Safety of care
Infective endocarditis — Still a challenge
Originally published December 2011
"Few diseases present greater difficulties in diagnosis than endocarditis, difficulties which, in many cases, are nearly insurmountable." — Sir William Osler, 1885
There have been major advances since the time of Osler in the diagnosis and treatment of infective endocarditis. Despite these advances, the disease still carries a substantial risk of morbidity and mortality, especially when there is a delay in making this often still elusive diagnosis.
The CMPA's review of medico-legal files related to infective endocarditis provides insights that may improve patient outcomes and help reduce medico-legal risks.
The medico-legal problems reviewed include legal actions, complaints to a medical regulatory authority (College), hospital enquiries, and inquests. During the time period of January 1, 2003 to December 31, 2010, a total of 73 cases (62 closed, 11 open) were identified, of which 51 (70%) are legal actions. Of the outcomes of the 62 closed cases, 39 (63 %) favoured the physicians involved. A settlement was negotiated in 10 (25%) of the legal actions. Family physicians and emergency physicians were named in 80% of the legal actions.
Peer experts — physicians of similar training and working in similar circumstances — were asked to comment on the care provided in these cases. These experts identified four recurring challenges:
- delay in diagnosis due to non-specific symptoms and a paucity of definitive clinical signs
- under-appreciation of risk factors
- underutilization of diagnostic modalities such as microbiology and imaging
- uncertainty about the current indications for antibiotic prophylaxis prior to invasive procedures
The following case illustrates some of these challenges.
Shortly after arriving in a new community, a 30-year-old male with a past history of scoliosis and aortic insufficiency (AI) attended his new family physician for a periodic health examination. The patient was noted to be tall and slender with a diastolic murmur consistent with AI. A transthoracic ECHO was ordered which showed "minimal" AI and "trivial" pulmonary insufficiency. There were no comments concerning any anatomic abnormalities of the aortic valve leaflets.
One year later, three weeks after a routine dental cleaning, the patient presented with a three-week history of fevers and chills, myalgias, cough, fatigue, and anorexia. Physical examination was unremarkable, although auscultation of the heart was difficult due to paroxysms of coughing. No temperature measurement was recorded. At the time, the community was in the midst of an Influenza A epidemic. A presumptive diagnosis of a viral illness was made and routine measures were advised.
Two weeks later the patient presented with erythema and pain over his right mid-foot which was attributed to post-viral arthritis. Routine blood work showed a normal hemoglobin and white count, and an ESR of 72. Treatment with a non-steroidal medication (NSAID) was started.
At a follow-up visit two weeks later, the patient's foot had improved but not his constitutional symptoms. Six weeks after that visit, the patient presented with similar symptoms in his left foot, and was again treated with an NSAID. At the next follow-up visit 10 days later, his foot had improved, but he had continuing fever and chills, nausea and intermittent vomiting, myalgias, worsening fatigue, and weight loss.
Three weeks later (15 weeks after the onset of the illness), he presented to an emergency department with a temperature of 38 degrees Celsius, a II/IV diastolic murmur, lower limb petechiae, and a weight loss of 44 pounds. Three out of three blood cultures were positive for Streptococcus viridans, and intravenous antibiotics were started. A transesophageal ECHO showed a bicuspid aortic valve with vegetations. He eventually required a prosthetic aortic valve and long-term anticoagulation. A legal action ensued, naming the family doctor as the sole defendant.
A family physician and an infectious disease specialist were experts for the plaintiff (patient), while two family physicians were retained as experts for the defendant.
The patient's experts made the following observations:
- It is unlikely that a routine viral illness will persist for three weeks.
- It was incumbent on the family physician to auscultate the heart in a quiet environment during the initial and subsequent visits.
- Risk factors for infective endocarditis include: any prosthetic valve, anatomic valvular abnormalities, congenital heart disease, antecedent bacteremia, history of infectious endocarditis, recent surgical or dental procedures, intravenous drug use, and immunocompromise.
- On the basis of turbulent flow, the AI was a risk factor for endocarditis even in the absence of documented anatomic abnormality of the aortic valve.
- The sensitivity of diagnostic imaging is affected by both the choice of imaging modalities and the duration of the illness.
- The family physician remained "anchored" to his initial diagnosis of a viral illness despite the prolonged duration and severity of symptoms. Other unifying diagnoses should have been considered. Further investigations were indicated to address other possible etiologies such as infection, malignancy, and collagen vascular disorders.
- The family physician was dissuaded from a diagnosis of endocarditis because the patient had a normal white count.
Defendant's expertsThe defendant's experts observed the following:
- The initial presentation was entirely consistent with a flu-like illness.
- The differential diagnosis was extensive.
- To diagnose endocarditis at the initial visit would have been nearly impossible.
- Blood cultures were not indicated at the initial visit.
- Isolated aortic regurgitation, in the presence of a normal aortic valve, is not a risk factor for endocarditis.
- Auscultation of the heart was not necessary given the knowledge of the pre-existent murmur. If auscultation had been performed at the time of the initial visit, it is likely that murmur would not have been significantly changed given the early stage of the disease.
- In the presence of aortic insufficiency with a presumably normal aortic valve, prophylaxis with antibiotics for a presumed viral illness was not indicated.
In his initial remarks, the judge stated: "the decision not to investigate the possibility of endocarditis cannot be judged by the result, nor from the promontory of hindsight."
However, after further consideration, the judge found the opinions of the plaintiff's experts more persuasive than those of the defendant's experts and concluded that the defendant family physician had not met the standard of care. In his opinion "there was sufficient indicia on top of the patient's history to have alerted a reasonably prudent general practitioner to the need for further investigation," particularly in light of the patient's continued symptomatology. With respect to the physical examination, he concluded that the defendant physician "elected to rely on an incomplete examination of the plaintiff and analysis of his symptoms." On the subject of the defendant's experts he noted that "an air of advocacy found its way into their reports and testimony." From a causation standpoint (i.e. the failure to meet the standard of care resulted in harm), the judge decided that it was probable that the administration of antibiotic therapy 12 weeks earlier would have led to a better outcome, as surgery may have been avoided.
An award was paid by the CMPA to the patient on behalf of the family physician.
Risk management considerations
The following risk management considerations are based on the expert opinions in the analyzed cases:
- When evaluating a patient with persisting non-specific symptoms suggestive of a febrile illness, it may be appropriate to include endocarditis in the differential diagnosis.
- Confirm whether the patient has identifiable risks for infective endocarditis.
- The physical examination should be sufficiently thorough to detect subtle signs of infective endocarditis or other conditions.
- Consider whether the documentation in the medical record includes a differential diagnosis.
- Consider ordering appropriate investigations to either include or rule out high-risk diagnoses.
- Follow up should be vigilant.
- Referrals may be indicated
- Consider current recommendations with respect to prophylaxis of infective endocarditis.