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Lyme disease is a recognised cause of atrioventricular heart block. In the majority of cases conduction disturbances are reversed with antibiotic treatment. The diagnosis of Lyme disease is not always obvious and its recognition is important if unnecessary implantation of a permanent pacemaker is to be avoided. A 34-year-old man presented to our hospital with complete heart block due to Lyme carditis. This resolved completely within a few days after treatment with appropriate antibiotics.
Lyme disease is a systemic illness characterised by a pathognomonic rash, with associated flu-like illness. The disease is caused by the spirochete Borrelia burgdorferi, which is transmitted by tick bites. Lyme carditis occurs up to 10% of cases.1 It usually presents as transient myocarditis with varying degrees of heart block. Lyme carditis generally resolves completely with antibiotic treatment. The diagnosis of Lyme disease is not always apparent and therefore a high index of suspicion is necessary. Our case report highlights the importance of a good history taking including that of travel abroad.
A 34-year-old man was admitted with a 1 week history of intermittent dizziness and palpitations. He denied any blackouts. His past medical history included hay fever. There was no significant family history. He was normally very athletic and took vitamin/protein supplements. He was a recreational drug user and used cocaine until 2 months before this admission. He was a non-smoker and drank 20 units of alcohol over weekends. His clinical examination revealed bradycardia at 50 beats/min (bpm). His blood pressure was stable. There was no lymphadenopathy. Examination of the cardiovascular, respiratory, abdomen and central nervous system were normal. His baseline blood investigations including full blood count, urea, creatinine and electrolytes were normal. His resting electrocardiogram revealed complete heart block with a rate of 47 bpm and a narrow QRS complex (fig 1, lead V5 missing). His echocardiogram was normal. Retrospect detailed history taking revealed that the patient was on holiday in Hungary 6 weeks before this admission and he recalled being bitten by an insect. His serology test later was positive for borreliosis. He was treated with a 3 week course of antibiotics initially with intravenous ceftriaxone and later with oral doxycycline. His heart completely resolved within a few days (fig 2) with antibiotic treatment and without the need for temporary pacemaker insertion.
The patient remained well at 6 months follow-up with no evidence of Lyme carditis, with the ECG showing no signs of heart block.
Lyme disease, which is also known as borreliosis, is a systemic illness characterised initially by a pathognomic rash erythema chronicam migrans, with associated vague flu-like symptoms. The disease is caused by the spirochete B burgdorferi which is transmitted by tick bites. Lyme disease is the most common tick borne disease in North America and Europe. There are an estimated 20 000 cases of newly diagnosed Lyme disease/year in Hungary alone.2 In the UK 797 cases were identified during 2007 with an incidence of 1.49/100 000 total population.3 Approximately two thirds of indigenously acquired infections were acquired in southern counties of England (the south west and south east health regions). These areas include well known regional foci of Lyme borreliosis around the New Forest, Salisbury Plain, Exmoor, and the South Downs, parts of Wiltshire and Berkshire, and Thetford Forest. Other endemic areas include the Lake District, the Yorkshire moors and the Scottish Highlands and Islands.3
After an incubation period of 1–4 weeks, Lyme disease can involve various organs including the cardiovascular and central nervous systems, and joints. Conduction disturbances are the most common cardiac manifestation and can occur up to 87% of cases of Lyme carditis.1 Presentation with pericarditis, myocarditis, or pancarditis or with the insidious development of dilated cardiomyopathy is much less common. Conduction disturbances generally resolve completely with antibiotic treatment. A temporary transvenous pacemaker is sometimes required if the patient is very symptomatic with bradycardia. With adequate and early treatment complete heart block persists rarely more than a week. Permanent complete heart block is very rare.
Antibody detection remains the mainstay of laboratory support for a clinical diagnosis. It is insensitive in early infection as an IgG response takes some weeks to develop. The great majority of patients with established late stage infection are seropositive. Seropositivity alone is not sufficient to confirm a diagnosis of active Lyme disease. A positive antibody test may reflect past rather than current infection, though a high or rising titre provides useful supplementary evidence for active infection. Serological tests must be interpreted in the light of the clinical presentation and history of possible exposure. In the first phase of the disease, where erythema chronicum migrans is present, treatment with oral tetracycline is usually sufficient. In the second disseminated phase intravenous ceftriaxone is more effective because of better tissue penetration. In our patient the heart block resolved within a few days after starting the treatment.
The diagnosis of Lyme disease is not always obvious and its recognition is important if unnecessary implantation of a permanent pacemaker is to be avoided. Moreover, this case illustrates the importance a detailed history taking, including history of travel abroad.
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication