision loss is seen as a presenting finding, albeit in <1% of cases [ ]. Endogenous endophthalmitis, which also presents with decreased visual acuity, accounts for 2%–8% of all cases of endophthalmitis. However, nearly 40% of endogenous endophthalmitis cases are caused by infectious endocarditis, and in certain instances this intraocular diagnosis is the primary manifestation of the underlying cardiac infection [ ]. Approximately 3% of endocarditis patients may be subsequently found to have Roth spots, or small white spots, on the retina with associated retinal hemorrhage but these are typically asymptomatic and are only identifiable on dilated eye examination [ ].

Cutaneous signs and symptoms

Dermatologic manifestations of infectious endocarditis have decreased in frequency since the introduction of antibiotics. Classic findings including splinter hemorrhages, or petechial appearing lesions that run parallel to the finger nails, can be identified in as many as 19% of endocarditis cases but this finding is nonspecific as they are also seen in patients with frequent trauma to the hands, mitral stenosis, and renal failure on peritoneal dialysis [ ]. Janeway lesions, or painless macules, seen on the palmar and plantar surfaces are secondary to microembolic phenomenon and can be seen in 2.2% of endocarditis cases. Osler's nodes, painful erythematous nodules typically on the palms, fingers, or toes, have been hypothesized to be secondary to either immunologic or embolic phenomenon and have fallen from an incidence of 40%–90% in the preantibiotic era to 6.7% in a 1995 retrospective study of 139 endocarditis cases [ , ]. Despite their decreasing prevalence, these dermatologic manifestations retain clinical importance as they are included in the Modified Duke Criteria [ ].