Lyme Carditis: From Pathophysiology to Clinical Management

Animal models of Lyme carditis. Understanding how to study a complex disease

Lyme carditis, a well-established manifestation of Lyme disease, has been studied in animal models to improve understanding of its pathogenesis. This review synthesizes existing literature on these models and associated disease mechanisms. Searches in MEDLINE, Embase, BIOSIS, and Web of Science yielded 53 articles (47 mice models and 6 other animal models). Key findings include: 1) Onset of carditis correlates with spirochete localization in the heart; 2) Carditis occurs within 10 days of infection, progressing to peak inflammation within 30 days; 3) Infiltrates were predominantly composed of Mac-1+ macrophages and were associated with increases in TNF-α, IL-1 and IL-12 cytokines; 4) Resolution of inflammation was primarily mediated by lymphocytes; 5) Immune system is a double-edged sword: it can play a role in the progression and severity of carditis, but can also have a protective effect. Animal models offer valuable insights into the evolution and pathophysiologic mechanisms of Lyme carditis.

A Comprehensive Review of Lyme Disease: A Focus on Cardiovascular Manifestations

Lyme disease is a tick-borne illness known for its ability to cause multi-systemic manifestations. It can affect several different systems, including neurological, musculoskeletal, and dermatological systems. However, one of the most concerning biological systems affected is the cardiac system. Lyme carditis typically presents with varying degrees of atrioventricular (AV) block. Additionally, current literature also endorses atypical manifestations, including but not limited to atrial fibrillation and bundle branch blocks. These atypical manifestations are important as they can be the first presenting symptoms in patients with Lyme disease. Therefore, educating clinicians on various signs, symptoms, and manifestations of Lyme carditis remains paramount in reducing morbidity and mortality. We conducted a literature review using PubMed, MEDLINE, and CINAHL, collecting a total of 13 articles to gather information on atypical manifestations of Lyme carditis. This literature review serves to summarize the current research and studies describing these cardiac manifestations and the cardiac pathophysiology associated with Lyme disease. These findings aim to contribute to the expanding understanding of Lyme carditis, subsequently preventing long-term effects through prompt diagnosis and treatment.

Associations of Atrioventricular Blocks and Other Arrhythmias in Patients with Lyme Carditis: A Systematic Review and Meta-Analysis

Lyme disease often leads to cardiac injury and electrophysiological abnormalities. This study aimed to explore links between atrioventricular blocks and additional arrhythmias in Lyme carditis patients. This systematic review and meta-analysis of existing literature was performed from 1990 to 2023, and aimed to identify cases of Lyme carditis through serology or clinical diagnosis with concomitant arrhythmias. Pubmed and Web of Science were searched using appropriate MESH terms. Patients were divided into groups with atrioventricular blocks and other arrhythmias for cardiovascular (CV) outcome assessment. A total of 110 cases were analyzed. The majority (77.3%) were male, with mean age = 39.65 ± 14.80 years. Most patients presented within one week of symptom onset (30.9%). Men were more likely to have first-degree atrioventricular blocks (OR = 1.36 [95% CI 1.12-3.96], p = 0.01); these blocks tended to be reversible in nature (OR = 1.51 [95% CI 1.39-3.92], p = 0.01). Men exhibited a higher likelihood of experiencing variable arrhythmias (OR = 1.31 [95% CI 1.08-2.16], p < 0.001). Ventricular and supraventricular arrhythmias were more likely to exhibit instability (OR = 0.96 [95% CI 0.81-1.16] p = 0.01) and variability (OR = 1.99 [95% CI 0.47-8.31], p < 0.001). Men with Lyme carditis are likely to present with various atrioventricular blocks. These atrioventricular blocks are benign, and follow a predictable and stable clinical course. Further large-scale studies are warranted to confirm these associations.

Lyme disease and Whipple's disease: a comprehensive review for the rheumatologist

Despite their rarity, Lyme disease and Whipple's disease are of significant importance in rheumatology, as both can manifest as chronic arthritis, presenting challenges in the differential diagnosis of inflammatory arthropathies. In Lyme disease, arthritis typically emerges as a late manifestation, usually occurring six months after the onset of erythema migrans. The predominant presentation involves mono- or oligoarthritis of large joints, with a chronic or remitting-recurrent course. Even with appropriate antimicrobial treatment, arthritis may persist due to inadequate immunological control triggered by the disease. In contrast, Whipple's disease may present with a migratory and intermittent seronegative poly- or oligoarthritis of large joints, preceding classic gastrointestinal symptoms by several years. Both disorders, particularly Whipple's disease, can be misdiagnosed as more common autoimmune rheumatic conditions such as rheumatoid arthritis and spondyloarthritis. Epidemiology is crucial in suspecting and diagnosing Lyme disease, as the condition is transmitted by ticks prevalent in specific areas of the United States, Europe, and Asia. On the contrary, the causative agent of Whipple's disease is widespread in the environment, yet invasive disease is rare and likely dependent on host genetic factors. In addition to erythema migrans in Lyme disease and gastrointestinal manifestations in Whipple's disease, neurological and cardiac involvement can further complicate the course of both. This article offers a comprehensive review of the epidemiological, pathophysiological, clinical, and therapeutic aspects of both diseases.

By-degree Health and Economic Impacts of Lyme Disease, Eastern and Midwestern United States

Lyme disease (LD) is the most common vector-borne disease in the United States (U.S.). This paper assesses how climate change may influence LD incidence in the eastern and upper Midwestern U.S. and the associated economic burden. We estimated future Ixodes scapularis habitat suitability and LD incidence with a by-degree approach using variables from an ensemble of multiple climate models. We then applied estimates for present-day and projected habitat suitability for I. scapularis, present-day presence of Borrelia burgdorferi, and projected climatological variables to model reported LD incidence at the county level among adults, children, and the total population. Finally, we applied an estimate of healthcare expenses to project economic impacts. We show an overall increase in LD cases with regional variation. We estimate an increase in incidence in New England and the upper Midwestern U.S. and a concurrent decrease in incidence in Virginia and North Carolina. At 3°C of national warming from the 1986-2015 baseline climate, we project approximately 55,000 LD cases, a 38-percent increase from present-day estimates. At 6°C of warming, our most extreme scenario, we project approximately 92,000 LD cases in the region, an increase of 145 percent relative to current levels. Annual LD-related healthcare expenses at 3°C of warming are estimated to be $236 million (2021 dollars), approximately 38 percent greater than present-day. These results may inform decision-makers tasked with addressing climate risks, the public, and healthcare professionals preparing for treatment and prevention of LD.

Lyme-Associated Pericarditis: A Case Report and Literature Review

Lyme disease is caused by Borrelia burgdorferi (B. burgdorferi), which is a spirochete transmitted by ticks of the genus Ixodes. Complications related to the cardiovascular system usually occur in the early phase of infection, and the most common cardiovascular complication of Lyme disease is atrioventricular block, especially third-degree heart block. We report a case of a young Caucasian male patient who presented to the emergency department (ED) with complaints of chest pain and shortness of breath. Initial investigations, including chest X-ray, were negative. An EKG revealed ST elevation and PR depression with troponin elevation. The echocardiogram showed a normal ejection fraction with no pericardial effusion. Skin examination was positive for erythema migrans concerning Lyme. Initial Lyme testing was negative in the patient and it should be repeated after four to six weeks, according to the guidelines. This case report highlights the importance of keeping the differentials broad in these patients even if the initial testing is negative, especially since misdiagnosis or delayed diagnosis can cause cardiac complications.

Incidence of Lyme Carditis and Lyme Carditis as a Cause of Pacemaker Implantation: A Nationwide Registry-Based Case-Control Study

Background

Lyme borreliosis (LB) of the heart is called Lyme carditis (LC), which often manifests with high-grade atrioventricular block (AVB) requiring pacemaker implantation. LC is treated with antibiotics, and most patients recover fully after treatment. The overall incidence of LC, and of LC as a cause of pacemaker implantation, has not previously been systematically studied.

Methods

This was a case-control study based on data from Swedish national registers. The study was divided into two parts; part 1 including all patients diagnosed with AVB between 2001 and 2018, and part 2 including all patients who had received a pacemaker due to AVB between 2010 and 2018. Patients diagnosed with LB 90 days before and 180 days after the AVB diagnosis were identified among the patients and compared to matched control groups generated from the general population.

Results

Of 81 063 patients with AVB, 102 were diagnosed with LB. In the control group, 27 were diagnosed with LB. The yearly incidence of LC was 0.056 per 100 000 adults and year. Of 25 241 patients who had received a pacemaker for AVB, 31 were diagnosed with LB. In the control group, 8 were diagnosed with LB. The yearly incidence of LC as a cause of pacemaker implantation was 0.033 per 100 000 adults and year. The estimated risk for patients with LC to receive a permanent pacemaker was 59%.

Conclusions

LC is a rare cause of AVB. Nevertheless, more than half of patients with LC receive a permanent pacemaker for a condition that is easily cured with antibiotics.

Adolescent Onset of Acute Heart Failure

Heart failure in adolescents can manifest due to a multitude of causes. Presentation is often quite variable ranging from asymptomatic to decompensated heart failure or sudden cardiac death. Because of the diverse nature of this disease, a thoughtful and extensive evaluation is critical to establishing the diagnosis and treatment plan. Identifying and addressing reversible pathologies often leads to functional cardiac recovery. Some disease states are irreversible and progressive, requiring chronic heart failure management and potentially advanced therapies such as transplantation.

Infectious Neuropathies

OBJECTIVE

This article discusses the clinical manifestations and management of infectious peripheral neuropathies.

LATEST DEVELOPMENTS

Several infectious etiologies of peripheral neuropathy are well-recognized and their treatments are firmly established. The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with several central and peripheral nervous system manifestations, including peripheral neuropathies. Additionally, some COVID-19 vaccines have been associated with Guillain-Barré syndrome. These disorders are an active area of surveillance and research. Recent evidence-based guidelines have provided updated recommendations for the diagnosis and treatment of Lyme disease.

ESSENTIAL POINTS

Infectious agents of many types (primarily bacteria and viruses) can affect the peripheral nerves, resulting in various clinical syndromes such as mononeuropathy or mononeuropathy multiplex, distal symmetric polyneuropathy, radiculopathy, inflammatory demyelinating polyradiculoneuropathy, and motor neuronopathy. Knowledge of these infections and the spectrum of peripheral nervous system disorders associated with them is essential because many have curative treatments. Furthermore, understanding the neuropathic presentations of these disorders may assist in diagnosing the underlying infection.

SYNCOPE: A RARE PRESENTATION OF LYME DISEASE

BACKGROUND

Lyme disease is one of the most common vector-borne illnesses in the United States. It is caused by Borrelia burgdorferi infection transmitted via the Ixodes tick. Rarely, it can progress to early disseminated Lyme disease with cardiac or neurologic manifestations, or both.

CASE REPORT

A 41-year-old previously healthy man presented to the emergency department (ED) by ambulance after an episode of syncope. Electrocardiogram revealed right bundle branch block with borderline first-degree atrioventricular nodal block. During his admission he was noted to have night sweats and elevated procalcitonin. Infectious workup revealed positive Borrelia enzyme-linked immunosorbent assay. Further testing revealed positive Borrelia immunoglobulin M with negative immunoglobulin G, indicating a recent infection. Why should an emergency physician be aware of this? Lyme disease should be on the differential for patients presenting with vague, flu-like symptoms in the summer months in endemic areas. Treatment of early Lyme disease with doxycycline can prevent progression to secondary Lyme, which can present as a true cardiac or neurologic emergency.

Prevalence of Lyme Carditis in Patients with Atrioventricular Blocks

Infections with Borrelia may cause cardiac conduction system abnormalities, including atrioventricular blocks (AVBs). Therefore, we aimed to identify patients in whom Lyme carditis (LC) could be considered as the initial diagnosis among consecutive subjects who were referred for implantation of a permanent pacemaker due to symptomatic AVBs. To date, such a systematic evaluation has not been reported yet. Validation of the Suspicious Index for Lyme Carditis (SILC) in our study population was considered as an additional goal. We investigated consecutive patients with AVB admitted to our department for a pacemaker implantation. Serological diagnostic tests against Borrelia burgdorferi sensu lato (Bbsl) were performed in those with no obvious cardiac causes of AVB. The final study population consisted of 130 patients (80 M, mean age 67.4 ± 17.6). Lyme carditis was assumed as the initial diagnosis in 16 patients (12%) based on ABV and IgM Bbsl seropositivity. The patients with LC were younger and more frequently manifested constitutional symptoms of infection and fluctuating AVB. The highest prognostic value for identification of LC patients was obtained for the modified SILC, which included the following parameters: (1) age lower than 75 years; (2) risky outdoor activity and living in the countryside; (3) tick bite; (4) constitutional symptoms of Lyme disease; (5) erythema migrans; (6) male sex and (7) fluctuating atrioventricular block. We concluded that diagnostics for LC should be routinely considered in patients with advanced AVB. Modified SILC may identify the patients at risk of LC.

Detection of 41-kDa bacterial flagellin protein by the lymphocyte transformation test-memory lymphocyte immunostimulation assay

BACKGROUND/OBJECTIVES

Diagnosis of human infection by various species of the bacterial genus Borrelia is mainly reliant on serological testing, polymerase chain reaction (PCR) or culture but such serological tests have been reported to have heterogeneous sensitivities, while Borrelia PCR and culture have been reported as being of modest diagnostic value. It has been suggested that the adjunctive use of the lymphocyte transformation test-memory lymphocyte immunostimulation assay (LTT-MELISA) may be helpful in this regard; however, the clinical usefulness of this assay has been questioned. The Borrelia immunodominant 41-kDa flagellin protein almost always gives rise to a marked human antibody response following infection. It was therefore decided to determine whether the LTT-MELISA detects the human antibody response to this antigen.

METHODS

Blood samples from consecutive patients with possible borreliosis attending a clinic were independently tested by both Western blots and LTT-MELISA.

RESULTS

After omitting cases with indeterminate Western blot results and equivocal LTT-MELISA results, multiple linear regression modelling demonstrated that the 41-kDa flagellin immunoglobulin (Ig) M level was predictable from two LTT-MELISA variables (F _2,51 = 5.981, P = 0.005). Similarly, the corresponding 41-kDa IgG model also contained two LTT-MELISA variables (F _2,57 = 3.700, P = 0.031).

CONCLUSION

It is concluded that the LTT-MELISA appears to be able to detect the response to this antigen.