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Suspicious index in Lyme carditis: Systematic review and proposed new risk score
Georgia Besant1, Douglas Wan1, Cynthia Yeung1
1Division of Cardiology, Kingston Health Sciences Centre, Queen's University, Kingston, Ontario, Canada.
Insights
A new risk score, the Suspicious Index in Lyme Carditis (SILC) score, helps identify Lyme carditis (LC) causing heart block. This tool aims to reduce unnecessary permanent pacemaker implants in patients with reversible Lyme disease.
Area of Science:
- Cardiology
- Infectious Diseases
- Medical Diagnostics
Background:
- Lyme carditis (LC) is an early Lyme disease manifestation often causing high-degree atrioventricular block (AVB).
- Misdiagnosis of LC can lead to inappropriate permanent pacemaker implantation for a reversible condition.
Purpose of the Study:
- To evaluate the likelihood of high-degree AVB being caused by LC using clinical characteristics.
- To develop and validate a risk stratification tool for identifying LC in AVB patients.
Main Methods:
- Systematic review of published LC cases with high-degree AVB, supplemented by author experience.
- Development of the Suspicious Index in Lyme Carditis (SILC) score.
- Application of the SILC score to assess risk in reviewed cases.
Main Results:
- The SILC score classified 58% of 88 cases as high-risk for LC (sensitivity 93.2%).
- In a subset of 32 cases, the SILC score achieved 100% sensitivity for high-risk or intermediate-risk LC.
- Six of 11 patients receiving pacemakers showed AVB reversal with antibiotics, highlighting potential for unnecessary procedures.
Conclusions:
- The SILC score, alongside the COSTAR mnemonic, aids in identifying LC presenting as high-degree AVB.
- This risk stratification can minimize inappropriate permanent pacemaker implantation in reversible conduction disorders.
Background:
Lyme carditis (LC), an early manifestation of Lyme disease that most commonly presents as high-degree atrioventricular block (AVB), usually resolves with antibiotic treatment. When LC is not identified as the cause of AVB, a permanent pacemaker may be inappropriately implanted in a reversible cardiac conduction disorder.
Hypothesis:
The likelihood that a patient's high-degree AVB is caused by LC can be evaluated by clinical characteristics incorporated into a risk stratification tool.
Methods:
A systematic review of all published cases of LC with high-degree AVB, and five cases from the authors' experience, was conducted. The results informed the development of a new risk stratification tool, the Suspicious Index in LC (SILC) score. The SILC score was then applied to each case included in the review.
Results:
Of the 88 cases included, 51 (58%) were high-risk, 31 (35.2%) intermediate-risk, and 6 (6.8%) low-risk for LC according to the SILC score (sensitivity 93.2%). For the subset of 32 cases that reported on all SILC variables, 24 (75%) cases were classified as high-risk, 8 (25%) intermediate-risk, and 0 low-risk (sensitivity 100%). Specificity could not be assessed (no control group). Notably, 6 of the 11 patients who received permanent pacemakers had reversal of AVB with antibiotic treatment.
Conclusion:
The SILC risk score and COSTAR mnemonic (constitutional symptoms; outdoor activity; sex = male; tick bite; age < 50; rash = erythema migrans) may help to identify LC in patients presenting with high-degree AVB, and ultimately, minimize the implantation of unnecessary permanent pacemakers.
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